process_event.c

#if HAVE_CONFIG_H
#include "config.h"
#endif

#define _GNU_SOURCE
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <signal.h>
#include <assert.h>

#include "ltrace.h"
#include "output.h"
#include "options.h"
#include "elf.h"
#include "debug.h"

#ifdef __powerpc__
#include <sys/ptrace.h>
#endif

static void process_signal(struct event * event);
static void process_exit(struct event * event);
static void process_exit_signal(struct event * event);
static void process_syscall(struct event * event);
static void process_sysret(struct event * event);
static void process_breakpoint(struct event * event);
static void remove_proc(struct process * proc);

static void callstack_push_syscall(struct process * proc, int sysnum);
static void callstack_push_symfunc(struct process * proc, struct library_symbol * sym);
static void callstack_pop(struct process * proc);

void
process_event(struct event * event) {
	switch (event->thing) {
		case LT_EV_NONE:
			debug(1, "event: none");
			return;
		case LT_EV_SIGNAL:
			debug(1, "event: signal (%d)", event->e_un.signum);
			process_signal(event);
			return;
		case LT_EV_EXIT:
			debug(1, "event: exit (%d)", event->e_un.ret_val);
			process_exit(event);
			return;
		case LT_EV_EXIT_SIGNAL:
			debug(1, "event: exit signal (%d)", event->e_un.signum);
			process_exit_signal(event);
			return;
		case LT_EV_SYSCALL:
			debug(1, "event: syscall (%d)", event->e_un.sysnum);
			process_syscall(event);
			return;
		case LT_EV_SYSRET:
			debug(1, "event: sysret (%d)", event->e_un.sysnum);
			process_sysret(event);
			return;
		case LT_EV_BREAKPOINT:
			debug(1, "event: breakpoint");
			process_breakpoint(event);
			return;
		default:
			fprintf(stderr, "Error! unknown event?\n");
			exit(1);
	}
}

static char *
shortsignal(int signum) {
	static char * signalent0[] = {
	#include "signalent.h"
	};
	int nsignals0 = sizeof signalent0 / sizeof signalent0[0];

	if (signum<0 || signum>=nsignals0) {
		return "UNKNOWN_SIGNAL";
	} else {
		return signalent0[signum];
	}
}

static char *
sysname(int sysnum) {
	static char result[128];
	static char * syscalent0[] = {
	#include "syscallent.h"
	};
	int nsyscals0 = sizeof syscalent0 / sizeof syscalent0[0];

	if (sysnum<0 || sysnum>nsyscals0) {
		sprintf(result, "SYS_%d", sysnum);
		return result;
	} else {
		sprintf(result, "SYS_%s", syscalent0[sysnum]);
		return result;
	}
}

static void
process_signal(struct event * event) {
	if (exiting && event->e_un.signum == SIGSTOP) {
		pid_t pid = event->proc->pid;
		disable_all_breakpoints(event->proc);
		untrace_pid(pid);
		remove_proc(event->proc);
		continue_after_signal(pid, event->e_un.signum);
		return;
	}
	output_line(event->proc, "--- %s (%s) ---",
		shortsignal(event->e_un.signum), strsignal(event->e_un.signum));
	continue_after_signal(event->proc->pid, event->e_un.signum);
}

static void
process_exit(struct event * event) {
	output_line(event->proc, "+++ exited (status %d) +++",
		event->e_un.ret_val);
	remove_proc(event->proc);
}

static void
process_exit_signal(struct event * event) {
	output_line(event->proc, "+++ killed by %s +++",
		shortsignal(event->e_un.signum));
	remove_proc(event->proc);
}

static void
remove_proc(struct process * proc) {
	struct process *tmp, *tmp2;

	debug(1, "Removing pid %u\n", proc->pid);

	if (list_of_processes == proc) {
		tmp = list_of_processes;
		list_of_processes = list_of_processes->next;
		free(tmp);
		return;
	}
	tmp = list_of_processes;
	while(tmp->next) {
		if (tmp->next==proc) {
			tmp2 = tmp->next;
			tmp->next = tmp->next->next;
			free(tmp2);
			continue;
		}
		tmp = tmp->next;
	}
}

static void
process_syscall(struct event * event) {
	if (opt_S) {
		output_left(LT_TOF_SYSCALL, event->proc, sysname(event->e_un.sysnum));
	}
	callstack_push_syscall(event->proc, event->e_un.sysnum);
	if (fork_p(event->e_un.sysnum) || exec_p(event->e_un.sysnum)) {
		disable_all_breakpoints(event->proc);
	} else if (!event->proc->breakpoints_enabled) {
		enable_all_breakpoints(event->proc);
	}
	continue_process(event->proc->pid);
}

static void
process_sysret(struct event * event) {
	if (exec_p(event->e_un.sysnum)) {
		if (gimme_arg(LT_TOF_SYSCALL,event->proc,-1)==0) {

			event->proc->filename = pid2name(event->proc->pid);
			event->proc->list_of_symbols = read_elf(event->proc->filename);

			/* The kernel will stop the process just after an execve()
			 * and we will be able to enable breakpoints again
			 */
			event->proc->breakpoints_enabled = -1;
		}
	}
	if (fork_p(event->e_un.sysnum)) {
		if (opt_f) {
			pid_t child = gimme_arg(LT_TOF_SYSCALL,event->proc,-1);
			if (child>0) {
				open_pid(child, 0);
			}
		}
		enable_all_breakpoints(event->proc);
	}
	callstack_pop(event->proc);
	if (opt_S) {
		output_right(LT_TOF_SYSCALL, event->proc, sysname(event->e_un.sysnum));
	}
	continue_process(event->proc->pid);
}

static void
process_breakpoint(struct event * event) {
	struct library_symbol * tmp;
	int i,j;

	debug(2, "event: breakpoint (0x%08x)", event->e_un.brk_addr);
	if (event->proc->breakpoint_being_enabled) {
		/* Reinsert breakpoint */
		continue_enabling_breakpoint(event->proc->pid, event->proc->breakpoint_being_enabled);
		event->proc->breakpoint_being_enabled = NULL;
		return;
	}

	for(i=event->proc->callstack_depth-1; i>=0; i--) {
		if (event->e_un.brk_addr == event->proc->callstack[i].return_addr) {
#ifdef __powerpc__
                       unsigned long a;
                       unsigned long addr = event->proc->callstack[i].c_un.libfunc->enter_addr;
                       struct breakpoint *sbp = address2bpstruct(event->proc, addr);
                       unsigned char break_insn[] = BREAKPOINT_VALUE;

                       /*
                        * PPC HACK! (XXX FIXME TODO)
                        * The PLT gets modified during the first call,
                        * so be sure to re-enable the breakpoint.
                        */
                       a = ptrace(PTRACE_PEEKTEXT, event->proc->pid, addr);

                       if (memcmp(&a, break_insn, 4)) {
                               sbp->enabled--;
                               insert_breakpoint(event->proc, addr);
                       }
#endif
			for(j=event->proc->callstack_depth-1; j>=i; j--) {
				callstack_pop(event->proc);
			}
			event->proc->return_addr = event->e_un.brk_addr;
			output_right(LT_TOF_FUNCTION, event->proc,
					event->proc->callstack[i].c_un.libfunc->name);
			continue_after_breakpoint(event->proc,
					address2bpstruct(event->proc, event->e_un.brk_addr));
			return;
		}
	}

	tmp = event->proc->list_of_symbols;
	while(tmp) {
		if (event->e_un.brk_addr == tmp->enter_addr) {
			event->proc->stack_pointer = get_stack_pointer(event->proc->pid);
			event->proc->return_addr = get_return_addr(event->proc->pid, event->proc->stack_pointer);
			output_left(LT_TOF_FUNCTION, event->proc, tmp->name);
			callstack_push_symfunc(event->proc, tmp);
			continue_after_breakpoint(event->proc, address2bpstruct(event->proc, tmp->enter_addr));
			return;
		}
		tmp = tmp->next;
	}
	output_line(event->proc, "breakpointed at 0x%08x (?)",
		(unsigned)event->e_un.brk_addr);
	continue_process(event->proc->pid);
}

static void
callstack_push_syscall(struct process * proc, int sysnum) {
	struct callstack_element * elem;

	/* FIXME: not good -- should use dynamic allocation. 19990703 mortene. */
	if (proc->callstack_depth == MAX_CALLDEPTH-1) {
		fprintf(stderr, "Error: call nesting too deep!\n");
		return;
	}

	elem = & proc->callstack[proc->callstack_depth];
	elem->is_syscall = 1;
	elem->c_un.syscall = sysnum;
	elem->return_addr = NULL;

	proc->callstack_depth++;
}

static void
callstack_push_symfunc(struct process * proc, struct library_symbol * sym) {
	struct callstack_element * elem;

	/* FIXME: not good -- should use dynamic allocation. 19990703 mortene. */
	if (proc->callstack_depth == MAX_CALLDEPTH-1) {
		fprintf(stderr, "Error: call nesting too deep!\n");
		return;
	}

	elem = & proc->callstack[proc->callstack_depth];
	elem->is_syscall = 0;
	elem->c_un.libfunc = sym;

	elem->return_addr = proc->return_addr;
	insert_breakpoint(proc, elem->return_addr);

	proc->callstack_depth++;
}

static void
callstack_pop(struct process * proc) {
	struct callstack_element * elem;
	assert(proc->callstack_depth > 0);

	elem = & proc->callstack[proc->callstack_depth-1];
	if (!elem->is_syscall) {
		delete_breakpoint(proc, elem->return_addr);
	}
	proc->callstack_depth--;
}