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

/* Fork a Unix child process, and set up to debug it, for GDB.
   Copyright 1990, 1991, 1992, 1993, 1994, 1996 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., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */

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

#include <signal.h>
#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif

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));
     int (*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");

      /* 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.  */

  /* Note that pid may be modified by this function.  */
  inferior_pid = pid = (*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.  */

  /* Allow target dependant code to play with the new process.  This might be
     used to have target-specific code initialize a variable in the new process
     prior to executing the first instruction.  */
  TARGET_CREATE_INFERIOR_HOOK (pid);

#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;

#ifdef STARTUP_INFERIOR
  STARTUP_INFERIOR (pending_execs);
#else
  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 */
	}
    }
#endif /* STARTUP_INFERIOR */
  stop_soon_quietly = 0;
}
Commit	Line	Data
3fbdd536	1	/* Fork a Unix child process, and set up to debug it, for GDB.
8fc2b417	2	Copyright 1990, 1991, 1992, 1993, 1994, 1996 Free Software Foundation, Inc.
3fbdd536 JG	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
6c9638b4	19	Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */
3fbdd536 JG	20
3fbdd536 JG	21	#include "defs.h"
2b576293	22	#include "gdb_string.h"
3fbdd536 JG	23	#include "frame.h" /* required by inferior.h */
	24	#include "inferior.h"
	25	#include "target.h"
	26	#include "wait.h"
	27	#include "gdbcore.h"
c18b613a	28	#include "terminal.h"
fdfa3315	29	#include "gdbthread.h"
3fbdd536 JG	30
3fbdd536 JG	31	#include <signal.h>
1a494973 C	32	#ifdef HAVE_UNISTD_H
	33	#include <unistd.h>
	34	#endif
3fbdd536	35
3fbdd536 JG	36	extern char **environ;
3fbdd536 JG	37
3fbdd536 JG	38	#ifndef SHELL_FILE
	39	#define SHELL_FILE "/bin/sh"
	40	#endif
	41
08f74b92 JK	42	/* Start an inferior Unix child process and sets inferior_pid to its pid.
	43	EXEC_FILE is the file to run.
	44	ALLARGS is a string containing the arguments to the program.
	45	ENV is the environment vector to pass. SHELL_FILE is the shell file,
	46	or NULL if we should pick one. Errors reported with error(). */
	47
3fbdd536	48	void
08f74b92 JK	49	fork_inferior (exec_file, allargs, env, traceme_fun, init_trace_fun,
08f74b92 JK	50	shell_file)
3fbdd536 JG	51	char *exec_file;
	52	char *allargs;
	53	char **env;
	54	void (*traceme_fun) PARAMS ((void));
8fc2b417	55	int (*init_trace_fun) PARAMS ((int));
08f74b92	56	char *shell_file;
3fbdd536 JG	57	{
	58	int pid;
	59	char *shell_command;
3fbdd536 JG	60	static char default_shell_file[] = SHELL_FILE;
3fbdd536 JG	61	int len;
3fbdd536 JG	62	/* Set debug_fork then attach to the child while it sleeps, to debug. */
	63	static int debug_fork = 0;
	64	/* This is set to the result of setpgrp, which if vforked, will be visible
	65	to you in the parent process. It's only used by humans for debugging. */
	66	static int debug_setpgrp = 657473;
	67	char **save_our_env;
	68
	69	/* If no exec file handed to us, get it from the exec-file command -- with
	70	a good, common error message if none is specified. */
	71	if (exec_file == 0)
	72	exec_file = get_exec_file(1);
	73
	74	/* The user might want tilde-expansion, and in general probably wants
	75	the program to behave the same way as if run from
	76	his/her favorite shell. So we let the shell run it for us.
4142aab8	77	FIXME-maybe, we might want a "set shell" command so the user can change
08f74b92 JK	78	the shell from within GDB (if so, change callers which pass in a non-NULL
	79	shell_file too). */
	80	if (shell_file == NULL)
	81	shell_file = getenv ("SHELL");
3fbdd536 JG	82	if (shell_file == NULL)
3fbdd536 JG	83	shell_file = default_shell_file;
3768398d JK	84
	85	/* Multiplying the length of exec_file by 4 is to account for the fact
	86	that it may expand when quoted; it is a worst-case number based on
	87	every character being '. */
	88	len = 5 + 4 * strlen (exec_file) + 1 + strlen (allargs) + 1 + /slop/ 12;
3fbdd536 JG	89	/* If desired, concat something onto the front of ALLARGS.
	90	SHELL_COMMAND is the result. */
	91	#ifdef SHELL_COMMAND_CONCAT
	92	shell_command = (char *) alloca (strlen (SHELL_COMMAND_CONCAT) + len);
	93	strcpy (shell_command, SHELL_COMMAND_CONCAT);
	94	#else
	95	shell_command = (char *) alloca (len);
	96	shell_command[0] = '\0';
	97	#endif
	98	strcat (shell_command, "exec ");
3768398d	99
38bbfd37	100	/* Now add exec_file, quoting as necessary. */
3768398d JK	101	{
3768398d JK	102	char *p;
38bbfd37	103	int need_to_quote;
3768398d	104
38bbfd37 JK	105	/* Quoting in this style is said to work with all shells. But csh
	106	on IRIX 4.0.1 can't deal with it. So we only quote it if we need
	107	to. */
	108	p = exec_file;
	109	while (1)
3768398d	110	{
38bbfd37 JK	111	switch (*p)
	112	{
	113	case '\'':
	114	case '"':
	115	case '(':
	116	case ')':
	117	case '$':
	118	case '&':
	119	case ';':
	120	case '<':
	121	case '>':
	122	case ' ':
	123	case '\n':
	124	case '\t':
	125	need_to_quote = 1;
	126	goto end_scan;
	127
	128	case '\0':
	129	need_to_quote = 0;
	130	goto end_scan;
	131
	132	default:
	133	break;
	134	}
	135	++p;
3768398d	136	}
38bbfd37 JK	137	end_scan:
	138	if (need_to_quote)
	139	{
	140	strcat (shell_command, "'");
	141	for (p = exec_file; *p != '\0'; ++p)
	142	{
	143	if (*p == '\'')
	144	strcat (shell_command, "'\\''");
	145	else
	146	strncat (shell_command, p, 1);
	147	}
	148	strcat (shell_command, "'");
	149	}
	150	else
	151	strcat (shell_command, exec_file);
3768398d JK	152	}
3768398d JK	153
3fbdd536 JG	154	strcat (shell_command, " ");
	155	strcat (shell_command, allargs);
	156
	157	/* exec is said to fail if the executable is open. */
	158	close_exec_file ();
	159
	160	/* Retain a copy of our environment variables, since the child will
	161	replace the value of environ and if we're vforked, we have to
	162	restore it. */
	163	save_our_env = environ;
	164
	165	/* Tell the terminal handling subsystem what tty we plan to run on;
	166	it will just record the information for later. */
	167
	168	new_tty_prefork (inferior_io_terminal);
	169
	170	/* It is generally good practice to flush any possible pending stdio
	171	output prior to doing a fork, to avoid the possibility of both the
	172	parent and child flushing the same data after the fork. */
	173
199b2450 TL	174	gdb_flush (gdb_stdout);
199b2450 TL	175	gdb_flush (gdb_stderr);
3fbdd536 JG	176
	177	#if defined(USG) && !defined(HAVE_VFORK)
	178	pid = fork ();
	179	#else
	180	if (debug_fork)
	181	pid = fork ();
	182	else
	183	pid = vfork ();
	184	#endif
	185
	186	if (pid < 0)
	187	perror_with_name ("vfork");
	188
	189	if (pid == 0)
	190	{
	191	if (debug_fork)
	192	sleep (debug_fork);
	193
3fbdd536	194	/* Run inferior in a separate process group. */
c2e247c4	195	debug_setpgrp = gdb_setpgid ();
3fbdd536 JG	196	if (debug_setpgrp == -1)
3fbdd536 JG	197	perror("setpgrp failed in child");
3fbdd536	198
3fbdd536 JG	199	/* Ask the tty subsystem to switch to the one we specified earlier
	200	(or to share the current terminal, if none was specified). */
	201
	202	new_tty ();
	203
	204	/* Changing the signal handlers for the inferior after
	205	a vfork can also change them for the superior, so we don't mess
	206	with signals here. See comments in
	207	initialize_signals for how we get the right signal handlers
	208	for the inferior. */
	209
	210	/* "Trace me, Dr. Memory!" */
	211	(*traceme_fun) ();
	212
	213	/* There is no execlpe call, so we have to set the environment
	214	for our child in the global variable. If we've vforked, this
	215	clobbers the parent, but environ is restored a few lines down
	216	in the parent. By the way, yes we do need to look down the
	217	path to find $SHELL. Rich Pixley says so, and I agree. */
	218	environ = env;
	219	execlp (shell_file, shell_file, "-c", shell_command, (char *)0);
	220
199b2450	221	fprintf_unfiltered (gdb_stderr, "Cannot exec %s: %s.\n", shell_file,
3fbdd536	222	safe_strerror (errno));
199b2450	223	gdb_flush (gdb_stderr);
3fbdd536 JG	224	_exit (0177);
	225	}
	226
	227	/* Restore our environment in case a vforked child clob'd it. */
	228	environ = save_our_env;
	229
de43d7d0 SG	230	init_thread_list();
de43d7d0 SG	231
bc28a06c JK	232	inferior_pid = pid; /* Needed for wait_for_inferior stuff below */
bc28a06c JK	233
3fbdd536 JG	234	/* Now that we have a child process, make it our target, and
3fbdd536 JG	235	initialize anything target-vector-specific that needs initializing. */
8fc2b417 SG	236
	237	/* Note that pid may be modified by this function. */
	238	inferior_pid = pid = (*init_trace_fun)(pid);
3fbdd536	239
bc28a06c JK	240	/* We are now in the child process of interest, having exec'd the
	241	correct program, and are poised at the first instruction of the
	242	new program. */
188c635f SG	243
	244	/* Allow target dependant code to play with the new process. This might be
	245	used to have target-specific code initialize a variable in the new process
	246	prior to executing the first instruction. */
	247	TARGET_CREATE_INFERIOR_HOOK (pid);
	248
bc28a06c JK	249	#ifdef SOLIB_CREATE_INFERIOR_HOOK
	250	SOLIB_CREATE_INFERIOR_HOOK (pid);
	251	#endif
	252	}
	253
	254	/* Accept NTRAPS traps from the inferior. */
	255
	256	void
	257	startup_inferior (ntraps)
	258	int ntraps;
	259	{
	260	int pending_execs = ntraps;
	261	int terminal_initted;
	262
5d76c8e6 JK	263	/* The process was started by the fork that created it,
	264	but it will have stopped one instruction after execing the shell.
	265	Here we must get it up to actual execution of the real program. */
3fbdd536	266
3fbdd536 JG	267	clear_proceed_status ();
3fbdd536 JG	268
3fbdd536 JG	269	init_wait_for_inferior ();
3fbdd536 JG	270
01dfd415	271	terminal_initted = 0;
3fbdd536	272
9f8219f1 SS	273	#ifdef STARTUP_INFERIOR
	274	STARTUP_INFERIOR (pending_execs);
	275	#else
3fbdd536 JG	276	while (1)
	277	{
	278	stop_soon_quietly = 1; /* Make wait_for_inferior be quiet */
	279	wait_for_inferior ();
67ac9759	280	if (stop_signal != TARGET_SIGNAL_TRAP)
3fbdd536 JG	281	{
	282	/* Let shell child handle its own signals in its own way */
	283	/* FIXME, what if child has exit()ed? Must exit loop somehow */
	284	resume (0, stop_signal);
	285	}
	286	else
	287	{
	288	/* We handle SIGTRAP, however; it means child did an exec. */
01dfd415 JK	289	if (!terminal_initted)
	290	{
	291	/* Now that the child has exec'd we know it has already set its
	292	process group. On POSIX systems, tcsetpgrp will fail with
	293	EPERM if we try it before the child's setpgid. */
	294
	295	/* Set up the "saved terminal modes" of the inferior
	296	based on what modes we are starting it with. */
	297	target_terminal_init ();
	298
	299	/* Install inferior's terminal modes. */
	300	target_terminal_inferior ();
	301
	302	terminal_initted = 1;
	303	}
3fbdd536 JG	304	if (0 == --pending_execs)
3fbdd536 JG	305	break;
67ac9759	306	resume (0, TARGET_SIGNAL_0); /* Just make it go on */
3fbdd536 JG	307	}
3fbdd536 JG	308	}
9f8219f1	309	#endif /* STARTUP_INFERIOR */
3fbdd536	310	stop_soon_quietly = 0;
3fbdd536	311	}