sysdeps/linux-gnu/events.c

#include "config.h"

#define	_GNU_SOURCE	1
#include <stdlib.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <errno.h>
#include <signal.h>
#include <string.h>
#include <sys/ptrace.h>

#include "common.h"

static Event event;

Event *
next_event(void) {
	pid_t pid;
	int status;
	int tmp;
	int stop_signal;

	debug(DEBUG_FUNCTION, "next_event()");
	if (!list_of_processes) {
		debug(DEBUG_EVENT, "event: No more traced programs: exiting");
		exit(0);
	}
	pid = waitpid(-1, &status, __WALL);
	if (pid == -1) {
		if (errno == ECHILD) {
			debug(DEBUG_EVENT, "event: No more traced programs: exiting");
			exit(0);
		} else if (errno == EINTR) {
			debug(DEBUG_EVENT, "event: none (wait received EINTR?)");
			event.type = EVENT_NONE;
			return &event;
		}
		perror("wait");
		exit(1);
	}
	event.proc = pid2proc(pid);
	if (!event.proc || event.proc->state == STATE_BEING_CREATED) {
		event.type = EVENT_NEW;
		event.e_un.newpid = pid;
		debug(DEBUG_EVENT, "event: NEW: pid=%d", pid);
		return &event;
	}
	get_arch_dep(event.proc);
	event.proc->instruction_pointer = NULL;
	debug(3, "event from pid %u", pid);
	if (event.proc->breakpoints_enabled == -1) {
		event.type = EVENT_NONE;
		trace_set_options(event.proc, event.proc->pid);
		enable_all_breakpoints(event.proc);
		continue_process(event.proc->pid);
		debug(DEBUG_EVENT, "event: NONE: pid=%d (enabling breakpoints)", pid);
		return &event;
	} else if (!event.proc->libdl_hooked) {
		/* debug struct may not have been written yet.. */
		if (linkmap_init(event.proc, &main_lte) == 0) {
			event.proc->libdl_hooked = 1;
		}
	}

	if (opt_i) {
		event.proc->instruction_pointer =
			get_instruction_pointer(event.proc);
	}
	switch (syscall_p(event.proc, status, &tmp)) {
		case 1:
			event.type = EVENT_SYSCALL;
			event.e_un.sysnum = tmp;
			debug(DEBUG_EVENT, "event: SYSCALL: pid=%d, sysnum=%d", pid, tmp);
			return &event;
		case 2:
			event.type = EVENT_SYSRET;
			event.e_un.sysnum = tmp;
			debug(DEBUG_EVENT, "event: SYSRET: pid=%d, sysnum=%d", pid, tmp);
			return &event;
		case 3:
			event.type = EVENT_ARCH_SYSCALL;
			event.e_un.sysnum = tmp;
			debug(DEBUG_EVENT, "event: ARCH_SYSCALL: pid=%d, sysnum=%d", pid, tmp);
			return &event;
		case 4:
			event.type = EVENT_ARCH_SYSRET;
			event.e_un.sysnum = tmp;
			debug(DEBUG_EVENT, "event: ARCH_SYSRET: pid=%d, sysnum=%d", pid, tmp);
			return &event;
		case -1:
			event.type = EVENT_NONE;
			continue_process(event.proc->pid);
			debug(DEBUG_EVENT, "event: NONE: pid=%d (syscall_p returned -1)", pid);
			return &event;
	}
	if (WIFSTOPPED(status) && ((status>>16 == PTRACE_EVENT_FORK) || (status>>16 == PTRACE_EVENT_VFORK) || (status>>16 == PTRACE_EVENT_CLONE))) {
		unsigned long data;
		ptrace(PTRACE_GETEVENTMSG, pid, NULL, &data);
		event.type = EVENT_CLONE;
		event.e_un.newpid = data;
		debug(DEBUG_EVENT, "event: CLONE: pid=%d, newpid=%d", pid, (int)data);
		return &event;
	}
	if (WIFSTOPPED(status) && (status>>16 == PTRACE_EVENT_EXEC)) {
		event.type = EVENT_EXEC;
		debug(DEBUG_EVENT, "event: EXEC: pid=%d", pid);
		return &event;
	}
	if (WIFEXITED(status)) {
		event.type = EVENT_EXIT;
		event.e_un.ret_val = WEXITSTATUS(status);
		debug(DEBUG_EVENT, "event: EXIT: pid=%d, status=%d", pid, event.e_un.ret_val);
		return &event;
	}
	if (WIFSIGNALED(status)) {
		event.type = EVENT_EXIT_SIGNAL;
		event.e_un.signum = WTERMSIG(status);
		debug(DEBUG_EVENT, "event: EXIT_SIGNAL: pid=%d, signum=%d", pid, event.e_un.signum);
		return &event;
	}
	if (!WIFSTOPPED(status)) {
		/* should never happen */
		event.type = EVENT_NONE;
		debug(DEBUG_EVENT, "event: NONE: pid=%d (wait error?)", pid);
		return &event;
	}

	stop_signal = WSTOPSIG(status);

	/* On some targets, breakpoints are signalled not using
	   SIGTRAP, but also with SIGILL, SIGSEGV or SIGEMT.  Check
	   for these. (TODO: is this true?) */
	if (stop_signal == SIGSEGV
			|| stop_signal == SIGILL
#ifdef SIGEMT
			|| stop_signal == SIGEMT
#endif
	   ) {
		if (!event.proc->instruction_pointer) {
			event.proc->instruction_pointer =
				get_instruction_pointer(event.proc);
		}

		if (address2bpstruct(event.proc, event.proc->instruction_pointer))
			stop_signal = SIGTRAP;
	}

	if (stop_signal != (SIGTRAP | event.proc->tracesysgood)
			&& stop_signal != SIGTRAP) {
		event.type = EVENT_SIGNAL;
		event.e_un.signum = stop_signal;
		debug(DEBUG_EVENT, "event: SIGNAL: pid=%d, signum=%d", pid, stop_signal);
		return &event;
	}

	/* last case [by exhaustion] */
	event.type = EVENT_BREAKPOINT;

	if (!event.proc->instruction_pointer) {
		event.proc->instruction_pointer =
			get_instruction_pointer(event.proc);
	}
	event.e_un.brk_addr =
		event.proc->instruction_pointer - DECR_PC_AFTER_BREAK;
	debug(DEBUG_EVENT, "event: BREAKPOINT: pid=%d, addr=%p", pid, event.e_un.brk_addr);
	return &event;
}