coregrind/vg_main.c

/*--------------------------------------------------------------------*/
/*--- Startup: the real stuff                            vg_main.c ---*/
/*--------------------------------------------------------------------*/

/*
   This file is part of Valgrind, an extensible x86 protected-mode
   emulator for monitoring program execution on x86-Unixes.

   Copyright (C) 2000-2004 Julian Seward 
      jseward@acm.org

   This program is free software; you can redistribute it and/or
   modify it under the terms of the GNU General Public License as
   published by the Free Software Foundation; either version 2 of the
   License, or (at your option) any later version.

   This program is distributed in the hope that it will be useful, but
   WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
   02111-1307, USA.

   The GNU General Public License is contained in the file COPYING.
*/

#define _FILE_OFFSET_BITS 64

#include "vg_include.h"
#include "ume.h"
#include "ume_arch.h"
#include "ume_archdefs.h"

#include <dirent.h>
#include <dlfcn.h>
#include <errno.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/mman.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/ptrace.h>
#include <sys/signal.h>
#include <sys/wait.h>
#include <unistd.h>

#ifndef AT_DCACHEBSIZE
#define AT_DCACHEBSIZE		19
#endif /* AT_DCACHEBSIZE */

#ifndef AT_ICACHEBSIZE
#define AT_ICACHEBSIZE		20
#endif /* AT_ICACHEBSIZE */

#ifndef AT_UCACHEBSIZE
#define AT_UCACHEBSIZE		21
#endif /* AT_UCACHEBSIZE */

#ifndef AT_SYSINFO
#define AT_SYSINFO		32
#endif /* AT_SYSINFO */

#ifndef AT_SYSINFO_EHDR
#define AT_SYSINFO_EHDR		33
#endif /* AT_SYSINFO_EHDR */

#ifndef AT_SECURE
#define AT_SECURE 23   /* secure mode boolean */
#endif	/* AT_SECURE */

/* Amount to reserve for Valgrind's internal heap */
#define VALGRIND_HEAPSIZE	(128*1024*1024)

/* Amount to reserve for Valgrind's internal mappings */
#define VALGRIND_MAPSIZE	(128*1024*1024)

/* redzone gap between client address space and shadow */
#define REDZONE_SIZE		(1 * 1024*1024)

/* size multiple for client address space */
#define CLIENT_SIZE_MULTIPLE	(64 * 1024*1024)

#define ISSPACE(cc)      ((cc) == ' ' || (cc) == '\t' || (cc) == '\n')

/*====================================================================*/
/*=== Global entities not referenced from generated code           ===*/
/*====================================================================*/

/* ---------------------------------------------------------------------
   Startup stuff                            
   ------------------------------------------------------------------ */
/* linker-defined base address */
extern char kickstart_base;	

/* Client address space, lowest to highest (see top of ume.c) */
Addr VG_(client_base);           /* client address space limits */
Addr VG_(client_end);
Addr VG_(client_mapbase);
Addr VG_(client_trampoline_code);
Addr VG_(clstk_base);
Addr VG_(clstk_end);

Addr VG_(brk_base);	         /* start of brk */
Addr VG_(brk_limit);	         /* current brk */

Addr VG_(shadow_base);	         /* skin's shadow memory */
Addr VG_(shadow_end);

Addr VG_(valgrind_base);	 /* valgrind's address range */
Addr VG_(valgrind_mmap_end);	 /* valgrind's mmaps are between valgrind_base and here */
Addr VG_(valgrind_end);

vki_rlimit VG_(client_rlimit_data);

/* This is set early to indicate whether this CPU has the
   SSE/fxsave/fxrestor features.  */
Bool VG_(have_ssestate);

/* Indicates presence, and holds address of client's sysinfo page, a
   feature of some modern kernels used to provide vsyscalls, etc. */
Bool VG_(sysinfo_page_exists) = False;
Addr VG_(sysinfo_page_addr) = 0;

/* stage1 (main) executable */
Int  VG_(vgexecfd) = -1;

/* client executable */
Int  VG_(clexecfd) = -1;

/* Path to library directory */
const Char *VG_(libdir) = VG_LIBDIR;

/* our argc/argv */
Int  VG_(vg_argc);
Char **VG_(vg_argv);

/* PID of the main thread */
Int VG_(main_pid);

/* PGRP of process */
Int VG_(main_pgrp);

/* Maximum allowed application-visible file descriptor */
Int VG_(max_fd) = -1;

/* As deduced from esp_at_startup, the client's argc, argv[] and
   envp[] as extracted from the client's stack at startup-time. */
Int    VG_(client_argc);
Char** VG_(client_argv);
Char** VG_(client_envp);

/* ---------------------------------------------------------------------
   Running stuff                            
   ------------------------------------------------------------------ */
/* Our signal delivery stack. */
UInt VG_(sigstack)[VG_SIGSTACK_SIZE_W];

/* Saving stuff across system calls. */
__attribute__ ((aligned (16)))
UInt VG_(real_sse_state_saved_over_syscall)[VG_SIZE_OF_SSESTATE_W];
Addr VG_(esp_saved_over_syscall);

/* jmp_buf for fatal signals */
Int	VG_(fatal_sigNo) = -1;
Bool	VG_(fatal_signal_set) = False;
jmp_buf VG_(fatal_signal_jmpbuf);

/* Counts downwards in VG_(run_innerloop). */
UInt VG_(dispatch_ctr);

/* 64-bit counter for the number of basic blocks done. */
ULong VG_(bbs_done);

/* This is the ThreadId of the last thread the scheduler ran. */
ThreadId VG_(last_run_tid) = 0;

/* Tell the logging mechanism whether we are logging to a file
   descriptor or a socket descriptor. */
Bool VG_(logging_to_filedes) = True;

/* This Bool is needed by wrappers in vg_clientmalloc.c to decide how
   to behave.  Initially we say False. */
Bool VG_(running_on_simd_CPU) = False;

/* This is the argument to __NR_exit() supplied by the first thread to
   call that syscall.  We eventually pass that to __NR_exit() for
   real. */
Int VG_(exitcode) = 0;


/*====================================================================*/
/*=== Counters, for profiling purposes only                        ===*/
/*====================================================================*/

/* Number of lookups which miss the fast tt helper. */
UInt VG_(tt_fast_misses) = 0;


/* Counts for TT/TC informational messages. */

/* Number and total o/t size of translations overall. */
UInt VG_(overall_in_count) = 0;
UInt VG_(overall_in_osize) = 0;
UInt VG_(overall_in_tsize) = 0;
/* Number and total o/t size of discards overall. */
UInt VG_(overall_out_count) = 0;
UInt VG_(overall_out_osize) = 0;
UInt VG_(overall_out_tsize) = 0;
/* The number of discards of TT/TC. */
UInt VG_(number_of_tc_discards) = 0;
/* Counts of chain and unchain operations done. */
UInt VG_(bb_enchain_count) = 0;
UInt VG_(bb_dechain_count) = 0;
/* Number of unchained jumps performed. */
UInt VG_(unchained_jumps_done) = 0;


/* Counts pertaining to the register allocator. */

/* total number of uinstrs input to reg-alloc */
UInt VG_(uinstrs_prealloc) = 0;

/* total number of uinstrs added due to spill code */
UInt VG_(uinstrs_spill) = 0;

/* number of bbs requiring spill code */
UInt VG_(translations_needing_spill) = 0;

/* total of register ranks over all translations */
UInt VG_(total_reg_rank) = 0;


/* Counts pertaining to internal sanity checking. */
UInt VG_(sanity_fast_count) = 0;
UInt VG_(sanity_slow_count) = 0;

/* Counts pertaining to the scheduler. */
UInt VG_(num_scheduling_events_MINOR) = 0;
UInt VG_(num_scheduling_events_MAJOR) = 0;


static __inline__ Int safe_idiv(Int a, Int b)
{
   return (b == 0 ? 0 : a / b);
}

static void show_counts ( void )
{
   VG_(message)(Vg_DebugMsg,
		"    TT/TC: %d tc sectors discarded.",
                VG_(number_of_tc_discards) );
   VG_(message)(Vg_DebugMsg,
                "           %d chainings, %d unchainings.",
                VG_(bb_enchain_count), VG_(bb_dechain_count) );
   VG_(message)(Vg_DebugMsg,
                "translate: new     %d (%d -> %d; ratio %d:10)",
                VG_(overall_in_count),
                VG_(overall_in_osize),
                VG_(overall_in_tsize),
                safe_idiv(10*VG_(overall_in_tsize), VG_(overall_in_osize)));
   VG_(message)(Vg_DebugMsg,
                "           discard %d (%d -> %d; ratio %d:10).",
                VG_(overall_out_count),
                VG_(overall_out_osize),
                VG_(overall_out_tsize),
                safe_idiv(10*VG_(overall_out_tsize), VG_(overall_out_osize)));
   VG_(message)(Vg_DebugMsg,
      " dispatch: %llu jumps (bb entries), of which %u (%lu%%) were unchained.",
      VG_(bbs_done), 
      VG_(unchained_jumps_done),
      ((ULong)(100) * (ULong)(VG_(unchained_jumps_done)))
         / ( VG_(bbs_done)==0 ? 1 : VG_(bbs_done) )
   );

   VG_(message)(Vg_DebugMsg,
      "           %d/%d major/minor sched events.  %d tt_fast misses.", 
                     VG_(num_scheduling_events_MAJOR), 
                     VG_(num_scheduling_events_MINOR), 
                     VG_(tt_fast_misses));

   VG_(message)(Vg_DebugMsg, 
                "reg-alloc: %d t-req-spill, "
                "%d+%d orig+spill uis, %d total-reg-r.",
                VG_(translations_needing_spill),
                VG_(uinstrs_prealloc),
                VG_(uinstrs_spill),
                VG_(total_reg_rank) );
   VG_(message)(Vg_DebugMsg, 
                "   sanity: %d cheap, %d expensive checks.",
                VG_(sanity_fast_count), 
                VG_(sanity_slow_count) );
   VG_(print_ccall_stats)();
}


/*====================================================================*/
/*=== Miscellaneous global functions                               ===*/
/*====================================================================*/

/* Start debugger and get it to attach to this process.  Called if the
   user requests this service after an error has been shown, so she can
   poke around and look at parameters, memory, etc.  You can't
   meaningfully get the debugger to continue the program, though; to
   continue, quit the debugger.  */
void VG_(start_debugger) ( Int tid )
{
   Int pid;

   if ((pid = fork()) == 0) {
      ptrace(PTRACE_TRACEME, 0, NULL, NULL);
      VG_(kkill)(VG_(getpid)(), VKI_SIGSTOP);

   } else if (pid > 0) {
      struct user_regs_struct regs;
      Int status;
      Int res;

      if (VG_(is_running_thread)( tid )) {
         regs.cs  = VG_(baseBlock)[VGOFF_(m_cs)];
         regs.ss  = VG_(baseBlock)[VGOFF_(m_ss)];
         regs.ds  = VG_(baseBlock)[VGOFF_(m_ds)];
         regs.es  = VG_(baseBlock)[VGOFF_(m_es)];
         regs.fs  = VG_(baseBlock)[VGOFF_(m_fs)];
         regs.gs  = VG_(baseBlock)[VGOFF_(m_gs)];
         regs.eax = VG_(baseBlock)[VGOFF_(m_eax)];
         regs.ebx = VG_(baseBlock)[VGOFF_(m_ebx)];
         regs.ecx = VG_(baseBlock)[VGOFF_(m_ecx)];
         regs.edx = VG_(baseBlock)[VGOFF_(m_edx)];
         regs.esi = VG_(baseBlock)[VGOFF_(m_esi)];
         regs.edi = VG_(baseBlock)[VGOFF_(m_edi)];
         regs.ebp = VG_(baseBlock)[VGOFF_(m_ebp)];
         regs.esp = VG_(baseBlock)[VGOFF_(m_esp)];
         regs.eflags = VG_(baseBlock)[VGOFF_(m_eflags)];
         regs.eip = VG_(baseBlock)[VGOFF_(m_eip)];
      } else {
         ThreadState* tst = & VG_(threads)[ tid ];
         
         regs.cs  = tst->m_cs;
         regs.ss  = tst->m_ss;
         regs.ds  = tst->m_ds;
         regs.es  = tst->m_es;
         regs.fs  = tst->m_fs;
         regs.gs  = tst->m_gs;
         regs.eax = tst->m_eax;
         regs.ebx = tst->m_ebx;
         regs.ecx = tst->m_ecx;
         regs.edx = tst->m_edx;
         regs.esi = tst->m_esi;
         regs.edi = tst->m_edi;
         regs.ebp = tst->m_ebp;
         regs.esp = tst->m_esp;
         regs.eflags = tst->m_eflags;
         regs.eip = tst->m_eip;
      }

      if ((res = VG_(waitpid)(pid, &status, 0)) == pid &&
          WIFSTOPPED(status) && WSTOPSIG(status) == SIGSTOP &&
          ptrace(PTRACE_SETREGS, pid, NULL, &regs) == 0 &&
          kill(pid, SIGSTOP) == 0 &&
          ptrace(PTRACE_DETACH, pid, NULL, 0) == 0) {
         Char pidbuf[15];
         Char file[30];
         Char buf[100];
         Char *bufptr;
         Char *cmdptr;
         
         VG_(sprintf)(pidbuf, "%d", pid);
         VG_(sprintf)(file, "/proc/%d/fd/%d", pid, VG_(clexecfd));
 
         bufptr = buf;
         cmdptr = VG_(clo_db_command);
         
         while (*cmdptr) {
            switch (*cmdptr) {
               case '%':
                  switch (*++cmdptr) {
                     case 'f':
                        VG_(memcpy)(bufptr, file, VG_(strlen)(file));
                        bufptr += VG_(strlen)(file);
                        cmdptr++;
                        break;
                  case 'p':
                     VG_(memcpy)(bufptr, pidbuf, VG_(strlen)(pidbuf));
                     bufptr += VG_(strlen)(pidbuf);
                     cmdptr++;
                     break;
                  default:
                     *bufptr++ = *cmdptr++;
                     break;
                  }
                  break;
               default:
                  *bufptr++ = *cmdptr++;
                  break;
            }
         }
         
         *bufptr++ = '\0';
  
         VG_(message)(Vg_UserMsg, "starting debugger with cmd: %s", buf);
         res = VG_(system)(buf);
         if (res == 0) {      
            VG_(message)(Vg_UserMsg, "");
            VG_(message)(Vg_UserMsg, 
                         "Debugger has detached.  Valgrind regains control.  We continue.");
         } else {
            VG_(message)(Vg_UserMsg, "Apparently failed!");
            VG_(message)(Vg_UserMsg, "");
         }
      }

      VG_(kkill)(pid, VKI_SIGKILL);
      VG_(waitpid)(pid, &status, 0);
   }
}


/* Print some helpful-ish text about unimplemented things, and give
   up. */
void VG_(unimplemented) ( Char* msg )
{
   VG_(message)(Vg_UserMsg, "");
   VG_(message)(Vg_UserMsg, 
      "Valgrind detected that your program requires");
   VG_(message)(Vg_UserMsg, 
      "the following unimplemented functionality:");
   VG_(message)(Vg_UserMsg, "   %s", msg);
   VG_(message)(Vg_UserMsg,
      "This may be because the functionality is hard to implement,");
   VG_(message)(Vg_UserMsg,
      "or because no reasonable program would behave this way,");
   VG_(message)(Vg_UserMsg,
      "or because nobody has yet needed it.  In any case, let us know at");
   VG_(message)(Vg_UserMsg,
      "%s and/or try to work around the problem, if you can.", VG_BUGS_TO);
   VG_(message)(Vg_UserMsg,
      "");
   VG_(message)(Vg_UserMsg,
      "Valgrind has to exit now.  Sorry.  Bye!");
   VG_(message)(Vg_UserMsg,
      "");
   VG_(pp_sched_status)();
   VG_(exit)(1);
}

Addr VG_(get_stack_pointer) ( void )
{
   return VG_(baseBlock)[VGOFF_(m_esp)];
}

/* Debugging thing .. can be called from assembly with OYNK macro. */
void VG_(oynk) ( Int n )
{
   OINK(n);
}

/* Initialize the PID and PGRP of scheduler LWP; this is also called
   in any new children after fork. */
static void newpid(ThreadId unused)
{
   /* PID of scheduler LWP */
   VG_(main_pid)  = VG_(getpid)();
   VG_(main_pgrp) = VG_(getpgrp)();
}

/*====================================================================*/
/*=== Check we were launched by stage 1                            ===*/
/*====================================================================*/

/* Look for our AUXV table */
static void scan_auxv(void)
{
   const struct ume_auxv *auxv = find_auxv((int *)ume_exec_esp);
   int found = 0;

   for (; auxv->a_type != AT_NULL; auxv++)
      switch(auxv->a_type) {
      case AT_UME_PADFD:
	 as_setpadfd(auxv->u.a_val);
	 found |= 1;
	 break;

      case AT_UME_EXECFD:
	 VG_(vgexecfd) = auxv->u.a_val;
	 found |= 2;
	 break;
      }

   if ( ! (1|2) ) {
      fprintf(stderr, "stage2 must be launched by stage1\n");
      exit(127);
   }
}


/*====================================================================*/
/*=== Address space determination                                  ===*/
/*====================================================================*/

/* Pad client space so it doesn't get filled in before the right time */
static void layout_client_space(Addr argc_addr)
{
   VG_(client_base)       = CLIENT_BASE;
   VG_(valgrind_mmap_end) = (addr_t)&kickstart_base; /* end of V's mmaps */
   VG_(valgrind_base)     = VG_(valgrind_mmap_end) - VALGRIND_MAPSIZE;
   VG_(valgrind_end)      = ROUNDUP(argc_addr, 0x10000); /* stack */

   if (0)
      printf("client base:        %x\n"
             "valgrind base--end: %x--%x (%x)\n"
             "valgrind mmap end:  %x\n\n",
             VG_(client_base),
             VG_(valgrind_base), VG_(valgrind_end),
             VG_(valgrind_end) - VG_(valgrind_base),
             VG_(valgrind_mmap_end));

   as_pad((void *)VG_(client_base), (void *)VG_(valgrind_base));
}

static void layout_remaining_space(float ratio)
{
   /* This tries to give the client as large as possible address space while
    * taking into account the tool's shadow needs.  */
   addr_t client_size = ROUNDDN((VG_(valgrind_base) - REDZONE_SIZE) / (1. + ratio), 
                         CLIENT_SIZE_MULTIPLE);
   addr_t shadow_size = PGROUNDUP(client_size * ratio);

   VG_(client_end)     = VG_(client_base) + client_size;
   VG_(client_mapbase) = PGROUNDDN((client_size/4)*3); /* where !FIXED mmap goes */
   VG_(client_trampoline_code) = VG_(client_end) - VKI_BYTES_PER_PAGE;

   VG_(shadow_base) = VG_(client_end) + REDZONE_SIZE;
   VG_(shadow_end)  = VG_(shadow_base) + shadow_size;

   if (0)
      printf("client base--end:   %x--%x (%x)\n"
             "client mapbase:     %x\n"
             "shadow base--end:   %x--%x (%x)\n\n",
             VG_(client_base), VG_(client_end), client_size,
             VG_(client_mapbase),
             VG_(shadow_base), VG_(shadow_end), shadow_size);

   // Ban redzone
   mmap((void *)VG_(client_end), REDZONE_SIZE, PROT_NONE,
	MAP_FIXED|MAP_ANON|MAP_PRIVATE, -1, 0);

   // Make client hole
   munmap((void*)VG_(client_base), client_size);

   // Map shadow memory.
   // Initially all inaccessible, incrementally initialized as it is used
   if (shadow_size != 0)
      mmap((char *)VG_(shadow_base), shadow_size, PROT_NONE,
         MAP_PRIVATE|MAP_ANON|MAP_FIXED, -1, 0);
}

/*====================================================================*/
/*=== Command line setup                                           ===*/
/*====================================================================*/

/* Nb: malloc'd memory never freed -- kept throughout like argv, envp */
static char* get_file_clo(char* dir)
{
#  define FLEN 512
   Int fd, n;
   struct stat s1;
   char* f_clo = NULL;
   char filename[FLEN];

   snprintf(filename, FLEN, "%s/.valgrindrc", ( NULL == dir ? "" : dir ) );
   fd = VG_(open)(filename, 0, VKI_S_IRUSR);
   if ( fd > 0 ) {
      if ( 0 == fstat(fd, &s1) ) {
         f_clo = malloc(s1.st_size+1);
         vg_assert(f_clo);
         n = read(fd, f_clo, s1.st_size);
         if (n == -1) n = 0;
         f_clo[n] = '\0';
      }
      close(fd);
   }
   return f_clo;
#  undef FLEN
}

static Int count_args(char* s)
{
   Int n = 0;
   if (s) {
      char* cp = s;
      while (True) {
         // We have alternating sequences: blanks, non-blanks, blanks...
         // count the non-blanks sequences.
         while ( ISSPACE(*cp) )         cp++;
         if    ( !*cp )                 break;
         n++;
         while ( !ISSPACE(*cp) && *cp ) cp++;
      }
   }
   return n;
}

/* add args out of environment, skipping multiple spaces and -- args */
static char** copy_args( char* s, char** to )
{
   if (s) {
      char* cp = s;
      while (True) {
         // We have alternating sequences: blanks, non-blanks, blanks...
         // copy the non-blanks sequences, and add terminating '\0'
         while ( ISSPACE(*cp) )         cp++;
         if    ( !*cp )                 break;
         *to++ = cp;
         while ( !ISSPACE(*cp) && *cp ) cp++;
         if ( *cp ) *cp++ = '\0';            // terminate if necessary
         if (VG_STREQ(to[-1], "--")) to--;   // undo any '--' arg
      }
   }
   return to;
}

// Augment command line with arguments from environment and .valgrindrc
// files.
static void augment_command_line(Int* vg_argc_inout, char*** vg_argv_inout)
{
   int    vg_argc = *vg_argc_inout;
   char** vg_argv = *vg_argv_inout;

   char*  env_clo = getenv(VALGRINDOPTS);
   char*  f1_clo  = get_file_clo( getenv("HOME") );
   char*  f2_clo  = get_file_clo(".");

   /* copy any extra args from file or environment, if present */
   if ( (env_clo && *env_clo) || (f1_clo && *f1_clo) || (f2_clo && *f2_clo) ) {
      /* ' ' separated extra options */
      char **from;
      char **to;
      int env_arg_count, f1_arg_count, f2_arg_count;
      
      env_arg_count = count_args(env_clo);
      f1_arg_count  = count_args(f1_clo);
      f2_arg_count  = count_args(f2_clo);

      if (0)
	 printf("extra-argc=%d %d %d\n",
		env_arg_count, f1_arg_count, f2_arg_count);

      /* +2: +1 for null-termination, +1 for added '--' */
      from    = vg_argv;
      vg_argv = malloc( (vg_argc + env_arg_count + f1_arg_count 
                          + f2_arg_count + 2) * sizeof(char **));
      to      = vg_argv;

      /* copy argv[0] */
      *to++ = *from++;

      /* Copy extra args from env var and file, in the order: ~/.valgrindrc,
       * $VALGRIND_OPTS, ./.valgrindrc -- more local options are put later
       * to override less local ones. */
      to = copy_args(f1_clo,  to);
      to = copy_args(env_clo, to);
      to = copy_args(f2_clo,  to);

      /* copy original arguments, stopping at command or -- */
      while (*from) {
	 if (**from != '-')
	    break;
	 if (VG_STREQ(*from, "--")) {
	    from++;		/* skip -- */
	    break;
	 }
	 *to++ = *from++;
      }

      /* add -- */
      *to++ = "--";

      vg_argc = to - vg_argv;

      /* copy rest of original command line, then NULL */
      while (*from) *to++ = *from++;
      *to = NULL;
   }

   *vg_argc_inout = vg_argc;
   *vg_argv_inout = vg_argv;
}

static void get_command_line( int argc, char** argv,
                              Int* vg_argc_out, Char*** vg_argv_out, 
                                                char*** cl_argv_out )
{
   int    vg_argc;
   char** vg_argv;
   char** cl_argv;
   char*  env_clo = getenv(VALGRINDCLO);

   if (env_clo != NULL && *env_clo != '\0') {
      char *cp;
      char **cpp;

      /* OK, we're getting all our arguments from the environment - the
	 entire command line belongs to the client (including argv[0]) */
      vg_argc = 1;		/* argv[0] */
      for (cp = env_clo; *cp; cp++)
	 if (*cp == '\01')
	    vg_argc++;

      vg_argv = malloc(sizeof(char **) * (vg_argc + 1));

      cpp = vg_argv;

      *cpp++ = "valgrind";	/* nominal argv[0] */
      *cpp++ = env_clo;

      for (cp = env_clo; *cp; cp++) {
	 if (*cp == '\01') {
	    *cp++ = '\0';	/* chop it up in place */
	    *cpp++ = cp;
	 }
      }
      *cpp = NULL;
      cl_argv = argv;

   } else {
      /* Count the arguments on the command line. */
      vg_argv = argv;

      for (vg_argc = 1; vg_argc < argc; vg_argc++) {
	 if (argv[vg_argc][0] != '-') /* exe name */
	    break;
	 if (VG_STREQ(argv[vg_argc], "--")) { /* dummy arg */
	    vg_argc++;
	    break;
	 }
      }
      cl_argv = &argv[vg_argc];

      /* Get extra args from VALGRIND_OPTS and .valgrindrc files.
       * Note we don't do this if getting args from VALGRINDCLO. */
      augment_command_line(&vg_argc, &vg_argv);
   }

   if (0) {
      Int i;
      for (i = 0; i < vg_argc; i++)
         printf("vg_argv[%d]=\"%s\"\n", i, vg_argv[i]);
   }

   *vg_argc_out =         vg_argc;
   *vg_argv_out = (Char**)vg_argv;
   *cl_argv_out =         cl_argv;
}


/*====================================================================*/
/*=== Environment and stack setup                                  ===*/
/*====================================================================*/

/* Scan a colon-separated list, and call a function on each element.
   The string must be mutable, because we insert a temporary '\0', but
   the string will end up unmodified.  (*func) should return 1 if it
   doesn't need to see any more.
*/
static void scan_colsep(char *colsep, int (*func)(const char *))
{
   char *cp, *entry;
   int end;

   if (colsep == NULL ||
       *colsep == '\0')
      return;

   entry = cp = colsep;

   do {
      end = (*cp == '\0');

      if (*cp == ':' || *cp == '\0') {
	 char save = *cp;

	 *cp = '\0';
	 if ((*func)(entry))
	    end = 1;
	 *cp = save;
	 entry = cp+1;
      }
      cp++;
   } while(!end);
}

/* Prepare the client's environment.  This is basically a copy of our
   environment, except:
   1. LD_LIBRARY_PATH=$VALGRINDLIB:$LD_LIBRARY_PATH
   2. LD_PRELOAD=$VALGRINDLIB/vg_inject.so:($VALGRINDLIB/vgpreload_TOOL.so:)?$LD_PRELOAD

   If any of these is missing, then it is added.

   Yummy.  String hacking in C.

   If this needs to handle any more variables it should be hacked
   into something table driven.
 */
static char **fix_environment(char **origenv, const char *preload)
{
   static const char inject_so[]          = "vg_inject.so";
   static const char ld_library_path[]    = "LD_LIBRARY_PATH=";
   static const char ld_preload[]         = "LD_PRELOAD=";
   static const char valgrind_clo[]       = VALGRINDCLO "=";
   static const int  ld_library_path_len  = sizeof(ld_library_path)-1;
   static const int  ld_preload_len       = sizeof(ld_preload)-1;
   static const int  valgrind_clo_len     = sizeof(valgrind_clo)-1;
   int ld_preload_done       = 0;
   int ld_library_path_done  = 0;
   char *inject_path;
   int   inject_path_len;
   int vgliblen = strlen(VG_(libdir));
   char **cpp;
   char **ret;
   int envc;
   const int preloadlen = (preload == NULL) ? 0 : strlen(preload);

   /* Find the vg_inject.so; also make room for the tool preload
      library */
   inject_path_len = sizeof(inject_so) + vgliblen + preloadlen + 16;
   inject_path = malloc(inject_path_len);

   if (preload)
      snprintf(inject_path, inject_path_len, "%s/%s:%s", 
	       VG_(libdir), inject_so, preload);
   else
      snprintf(inject_path, inject_path_len, "%s/%s", 
	       VG_(libdir), inject_so);
   
   /* Count the original size of the env */
   envc = 0;			/* trailing NULL */
   for (cpp = origenv; cpp && *cpp; cpp++)
      envc++;

   /* Allocate a new space */
   ret = malloc(sizeof(char *) * (envc+3+1)); /* 3 new entries + NULL */

   /* copy it over */
   for (cpp = ret; *origenv; )
      *cpp++ = *origenv++;
   *cpp = NULL;
   
   vg_assert(envc == (cpp - ret));

   /* Walk over the new environment, mashing as we go */
   for (cpp = ret; cpp && *cpp; cpp++) {
      if (memcmp(*cpp, ld_library_path, ld_library_path_len) == 0) {
	 int done = 0;
	 int contains(const char *p) {
	    if (VG_STREQ(p, VG_(libdir))) {
	       done = 1;
	       return 1;
	    }
	    return 0;
	 }

	 /* If the LD_LIBRARY_PATH already contains libdir, then don't
	    bother adding it again, even if it isn't the first (it
	    seems that the Java runtime will keep reexecing itself
	    unless its paths are at the front of LD_LIBRARY_PATH) */
	 scan_colsep(*cpp + ld_library_path_len, contains);

	 if (!done) {
	    int len = strlen(*cpp) + vgliblen*2 + 16;
	    char *cp = malloc(len);

	    snprintf(cp, len, "%s%s:%s",
		     ld_library_path, VG_(libdir),
		     (*cpp)+ld_library_path_len);

	    *cpp = cp;
	 }

	 ld_library_path_done = 1;
      } else if (memcmp(*cpp, ld_preload, ld_preload_len) == 0) {
	 int len = strlen(*cpp) + inject_path_len;
	 char *cp = malloc(len);

	 snprintf(cp, len, "%s%s:%s",
		  ld_preload, inject_path, (*cpp)+ld_preload_len);

	 *cpp = cp;
	 
	 ld_preload_done = 1;
      } else if (memcmp(*cpp, valgrind_clo, valgrind_clo_len) == 0) {
	 *cpp = "";
      }
   }

   /* Add the missing bits */

   if (!ld_library_path_done) {
      int len = ld_library_path_len + vgliblen*2 + 16;
      char *cp = malloc(len);

      snprintf(cp, len, "%s%s", ld_library_path, VG_(libdir));

      ret[envc++] = cp;
   }

   if (!ld_preload_done) {
      int len = ld_preload_len + inject_path_len;
      char *cp = malloc(len);
      
      snprintf(cp, len, "%s%s",
	       ld_preload, inject_path);
      
      ret[envc++] = cp;
   }

   ret[envc] = NULL;

   return ret;
}

extern char **environ;		/* our environment */
//#include <error.h>

/* Add a string onto the string table, and return its address */
static char *copy_str(char **tab, const char *str)
{
   char *cp = *tab;
   char *orig = cp;

   while(*str)
      *cp++ = *str++;
   *cp++ = '\0';

   if (0)
      printf("copied %p \"%s\" len %d\n",
	     orig, orig, cp-orig);

   *tab = cp;

   return orig;
}

/* 
   This sets up the client's initial stack, containing the args,
   environment and aux vector.

   The format of the stack is:

   higher address +-----------------+
		  | Trampoline code |
		  +-----------------+
                  |                 |
		  : string table    :
		  |                 |
		  +-----------------+
		  | AT_NULL         |
		  -                 -
		  | auxv            |
		  +-----------------+
		  |  NULL           |
		  -                 -
		  | envp            |
		  +-----------------+
		  |  NULL           |
		  -                 -
		  | argv            |
		  +-----------------+
		  | argc            |
   lower address  +-----------------+ <- esp
                  | undefined       |
		  :                 :
 */
static Addr setup_client_stack(char **orig_argv, char **orig_envp, 
			       const struct exeinfo *info,
                               UInt** client_auxv)
{
   char **cpp;
   char *strtab;		/* string table */
   char *stringbase;
   addr_t *ptr;
   struct ume_auxv *auxv;
   const struct ume_auxv *orig_auxv;
   const struct ume_auxv *cauxv;
   unsigned stringsize;		/* total size of strings in bytes */
   unsigned auxsize;		/* total size of auxv in bytes */
   int argc;			/* total argc */
   int envc;			/* total number of env vars */
   unsigned stacksize;		/* total client stack size */
   addr_t cl_esp;		/* client stack base (initial esp) */

   /* use our own auxv as a prototype */
   orig_auxv = find_auxv(ume_exec_esp);

   /* ==================== compute sizes ==================== */

   /* first of all, work out how big the client stack will be */
   stringsize = 0;

   /* paste on the extra args if the loader needs them (ie, the #! 
      interpreter and its argument) */
   argc = 0;
   if (info->argv0 != NULL) {
      argc++;
      stringsize += strlen(info->argv0) + 1;
   }
   if (info->argv1 != NULL) {
      argc++;
      stringsize += strlen(info->argv1) + 1;
   }

   /* now scan the args we're given... */
   for (cpp = orig_argv; *cpp; cpp++) {
      argc++;
      stringsize += strlen(*cpp) + 1;
   }
   
   /* ...and the environment */
   envc = 0;
   for (cpp = orig_envp; cpp && *cpp; cpp++) {
      envc++;
      stringsize += strlen(*cpp) + 1;
   }

   /* now, how big is the auxv? */
   auxsize = sizeof(*auxv);	/* there's always at least one entry: AT_NULL */
   for (cauxv = orig_auxv; cauxv->a_type != AT_NULL; cauxv++) {
      if (cauxv->a_type == AT_PLATFORM)
	 stringsize += strlen(cauxv->u.a_ptr) + 1;
      auxsize += sizeof(*cauxv);
   }

   /* OK, now we know how big the client stack is */
   stacksize =
      sizeof(int) +			/* argc */
      sizeof(char **)*argc +		/* argv */
      sizeof(char **) +			/* terminal NULL */
      sizeof(char **)*envc +		/* envp */
      sizeof(char **) +			/* terminal NULL */
      auxsize +				/* auxv */
      ROUNDUP(stringsize, sizeof(int)) +/* strings (aligned) */
      VKI_BYTES_PER_PAGE;		/* page for trampoline code */

   /* cl_esp is the client's stack pointer */
   cl_esp = VG_(client_end) - stacksize;
   cl_esp = ROUNDDN(cl_esp, 16); /* make stack 16 byte aligned */

   if (0)
      printf("stringsize=%d auxsize=%d stacksize=%d\n",
	     stringsize, auxsize, stacksize);


   /* base of the string table (aligned) */
   stringbase = strtab = (char *)(VG_(client_trampoline_code) - ROUNDUP(stringsize, sizeof(int)));

   VG_(clstk_base) = PGROUNDDN(cl_esp);
   VG_(clstk_end)  = VG_(client_end);

   /* ==================== allocate space ==================== */

   /* allocate a stack - mmap enough space for the stack */
   mmap((void *)PGROUNDDN(cl_esp),
	VG_(client_end) - PGROUNDDN(cl_esp),
	PROT_READ | PROT_WRITE | PROT_EXEC, 
	MAP_PRIVATE | MAP_ANON | MAP_FIXED, -1, 0);
   

   /* ==================== copy client stack ==================== */

   ptr = (addr_t *)cl_esp;

   /* --- argc --- */
   *ptr++ = argc;		/* client argc */

   /* --- argv --- */
   if (info->argv0) {
      *ptr++ = (addr_t)copy_str(&strtab, info->argv0);
      free(info->argv0);
   }
   if (info->argv1) {
      *ptr++ = (addr_t)copy_str(&strtab, info->argv1);
      free(info->argv1);
   }
   for (cpp = orig_argv; *cpp; ptr++, cpp++) {
      *ptr = (addr_t)copy_str(&strtab, *cpp);
   }
   *ptr++ = 0;

   /* --- envp --- */
   VG_(client_envp) = (Char **)ptr;
   for (cpp = orig_envp; cpp && *cpp; ptr++, cpp++)
      *ptr = (addr_t)copy_str(&strtab, *cpp);
   *ptr++ = 0;

   /* --- auxv --- */
   auxv = (struct ume_auxv *)ptr;
   *client_auxv = (UInt *)auxv;

   for (; orig_auxv->a_type != AT_NULL; auxv++, orig_auxv++) {
      /* copy the entry... */
      *auxv = *orig_auxv;

      /* ...and fix up the copy */
      switch(auxv->a_type) {
      case AT_PHDR:
	 if (info->phdr == 0)
	    auxv->a_type = AT_IGNORE;
	 else
	    auxv->u.a_val = info->phdr;
	 break;

      case AT_PHNUM:
	 if (info->phdr == 0)
	    auxv->a_type = AT_IGNORE;
	 else
	    auxv->u.a_val = info->phnum;
	 break;

      case AT_BASE:
	 if (info->interp_base == 0)
	    auxv->a_type = AT_IGNORE;
	 else
	    auxv->u.a_val = info->interp_base;
	 break;

      case AT_PLATFORM:		/* points to a platform description string */
	 auxv->u.a_ptr = copy_str(&strtab, orig_auxv->u.a_ptr);
	 break;

      case AT_ENTRY:
	 auxv->u.a_val = info->entry;
	 break;

      case AT_IGNORE:
      case AT_EXECFD:
      case AT_PHENT:
      case AT_PAGESZ:
      case AT_FLAGS:
      case AT_NOTELF:
      case AT_UID:
      case AT_EUID:
      case AT_GID:
      case AT_EGID:
      case AT_CLKTCK:
      case AT_HWCAP:
      case AT_FPUCW:
      case AT_DCACHEBSIZE:
      case AT_ICACHEBSIZE:
      case AT_UCACHEBSIZE:
	 /* All these are pointerless, so we don't need to do anything
	    about them. */
	 break;

      case AT_SECURE:
	 /* If this is 1, then it means that this program is running
	    suid, and therefore the dynamic linker should be careful
	    about LD_PRELOAD, etc.  However, since stage1 (the thing
	    the kernel actually execve's) should never be SUID, and we
	    need LD_PRELOAD/LD_LIBRARY_PATH to work for the client, we
	    set AT_SECURE to 0. */
	 auxv->u.a_val = 0;
	 break;

      case AT_SYSINFO:
	 /* Leave this unmolested for now, but we'll update it later
	    when we set up the client trampoline code page */
	 break;

      case AT_SYSINFO_EHDR:
	 /* Trash this, because we don't reproduce it */
	 auxv->a_type = AT_IGNORE;
	 break;

      default:
	 /* stomp out anything we don't know about */
	 if (0)
	    printf("stomping auxv entry %d\n", auxv->a_type);
	 auxv->a_type = AT_IGNORE;
	 break;
	 
      }
   }
   *auxv = *orig_auxv;
   vg_assert(auxv->a_type == AT_NULL);

   vg_assert((strtab-stringbase) == stringsize);

   return cl_esp;
}

/*====================================================================*/
/*=== Find executable                                              ===*/
/*====================================================================*/

static const char* find_executable(const char* exec)
{
   vg_assert(NULL != exec);
   if (strchr(exec, '/') == NULL) {
      /* no '/' - we need to search the path */
      char *path = getenv("PATH");
      int pathlen = path ? strlen(path) : 0;

      int match_exe(const char *entry) {
         char buf[pathlen + strlen(entry) + 3];

         /* empty PATH element means . */
         if (*entry == '\0')
            entry = ".";

         snprintf(buf, sizeof(buf), "%s/%s", entry, exec);

         if (access(buf, R_OK|X_OK) == 0) {
            exec = strdup(buf);
            vg_assert(NULL != exec);
            return 1;
         }
         return 0;
      }
      scan_colsep(path, match_exe);
   }
   return exec;
}


/*====================================================================*/
/*=== Loading tools                                                ===*/
/*====================================================================*/

static void list_tools(void)
{
   DIR *dir = opendir(VG_(libdir));
   struct dirent *de;
   int first = 1;

   if (dir == NULL) {
      fprintf(stderr, "Can't open %s: %s (installation problem?)\n",
              VG_(libdir), strerror(errno));
      return;
   }

   while ((de = readdir(dir)) != NULL) {
      int len = strlen(de->d_name);

      /* look for vgskin_TOOL.so names */
      if (len > (7+1+3) &&   /* "vgskin_" + at least 1-char toolname + ".so" */
         strncmp(de->d_name, "vgskin_", 7) == 0 &&
         VG_STREQ(de->d_name + len - 3, ".so")) {
         if (first) {
            fprintf(stderr, "Available tools:\n");
            first = 0;
         }
         de->d_name[len-3] = '\0';
         fprintf(stderr, "\t%s\n", de->d_name+7);
      }
   }

   closedir(dir);

   if (first)
      fprintf(stderr, "No tools available in \"%s\" (installation problem?)\n",
             VG_(libdir));
}


/* Find and load a tool, and check it looks ok.  Also looks to see if there's 
 * a matching vgpreload_*.so file, and returns its name in *preloadpath. */
static void load_tool( const char *toolname, void** handle_out,
                       ToolInfo** toolinfo_out, char **preloadpath_out )
{
   Bool      ok;
   int       len = strlen(VG_(libdir)) + strlen(toolname)*2 + 16;
   char      buf[len];
   void*     handle;
   ToolInfo* toolinfo;
   char*     preloadpath = NULL;
   Int*      vg_malloc_redzonep;

   // XXX: allowing full paths for --tool option -- does it make sense?
   // Doesn't allow for vgpreload_<tool>.so.

   if (strchr(toolname, '/') != 0) {
      /* toolname contains '/', and so must be a pathname */
      handle = dlopen(toolname, RTLD_NOW);
   } else {
      /* just try in the libdir */
      snprintf(buf, len, "%s/vgskin_%s.so", VG_(libdir), toolname);
      handle = dlopen(buf, RTLD_NOW);

      if (handle != NULL) {
	 snprintf(buf, len, "%s/vgpreload_%s.so", VG_(libdir), toolname);
	 if (access(buf, R_OK) == 0) {
	    preloadpath = strdup(buf);
            vg_assert(NULL != preloadpath);
         }
      }
   }

   ok = (NULL != handle);
   if (!ok) {
      fprintf(stderr, "Can't open tool \"%s\": %s\n", toolname, dlerror());
      goto bad_load;
   }

   toolinfo = dlsym(handle, "vgSkin_tool_info");
   ok = (NULL != toolinfo);
   if (!ok) {
      fprintf(stderr, "Tool \"%s\" doesn't define SK_(tool_info) - "
                      "add VG_DETERMINE_INTERFACE_VERSION?\n", toolname);
      goto bad_load;
   }

   ok = (toolinfo->sizeof_ToolInfo == sizeof(*toolinfo) &&
     toolinfo->interface_major_version == VG_CORE_INTERFACE_MAJOR_VERSION &&
     toolinfo->sk_pre_clo_init != NULL);
   if (!ok) { 
      fprintf(stderr, "Error:\n"
              "  Tool and core interface versions do not match.\n"
              "  Interface version used by core is: %d.%d (size %d)\n"
              "  Interface version used by tool is: %d.%d (size %d)\n"
              "  The major version numbers must match.\n",
              VG_CORE_INTERFACE_MAJOR_VERSION, 
              VG_CORE_INTERFACE_MINOR_VERSION,
              sizeof(*toolinfo),
              toolinfo->interface_major_version,
              toolinfo->interface_minor_version, 
              toolinfo->sizeof_ToolInfo);
      fprintf(stderr, "  You need to at least recompile, and possibly update,\n");
      if (VG_CORE_INTERFACE_MAJOR_VERSION > toolinfo->interface_major_version)
         fprintf(stderr, "  your skin to work with this version of Valgrind.\n");
      else
         fprintf(stderr, "  your version of Valgrind to work with this skin.\n");
      goto bad_load;
   }

   // Set redzone size for V's allocator
   vg_malloc_redzonep = dlsym(handle, STR(VG_(vg_malloc_redzone_szB)));
   if ( NULL != vg_malloc_redzonep ) {
      VG_(vg_malloc_redzone_szB) = *vg_malloc_redzonep;
   }

   vg_assert(NULL != handle && NULL != toolinfo);
   *handle_out      = handle;
   *toolinfo_out    = toolinfo;
   *preloadpath_out = preloadpath;
   return;


 bad_load:
   if (handle != NULL)
      dlclose(handle);

   fprintf(stderr, "valgrind: couldn't load tool\n");
   list_tools();
   exit(127);
}


/*====================================================================*/
/*=== Command line errors                                          ===*/
/*====================================================================*/

static void abort_msg ( void )
{
   VG_(clo_log_to) = VgLogTo_Fd;
   VG_(clo_log_fd) = 2; /* stderr */
}

void VG_(bad_option) ( Char* opt )
{
   abort_msg();
   VG_(printf)("valgrind: Bad option `%s'; aborting.\n", opt);
   VG_(printf)("valgrind: Use --help for more information.\n");
   VG_(exit)(1);
}

static void missing_tool_option ( void  )
{
   abort_msg();
   VG_(printf)("valgrind: Missing --tool option\n");
   list_tools();
   VG_(printf)("valgrind: Use --help for more information.\n");
   VG_(exit)(1);
}

static void missing_prog ( void  )
{
   abort_msg();
   VG_(printf)("valgrind: no program specified\n");
   VG_(printf)("valgrind: Use --help for more information.\n");
   VG_(exit)(1);
}

static void config_error ( Char* msg )
{
   abort_msg();
   VG_(printf)("valgrind: Startup or configuration error:\n   %s\n", msg);
   VG_(printf)("valgrind: Unable to start up properly.  Giving up.\n");
   VG_(exit)(1);
}


/*====================================================================*/
/*=== Loading the client                                           ===*/
/*====================================================================*/

static void load_client(char* cl_argv[], const char* exec, Int need_help,
                 /*out*/struct exeinfo* info, /*out*/Addr* client_eip)
{
   // If they didn't specify an executable with --exec, and didn't specify 
   // --help, then use client argv[0] (searching $PATH if necessary).
   if (NULL == exec && !need_help) {
      if (cl_argv[0] == NULL || 
          ( NULL == (exec = find_executable(cl_argv[0])) ) )
      {
         missing_prog();
      }
   }

   info->map_base = VG_(client_mapbase);

   info->exe_base = VG_(client_base);
   info->exe_end  = VG_(client_end);
   info->argv     = cl_argv;

   if (need_help) {
      VG_(clexecfd) = -1;
      info->argv0 = NULL;
      info->argv1 = NULL;
   } else {
      Int ret;
      VG_(clexecfd) = VG_(open)(exec, O_RDONLY, VKI_S_IRUSR);
      ret = do_exec(exec, info);
      if (ret != 0) {
         fprintf(stderr, "valgrind: do_exec(%s) failed: %s\n", exec, strerror(ret));
         exit(127);
      }
   }

   /* Copy necessary bits of 'info' that were filled in */
   *client_eip = info->init_eip;
   VG_(brk_base) = VG_(brk_limit) = info->brkbase;
}


/*====================================================================*/
/*=== Command-line: variables, processing                          ===*/
/*====================================================================*/

/* Define, and set defaults. */
Bool   VG_(clo_error_limit)    = True;
Bool   VG_(clo_db_attach)      = False;
Char*  VG_(clo_db_command)     = VG_CLO_DEFAULT_DBCOMMAND;
Bool   VG_(clo_gen_suppressions) = False;
Int    VG_(clo_sanity_level)   = 1;
Int    VG_(clo_verbosity)      = 1;
Bool   VG_(clo_demangle)       = True;
Bool   VG_(clo_trace_children) = False;

/* See big comment in vg_include.h for meaning of these three.
   fd is initially stdout, for --help, but gets moved to stderr by default
   immediately afterwards. */
VgLogTo VG_(clo_log_to)        = VgLogTo_Fd;
Int     VG_(clo_log_fd)        = 1;
Char*   VG_(clo_log_name)      = NULL;

Int    VG_(clo_input_fd)       = 0; /* stdin */
Int    VG_(clo_n_suppressions) = 0;
Char*  VG_(clo_suppressions)[VG_CLO_MAX_SFILES];
Bool   VG_(clo_profile)        = False;
Bool   VG_(clo_single_step)    = False;
Bool   VG_(clo_optimise)       = True;
UChar  VG_(clo_trace_codegen)  = 0; // 00000000b
Bool   VG_(clo_trace_syscalls) = False;
Bool   VG_(clo_trace_signals)  = False;
Bool   VG_(clo_trace_symtab)   = False;
Bool   VG_(clo_trace_sched)    = False;
Int    VG_(clo_trace_pthread_level) = 0;
Int    VG_(clo_dump_error)     = 0;
Int    VG_(clo_backtrace_size) = 4;
Char*  VG_(clo_weird_hacks)    = NULL;
Bool   VG_(clo_run_libc_freeres) = True;
Bool   VG_(clo_track_fds)      = False;
Bool   VG_(clo_chain_bb)       = True;
Bool   VG_(clo_show_below_main) = False;
Bool   VG_(clo_pointercheck)   = True;
Bool   VG_(clo_branchpred)     = False;

static Bool   VG_(clo_wait_for_gdb)   = False;

/* If we're doing signal routing, poll for signals every 50mS by
   default. */
Int    VG_(clo_signal_polltime) = 50;

/* These flags reduce thread wakeup latency on syscall completion and
   signal delivery, respectively.  The downside is possible unfairness. */
Bool   VG_(clo_lowlat_syscalls) = False; /* low-latency syscalls */
Bool   VG_(clo_lowlat_signals)  = False; /* low-latency signals */


void usage ( Bool debug_help )
{
   Char* usage1 = 
"usage: valgrind --tool=<toolname> [options] prog-and-args\n"
"\n"
"  common user options for all Valgrind tools, with defaults in [ ]:\n"
"    --tool=<name>             use the Valgrind tool named <name>\n"
"    -h --help                 show this message\n"
"    --help-debug              show this message, plus debugging options\n"
"    --version                 show version\n"
"    -q --quiet                run silently; only print error msgs\n"
"    -v --verbose              be more verbose, incl counts of errors\n"
"    --trace-children=no|yes   Valgrind-ise child processes? [no]\n"
"    --track-fds=no|yes        track open file descriptors? [no]\n"
"\n"
"  uncommon user options for all Valgrind tools:\n"
"    --run-libc-freeres=no|yes free up glibc memory at exit? [yes]\n"
"    --weird-hacks=hack1,hack2,...  recognised hacks: lax-ioctls [none]\n"
"    --signal-polltime=<time>  signal poll period (mS) for older kernels [50]\n"
"    --lowlat-signals=no|yes   improve thread signal wake-up latency [no]\n"
"    --lowlat-syscalls=no|yes  improve thread syscall wake-up latency [no]\n"
"    --pointercheck=no|yes     enforce client address space limits [yes]\n"
"\n"
"  user options for Valgrind tools that report errors:\n"
"    --log-fd=<number>         log messages to file descriptor [2=stderr]\n"
"    --log-file=<file>         log messages to <file>.pid<pid>\n"
"    --log-socket=ipaddr:port  log messages to socket ipaddr:port\n"
"    --demangle=no|yes         automatically demangle C++ names? [yes]\n"
"    --num-callers=<number>    show <num> callers in stack traces [4]\n"
"    --error-limit=no|yes      stop showing new errors if too many? [yes]\n"
"    --show-below-main=no|yes  continue stack traces below main() [no]\n"
"    --suppressions=<filename> suppress errors described in <filename>\n"
"    --gen-suppressions=no|yes print suppressions for errors detected [no]\n"
"    --db-attach=no|yes        start debugger when errors detected? [no]\n"
"    --db-command=<command>    command to start debugger [gdb -nw %%f %%p]\n"
"    --input-fd=<number>       file descriptor for input [0=stdin]\n"
"\n";

   Char* usage2 = 
"\n"
"  debugging options for all Valgrind tools:\n"
"    --sanity-level=<number>   level of sanity checking to do [1]\n"
"    --single-step=no|yes      translate each instr separately? [no]\n"
"    --optimise=no|yes         improve intermediate code? [yes]\n"
"    --profile=no|yes          profile? (tool must be built for it) [no]\n"
"    --chain-bb=no|yes         do basic-block chaining? [yes]\n"
"    --branchpred=yes|no       generate branch prediction hints [no]\n"
"    --trace-codegen=<XXXXX>   show generated code? (X = 0|1) [00000]\n"
"    --trace-syscalls=no|yes   show all system calls? [no]\n"
"    --trace-signals=no|yes    show signal handling details? [no]\n"
"    --trace-symtab=no|yes     show symbol table details? [no]\n"
"    --trace-sched=no|yes      show thread scheduler details? [no]\n"
"    --trace-pthread=none|some|all  show pthread event details? [none]\n"
"    --wait-for-gdb=yes|no     pause on startup to wait for gdb attach\n"
"\n"
"  debugging options for Valgrind tools that report errors\n"
"    --dump-error=<number>     show translation for basic block associated\n"
"                              with <number>'th error context [0=show none]\n"
"\n";

   Char* usage3 =
"\n"
"  Extra options read from ~/.valgrindrc, $VALGRIND_OPTS, ./.valgrindrc\n"
"\n"
"  Valgrind is Copyright (C) 2000-2004 Julian Seward\n"
"  and licensed under the GNU General Public License, version 2.\n"
"  Bug reports, feedback, admiration, abuse, etc, to: %s.\n"
"\n"
"  Tools are copyright and licensed by their authors.  See each\n"
"  tool's start-up message for more information.\n"
"\n";

   VG_(printf)(usage1);
   if (VG_(details).name) {
      VG_(printf)("  user options for %s:\n", VG_(details).name);
      if (VG_(needs).command_line_options)
	 SK_(print_usage)();
      else
	 VG_(printf)("    (none)\n");
   }
   if (debug_help) {
      VG_(printf)(usage2);

      if (VG_(details).name) {
         VG_(printf)("  debugging options for %s:\n", VG_(details).name);
      
         if (VG_(needs).command_line_options)
            SK_(print_debug_usage)();
         else
            VG_(printf)("    (none)\n");
      }
   }
   VG_(printf)(usage3, VG_BUGS_TO);
   VG_(exit)(0);
}

static void pre_process_cmd_line_options
      ( Int* need_help, const char** tool, const char** exec )
{
   UInt i;

   /* parse the options we have (only the options we care about now) */
   for (i = 1; i < VG_(vg_argc); i++) {

      if (strcmp(VG_(vg_argv)[i], "--version") == 0) {
         printf("valgrind-" VERSION "\n");
         exit(0);

      } else if (VG_CLO_STREQ(VG_(vg_argv)[i], "--help") ||
                 VG_CLO_STREQ(VG_(vg_argv)[i], "-h")) {
         *need_help = 1;

      } else if (VG_CLO_STREQ(VG_(vg_argv)[i], "--help-debug")) {
         *need_help = 2;

      } else if (VG_CLO_STREQN(7, VG_(vg_argv)[i], "--tool=") ||
	         VG_CLO_STREQN(7, VG_(vg_argv)[i], "--skin=")) {
	 *tool = &VG_(vg_argv)[i][7];
	 
      } else if (VG_CLO_STREQN(7, VG_(vg_argv)[i], "--exec=")) {
	 *exec = &VG_(vg_argv)[i][7];
      }
   }

   /* If no tool specified, can act appropriately without loading tool */
   if (*tool == NULL) {
      if (0 == *need_help) {
         // neither --tool nor --help/--help-debug specified
         missing_tool_option();
      } else {
         // Give help message, without any tool-specific help
         usage(/*help-debug?*/2 == *need_help);
      }
   }
}

static void process_cmd_line_options
      ( UInt* client_auxv, Addr esp_at_startup, const char* toolname )
{
   Int  i, eventually_log_fd;
   Int *auxp;
   Int  toolname_len = VG_(strlen)(toolname);

   /* log to stderr by default, but usage message goes to stdout */
   eventually_log_fd = 2; 

   /* Check for sane path in ./configure --prefix=... */
   if (VG_LIBDIR[0] != '/') 
     config_error("Please use absolute paths in "
                  "./configure --prefix=... or --libdir=...");

   for (auxp = client_auxv; auxp[0] != VKI_AT_NULL; auxp += 2) {
      switch(auxp[0]) {
      case VKI_AT_SYSINFO:
	 VG_(sysinfo_page_exists) = True;
	 auxp[1] = (Int)(VG_(client_trampoline_code) + VG_(tramp_syscall_offset));
	 VG_(sysinfo_page_addr) = auxp[1];
	 break;
      }
   } 

   /* We know the initial ESP is pointing at argc/argv */
   VG_(client_argc) = *(Int *)esp_at_startup;
   VG_(client_argv) = (Char **)(esp_at_startup + sizeof(Int));

   for (i = 1; i < VG_(vg_argc); i++) {

      Char* arg = VG_(vg_argv)[i];

      // XXX: allow colons in options, for Josef

      /* Look for matching "--toolname:foo" */
      if (VG_(strstr)(arg, ":")) {
         if (VG_CLO_STREQN(2,            arg,                "--") && 
             VG_CLO_STREQN(toolname_len, arg+2,              toolname) &&
             VG_CLO_STREQN(1,            arg+2+toolname_len, ":"))
         {
            // prefix matches, convert "--toolname:foo" to "--foo"
            if (0)
               VG_(printf)("tool-specific arg: %s\n", arg);
            arg += toolname_len + 1;
            arg[0] = '-';
            arg[1] = '-';

         } else {
            // prefix doesn't match, skip to next arg
            continue;
         }
      }
      
      /* Ignore these options - they've already been handled */
      if (VG_CLO_STREQN(7, arg, "--tool=") ||
	  VG_CLO_STREQN(7, arg, "--skin="))
	 continue;
      if (VG_CLO_STREQN(7, arg, "--exec="))
	 continue;

      if (     VG_CLO_STREQ(arg, "--"))
	 continue;

      else if (VG_CLO_STREQ(arg, "-v") ||
               VG_CLO_STREQ(arg, "--verbose"))
         VG_(clo_verbosity)++;

      else if (VG_CLO_STREQ(arg, "-q") ||
               VG_CLO_STREQ(arg, "--quiet"))
         VG_(clo_verbosity)--;

      else VG_BOOL_CLO("--branchpred",       VG_(clo_branchpred))
      else VG_BOOL_CLO("--chain-bb",         VG_(clo_chain_bb))
      else VG_BOOL_CLO("--db-attach",        VG_(clo_db_attach))
      else VG_BOOL_CLO("--demangle",         VG_(clo_demangle))
      else VG_BOOL_CLO("--error-limit",      VG_(clo_error_limit))
      else VG_BOOL_CLO("--gen-suppressions", VG_(clo_gen_suppressions))
      else VG_BOOL_CLO("--lowlat-signals",   VG_(clo_lowlat_signals))
      else VG_BOOL_CLO("--lowlat-syscalls",  VG_(clo_lowlat_syscalls))
      else VG_BOOL_CLO("--optimise",         VG_(clo_optimise))
      else VG_BOOL_CLO("--pointercheck",     VG_(clo_pointercheck))
      else VG_BOOL_CLO("--profile",          VG_(clo_profile))
      else VG_BOOL_CLO("--run-libc-freeres", VG_(clo_run_libc_freeres))
      else VG_BOOL_CLO("--show-below-main",  VG_(clo_show_below_main))
      else VG_BOOL_CLO("--single-step",      VG_(clo_single_step))
      else VG_BOOL_CLO("--track-fds",        VG_(clo_track_fds))
      else VG_BOOL_CLO("--trace-children",   VG_(clo_trace_children))
      else VG_BOOL_CLO("--trace-sched",      VG_(clo_trace_sched))
      else VG_BOOL_CLO("--trace-signals",    VG_(clo_trace_signals))
      else VG_BOOL_CLO("--trace-symtab",     VG_(clo_trace_symtab))
      else VG_BOOL_CLO("--trace-syscalls",   VG_(clo_trace_syscalls))
      else VG_BOOL_CLO("--wait-for-gdb",     VG_(clo_wait_for_gdb))

      else VG_STR_CLO ("--db-command",        VG_(clo_db_command))
      else VG_STR_CLO ("--weird-hacks",       VG_(clo_weird_hacks))

      else VG_NUM_CLO ("--dump-error",        VG_(clo_dump_error))
      else VG_NUM_CLO ("--input-fd",          VG_(clo_input_fd))
      else VG_NUM_CLO ("--sanity-level",      VG_(clo_sanity_level))
      else VG_NUM_CLO ("--signal­polltime",   VG_(clo_signal_polltime))
      else VG_BNUM_CLO("--num-callers",       VG_(clo_backtrace_size), 1,
                                                VG_DEEPEST_BACKTRACE)

      // for backwards compatibility, replaced by --log-fd
      else if (VG_CLO_STREQN(13, arg, "--logfile-fd=")) {
         VG_(clo_log_to)   = VgLogTo_Fd;
         VG_(clo_log_name) = NULL;
         eventually_log_fd = (Int)VG_(atoll)(&arg[13]);
      }
      else if (VG_CLO_STREQN(9,  arg, "--log-fd=")) {
         VG_(clo_log_to)   = VgLogTo_Fd;
         VG_(clo_log_name) = NULL;
         eventually_log_fd = (Int)VG_(atoll)(&arg[9]);
      }

      // for backwards compatibility, replaced by --log-file
      else if (VG_CLO_STREQN(10, arg, "--logfile=")) {
         VG_(clo_log_to)   = VgLogTo_File;
         VG_(clo_log_name) = &arg[10];
      }
      else if (VG_CLO_STREQN(11, arg, "--log-file=")) {
         VG_(clo_log_to)   = VgLogTo_File;
         VG_(clo_log_name) = &arg[11];
      }

      // for backwards compatibility, replaced by --log-socket
      else if (VG_CLO_STREQN(12, arg, "--logsocket=")) {
         VG_(clo_log_to)   = VgLogTo_Socket;
         VG_(clo_log_name) = &arg[12];
      }
      else if (VG_CLO_STREQN(13, arg, "--log-socket=")) {
         VG_(clo_log_to)   = VgLogTo_Socket;
         VG_(clo_log_name) = &arg[13];
      }

      else if (VG_CLO_STREQN(15, arg, "--suppressions=")) {
         if (VG_(clo_n_suppressions) >= VG_CLO_MAX_SFILES) {
            VG_(message)(Vg_UserMsg, "Too many suppression files specified.");
            VG_(message)(Vg_UserMsg, 
                         "Increase VG_CLO_MAX_SFILES and recompile.");
            VG_(bad_option)(arg);
         }
         VG_(clo_suppressions)[VG_(clo_n_suppressions)] = &arg[15];
         VG_(clo_n_suppressions)++;
      }

      /* "vwxyz" --> 000zyxwv (binary) */
      else if (VG_CLO_STREQN(16, arg, "--trace-codegen=")) {
         Int j;
         char* opt = & arg[16];
   
         if (5 != VG_(strlen)(opt)) {
            VG_(message)(Vg_UserMsg, 
                         "--trace-codegen argument must have 5 digits");
            VG_(bad_option)(arg);
         }
         for (j = 0; j < 5; j++) {
            if      ('0' == opt[j]) { /* do nothing */ }
            else if ('1' == opt[j]) VG_(clo_trace_codegen) |= (1 << j);
            else {
               VG_(message)(Vg_UserMsg, "--trace-codegen argument can only "
                                        "contain 0s and 1s");
               VG_(bad_option)(arg);
            }
         }
      }

      else if (VG_CLO_STREQ(arg, "--trace-pthread=none"))
         VG_(clo_trace_pthread_level) = 0;
      else if (VG_CLO_STREQ(arg, "--trace-pthread=some"))
         VG_(clo_trace_pthread_level) = 1;
      else if (VG_CLO_STREQ(arg, "--trace-pthread=all"))
         VG_(clo_trace_pthread_level) = 2;

      else if ( ! VG_(needs).command_line_options
             || ! SK_(process_cmd_line_option)(arg) ) {
         VG_(bad_option)(arg);
      }
   }

   // Check various option values

   if (VG_(clo_verbosity) < 0)
      VG_(clo_verbosity) = 0;

   if (VG_(clo_db_attach) && VG_(clo_trace_children)) {
      VG_(message)(Vg_UserMsg, "");
      VG_(message)(Vg_UserMsg, 
         "--db-attach=yes conflicts with --trace-children=yes");
      VG_(message)(Vg_UserMsg, 
         "Please choose one or the other, but not both.");
      VG_(bad_option)("--db-attach=yes and --trace-children=yes");
   }

   /* Set up logging now.  After this is done, VG_(clo_log_fd)
      should be connected to whatever sink has been selected, and we
      indiscriminately chuck stuff into it without worrying what the
      nature of it is.  Oh the wonder of Unix streams. */

   /* So far we should be still attached to stdout, so we can show on
      the terminal any problems to do with processing command line
      opts. */
   vg_assert(VG_(clo_log_fd) == 1 /* stdout */);
   vg_assert(VG_(logging_to_filedes) == True);

   switch (VG_(clo_log_to)) {

      case VgLogTo_Fd: 
         vg_assert(VG_(clo_log_name) == NULL);
         VG_(clo_log_fd) = eventually_log_fd;
         break;

      case VgLogTo_File: {
         Char logfilename[1000];
	 Int seq = 0;
	 Int pid = VG_(getpid)();

         vg_assert(VG_(clo_log_name) != NULL);
         vg_assert(VG_(strlen)(VG_(clo_log_name)) <= 900); /* paranoia */

	 for (;;) {
	    if (seq == 0)
	       VG_(sprintf)(logfilename, "%s.pid%d",
			    VG_(clo_log_name), pid );
	    else
	       VG_(sprintf)(logfilename, "%s.pid%d.%d",
			    VG_(clo_log_name), pid, seq );
	    seq++;

	    eventually_log_fd 
	       = VG_(open)(logfilename, 
			   VKI_O_CREAT|VKI_O_WRONLY|VKI_O_EXCL|VKI_O_TRUNC, 
			   VKI_S_IRUSR|VKI_S_IWUSR);
	    if (eventually_log_fd >= 0) {
	       VG_(clo_log_fd) = VG_(safe_fd)(eventually_log_fd);
	       break;
	    } else {
	       if (eventually_log_fd != -VKI_EEXIST) {
		  VG_(message)(Vg_UserMsg, 
			       "Can't create/open log file `%s.pid%d'; giving up!", 
			       VG_(clo_log_name), pid);
		  VG_(bad_option)(
		     "--log-file=<file> didn't work out for some reason.");
		  break;
	       }
	    }
	 }
         break;
      }

      case VgLogTo_Socket: {
         vg_assert(VG_(clo_log_name) != NULL);
         vg_assert(VG_(strlen)(VG_(clo_log_name)) <= 900); /* paranoia */
         eventually_log_fd = VG_(connect_via_socket)( VG_(clo_log_name) );
         if (eventually_log_fd == -1) {
            VG_(message)(Vg_UserMsg, 
               "Invalid --log-socket=ipaddr or --log-socket=ipaddr:port spec"); 
            VG_(message)(Vg_UserMsg, 
               "of `%s'; giving up!", VG_(clo_log_name) );
            VG_(bad_option)(
               "--log-socket=");
	 }
         if (eventually_log_fd == -2) {
            VG_(message)(Vg_UserMsg, 
               "valgrind: failed to connect to logging server `%s'.",
               VG_(clo_log_name) ); 
            VG_(message)(Vg_UserMsg, 
                "Log messages will sent to stderr instead." );
            VG_(message)(Vg_UserMsg, 
                "" );
            /* We don't change anything here. */
	 } else {
            vg_assert(eventually_log_fd > 0);
            VG_(clo_log_fd) = eventually_log_fd;
            VG_(logging_to_filedes) = False;
         }
         break;
      }

   }

   /* Move log_fd into the safe range, so it doesn't conflict with any app fds */
   eventually_log_fd = VG_(fcntl)(VG_(clo_log_fd), VKI_F_DUPFD, VG_(max_fd)+1);
   if (eventually_log_fd < 0)
      VG_(message)(Vg_UserMsg, "valgrind: failed to move logfile fd into safe range");
   else {
      VG_(clo_log_fd) = eventually_log_fd;
      VG_(fcntl)(VG_(clo_log_fd), VKI_F_SETFD, VKI_FD_CLOEXEC);
   }

   /* Ok, the logging sink is running now.  Print a suitable preamble.
      If logging to file or a socket, write details of parent PID and
      command line args, to help people trying to interpret the
      results of a run which encompasses multiple processes. */

   if (VG_(clo_verbosity > 0)) {
      /* Skin details */
      VG_(message)(Vg_UserMsg, "%s%s%s, %s for x86-linux.",
                   VG_(details).name, 
                   NULL == VG_(details).version ?        "" : "-",
                   NULL == VG_(details).version 
                      ? (Char*)"" : VG_(details).version,
                   VG_(details).description);
      VG_(message)(Vg_UserMsg, "%s", VG_(details).copyright_author);

      /* Core details */
      VG_(message)(Vg_UserMsg,
         "Using valgrind-%s, a program supervision framework for x86-linux.",
         VERSION);
      VG_(message)(Vg_UserMsg, 
         "Copyright (C) 2000-2004, and GNU GPL'd, by Julian Seward.");
   }

   if (VG_(clo_verbosity) > 0 && VG_(clo_log_to) != VgLogTo_Fd) {
      VG_(message)(Vg_UserMsg, "");
      VG_(message)(Vg_UserMsg, 
         "My PID = %d, parent PID = %d.  Prog and args are:",
         VG_(getpid)(), VG_(getppid)() );
      for (i = 0; i < VG_(client_argc); i++) 
         VG_(message)(Vg_UserMsg, "   %s", VG_(client_argv)[i]);
   }

   if (VG_(clo_verbosity) > 1) {
      Int fd;
      if (VG_(clo_log_to) != VgLogTo_Fd)
         VG_(message)(Vg_UserMsg, "");
      VG_(message)(Vg_UserMsg, "Valgrind library directory: %s", VG_(libdir));
      VG_(message)(Vg_UserMsg, "Command line");
      for (i = 0; i < VG_(client_argc); i++)
         VG_(message)(Vg_UserMsg, "   %s", VG_(client_argv)[i]);

      VG_(message)(Vg_UserMsg, "Startup, with flags:");
      for (i = 1; i < VG_(vg_argc); i++) {
         VG_(message)(Vg_UserMsg, "   %s", VG_(vg_argv)[i]);
      }

      VG_(message)(Vg_UserMsg, "Contents of /proc/version:");
      fd = VG_(open) ( "/proc/version", VKI_O_RDONLY, 0 );
      if (fd < 0) {
         VG_(message)(Vg_UserMsg, "  can't open /proc/version");
      } else {
         #define BUF_LEN    256
         Char version_buf[BUF_LEN];
         Int n = VG_(read) ( fd, version_buf, BUF_LEN );
         vg_assert(n <= 256);
         if (n > 0) {
            version_buf[n-1] = '\0';
            VG_(message)(Vg_UserMsg, "  %s", version_buf);
         } else {
            VG_(message)(Vg_UserMsg, "  (empty?)");
         }
         VG_(close)(fd);
         #undef BUF_LEN
      }
   }

   if (VG_(clo_n_suppressions) < VG_CLO_MAX_SFILES-1 &&
       (VG_(needs).core_errors || VG_(needs).skin_errors)) {
      /* If there are no suppression files specified and the skin
	 needs one, load the default */
      static const Char default_supp[] = "default.supp";
      Int len = VG_(strlen)(VG_(libdir)) + 1 + sizeof(default_supp);
      Char *buf = VG_(arena_malloc)(VG_AR_CORE, len);
      VG_(sprintf)(buf, "%s/%s", VG_(libdir), default_supp);
      VG_(clo_suppressions)[VG_(clo_n_suppressions)] = buf;
      VG_(clo_n_suppressions)++;
   }

   if (VG_(clo_gen_suppressions) && 
       !VG_(needs).core_errors && !VG_(needs).skin_errors) {
      VG_(message)(Vg_UserMsg, 
                   "Can't use --gen-suppressions=yes with this tool,");
      VG_(message)(Vg_UserMsg, 
                   "as it doesn't generate errors.");
      VG_(bad_option)("--gen-suppressions=yes");
   }
}


/*====================================================================*/
/*=== File descriptor setup                                        ===*/
/*====================================================================*/

static void setup_file_descriptors(void)
{
   struct vki_rlimit rl;

   /* Get the current file descriptor limits. */
   if (VG_(getrlimit)(VKI_RLIMIT_NOFILE, &rl) < 0) {
      rl.rlim_cur = 1024;
      rl.rlim_max = 1024;
   }

   /* Work out where to move the soft limit to. */
   if (rl.rlim_cur + VG_N_RESERVED_FDS <= rl.rlim_max) {
      rl.rlim_cur = rl.rlim_cur + VG_N_RESERVED_FDS;
   } else {
      rl.rlim_cur = rl.rlim_max;
   }

   /* Reserve some file descriptors for our use. */
   VG_(max_fd) = rl.rlim_cur - VG_N_RESERVED_FDS;

   /* Update the soft limit. */
   VG_(setrlimit)(VKI_RLIMIT_NOFILE, &rl);

   if (VG_(vgexecfd) != -1)
      VG_(vgexecfd) = VG_(safe_fd)( VG_(vgexecfd) );
   if (VG_(clexecfd) != -1)
      VG_(clexecfd) = VG_(safe_fd)( VG_(clexecfd) );
}


/*====================================================================*/
/*=== baseBlock: definition + setup                                ===*/
/*====================================================================*/

/* The variables storing offsets. */

#define INVALID_OFFSET (-1)

Int VGOFF_(m_eax) = INVALID_OFFSET;
Int VGOFF_(m_ecx) = INVALID_OFFSET;
Int VGOFF_(m_edx) = INVALID_OFFSET;
Int VGOFF_(m_ebx) = INVALID_OFFSET;
Int VGOFF_(m_esp) = INVALID_OFFSET;
Int VGOFF_(m_ebp) = INVALID_OFFSET;
Int VGOFF_(m_esi) = INVALID_OFFSET;
Int VGOFF_(m_edi) = INVALID_OFFSET;
Int VGOFF_(m_eflags) = INVALID_OFFSET;
Int VGOFF_(m_dflag)  = INVALID_OFFSET;
Int VGOFF_(m_ssestate) = INVALID_OFFSET;
Int VGOFF_(ldt)   = INVALID_OFFSET;
Int VGOFF_(tls)   = INVALID_OFFSET;
Int VGOFF_(m_cs)  = INVALID_OFFSET;
Int VGOFF_(m_ss)  = INVALID_OFFSET;
Int VGOFF_(m_ds)  = INVALID_OFFSET;
Int VGOFF_(m_es)  = INVALID_OFFSET;
Int VGOFF_(m_fs)  = INVALID_OFFSET;
Int VGOFF_(m_gs)  = INVALID_OFFSET;
Int VGOFF_(m_eip) = INVALID_OFFSET;
Int VGOFF_(spillslots) = INVALID_OFFSET;
Int VGOFF_(sh_eax) = INVALID_OFFSET;
Int VGOFF_(sh_ecx) = INVALID_OFFSET;
Int VGOFF_(sh_edx) = INVALID_OFFSET;
Int VGOFF_(sh_ebx) = INVALID_OFFSET;
Int VGOFF_(sh_esp) = INVALID_OFFSET;
Int VGOFF_(sh_ebp) = INVALID_OFFSET;
Int VGOFF_(sh_esi) = INVALID_OFFSET;
Int VGOFF_(sh_edi) = INVALID_OFFSET;
Int VGOFF_(sh_eflags) = INVALID_OFFSET;

Int VGOFF_(helper_idiv_64_32) = INVALID_OFFSET;
Int VGOFF_(helper_div_64_32) = INVALID_OFFSET;
Int VGOFF_(helper_idiv_32_16) = INVALID_OFFSET;
Int VGOFF_(helper_div_32_16) = INVALID_OFFSET;
Int VGOFF_(helper_idiv_16_8) = INVALID_OFFSET;
Int VGOFF_(helper_div_16_8) = INVALID_OFFSET;
Int VGOFF_(helper_imul_32_64) = INVALID_OFFSET;
Int VGOFF_(helper_mul_32_64) = INVALID_OFFSET;
Int VGOFF_(helper_imul_16_32) = INVALID_OFFSET;
Int VGOFF_(helper_mul_16_32) = INVALID_OFFSET;
Int VGOFF_(helper_imul_8_16) = INVALID_OFFSET;
Int VGOFF_(helper_mul_8_16) = INVALID_OFFSET;
Int VGOFF_(helper_CLD) = INVALID_OFFSET;
Int VGOFF_(helper_STD) = INVALID_OFFSET;
Int VGOFF_(helper_get_dirflag) = INVALID_OFFSET;
Int VGOFF_(helper_CLC) = INVALID_OFFSET;
Int VGOFF_(helper_STC) = INVALID_OFFSET;
Int VGOFF_(helper_CMC) = INVALID_OFFSET;
Int VGOFF_(helper_shldl) = INVALID_OFFSET;
Int VGOFF_(helper_shldw) = INVALID_OFFSET;
Int VGOFF_(helper_shrdl) = INVALID_OFFSET;
Int VGOFF_(helper_shrdw) = INVALID_OFFSET;
Int VGOFF_(helper_IN) = INVALID_OFFSET;
Int VGOFF_(helper_OUT) = INVALID_OFFSET;
Int VGOFF_(helper_RDTSC) = INVALID_OFFSET;
Int VGOFF_(helper_CPUID) = INVALID_OFFSET;
Int VGOFF_(helper_BSWAP) = INVALID_OFFSET;
Int VGOFF_(helper_bsfw) = INVALID_OFFSET;
Int VGOFF_(helper_bsfl) = INVALID_OFFSET;
Int VGOFF_(helper_bsrw) = INVALID_OFFSET;
Int VGOFF_(helper_bsrl) = INVALID_OFFSET;
Int VGOFF_(helper_fstsw_AX) = INVALID_OFFSET;
Int VGOFF_(helper_SAHF) = INVALID_OFFSET;
Int VGOFF_(helper_LAHF) = INVALID_OFFSET;
Int VGOFF_(helper_DAS) = INVALID_OFFSET;
Int VGOFF_(helper_DAA) = INVALID_OFFSET;
Int VGOFF_(helper_AAS) = INVALID_OFFSET;
Int VGOFF_(helper_AAA) = INVALID_OFFSET;
Int VGOFF_(helper_AAD) = INVALID_OFFSET;
Int VGOFF_(helper_AAM) = INVALID_OFFSET;
Int VGOFF_(helper_cmpxchg8b) = INVALID_OFFSET;
Int VGOFF_(helper_undefined_instruction) = INVALID_OFFSET;

/* MAX_NONCOMPACT_HELPERS can be increased easily.  If MAX_COMPACT_HELPERS is
 * increased too much, they won't really be compact any more... */
#define  MAX_COMPACT_HELPERS     8
#define  MAX_NONCOMPACT_HELPERS  50 

UInt VG_(n_compact_helpers)    = 0;
UInt VG_(n_noncompact_helpers) = 0;

Addr VG_(compact_helper_addrs)  [MAX_COMPACT_HELPERS];
Int  VG_(compact_helper_offsets)[MAX_COMPACT_HELPERS];
Addr VG_(noncompact_helper_addrs)  [MAX_NONCOMPACT_HELPERS];
Int  VG_(noncompact_helper_offsets)[MAX_NONCOMPACT_HELPERS];

/* This is the actual defn of baseblock. */
UInt VG_(baseBlock)[VG_BASEBLOCK_WORDS];

/* Words. */
static Int baB_off = 0;


UInt VG_(insertDflag)(UInt eflags, Int d)
{
   vg_assert(d == 1 || d == -1);
   eflags &= ~EFlagD;

   if (d < 0)
      eflags |= EFlagD;

   return eflags;
}

Int VG_(extractDflag)(UInt eflags)
{
   Int ret;

   if (eflags & EFlagD)
      ret = -1;
   else
      ret = 1;

   return ret;
}

/* Returns the offset, in words. */
static Int alloc_BaB ( Int words )
{
   Int off = baB_off;
   baB_off += words;
   if (baB_off >= VG_BASEBLOCK_WORDS)
      VG_(core_panic)( "alloc_BaB: baseBlock is too small");

   return off;   
}

/* Align offset, in *bytes* */
static void align_BaB ( UInt align )
{
   vg_assert(2 == align || 4 == align || 8 == align || 16 == align);
   baB_off +=  (align-1);
   baB_off &= ~(align-1);
}

/* Allocate 1 word in baseBlock and set it to the given value. */
static Int alloc_BaB_1_set ( Addr a )
{
   Int off = alloc_BaB(1);
   VG_(baseBlock)[off] = (UInt)a;
   return off;
}

/* Registers a function in compact_helper_addrs;  compact_helper_offsets is
   filled in later. */
void VG_(register_compact_helper)(Addr a)
{
   if (MAX_COMPACT_HELPERS <= VG_(n_compact_helpers)) {
      VG_(printf)("Can only register %d compact helpers\n", 
                  MAX_COMPACT_HELPERS);
      VG_(core_panic)("Too many compact helpers registered");
   }
   VG_(compact_helper_addrs)[VG_(n_compact_helpers)] = a;
   VG_(n_compact_helpers)++;
}

/* Registers a function in noncompact_helper_addrs;  noncompact_helper_offsets
 * is filled in later.
 */
void VG_(register_noncompact_helper)(Addr a)
{
   if (MAX_NONCOMPACT_HELPERS <= VG_(n_noncompact_helpers)) {
      VG_(printf)("Can only register %d non-compact helpers\n", 
                  MAX_NONCOMPACT_HELPERS);
      VG_(printf)("Try increasing MAX_NON_COMPACT_HELPERS\n");
      VG_(core_panic)("Too many non-compact helpers registered");
   }
   VG_(noncompact_helper_addrs)[VG_(n_noncompact_helpers)] = a;
   VG_(n_noncompact_helpers)++;
}

/* Allocate offsets in baseBlock for the skin helpers */
static 
void assign_helpers_in_baseBlock(UInt n, Int offsets[], Addr addrs[])
{
   UInt i;
   for (i = 0; i < n; i++) 
      offsets[i] = alloc_BaB_1_set( addrs[i] );
}

Bool VG_(need_to_handle_esp_assignment)(void)
{
   return ( VG_(defined_new_mem_stack_4)()  ||
            VG_(defined_die_mem_stack_4)()  ||
            VG_(defined_new_mem_stack_8)()  ||
            VG_(defined_die_mem_stack_8)()  ||
            VG_(defined_new_mem_stack_12)() ||
            VG_(defined_die_mem_stack_12)() ||
            VG_(defined_new_mem_stack_16)() ||
            VG_(defined_die_mem_stack_16)() ||
            VG_(defined_new_mem_stack_32)() ||
            VG_(defined_die_mem_stack_32)() ||
            VG_(defined_new_mem_stack)()    ||
            VG_(defined_die_mem_stack)()
          );
}

/* Here we assign actual offsets.  It's important to get the most
   popular referents within 128 bytes of the start, so we can take
   advantage of short addressing modes relative to %ebp.  Popularity
   of offsets was measured on 22 Feb 02 running a KDE application, and
   the slots rearranged accordingly, with a 1.5% reduction in total
   size of translations. */
static void init_baseBlock ( Addr client_eip, Addr esp_at_startup )
{
   /* Those with offsets under 128 are carefully chosen. */

   /* WORD offsets in this column */
   /* 0   */ VGOFF_(m_eax)     = alloc_BaB_1_set(0);
   /* 1   */ VGOFF_(m_ecx)     = alloc_BaB_1_set(0);
   /* 2   */ VGOFF_(m_edx)     = alloc_BaB_1_set(0);
   /* 3   */ VGOFF_(m_ebx)     = alloc_BaB_1_set(0);
   /* 4   */ VGOFF_(m_esp)     = alloc_BaB_1_set(esp_at_startup);
   /* 5   */ VGOFF_(m_ebp)     = alloc_BaB_1_set(0);
   /* 6   */ VGOFF_(m_esi)     = alloc_BaB_1_set(0);
   /* 7   */ VGOFF_(m_edi)     = alloc_BaB_1_set(0);
   /* 8   */ VGOFF_(m_eflags)  = alloc_BaB_1_set(0);

   if (VG_(needs).shadow_regs) {
      /* 9   */ VGOFF_(sh_eax)    = alloc_BaB_1_set(0);
      /* 10  */ VGOFF_(sh_ecx)    = alloc_BaB_1_set(0);
      /* 11  */ VGOFF_(sh_edx)    = alloc_BaB_1_set(0);
      /* 12  */ VGOFF_(sh_ebx)    = alloc_BaB_1_set(0);
      /* 13  */ VGOFF_(sh_esp)    = alloc_BaB_1_set(0);
      /* 14  */ VGOFF_(sh_ebp)    = alloc_BaB_1_set(0);
      /* 15  */ VGOFF_(sh_esi)    = alloc_BaB_1_set(0);
      /* 16  */ VGOFF_(sh_edi)    = alloc_BaB_1_set(0);
      /* 17  */ VGOFF_(sh_eflags) = alloc_BaB_1_set(0);
      VG_TRACK( post_regs_write_init );
   }

   /* 9,10,11 or 18,19,20... depends on number whether shadow regs are used
    * and on compact helpers registered */ 

   /* Make these most-frequently-called specialised ones compact, if they
      are used. */
   if (VG_(defined_new_mem_stack_4)())
      VG_(register_compact_helper)( (Addr) VG_(tool_interface).track_new_mem_stack_4);

   if (VG_(defined_die_mem_stack_4)())
      VG_(register_compact_helper)( (Addr) VG_(tool_interface).track_die_mem_stack_4);

   /* (9 or 18) + n_compact_helpers  */
   /* Allocate slots for compact helpers */
   assign_helpers_in_baseBlock(VG_(n_compact_helpers), 
                               VG_(compact_helper_offsets), 
                               VG_(compact_helper_addrs));

   /* (9/10 or 18/19) + n_compact_helpers */
   VGOFF_(m_eip) = alloc_BaB_1_set(client_eip);

   /* There are currently 24 spill slots */
   /* (11+/20+ .. 32+/43+) + n_compact_helpers.  This can overlap the magic
    * boundary at >= 32 words, but most spills are to low numbered spill
    * slots, so the ones above the boundary don't see much action. */
   VGOFF_(spillslots) = alloc_BaB(VG_MAX_SPILLSLOTS);

   /* I gave up counting at this point.  Since they're above the
      short-amode-boundary, there's no point. */

   VGOFF_(m_dflag) = alloc_BaB_1_set(1);  // 1 == forward D-flag

   /* The FPU/SSE state.  This _must_ be 16-byte aligned.  Initial
      state doesn't matter much, as long as it's not totally borked. */
   align_BaB(16);
   VGOFF_(m_ssestate) = alloc_BaB(VG_SIZE_OF_SSESTATE_W);
   vg_assert( 
      0 == ( ((UInt)(& VG_(baseBlock)[VGOFF_(m_ssestate)])) % 16 )
   );

   /* I assume that if we have SSE2 we also have SSE */
   VG_(have_ssestate) = 
	   VG_(cpu_has_feature)(VG_X86_FEAT_FXSR) &&
	   VG_(cpu_has_feature)(VG_X86_FEAT_SSE);

   /* set up an initial FPU state (doesn't really matter what it is,
      so long as it's somewhat valid) */
   if (!VG_(have_ssestate))
      asm volatile("fwait; fnsave %0; fwait; frstor %0; fwait" 
                   : 
                   : "m" (VG_(baseBlock)[VGOFF_(m_ssestate)]) 
                   : "cc", "memory");
   else
      asm volatile("fwait; fxsave %0; fwait; andl $0xffbf, %1;"
                   "fxrstor %0; fwait"
                   : 
                   : "m" (VG_(baseBlock)[VGOFF_(m_ssestate)]), 
                     "m" (VG_(baseBlock)[VGOFF_(m_ssestate)+(24/4)]) 
                   : "cc", "memory");

   if (0) {
      if (VG_(have_ssestate))
         VG_(printf)("Looks like a SSE-capable CPU\n");
      else
         VG_(printf)("Looks like a MMX-only CPU\n");
   }

   /* LDT pointer: pretend the root thread has an empty LDT to start with. */
   VGOFF_(ldt)   = alloc_BaB_1_set((UInt)NULL);

   /* TLS pointer: pretend the root thread has no TLS array for now. */
   VGOFF_(tls)   = alloc_BaB_1_set((UInt)NULL);

   /* segment registers */
   VGOFF_(m_cs)  = alloc_BaB_1_set(0);
   VGOFF_(m_ss)  = alloc_BaB_1_set(0);
   VGOFF_(m_ds)  = alloc_BaB_1_set(0);
   VGOFF_(m_es)  = alloc_BaB_1_set(0);
   VGOFF_(m_fs)  = alloc_BaB_1_set(0);
   VGOFF_(m_gs)  = alloc_BaB_1_set(0);

   /* initialise %cs, %ds and %ss to point at the operating systems
      default code, data and stack segments */
   asm volatile("movw %%cs, %0"
                :
                : "m" (VG_(baseBlock)[VGOFF_(m_cs)]));
   asm volatile("movw %%ds, %0"
                :
                : "m" (VG_(baseBlock)[VGOFF_(m_ds)]));
   asm volatile("movw %%ss, %0"
                :
                : "m" (VG_(baseBlock)[VGOFF_(m_ss)]));

   VG_(register_noncompact_helper)( (Addr) & VG_(do_useseg) );

#define REG(kind, size) \
   if (VG_(defined_##kind##_mem_stack##size)()) \
      VG_(register_noncompact_helper)(           \
          (Addr) VG_(tool_interface).track_##kind##_mem_stack##size );
   REG(new, _8);
   REG(new, _12);
   REG(new, _16);
   REG(new, _32);
   REG(new, );
   REG(die, _8);
   REG(die, _12);
   REG(die, _16);
   REG(die, _32);
   REG(die, );
#undef REG

   if (VG_(need_to_handle_esp_assignment)())
      VG_(register_noncompact_helper)((Addr) VG_(unknown_esp_update));

#  define HELPER(name) \
   VGOFF_(helper_##name) = alloc_BaB_1_set( (Addr) & VG_(helper_##name))

   /* Helper functions. */
   HELPER(idiv_64_32);     HELPER(div_64_32);
   HELPER(idiv_32_16);     HELPER(div_32_16);
   HELPER(idiv_16_8);      HELPER(div_16_8);

   HELPER(imul_32_64);     HELPER(mul_32_64);
   HELPER(imul_16_32);     HELPER(mul_16_32);
   HELPER(imul_8_16);      HELPER(mul_8_16);

   HELPER(CLD);            HELPER(STD);
   HELPER(get_dirflag);

   HELPER(CLC);            HELPER(STC);
   HELPER(CMC);

   HELPER(shldl);          HELPER(shldw);
   HELPER(shrdl);          HELPER(shrdw);

   HELPER(RDTSC);          HELPER(CPUID);

   HELPER(bsfw);           HELPER(bsfl);
   HELPER(bsrw);           HELPER(bsrl);

   HELPER(fstsw_AX);
   HELPER(SAHF);           HELPER(LAHF);
   HELPER(DAS);            HELPER(DAA);
   HELPER(AAS);            HELPER(AAA);
   HELPER(AAD);            HELPER(AAM);
   HELPER(IN);             HELPER(OUT);
   HELPER(cmpxchg8b);

   HELPER(undefined_instruction);

#  undef HELPER

   /* Allocate slots for noncompact helpers */
   assign_helpers_in_baseBlock(VG_(n_noncompact_helpers), 
                               VG_(noncompact_helper_offsets), 
                               VG_(noncompact_helper_addrs));
}


/*====================================================================*/
/*=== Setup pointercheck                                           ===*/
/*====================================================================*/

static void setup_pointercheck(void)
{
   int ret;

   if (VG_(clo_pointercheck)) {
      vki_modify_ldt_t ldt = { 
         VG_POINTERCHECK_SEGIDX,    // entry_number
         VG_(client_base),          // base_addr
         (VG_(client_end)-VG_(client_base)) / VKI_BYTES_PER_PAGE, // limit
         1,                         // seg_32bit
         0,                         // contents: data, RW, non-expanding
         0,                         // ! read_exec_only
         1,                         // limit_in_pages
         0,                         // ! seg not present
         1,                         // useable
      };
      ret = VG_(do_syscall)(__NR_modify_ldt, 1, &ldt, sizeof(ldt));
      if (ret < 0) {
	 VG_(message)(Vg_UserMsg,
		      "Warning: ignoring --pointercheck=yes, "
		      "because modify_ldt failed (errno=%d)", -ret);
	 VG_(clo_pointercheck) = False;
      }
   }
}

/*====================================================================*/
/*===  Initialise program data/text, etc.                          ===*/
/*====================================================================*/

static void build_valgrind_map_callback 
      ( Addr start, UInt size, Char rr, Char ww, Char xx, 
        UInt dev, UInt ino, ULong foffset, const UChar* filename )
{
   UInt prot  = 0;
   UInt flags = SF_MMAP|SF_NOSYMS;
   Bool is_stack_segment;

   is_stack_segment = 
      (start == VG_(clstk_base) && (start+size) == VG_(clstk_end));

   /* Only record valgrind mappings for now, without loading any
      symbols.  This is so we know where the free space is before we
      start allocating more memory (note: heap is OK, it's just mmap
      which is the problem here). */
   if (start >= VG_(valgrind_base) && (start+size) <= VG_(valgrind_end)) {
      flags |= SF_VALGRIND;
      VG_(map_file_segment)(start, size, prot, flags, dev, ino, foffset, filename);
   }
}

// Global var used to pass local data to callback
Addr esp_at_startup___global_arg = 0;

static void build_segment_map_callback 
      ( Addr start, UInt size, Char rr, Char ww, Char xx,
        UInt dev, UInt ino, ULong foffset, const UChar* filename )
{
   UInt prot = 0;
   UInt flags;
   Bool is_stack_segment;
   Addr r_esp;

   is_stack_segment 
      = (start == VG_(clstk_base) && (start+size) == VG_(clstk_end));

   if (rr == 'r') prot |= VKI_PROT_READ;
   if (ww == 'w') prot |= VKI_PROT_WRITE;
   if (xx == 'x') prot |= VKI_PROT_EXEC;

   if (is_stack_segment)
      flags = SF_STACK | SF_GROWDOWN;
   else
      flags = SF_EXEC|SF_MMAP;

   if (filename != NULL)
      flags |= SF_FILE;

   if (start >= VG_(valgrind_base) && (start+size) <= VG_(valgrind_end))
      flags |= SF_VALGRIND;

   VG_(map_file_segment)(start, size, prot, flags, dev, ino, foffset, filename);

   if (VG_(is_client_addr)(start) && VG_(is_client_addr)(start+size-1))
      VG_TRACK( new_mem_startup, start, size, rr=='r', ww=='w', xx=='x' );

   /* If this is the stack segment mark all below %esp as noaccess. */
   r_esp = esp_at_startup___global_arg;
   vg_assert(0 != r_esp);
   if (is_stack_segment) {
      if (0)
         VG_(message)(Vg_DebugMsg, "invalidating stack area: %x .. %x",
                      start,r_esp);
      VG_TRACK( die_mem_stack, start, r_esp-start );
   }
}


/*====================================================================*/
/*=== Sanity check machinery (permanently engaged)                 ===*/
/*====================================================================*/

/* A fast sanity check -- suitable for calling circa once per
   millisecond. */

void VG_(do_sanity_checks) ( Bool force_expensive )
{
   VGP_PUSHCC(VgpCoreCheapSanity);

   if (VG_(clo_sanity_level) < 1) return;

   /* --- First do all the tests that we can do quickly. ---*/

   VG_(sanity_fast_count)++;

   /* Check stuff pertaining to the memory check system. */

   /* Check that nobody has spuriously claimed that the first or
      last 16 pages of memory have become accessible [...] */
   if (VG_(needs).sanity_checks) {
      VGP_PUSHCC(VgpSkinCheapSanity);
      vg_assert(SK_(cheap_sanity_check)());
      VGP_POPCC(VgpSkinCheapSanity);
   }

   /* --- Now some more expensive checks. ---*/

   /* Once every 25 times, check some more expensive stuff. */
   if ( force_expensive
     || VG_(clo_sanity_level) > 1
     || (VG_(clo_sanity_level) == 1 && (VG_(sanity_fast_count) % 25) == 0)) {

      VGP_PUSHCC(VgpCoreExpensiveSanity);
      VG_(sanity_slow_count)++;

      VG_(proxy_sanity)();

#     if 0
      { void zzzmemscan(void); zzzmemscan(); }
#     endif

      if ((VG_(sanity_fast_count) % 250) == 0)
         VG_(sanity_check_tc_tt)();

      if (VG_(needs).sanity_checks) {
          VGP_PUSHCC(VgpSkinExpensiveSanity);
          vg_assert(SK_(expensive_sanity_check)());
          VGP_POPCC(VgpSkinExpensiveSanity);
      }
      /* 
      if ((VG_(sanity_fast_count) % 500) == 0) VG_(mallocSanityCheckAll)(); 
      */
      VGP_POPCC(VgpCoreExpensiveSanity);
   }

   if (VG_(clo_sanity_level) > 1) {
      VGP_PUSHCC(VgpCoreExpensiveSanity);
      /* Check sanity of the low-level memory manager.  Note that bugs
         in the client's code can cause this to fail, so we don't do
         this check unless specially asked for.  And because it's
         potentially very expensive. */
      VG_(mallocSanityCheckAll)();
      VGP_POPCC(VgpCoreExpensiveSanity);
   }
   VGP_POPCC(VgpCoreCheapSanity);
}


/*====================================================================*/
/*=== main()                                                       ===*/
/*====================================================================*/

int main(int argc, char **argv)
{
   char **cl_argv;
   const char *tool = NULL;
   const char *exec = NULL;
   char *preload;          /* tool-specific LD_PRELOAD .so */
   char **env;
   Int need_help = 0;      // 0 = no, 1 = --help, 2 = --help-debug
   struct exeinfo info;
   ToolInfo *toolinfo = NULL;
   void *tool_dlhandle;
   Addr client_eip;
   Addr esp_at_startup;    /* client's %esp at the point we gained control. */
   UInt * client_auxv;
   VgSchedReturnCode src;
   vki_rlimit zero = { 0, 0 };

   //============================================================
   // Nb: startup is complex.  Prerequisites are shown at every step.
   //
   // *** Be very careful when messing with the order ***
   //============================================================

   //============================================================
   // Command line argument handling order:
   // * If --help/--help-debug are present, show usage message 
   //   (if --tool is also present, that includes the tool-specific usage)
   // * Then, if --tool is missing, abort with error msg
   // * Then, if client is missing, abort with error msg
   // * Then, if any cmdline args are bad, abort with error msg
   //============================================================

   // Get the current process datasize rlimit, and set it to zero.
   // This prevents any internal uses of brk() from having any effect.
   // We remember the old value so we can restore it on exec, so that
   // child processes will have a reasonable brk value.
   VG_(getrlimit)(VKI_RLIMIT_DATA, &VG_(client_rlimit_data));
   zero.rlim_max = VG_(client_rlimit_data).rlim_max;
   VG_(setrlimit)(VKI_RLIMIT_DATA, &zero);
   
   //--------------------------------------------------------------
   // Check we were launched by stage1
   //   p: n/a  [must be first step]
   //--------------------------------------------------------------
   scan_auxv();

   if (0) {
      int prmap(void *start, void *end, const char *perm, off_t off, 
                int maj, int min, int ino) {
         printf("mapping %10p-%10p %s %02x:%02x %d\n",
                start, end, perm, maj, min, ino);
         return True;
      }
      printf("========== main() ==========\n");
      foreach_map(prmap);
   }

   //--------------------------------------------------------------
   // Look for alternative libdir                                  
   //   p: n/a
   //--------------------------------------------------------------
   {  char *cp = getenv(VALGRINDLIB);
      if (cp != NULL)
	 VG_(libdir) = cp;
   }

   //--------------------------------------------------------------
   // Begin working out address space layout
   //   p: n/a
   //--------------------------------------------------------------
   layout_client_space( (Addr) & argc );

   //--------------------------------------------------------------
   // Get valgrind args + client args (inc. from VALGRIND_OPTS/.valgrindrc).
   // Pre-process the command line.
   //   p: n/a
   //--------------------------------------------------------------
   get_command_line(argc, argv, &VG_(vg_argc), &VG_(vg_argv), &cl_argv);
   pre_process_cmd_line_options(&need_help, &tool, &exec);

   //==============================================================
   // Nb: once a tool is specified, the tool.so must be loaded even if 
   // they specified --help or didn't specify a client program.
   //==============================================================

   //--------------------------------------------------------------
   // With client padded out, map in tool
   //   p: layout_client_space()          [for padding]
   //   p: set-libdir                     [for VG_(libdir)]
   //   p: pre_process_cmd_line_options() [for 'tool']
   //--------------------------------------------------------------
   load_tool(tool, &tool_dlhandle, &toolinfo, &preload);

   //==============================================================
   // Can use VG_(malloc)() and VG_(arena_malloc)() only after load_tool()
   // -- redzone size is now set.
   //==============================================================
   
   //--------------------------------------------------------------
   // Finalise address space layout
   //   p: layout_client_space(), load_tool()           [for 'toolinfo']
   //--------------------------------------------------------------
   layout_remaining_space( toolinfo->shadow_ratio );

   //--------------------------------------------------------------
   // Load client executable, finding in $PATH if necessary
   //   p: layout_client_space()           [so there's space]
   //   p: pre_process_cmd_line_options()  [for 'exec', 'need_help']
   //   p: layout_remaining_space          [so there's space]
   //--------------------------------------------------------------
   load_client(cl_argv, exec, need_help, &info, &client_eip);

   //--------------------------------------------------------------
   // Everything in place, unpad us
   //   p: layout_remaining_space()  [everything must be mapped in before now]  
   //   p: load_client()             [ditto] 
   //--------------------------------------------------------------
   as_unpad((void *)VG_(shadow_end), (void *)~0);
   as_closepadfile();		/* no more padding */

   //--------------------------------------------------------------
   // Set up client's environment
   //   p: set-libdir  [for VG_(libdir)]
   //   p: load_tool() [for 'preload']
   //--------------------------------------------------------------
   env = fix_environment(environ, preload);

   //--------------------------------------------------------------
   // Setup client stack and eip 
   //   p: load_client()     [for 'info']
   //   p: fix_environment() [for 'env']
   //--------------------------------------------------------------
   esp_at_startup = setup_client_stack(cl_argv, env, &info, &client_auxv);

   if (0)
      printf("entry=%x client esp=%x vg_argc=%d brkbase=%x\n",
	     client_eip, esp_at_startup, VG_(vg_argc), VG_(brk_base));

   //==============================================================
   // Finished setting up operating environment.  Now initialise
   // Valgrind.  (This is where the old VG_(main)() started.)
   //==============================================================

   //--------------------------------------------------------------
   // Read /proc/self/maps into a buffer
   //   p: all memory layout, environment setup   [so memory maps are right]
   //--------------------------------------------------------------
   VG_(read_procselfmaps)();

   //--------------------------------------------------------------
   // atfork
   //   p: n/a
   //--------------------------------------------------------------
   VG_(atfork)(NULL, NULL, newpid);
   newpid(VG_INVALID_THREADID);

   //--------------------------------------------------------------
   // setup file descriptors
   //   p: n/a
   //--------------------------------------------------------------
   setup_file_descriptors();

   //--------------------------------------------------------------
   // Setup tool
   //   p: VG_(read_procselfmaps)()  [so if sk_pre_clo_init calls
   //        VG_(malloc), any mmap'd superblocks aren't erroneously
   //        identified later as being owned by the client]
   // XXX: is that necessary, now that we look for V's segments separately?
   // XXX: alternatively, if sk_pre_clo_init does use VG_(malloc)(), is it
   //      wrong to ignore any segments that might add in parse_procselfmaps?
   //--------------------------------------------------------------
   (*toolinfo->sk_pre_clo_init)();
   VG_(tool_init_dlsym)(tool_dlhandle);
   VG_(sanity_check_needs)();

   //--------------------------------------------------------------
   // If --tool and --help/--help-debug was given, now give the core+tool
   // help message
   //   p: pre_clo_init()
   //--------------------------------------------------------------
   if (need_help) {
      usage(/*--help-debug?*/2 == need_help);
   }

   //--------------------------------------------------------------
   // Process Valgrind's + tool's command-line options
   //   p: load_tool()               [for 'tool']
   //   p: setup_file_descriptors()  [for 'VG_(max_fd)']
   //   p: sk_pre_clo_init           [to set 'command_line_options' need]
   //--------------------------------------------------------------
   process_cmd_line_options(client_auxv, esp_at_startup, tool);

   //--------------------------------------------------------------
   // Allow GDB attach
   //   p: process_cmd_line_options()  [for VG_(clo_wait_for_gdb)]
   //--------------------------------------------------------------
   /* Hook to delay things long enough so we can get the pid and
      attach GDB in another shell. */
   if (VG_(clo_wait_for_gdb)) {
      VG_(printf)("pid=%d\n", VG_(getpid)());
      /* do "jump *$eip" to skip this in gdb */
      VG_(do_syscall)(__NR_pause);
   }

   //--------------------------------------------------------------
   // Setup tool, post command-line processing
   //   p: process_cmd_line_options  [tool assumes it]
   //--------------------------------------------------------------
   SK_(post_clo_init)();

   //--------------------------------------------------------------
   // Set up baseBlock
   //   p: {pre,post}_clo_init()  [for tool helper registration]
   //      load_client()          [for 'client_eip']
   //      setup_client_stack()   [for 'esp_at_startup']
   //--------------------------------------------------------------
   init_baseBlock(client_eip, esp_at_startup);

   //--------------------------------------------------------------
   // Search for file descriptors that are inherited from our parent
   //   p: process_cmd_line_options  [for VG_(clo_track_fds)]
   //--------------------------------------------------------------
   if (VG_(clo_track_fds))
      VG_(init_preopened_fds)();

   //--------------------------------------------------------------
   // Initialise the scheduler
   //   p: init_baseBlock()  [baseBlock regs copied into VG_(threads)[1]]
   //   p: setup_file_descriptors() [else VG_(safe_fd)() breaks]
   //--------------------------------------------------------------
   VG_(scheduler_init)();

   //--------------------------------------------------------------
   // Set up the ProxyLWP machinery
   //   p: VG_(scheduler_init)()?  [XXX: subtle dependency?]
   // - subs: VG_(sigstartup_actions)()?
   //--------------------------------------------------------------
   VG_(proxy_init)();

   //--------------------------------------------------------------
   // Initialise the signal handling subsystem
   //   p: VG_(atfork)(NULL, NULL, newpid) [else problems with sigmasks]
   //   p: VG_(proxy_init)()               [else breaks...]
   //--------------------------------------------------------------
   // Nb: temporarily parks the saved blocking-mask in saved_sigmask.
   VG_(sigstartup_actions)();

   //--------------------------------------------------------------
   // Perhaps we're profiling Valgrind?
   //   p: process_cmd_line_options()  [for VG_(clo_profile)]
   //   p: others?
   //
   // XXX: this seems to be broken?   It always says the tool wasn't built
   // for profiling;  vg_profile.c's functions don't seem to be overriding
   // vg_dummy_profile.c's?
   //
   // XXX: want this as early as possible.  Looking for --profile
   // in pre_process_cmd_line_options() could get it earlier.
   //--------------------------------------------------------------
   if (VG_(clo_profile))
      VGP_(init_profiling)();

   VGP_PUSHCC(VgpStartup);

   //--------------------------------------------------------------
   // Reserve Valgrind's kickstart, heap and stack
   //   p: XXX ???
   //--------------------------------------------------------------
   VG_(map_segment)(VG_(valgrind_mmap_end),
                    VG_(valgrind_end)-VG_(valgrind_mmap_end),
                    VKI_PROT_NONE, SF_VALGRIND|SF_FIXED);

   //--------------------------------------------------------------
   // Identify Valgrind's segments
   //   p: read proc/self/maps
   //   p: VG_(map_segment)   [XXX ???]
   //   p: sk_pre_clo_init()  [to setup new_mem_startup tracker]
   //--------------------------------------------------------------
   VG_(parse_procselfmaps) ( build_valgrind_map_callback );

   // XXX: I can't see why these two need to be separate;  could they be
   // folded together?  If not, need a comment explaining why.
   //
   // XXX: can we merge reading and parsing of /proc/self/maps?
   //
   // XXX: can we dynamically allocate the /proc/self/maps buffer? (or mmap
   //      it?)  Or does that disturb its contents...

   //--------------------------------------------------------------
   // Build segment map (all segments)
   //   p: setup_client_stack()  [for 'esp_at_startup']
   //--------------------------------------------------------------
   esp_at_startup___global_arg = esp_at_startup;
   VG_(parse_procselfmaps) ( build_segment_map_callback );  /* everything */
   esp_at_startup___global_arg = 0;
   
   //==============================================================
   // Can only use VG_(map)() after VG_(map_segment)()  [XXX ???]
   //==============================================================

   //--------------------------------------------------------------
   // Build segment map (all segments)
   //   p: setup_client_stack()  [for 'esp_at_startup']
   //--------------------------------------------------------------
   /* Initialize our trampoline page (which is also sysinfo stuff) */
   VG_(memcpy)( (void *)VG_(client_trampoline_code),
                &VG_(trampoline_code_start), VG_(trampoline_code_length) );
   VG_(mprotect)( (void *)VG_(client_trampoline_code),
                 VG_(trampoline_code_length), VKI_PROT_READ|VKI_PROT_EXEC );

   //--------------------------------------------------------------
   // Read suppression file
   //   p: process_cmd_line_options()  [for VG_(clo_suppressions)]
   //--------------------------------------------------------------
   if (VG_(needs).core_errors || VG_(needs).skin_errors)
      VG_(load_suppressions)();

   //--------------------------------------------------------------
   // Initialise translation table and translation cache
   //   p: read_procselfmaps  [so the anonymous mmaps for the TT/TC
   //         aren't identified as part of the client, which would waste
   //         > 20M of virtual address space.]
   //--------------------------------------------------------------
   VG_(init_tt_tc)();

   //--------------------------------------------------------------
   // Read debug info to find glibc entry points to intercept
   //   p: parse_procselfmaps? [XXX for debug info?]
   //   p: init_tt_tc?  [XXX ???]
   //--------------------------------------------------------------
   VG_(setup_code_redirect_table)();

   //--------------------------------------------------------------
   // Verbosity message
   //   p: end_rdtsc_calibration [so startup message is printed first]
   //--------------------------------------------------------------
   if (VG_(clo_verbosity) == 1)
      VG_(message)(Vg_UserMsg, "For more details, rerun with: -v");
   if (VG_(clo_verbosity) > 0)
      VG_(message)(Vg_UserMsg, "");

   //--------------------------------------------------------------
   // Setup pointercheck
   //   p: process_cmd_line_options() [for VG_(clo_pointercheck)]
   //--------------------------------------------------------------
   setup_pointercheck();



   //--------------------------------------------------------------
   // Run!
   //--------------------------------------------------------------
   VG_(running_on_simd_CPU) = True;
   VGP_POPCC(VgpStartup);
   VGP_PUSHCC(VgpSched);

   if (__builtin_setjmp(&VG_(fatal_signal_jmpbuf)) == 0) {
      VG_(fatal_signal_set) = True;
      src = VG_(scheduler)();
   } else
      src = VgSrc_FatalSig;

   VGP_POPCC(VgpSched);
   VG_(running_on_simd_CPU) = False;



   //--------------------------------------------------------------
   // Finalisation: cleanup, messages, etc.  Order no so important, only
   // affects what order the messages come.
   //--------------------------------------------------------------
   if (VG_(clo_verbosity) > 0)
      VG_(message)(Vg_UserMsg, "");

   if (src == VgSrc_Deadlock) {
     VG_(message)(Vg_UserMsg, 
        "Warning: pthread scheduler exited due to deadlock");
   }

   /* Print out file descriptor summary and stats. */
   if (VG_(clo_track_fds))
      VG_(fd_stats)();

   if (VG_(needs).core_errors || VG_(needs).skin_errors)
      VG_(show_all_errors)();

   SK_(fini)( VG_(exitcode) );

   VG_(do_sanity_checks)( True /*include expensive checks*/ );

   if (VG_(clo_verbosity) > 1)
      show_counts();

   if (VG_(clo_verbosity) > 3)
      VG_(print_UInstr_histogram)();

   if (0) {
      VG_(message)(Vg_DebugMsg, "");
      VG_(message)(Vg_DebugMsg, 
         "------ Valgrind's internal memory use stats follow ------" );
      VG_(mallocSanityCheckAll)();
      VG_(show_all_arena_stats)();
      VG_(message)(Vg_DebugMsg, 
         "------ Valgrind's ExeContext management stats follow ------" );
      VG_(show_ExeContext_stats)();
   }
 
   if (VG_(clo_profile))
      VGP_(done_profiling)();

   /* We're exiting, so nuke all the threads and clean up the proxy LWPs */
   vg_assert(src == VgSrc_FatalSig ||
	     VG_(threads)[VG_(last_run_tid)].status == VgTs_Runnable ||
	     VG_(threads)[VG_(last_run_tid)].status == VgTs_WaitJoiner);
   VG_(nuke_all_threads_except)(VG_INVALID_THREADID);

   //--------------------------------------------------------------
   // Exit, according to the scheduler's return code
   //--------------------------------------------------------------
   switch (src) {
      case VgSrc_ExitSyscall: /* the normal way out */
         vg_assert(VG_(last_run_tid) > 0 
                   && VG_(last_run_tid) < VG_N_THREADS);
	 VG_(proxy_shutdown)();

         /* The thread's %EBX at the time it did __NR_exit() will hold
            the arg to __NR_exit(), so we just do __NR_exit() with
            that arg. */
         VG_(exit)( VG_(exitcode) );
         /* NOT ALIVE HERE! */
         VG_(core_panic)("entered the afterlife in main() -- ExitSyscall");
         break; /* what the hell :) */

      case VgSrc_Deadlock:
         /* Just exit now.  No point in continuing. */
	 VG_(proxy_shutdown)();
         VG_(exit)(0);
         VG_(core_panic)("entered the afterlife in main() -- Deadlock");
         break;

      case VgSrc_FatalSig:
	 /* We were killed by a fatal signal, so replicate the effect */
	 vg_assert(VG_(fatal_sigNo) != -1);
	 VG_(kill_self)(VG_(fatal_sigNo));
	 VG_(core_panic)("main(): signal was supposed to be fatal");
	 break;

      default:
         VG_(core_panic)("main(): unexpected scheduler return code");
   }

   abort();
}


/*--------------------------------------------------------------------*/
/*--- end                                                vg_main.c ---*/
/*--------------------------------------------------------------------*/