[deliverable/binutils-gdb.git] / gdb / fork-child.c

/* Fork a Unix child process, and set up to debug it, for GDB.
   Copyright 1990, 1991, 1992 Free Software Foundation, Inc.
   Contributed by Cygnus Support.

This file is part of GDB.

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., 675 Mass Ave, Cambridge, MA 02139, USA.  */

#include "defs.h"
#include "frame.h"  /* required by inferior.h */
#include "inferior.h"
#include "target.h"
#include "wait.h"
#include "gdbcore.h"
#include "terminal.h"
#include "thread.h"

#include <signal.h>

#ifdef SET_STACK_LIMIT_HUGE
#include <sys/time.h>
#include <sys/resource.h>

extern int original_stack_limit;
#endif /* SET_STACK_LIMIT_HUGE */

extern char **environ;

#ifndef SHELL_FILE
#define SHELL_FILE "/bin/sh"
#endif

/* Start an inferior Unix child process and sets inferior_pid to its pid.
   EXEC_FILE is the file to run.
   ALLARGS is a string containing the arguments to the program.
   ENV is the environment vector to pass.  SHELL_FILE is the shell file,
   or NULL if we should pick one.  Errors reported with error().  */

void
fork_inferior (exec_file, allargs, env, traceme_fun, init_trace_fun,
	       shell_file)
     char *exec_file;
     char *allargs;
     char **env;
     void (*traceme_fun) PARAMS ((void));
     void (*init_trace_fun) PARAMS ((int));
     char *shell_file;
{
  int pid;
  char *shell_command;
  static char default_shell_file[] = SHELL_FILE;
  int len;
  /* Set debug_fork then attach to the child while it sleeps, to debug. */
  static int debug_fork = 0;
  /* This is set to the result of setpgrp, which if vforked, will be visible
     to you in the parent process.  It's only used by humans for debugging.  */
  static int debug_setpgrp = 657473;
  char **save_our_env;

  /* If no exec file handed to us, get it from the exec-file command -- with
     a good, common error message if none is specified.  */
  if (exec_file == 0)
    exec_file = get_exec_file(1);

  /* The user might want tilde-expansion, and in general probably wants
     the program to behave the same way as if run from
     his/her favorite shell.  So we let the shell run it for us.
     FIXME-maybe, we might want a "set shell" command so the user can change
     the shell from within GDB (if so, change callers which pass in a non-NULL
     shell_file too).  */
  if (shell_file == NULL)
    shell_file = getenv ("SHELL");
  if (shell_file == NULL)
    shell_file = default_shell_file;

  /* Multiplying the length of exec_file by 4 is to account for the fact
     that it may expand when quoted; it is a worst-case number based on
     every character being '.  */
  len = 5 + 4 * strlen (exec_file) + 1 + strlen (allargs) + 1 + /*slop*/ 12;
  /* If desired, concat something onto the front of ALLARGS.
     SHELL_COMMAND is the result.  */
#ifdef SHELL_COMMAND_CONCAT
  shell_command = (char *) alloca (strlen (SHELL_COMMAND_CONCAT) + len);
  strcpy (shell_command, SHELL_COMMAND_CONCAT);
#else
  shell_command = (char *) alloca (len);
  shell_command[0] = '\0';
#endif
  strcat (shell_command, "exec ");

  /* Now add exec_file, quoting as necessary.  */
  {
    char *p;
    int need_to_quote;

    /* Quoting in this style is said to work with all shells.  But csh
       on IRIX 4.0.1 can't deal with it.  So we only quote it if we need
       to.  */
    p = exec_file;
    while (1)
      {
	switch (*p)
	  {
	  case '\'':
	  case '"':
	  case '(':
	  case ')':
	  case '$':
	  case '&':
	  case ';':
	  case '<':
	  case '>':
	  case ' ':
	  case '\n':
	  case '\t':
	    need_to_quote = 1;
	    goto end_scan;

	  case '\0':
	    need_to_quote = 0;
	    goto end_scan;

	  default:
	    break;
	  }
	++p;
      }
  end_scan:
    if (need_to_quote)
      {
	strcat (shell_command, "'");
	for (p = exec_file; *p != '\0'; ++p)
	  {
	    if (*p == '\'')
	      strcat (shell_command, "'\\''");
	    else
	      strncat (shell_command, p, 1);
	  }
	strcat (shell_command, "'");
      }
    else
      strcat (shell_command, exec_file);
  }

  strcat (shell_command, " ");
  strcat (shell_command, allargs);

  /* exec is said to fail if the executable is open.  */
  close_exec_file ();

  /* Retain a copy of our environment variables, since the child will
     replace the value of  environ  and if we're vforked, we have to 
     restore it.  */
  save_our_env = environ;

  /* Tell the terminal handling subsystem what tty we plan to run on;
     it will just record the information for later.  */

  new_tty_prefork (inferior_io_terminal);

  /* It is generally good practice to flush any possible pending stdio
     output prior to doing a fork, to avoid the possibility of both the
     parent and child flushing the same data after the fork. */

  gdb_flush (gdb_stdout);
  gdb_flush (gdb_stderr);

#if defined(USG) && !defined(HAVE_VFORK)
  pid = fork ();
#else
  if (debug_fork)
    pid = fork ();
  else
    pid = vfork ();
#endif

  if (pid < 0)
    perror_with_name ("vfork");

  if (pid == 0)
    {
      if (debug_fork) 
	sleep (debug_fork);

      /* Run inferior in a separate process group.  */
      debug_setpgrp = gdb_setpgid ();
      if (debug_setpgrp == -1)
	 perror("setpgrp failed in child");

#ifdef SET_STACK_LIMIT_HUGE
      /* Reset the stack limit back to what it was.  */
      {
	struct rlimit rlim;

	getrlimit (RLIMIT_STACK, &rlim);
	rlim.rlim_cur = original_stack_limit;
	setrlimit (RLIMIT_STACK, &rlim);
      }
#endif /* SET_STACK_LIMIT_HUGE */

      /* Ask the tty subsystem to switch to the one we specified earlier
	 (or to share the current terminal, if none was specified).  */

      new_tty ();

      /* Changing the signal handlers for the inferior after
	 a vfork can also change them for the superior, so we don't mess
	 with signals here.  See comments in
	 initialize_signals for how we get the right signal handlers
	 for the inferior.  */

      /* "Trace me, Dr. Memory!" */
      (*traceme_fun) ();

      /* There is no execlpe call, so we have to set the environment
	 for our child in the global variable.  If we've vforked, this
	 clobbers the parent, but environ is restored a few lines down
	 in the parent.  By the way, yes we do need to look down the
	 path to find $SHELL.  Rich Pixley says so, and I agree.  */
      environ = env;
      execlp (shell_file, shell_file, "-c", shell_command, (char *)0);

      fprintf_unfiltered (gdb_stderr, "Cannot exec %s: %s.\n", shell_file,
	       safe_strerror (errno));
      gdb_flush (gdb_stderr);
      _exit (0177);
    }

  /* Restore our environment in case a vforked child clob'd it.  */
  environ = save_our_env;

  init_thread_list();

  inferior_pid = pid;		/* Needed for wait_for_inferior stuff below */

  /* Now that we have a child process, make it our target, and
     initialize anything target-vector-specific that needs initializing.  */
  (*init_trace_fun)(pid);

  /* We are now in the child process of interest, having exec'd the
     correct program, and are poised at the first instruction of the
     new program.  */
#ifdef SOLIB_CREATE_INFERIOR_HOOK
  SOLIB_CREATE_INFERIOR_HOOK (pid);
#endif
}

/* Accept NTRAPS traps from the inferior.  */

void
startup_inferior (ntraps)
     int ntraps;
{
  int pending_execs = ntraps;
  int terminal_initted;

  /* The process was started by the fork that created it,
     but it will have stopped one instruction after execing the shell.
     Here we must get it up to actual execution of the real program.  */

  clear_proceed_status ();

  init_wait_for_inferior ();

  terminal_initted = 0;

  while (1)
    {
      stop_soon_quietly = 1;	/* Make wait_for_inferior be quiet */
      wait_for_inferior ();
      if (stop_signal != TARGET_SIGNAL_TRAP)
	{
	  /* Let shell child handle its own signals in its own way */
	  /* FIXME, what if child has exit()ed?  Must exit loop somehow */
	  resume (0, stop_signal);
	}
      else
	{
	  /* We handle SIGTRAP, however; it means child did an exec.  */
	  if (!terminal_initted)
	    {
	      /* Now that the child has exec'd we know it has already set its
		 process group.  On POSIX systems, tcsetpgrp will fail with
		 EPERM if we try it before the child's setpgid.  */

	      /* Set up the "saved terminal modes" of the inferior
		 based on what modes we are starting it with.  */
	      target_terminal_init ();

	      /* Install inferior's terminal modes.  */
	      target_terminal_inferior ();

	      terminal_initted = 1;
	    }
	  if (0 == --pending_execs)
	    break;
	  resume (0, TARGET_SIGNAL_0);		/* Just make it go on */
	}
    }
  stop_soon_quietly = 0;
}
Commit	Line	Data
3fbdd536 JG	1	/* Fork a Unix child process, and set up to debug it, for GDB.
	2	Copyright 1990, 1991, 1992 Free Software Foundation, Inc.
	3	Contributed by Cygnus Support.
	4
	5	This file is part of GDB.
	6
	7	This program is free software; you can redistribute it and/or modify
	8	it under the terms of the GNU General Public License as published by
	9	the Free Software Foundation; either version 2 of the License, or
	10	(at your option) any later version.
	11
	12	This program is distributed in the hope that it will be useful,
	13	but WITHOUT ANY WARRANTY; without even the implied warranty of
	14	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	15	GNU General Public License for more details.
	16
	17	You should have received a copy of the GNU General Public License
	18	along with this program; if not, write to the Free Software
	19	Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */
	20
	21	#include "defs.h"
	22	#include "frame.h" /* required by inferior.h */
	23	#include "inferior.h"
	24	#include "target.h"
	25	#include "wait.h"
	26	#include "gdbcore.h"
c18b613a	27	#include "terminal.h"
100f92e2	28	#include "thread.h"
3fbdd536 JG	29
	30	#include <signal.h>
	31
	32	#ifdef SET_STACK_LIMIT_HUGE
	33	#include <sys/time.h>
	34	#include <sys/resource.h>
	35
	36	extern int original_stack_limit;
	37	#endif /* SET_STACK_LIMIT_HUGE */
	38
	39	extern char **environ;
	40
3fbdd536 JG	41	#ifndef SHELL_FILE
	42	#define SHELL_FILE "/bin/sh"
	43	#endif
	44
08f74b92 JK	45	/* Start an inferior Unix child process and sets inferior_pid to its pid.
	46	EXEC_FILE is the file to run.
	47	ALLARGS is a string containing the arguments to the program.
	48	ENV is the environment vector to pass. SHELL_FILE is the shell file,
	49	or NULL if we should pick one. Errors reported with error(). */
	50
3fbdd536	51	void
08f74b92 JK	52	fork_inferior (exec_file, allargs, env, traceme_fun, init_trace_fun,
08f74b92 JK	53	shell_file)
3fbdd536 JG	54	char *exec_file;
	55	char *allargs;
	56	char **env;
	57	void (*traceme_fun) PARAMS ((void));
	58	void (*init_trace_fun) PARAMS ((int));
08f74b92	59	char *shell_file;
3fbdd536 JG	60	{
	61	int pid;
	62	char *shell_command;
3fbdd536 JG	63	static char default_shell_file[] = SHELL_FILE;
3fbdd536 JG	64	int len;
3fbdd536 JG	65	/* Set debug_fork then attach to the child while it sleeps, to debug. */
	66	static int debug_fork = 0;
	67	/* This is set to the result of setpgrp, which if vforked, will be visible
	68	to you in the parent process. It's only used by humans for debugging. */
	69	static int debug_setpgrp = 657473;
	70	char **save_our_env;
	71
	72	/* If no exec file handed to us, get it from the exec-file command -- with
	73	a good, common error message if none is specified. */
	74	if (exec_file == 0)
	75	exec_file = get_exec_file(1);
	76
	77	/* The user might want tilde-expansion, and in general probably wants
	78	the program to behave the same way as if run from
	79	his/her favorite shell. So we let the shell run it for us.
4142aab8	80	FIXME-maybe, we might want a "set shell" command so the user can change
08f74b92 JK	81	the shell from within GDB (if so, change callers which pass in a non-NULL
	82	shell_file too). */
	83	if (shell_file == NULL)
	84	shell_file = getenv ("SHELL");
3fbdd536 JG	85	if (shell_file == NULL)
3fbdd536 JG	86	shell_file = default_shell_file;
3768398d JK	87
	88	/* Multiplying the length of exec_file by 4 is to account for the fact
	89	that it may expand when quoted; it is a worst-case number based on
	90	every character being '. */
	91	len = 5 + 4 * strlen (exec_file) + 1 + strlen (allargs) + 1 + /slop/ 12;
3fbdd536 JG	92	/* If desired, concat something onto the front of ALLARGS.
	93	SHELL_COMMAND is the result. */
	94	#ifdef SHELL_COMMAND_CONCAT
	95	shell_command = (char *) alloca (strlen (SHELL_COMMAND_CONCAT) + len);
	96	strcpy (shell_command, SHELL_COMMAND_CONCAT);
	97	#else
	98	shell_command = (char *) alloca (len);
	99	shell_command[0] = '\0';
	100	#endif
	101	strcat (shell_command, "exec ");
3768398d	102
38bbfd37	103	/* Now add exec_file, quoting as necessary. */
3768398d JK	104	{
3768398d JK	105	char *p;
38bbfd37	106	int need_to_quote;
3768398d	107
38bbfd37 JK	108	/* Quoting in this style is said to work with all shells. But csh
	109	on IRIX 4.0.1 can't deal with it. So we only quote it if we need
	110	to. */
	111	p = exec_file;
	112	while (1)
3768398d	113	{
38bbfd37 JK	114	switch (*p)
	115	{
	116	case '\'':
	117	case '"':
	118	case '(':
	119	case ')':
	120	case '$':
	121	case '&':
	122	case ';':
	123	case '<':
	124	case '>':
	125	case ' ':
	126	case '\n':
	127	case '\t':
	128	need_to_quote = 1;
	129	goto end_scan;
	130
	131	case '\0':
	132	need_to_quote = 0;
	133	goto end_scan;
	134
	135	default:
	136	break;
	137	}
	138	++p;
3768398d	139	}
38bbfd37 JK	140	end_scan:
	141	if (need_to_quote)
	142	{
	143	strcat (shell_command, "'");
	144	for (p = exec_file; *p != '\0'; ++p)
	145	{
	146	if (*p == '\'')
	147	strcat (shell_command, "'\\''");
	148	else
	149	strncat (shell_command, p, 1);
	150	}
	151	strcat (shell_command, "'");
	152	}
	153	else
	154	strcat (shell_command, exec_file);
3768398d JK	155	}
3768398d JK	156
3fbdd536 JG	157	strcat (shell_command, " ");
	158	strcat (shell_command, allargs);
	159
	160	/* exec is said to fail if the executable is open. */
	161	close_exec_file ();
	162
	163	/* Retain a copy of our environment variables, since the child will
	164	replace the value of environ and if we're vforked, we have to
	165	restore it. */
	166	save_our_env = environ;
	167
	168	/* Tell the terminal handling subsystem what tty we plan to run on;
	169	it will just record the information for later. */
	170
	171	new_tty_prefork (inferior_io_terminal);
	172
	173	/* It is generally good practice to flush any possible pending stdio
	174	output prior to doing a fork, to avoid the possibility of both the
	175	parent and child flushing the same data after the fork. */
	176
199b2450 TL	177	gdb_flush (gdb_stdout);
199b2450 TL	178	gdb_flush (gdb_stderr);
3fbdd536 JG	179
	180	#if defined(USG) && !defined(HAVE_VFORK)
	181	pid = fork ();
	182	#else
	183	if (debug_fork)
	184	pid = fork ();
	185	else
	186	pid = vfork ();
	187	#endif
	188
	189	if (pid < 0)
	190	perror_with_name ("vfork");
	191
	192	if (pid == 0)
	193	{
	194	if (debug_fork)
	195	sleep (debug_fork);
	196
3fbdd536	197	/* Run inferior in a separate process group. */
c2e247c4	198	debug_setpgrp = gdb_setpgid ();
3fbdd536 JG	199	if (debug_setpgrp == -1)
3fbdd536 JG	200	perror("setpgrp failed in child");
3fbdd536 JG	201
	202	#ifdef SET_STACK_LIMIT_HUGE
	203	/* Reset the stack limit back to what it was. */
	204	{
	205	struct rlimit rlim;
	206
	207	getrlimit (RLIMIT_STACK, &rlim);
	208	rlim.rlim_cur = original_stack_limit;
	209	setrlimit (RLIMIT_STACK, &rlim);
	210	}
	211	#endif /* SET_STACK_LIMIT_HUGE */
	212
	213	/* Ask the tty subsystem to switch to the one we specified earlier
	214	(or to share the current terminal, if none was specified). */
	215
	216	new_tty ();
	217
	218	/* Changing the signal handlers for the inferior after
	219	a vfork can also change them for the superior, so we don't mess
	220	with signals here. See comments in
	221	initialize_signals for how we get the right signal handlers
	222	for the inferior. */
	223
	224	/* "Trace me, Dr. Memory!" */
	225	(*traceme_fun) ();
	226
	227	/* There is no execlpe call, so we have to set the environment
	228	for our child in the global variable. If we've vforked, this
	229	clobbers the parent, but environ is restored a few lines down
	230	in the parent. By the way, yes we do need to look down the
	231	path to find $SHELL. Rich Pixley says so, and I agree. */
	232	environ = env;
	233	execlp (shell_file, shell_file, "-c", shell_command, (char *)0);
	234
199b2450	235	fprintf_unfiltered (gdb_stderr, "Cannot exec %s: %s.\n", shell_file,
3fbdd536	236	safe_strerror (errno));
199b2450	237	gdb_flush (gdb_stderr);
3fbdd536 JG	238	_exit (0177);
	239	}
	240
	241	/* Restore our environment in case a vforked child clob'd it. */
	242	environ = save_our_env;
	243
de43d7d0 SG	244	init_thread_list();
de43d7d0 SG	245
bc28a06c JK	246	inferior_pid = pid; /* Needed for wait_for_inferior stuff below */
bc28a06c JK	247
3fbdd536 JG	248	/* Now that we have a child process, make it our target, and
	249	initialize anything target-vector-specific that needs initializing. */
	250	(*init_trace_fun)(pid);
	251
bc28a06c JK	252	/* We are now in the child process of interest, having exec'd the
	253	correct program, and are poised at the first instruction of the
	254	new program. */
	255	#ifdef SOLIB_CREATE_INFERIOR_HOOK
	256	SOLIB_CREATE_INFERIOR_HOOK (pid);
	257	#endif
	258	}
	259
	260	/* Accept NTRAPS traps from the inferior. */
	261
	262	void
	263	startup_inferior (ntraps)
	264	int ntraps;
	265	{
	266	int pending_execs = ntraps;
	267	int terminal_initted;
	268
5d76c8e6 JK	269	/* The process was started by the fork that created it,
	270	but it will have stopped one instruction after execing the shell.
	271	Here we must get it up to actual execution of the real program. */
3fbdd536	272
3fbdd536 JG	273	clear_proceed_status ();
3fbdd536 JG	274
3fbdd536 JG	275	init_wait_for_inferior ();
3fbdd536 JG	276
01dfd415	277	terminal_initted = 0;
3fbdd536 JG	278
	279	while (1)
	280	{
	281	stop_soon_quietly = 1; /* Make wait_for_inferior be quiet */
	282	wait_for_inferior ();
67ac9759	283	if (stop_signal != TARGET_SIGNAL_TRAP)
3fbdd536 JG	284	{
	285	/* Let shell child handle its own signals in its own way */
	286	/* FIXME, what if child has exit()ed? Must exit loop somehow */
	287	resume (0, stop_signal);
	288	}
	289	else
	290	{
	291	/* We handle SIGTRAP, however; it means child did an exec. */
01dfd415 JK	292	if (!terminal_initted)
	293	{
	294	/* Now that the child has exec'd we know it has already set its
	295	process group. On POSIX systems, tcsetpgrp will fail with
	296	EPERM if we try it before the child's setpgid. */
	297
	298	/* Set up the "saved terminal modes" of the inferior
	299	based on what modes we are starting it with. */
	300	target_terminal_init ();
	301
	302	/* Install inferior's terminal modes. */
	303	target_terminal_inferior ();
	304
	305	terminal_initted = 1;
	306	}
3fbdd536 JG	307	if (0 == --pending_execs)
3fbdd536 JG	308	break;
67ac9759	309	resume (0, TARGET_SIGNAL_0); /* Just make it go on */
3fbdd536 JG	310	}
	311	}
	312	stop_soon_quietly = 0;
3fbdd536	313	}