coregrind/m_libcproc.c

/*--------------------------------------------------------------------*/
/*--- Process-related libc stuff.                     m_libcproc.c ---*/
/*--------------------------------------------------------------------*/
 
/*
   This file is part of Valgrind, a dynamic binary instrumentation
   framework.

   Copyright (C) 2000-2005 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.
*/

#include "pub_core_basics.h"
#include "pub_core_libcbase.h"
#include "pub_core_libcassert.h"
#include "pub_core_libcprint.h"
#include "pub_core_libcproc.h"
#include "pub_core_mallocfree.h"
#include "pub_core_syscall.h"
#include "vki_unistd.h"

/* ---------------------------------------------------------------------
   Command line and environment stuff
   ------------------------------------------------------------------ */

/* As deduced from sp_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);

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

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

/* We do getenv without libc's help by snooping around in
   VG_(client_envp) as determined at startup time. */
Char *VG_(getenv)(Char *varname)
{
   Int i, n;
   n = VG_(strlen)(varname);
   for (i = 0; VG_(client_envp)[i] != NULL; i++) {
      Char* s = VG_(client_envp)[i];
      if (VG_(strncmp)(varname, s, n) == 0 && s[n] == '=') {
         return & s[n+1];
      }
   }
   return NULL;
}

void  VG_(env_unsetenv) ( Char **env, const Char *varname )
{
   Char **from;
   Char **to = NULL;
   Int len = VG_(strlen)(varname);

   for(from = to = env; from && *from; from++) {
      if (!(VG_(strncmp)(varname, *from, len) == 0 && (*from)[len] == '=')) {
	 *to = *from;
	 to++;
      }
   }
   *to = *from;
}

/* set the environment; returns the old env if a new one was allocated */
Char **VG_(env_setenv) ( Char ***envp, const Char* varname, const Char *val )
{
   Char **env = (*envp);
   Char **cpp;
   Int len = VG_(strlen)(varname);
   Char *valstr = VG_(arena_malloc)(VG_AR_CORE, len + VG_(strlen)(val) + 2);
   Char **oldenv = NULL;

   VG_(sprintf)(valstr, "%s=%s", varname, val);

   for(cpp = env; cpp && *cpp; cpp++) {
      if (VG_(strncmp)(varname, *cpp, len) == 0 && (*cpp)[len] == '=') {
	 *cpp = valstr;
	 return oldenv;
      }
   }

   if (env == NULL) {
      env = VG_(arena_malloc)(VG_AR_CORE, sizeof(Char **) * 2);
      env[0] = valstr;
      env[1] = NULL;

      *envp = env;

   }  else {
      Int envlen = (cpp-env) + 2;
      Char **newenv = VG_(arena_malloc)(VG_AR_CORE, envlen * sizeof(Char **));

      for(cpp = newenv; *env; )
	 *cpp++ = *env++;
      *cpp++ = valstr;
      *cpp++ = NULL;

      oldenv = *envp;

      *envp = newenv;
   }

   return oldenv;
}

/* Walk through a colon-separated environment variable, and remove the
   entries which match remove_pattern.  It slides everything down over
   the removed entries, and pads the remaining space with '\0'.  It
   modifies the entries in place (in the client address space), but it
   shouldn't matter too much, since we only do this just before an
   execve().

   This is also careful to mop up any excess ':'s, since empty strings
   delimited by ':' are considered to be '.' in a path.
*/
static void mash_colon_env(Char *varp, const Char *remove_pattern)
{
   Char *const start = varp;
   Char *entry_start = varp;
   Char *output = varp;

   if (varp == NULL)
      return;

   while(*varp) {
      if (*varp == ':') {
	 Char prev;
	 Bool match;

	 /* This is a bit subtle: we want to match against the entry
	    we just copied, because it may have overlapped with
	    itself, junking the original. */

	 prev = *output;
	 *output = '\0';

	 match = VG_(string_match)(remove_pattern, entry_start);

	 *output = prev;
	 
	 if (match) {
	    output = entry_start;
	    varp++;			/* skip ':' after removed entry */
	 } else
	    entry_start = output+1;	/* entry starts after ':' */
      }

      *output++ = *varp++;
   }

   /* match against the last entry */
   if (VG_(string_match)(remove_pattern, entry_start)) {
      output = entry_start;
      if (output > start) {
	 /* remove trailing ':' */
	 output--;
	 vg_assert(*output == ':');
      }
   }	 

   /* pad out the left-overs with '\0' */
   while(output < varp)
      *output++ = '\0';
}


// Removes all the Valgrind-added stuff from the passed environment.  Used
// when starting child processes, so they don't see that added stuff.
void VG_(env_remove_valgrind_env_stuff)(Char** envp)
{
   Int i;
   Char* ld_preload_str = NULL;
   Char* ld_library_path_str = NULL;
   Char* buf;

   // Find LD_* variables
   for (i = 0; envp[i] != NULL; i++) {
      if (VG_(strncmp)(envp[i], "LD_PRELOAD=", 11) == 0)
         ld_preload_str = &envp[i][11];
      if (VG_(strncmp)(envp[i], "LD_LIBRARY_PATH=", 16) == 0)
         ld_library_path_str = &envp[i][16];
   }

   buf = VG_(arena_malloc)(VG_AR_CORE, VG_(strlen)(VG_(libdir)) + 20);

   // Remove Valgrind-specific entries from LD_*.
   VG_(sprintf)(buf, "%s*/vg_preload_core.so", VG_(libdir));
   mash_colon_env(ld_preload_str, buf);
   VG_(sprintf)(buf, "%s*/vgpreload_*.so", VG_(libdir));
   mash_colon_env(ld_preload_str, buf);
   VG_(sprintf)(buf, "%s*", VG_(libdir));
   mash_colon_env(ld_library_path_str, buf);

   // Remove VALGRIND_CLO variable.
   VG_(env_unsetenv)(envp, VALGRINDCLO);

   // XXX if variable becomes empty, remove it completely?

   VG_(arena_free)(VG_AR_CORE, buf);
}

/* ---------------------------------------------------------------------
   Various important syscall wrappers
   ------------------------------------------------------------------ */

Int VG_(waitpid)(Int pid, Int *status, Int options)
{
   SysRes res = VG_(do_syscall4)(__NR_wait4, pid, (UWord)status, options, 0);
   return res.isError ? -1 : res.val;
}

Int VG_(poll)( struct vki_pollfd *ufds, UInt nfds, Int timeout)
{
   SysRes res = VG_(do_syscall3)(__NR_poll, (UWord)ufds, nfds, timeout);
   /* ASSUMES SYSCALL ALWAYS SUCCEEDS */
   return res.val;
}

/* clone the environment */
static Char **env_clone ( Char **oldenv )
{
   Char **oldenvp;
   Char **newenvp;
   Char **newenv;
   Int  envlen;

   for (oldenvp = oldenv; oldenvp && *oldenvp; oldenvp++);

   envlen = oldenvp - oldenv + 1;
   
   newenv = VG_(arena_malloc)(VG_AR_CORE, envlen * sizeof(Char **));

   oldenvp = oldenv;
   newenvp = newenv;
   
   while (oldenvp && *oldenvp) {
      *newenvp++ = *oldenvp++;
   }
   
   *newenvp = *oldenvp;

   return newenv;
}

/* Return -1 if error, else 0.  NOTE does not indicate return code of
   child! */
Int VG_(system) ( Char* cmd )
{
   Int    pid;
   SysRes res;
   if (cmd == NULL)
      return 1;
   res = VG_(do_syscall0)(__NR_fork);
   if (res.isError)
      return -1;
   pid = res.val;
   if (pid == 0) {
      /* child */
      static Char** envp = NULL;
      Char* argv[4];

      /* restore the DATA rlimit for the child */
      VG_(setrlimit)(VKI_RLIMIT_DATA, &VG_(client_rlimit_data));

      envp = env_clone(VG_(client_envp));
      VG_(env_remove_valgrind_env_stuff)( envp ); 

      argv[0] = "/bin/sh";
      argv[1] = "-c";
      argv[2] = cmd;
      argv[3] = 0;

      (void)VG_(do_syscall3)(__NR_execve, 
                             (UWord)"/bin/sh", (UWord)argv, (UWord)envp);

      /* If we're still alive here, execve failed. */
      VG_(exit)(1);
   } else {
      /* parent */
      Int zzz = VG_(waitpid)(pid, NULL, 0);
      return zzz == -1 ? -1 : 0;
   }
}

/* ---------------------------------------------------------------------
   Resource limits
   ------------------------------------------------------------------ */

struct vki_rlimit VG_(client_rlimit_data);
struct vki_rlimit VG_(client_rlimit_stack);

/* Support for getrlimit. */
Int VG_(getrlimit) (Int resource, struct vki_rlimit *rlim)
{
   SysRes res = VG_(mk_SysRes_Error)(VKI_ENOSYS);
   /* res = getrlimit( resource, rlim ); */
#  ifdef __NR_ugetrlimit
   res = VG_(do_syscall2)(__NR_ugetrlimit, resource, (UWord)rlim);
#  endif
   if (res.isError && res.val == VKI_ENOSYS)
      res = VG_(do_syscall2)(__NR_getrlimit, resource, (UWord)rlim);
   return res.isError ? -1 : res.val;
}


/* Support for setrlimit. */
Int VG_(setrlimit) (Int resource, const struct vki_rlimit *rlim)
{
   SysRes res;
   /* res = setrlimit( resource, rlim ); */
   res = VG_(do_syscall2)(__NR_setrlimit, resource, (UWord)rlim);
   return res.isError ? -1 : res.val;
}

/* ---------------------------------------------------------------------
   pids, etc
   ------------------------------------------------------------------ */

Int VG_(gettid)(void)
{
   SysRes res = VG_(do_syscall0)(__NR_gettid);

   if (res.isError && res.val == VKI_ENOSYS) {
      Char pid[16];      
      /*
       * The gettid system call does not exist. The obvious assumption
       * to make at this point would be that we are running on an older
       * system where the getpid system call actually returns the ID of
       * the current thread.
       *
       * Unfortunately it seems that there are some systems with a kernel
       * where getpid has been changed to return the ID of the thread group
       * leader but where the gettid system call has not yet been added.
       *
       * So instead of calling getpid here we use readlink to see where
       * the /proc/self link is pointing...
       */

      res = VG_(do_syscall3)(__NR_readlink, (UWord)"/proc/self",
                             (UWord)pid, sizeof(pid));
      if (!res.isError && res.val > 0) {
         pid[res.val] = '\0';
         res.val = VG_(atoll)(pid);
      }
   }

   return res.val;
}

/* You'd be amazed how many places need to know the current pid. */
Int VG_(getpid) ( void )
{
   /* ASSUMES SYSCALL ALWAYS SUCCEEDS */
   return VG_(do_syscall0)(__NR_getpid) . val;
}

Int VG_(getpgrp) ( void )
{
   /* ASSUMES SYSCALL ALWAYS SUCCEEDS */
   return VG_(do_syscall0)(__NR_getpgrp) . val;
}

Int VG_(getppid) ( void )
{
   /* ASSUMES SYSCALL ALWAYS SUCCEEDS */
   return VG_(do_syscall0)(__NR_getppid) . val;
}

Int VG_(setpgid) ( Int pid, Int pgrp )
{
   /* ASSUMES SYSCALL ALWAYS SUCCEEDS */
   return VG_(do_syscall2)(__NR_setpgid, pid, pgrp) . val;
}

/* ---------------------------------------------------------------------
   Timing stuff
   ------------------------------------------------------------------ */

UInt VG_(read_millisecond_timer) ( void )
{
   static ULong base = 0;
   struct vki_timeval tv_now;
   ULong  now;
   SysRes res;

   res = VG_(do_syscall2)(__NR_gettimeofday, (UWord)&tv_now, (UWord)NULL);
   
   now = tv_now.tv_sec * 1000000ULL + tv_now.tv_usec;
   
   if (base == 0)
      base = now;

   return (now - base) / 1000;
}


void VG_(nanosleep)(struct vki_timespec *ts)
{
   (void)VG_(do_syscall2)(__NR_nanosleep, (UWord)ts, (UWord)NULL);
}

/* ---------------------------------------------------------------------
   A trivial atfork() facility for Valgrind's internal use
   ------------------------------------------------------------------ */

// Trivial because it only supports a single post-fork child action, which
// is all we need.

static vg_atfork_t atfork_child = NULL;

void VG_(atfork_child)(vg_atfork_t child)
{
   if (NULL != atfork_child)
      VG_(core_panic)("More than one atfork_child handler requested");

   atfork_child = child;
}

void VG_(do_atfork_child)(ThreadId tid)
{
   if (NULL != atfork_child)
      (*atfork_child)(tid);
}

/*--------------------------------------------------------------------*/
/*--- end                                                          ---*/
/*--------------------------------------------------------------------*/