[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 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 <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 "thread.h"

#include <signal.h>

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");

      /* 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;

#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.
ba47c66a	2	Copyright 1990, 1991, 1992, 1993, 1994 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
	19	Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */
	20
	21	#include "defs.h"
ba47c66a	22	#include <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"
100f92e2	29	#include "thread.h"
3fbdd536 JG	30
	31	#include <signal.h>
	32
3fbdd536 JG	33	extern char **environ;
3fbdd536 JG	34
3fbdd536 JG	35	#ifndef SHELL_FILE
	36	#define SHELL_FILE "/bin/sh"
	37	#endif
	38
08f74b92 JK	39	/* Start an inferior Unix child process and sets inferior_pid to its pid.
	40	EXEC_FILE is the file to run.
	41	ALLARGS is a string containing the arguments to the program.
	42	ENV is the environment vector to pass. SHELL_FILE is the shell file,
	43	or NULL if we should pick one. Errors reported with error(). */
	44
3fbdd536	45	void
08f74b92 JK	46	fork_inferior (exec_file, allargs, env, traceme_fun, init_trace_fun,
08f74b92 JK	47	shell_file)
3fbdd536 JG	48	char *exec_file;
	49	char *allargs;
	50	char **env;
	51	void (*traceme_fun) PARAMS ((void));
	52	void (*init_trace_fun) PARAMS ((int));
08f74b92	53	char *shell_file;
3fbdd536 JG	54	{
	55	int pid;
	56	char *shell_command;
3fbdd536 JG	57	static char default_shell_file[] = SHELL_FILE;
3fbdd536 JG	58	int len;
3fbdd536 JG	59	/* Set debug_fork then attach to the child while it sleeps, to debug. */
	60	static int debug_fork = 0;
	61	/* This is set to the result of setpgrp, which if vforked, will be visible
	62	to you in the parent process. It's only used by humans for debugging. */
	63	static int debug_setpgrp = 657473;
	64	char **save_our_env;
	65
	66	/* If no exec file handed to us, get it from the exec-file command -- with
	67	a good, common error message if none is specified. */
	68	if (exec_file == 0)
	69	exec_file = get_exec_file(1);
	70
	71	/* The user might want tilde-expansion, and in general probably wants
	72	the program to behave the same way as if run from
	73	his/her favorite shell. So we let the shell run it for us.
4142aab8	74	FIXME-maybe, we might want a "set shell" command so the user can change
08f74b92 JK	75	the shell from within GDB (if so, change callers which pass in a non-NULL
	76	shell_file too). */
	77	if (shell_file == NULL)
	78	shell_file = getenv ("SHELL");
3fbdd536 JG	79	if (shell_file == NULL)
3fbdd536 JG	80	shell_file = default_shell_file;
3768398d JK	81
	82	/* Multiplying the length of exec_file by 4 is to account for the fact
	83	that it may expand when quoted; it is a worst-case number based on
	84	every character being '. */
	85	len = 5 + 4 * strlen (exec_file) + 1 + strlen (allargs) + 1 + /slop/ 12;
3fbdd536 JG	86	/* If desired, concat something onto the front of ALLARGS.
	87	SHELL_COMMAND is the result. */
	88	#ifdef SHELL_COMMAND_CONCAT
	89	shell_command = (char *) alloca (strlen (SHELL_COMMAND_CONCAT) + len);
	90	strcpy (shell_command, SHELL_COMMAND_CONCAT);
	91	#else
	92	shell_command = (char *) alloca (len);
	93	shell_command[0] = '\0';
	94	#endif
	95	strcat (shell_command, "exec ");
3768398d	96
38bbfd37	97	/* Now add exec_file, quoting as necessary. */
3768398d JK	98	{
3768398d JK	99	char *p;
38bbfd37	100	int need_to_quote;
3768398d	101
38bbfd37 JK	102	/* Quoting in this style is said to work with all shells. But csh
	103	on IRIX 4.0.1 can't deal with it. So we only quote it if we need
	104	to. */
	105	p = exec_file;
	106	while (1)
3768398d	107	{
38bbfd37 JK	108	switch (*p)
	109	{
	110	case '\'':
	111	case '"':
	112	case '(':
	113	case ')':
	114	case '$':
	115	case '&':
	116	case ';':
	117	case '<':
	118	case '>':
	119	case ' ':
	120	case '\n':
	121	case '\t':
	122	need_to_quote = 1;
	123	goto end_scan;
	124
	125	case '\0':
	126	need_to_quote = 0;
	127	goto end_scan;
	128
	129	default:
	130	break;
	131	}
	132	++p;
3768398d	133	}
38bbfd37 JK	134	end_scan:
	135	if (need_to_quote)
	136	{
	137	strcat (shell_command, "'");
	138	for (p = exec_file; *p != '\0'; ++p)
	139	{
	140	if (*p == '\'')
	141	strcat (shell_command, "'\\''");
	142	else
	143	strncat (shell_command, p, 1);
	144	}
	145	strcat (shell_command, "'");
	146	}
	147	else
	148	strcat (shell_command, exec_file);
3768398d JK	149	}
3768398d JK	150
3fbdd536 JG	151	strcat (shell_command, " ");
	152	strcat (shell_command, allargs);
	153
	154	/* exec is said to fail if the executable is open. */
	155	close_exec_file ();
	156
	157	/* Retain a copy of our environment variables, since the child will
	158	replace the value of environ and if we're vforked, we have to
	159	restore it. */
	160	save_our_env = environ;
	161
	162	/* Tell the terminal handling subsystem what tty we plan to run on;
	163	it will just record the information for later. */
	164
	165	new_tty_prefork (inferior_io_terminal);
	166
	167	/* It is generally good practice to flush any possible pending stdio
	168	output prior to doing a fork, to avoid the possibility of both the
	169	parent and child flushing the same data after the fork. */
	170
199b2450 TL	171	gdb_flush (gdb_stdout);
199b2450 TL	172	gdb_flush (gdb_stderr);
3fbdd536 JG	173
	174	#if defined(USG) && !defined(HAVE_VFORK)
	175	pid = fork ();
	176	#else
	177	if (debug_fork)
	178	pid = fork ();
	179	else
	180	pid = vfork ();
	181	#endif
	182
	183	if (pid < 0)
	184	perror_with_name ("vfork");
	185
	186	if (pid == 0)
	187	{
	188	if (debug_fork)
	189	sleep (debug_fork);
	190
3fbdd536	191	/* Run inferior in a separate process group. */
c2e247c4	192	debug_setpgrp = gdb_setpgid ();
3fbdd536 JG	193	if (debug_setpgrp == -1)
3fbdd536 JG	194	perror("setpgrp failed in child");
3fbdd536	195
3fbdd536 JG	196	/* Ask the tty subsystem to switch to the one we specified earlier
	197	(or to share the current terminal, if none was specified). */
	198
	199	new_tty ();
	200
	201	/* Changing the signal handlers for the inferior after
	202	a vfork can also change them for the superior, so we don't mess
	203	with signals here. See comments in
	204	initialize_signals for how we get the right signal handlers
	205	for the inferior. */
	206
	207	/* "Trace me, Dr. Memory!" */
	208	(*traceme_fun) ();
	209
	210	/* There is no execlpe call, so we have to set the environment
	211	for our child in the global variable. If we've vforked, this
	212	clobbers the parent, but environ is restored a few lines down
	213	in the parent. By the way, yes we do need to look down the
	214	path to find $SHELL. Rich Pixley says so, and I agree. */
	215	environ = env;
	216	execlp (shell_file, shell_file, "-c", shell_command, (char *)0);
	217
199b2450	218	fprintf_unfiltered (gdb_stderr, "Cannot exec %s: %s.\n", shell_file,
3fbdd536	219	safe_strerror (errno));
199b2450	220	gdb_flush (gdb_stderr);
3fbdd536 JG	221	_exit (0177);
	222	}
	223
	224	/* Restore our environment in case a vforked child clob'd it. */
	225	environ = save_our_env;
	226
de43d7d0 SG	227	init_thread_list();
de43d7d0 SG	228
bc28a06c JK	229	inferior_pid = pid; /* Needed for wait_for_inferior stuff below */
bc28a06c JK	230
3fbdd536 JG	231	/* Now that we have a child process, make it our target, and
	232	initialize anything target-vector-specific that needs initializing. */
	233	(*init_trace_fun)(pid);
	234
bc28a06c JK	235	/* We are now in the child process of interest, having exec'd the
	236	correct program, and are poised at the first instruction of the
	237	new program. */
	238	#ifdef SOLIB_CREATE_INFERIOR_HOOK
	239	SOLIB_CREATE_INFERIOR_HOOK (pid);
	240	#endif
	241	}
	242
	243	/* Accept NTRAPS traps from the inferior. */
	244
	245	void
	246	startup_inferior (ntraps)
	247	int ntraps;
	248	{
	249	int pending_execs = ntraps;
	250	int terminal_initted;
	251
5d76c8e6 JK	252	/* The process was started by the fork that created it,
	253	but it will have stopped one instruction after execing the shell.
	254	Here we must get it up to actual execution of the real program. */
3fbdd536	255
3fbdd536 JG	256	clear_proceed_status ();
3fbdd536 JG	257
3fbdd536 JG	258	init_wait_for_inferior ();
3fbdd536 JG	259
01dfd415	260	terminal_initted = 0;
3fbdd536	261
9f8219f1 SS	262	#ifdef STARTUP_INFERIOR
	263	STARTUP_INFERIOR (pending_execs);
	264	#else
3fbdd536 JG	265	while (1)
	266	{
	267	stop_soon_quietly = 1; /* Make wait_for_inferior be quiet */
	268	wait_for_inferior ();
67ac9759	269	if (stop_signal != TARGET_SIGNAL_TRAP)
3fbdd536 JG	270	{
	271	/* Let shell child handle its own signals in its own way */
	272	/* FIXME, what if child has exit()ed? Must exit loop somehow */
	273	resume (0, stop_signal);
	274	}
	275	else
	276	{
	277	/* We handle SIGTRAP, however; it means child did an exec. */
01dfd415 JK	278	if (!terminal_initted)
	279	{
	280	/* Now that the child has exec'd we know it has already set its
	281	process group. On POSIX systems, tcsetpgrp will fail with
	282	EPERM if we try it before the child's setpgid. */
	283
	284	/* Set up the "saved terminal modes" of the inferior
	285	based on what modes we are starting it with. */
	286	target_terminal_init ();
	287
	288	/* Install inferior's terminal modes. */
	289	target_terminal_inferior ();
	290
	291	terminal_initted = 1;
	292	}
3fbdd536 JG	293	if (0 == --pending_execs)
3fbdd536 JG	294	break;
67ac9759	295	resume (0, TARGET_SIGNAL_0); /* Just make it go on */
3fbdd536 JG	296	}
3fbdd536 JG	297	}
9f8219f1	298	#endif /* STARTUP_INFERIOR */
3fbdd536	299	stop_soon_quietly = 0;
3fbdd536	300	}