[thirdparty/binutils-gdb.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>

#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	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
	33	#ifdef SET_STACK_LIMIT_HUGE
	34	#include <sys/time.h>
	35	#include <sys/resource.h>
	36
	37	extern int original_stack_limit;
	38	#endif /* SET_STACK_LIMIT_HUGE */
	39
	40	extern char **environ;
	41
3fbdd536 JG	42	#ifndef SHELL_FILE
	43	#define SHELL_FILE "/bin/sh"
	44	#endif
	45
08f74b92 JK	46	/* Start an inferior Unix child process and sets inferior_pid to its pid.
	47	EXEC_FILE is the file to run.
	48	ALLARGS is a string containing the arguments to the program.
	49	ENV is the environment vector to pass. SHELL_FILE is the shell file,
	50	or NULL if we should pick one. Errors reported with error(). */
	51
3fbdd536	52	void
08f74b92 JK	53	fork_inferior (exec_file, allargs, env, traceme_fun, init_trace_fun,
08f74b92 JK	54	shell_file)
3fbdd536 JG	55	char *exec_file;
	56	char *allargs;
	57	char **env;
	58	void (*traceme_fun) PARAMS ((void));
	59	void (*init_trace_fun) PARAMS ((int));
08f74b92	60	char *shell_file;
3fbdd536 JG	61	{
	62	int pid;
	63	char *shell_command;
3fbdd536 JG	64	static char default_shell_file[] = SHELL_FILE;
3fbdd536 JG	65	int len;
3fbdd536 JG	66	/* Set debug_fork then attach to the child while it sleeps, to debug. */
	67	static int debug_fork = 0;
	68	/* This is set to the result of setpgrp, which if vforked, will be visible
	69	to you in the parent process. It's only used by humans for debugging. */
	70	static int debug_setpgrp = 657473;
	71	char **save_our_env;
	72
	73	/* If no exec file handed to us, get it from the exec-file command -- with
	74	a good, common error message if none is specified. */
	75	if (exec_file == 0)
	76	exec_file = get_exec_file(1);
	77
	78	/* The user might want tilde-expansion, and in general probably wants
	79	the program to behave the same way as if run from
	80	his/her favorite shell. So we let the shell run it for us.
4142aab8	81	FIXME-maybe, we might want a "set shell" command so the user can change
08f74b92 JK	82	the shell from within GDB (if so, change callers which pass in a non-NULL
	83	shell_file too). */
	84	if (shell_file == NULL)
	85	shell_file = getenv ("SHELL");
3fbdd536 JG	86	if (shell_file == NULL)
3fbdd536 JG	87	shell_file = default_shell_file;
3768398d JK	88
	89	/* Multiplying the length of exec_file by 4 is to account for the fact
	90	that it may expand when quoted; it is a worst-case number based on
	91	every character being '. */
	92	len = 5 + 4 * strlen (exec_file) + 1 + strlen (allargs) + 1 + /slop/ 12;
3fbdd536 JG	93	/* If desired, concat something onto the front of ALLARGS.
	94	SHELL_COMMAND is the result. */
	95	#ifdef SHELL_COMMAND_CONCAT
	96	shell_command = (char *) alloca (strlen (SHELL_COMMAND_CONCAT) + len);
	97	strcpy (shell_command, SHELL_COMMAND_CONCAT);
	98	#else
	99	shell_command = (char *) alloca (len);
	100	shell_command[0] = '\0';
	101	#endif
	102	strcat (shell_command, "exec ");
3768398d	103
38bbfd37	104	/* Now add exec_file, quoting as necessary. */
3768398d JK	105	{
3768398d JK	106	char *p;
38bbfd37	107	int need_to_quote;
3768398d	108
38bbfd37 JK	109	/* Quoting in this style is said to work with all shells. But csh
	110	on IRIX 4.0.1 can't deal with it. So we only quote it if we need
	111	to. */
	112	p = exec_file;
	113	while (1)
3768398d	114	{
38bbfd37 JK	115	switch (*p)
	116	{
	117	case '\'':
	118	case '"':
	119	case '(':
	120	case ')':
	121	case '$':
	122	case '&':
	123	case ';':
	124	case '<':
	125	case '>':
	126	case ' ':
	127	case '\n':
	128	case '\t':
	129	need_to_quote = 1;
	130	goto end_scan;
	131
	132	case '\0':
	133	need_to_quote = 0;
	134	goto end_scan;
	135
	136	default:
	137	break;
	138	}
	139	++p;
3768398d	140	}
38bbfd37 JK	141	end_scan:
	142	if (need_to_quote)
	143	{
	144	strcat (shell_command, "'");
	145	for (p = exec_file; *p != '\0'; ++p)
	146	{
	147	if (*p == '\'')
	148	strcat (shell_command, "'\\''");
	149	else
	150	strncat (shell_command, p, 1);
	151	}
	152	strcat (shell_command, "'");
	153	}
	154	else
	155	strcat (shell_command, exec_file);
3768398d JK	156	}
3768398d JK	157
3fbdd536 JG	158	strcat (shell_command, " ");
	159	strcat (shell_command, allargs);
	160
	161	/* exec is said to fail if the executable is open. */
	162	close_exec_file ();
	163
	164	/* Retain a copy of our environment variables, since the child will
	165	replace the value of environ and if we're vforked, we have to
	166	restore it. */
	167	save_our_env = environ;
	168
	169	/* Tell the terminal handling subsystem what tty we plan to run on;
	170	it will just record the information for later. */
	171
	172	new_tty_prefork (inferior_io_terminal);
	173
	174	/* It is generally good practice to flush any possible pending stdio
	175	output prior to doing a fork, to avoid the possibility of both the
	176	parent and child flushing the same data after the fork. */
	177
199b2450 TL	178	gdb_flush (gdb_stdout);
199b2450 TL	179	gdb_flush (gdb_stderr);
3fbdd536 JG	180
	181	#if defined(USG) && !defined(HAVE_VFORK)
	182	pid = fork ();
	183	#else
	184	if (debug_fork)
	185	pid = fork ();
	186	else
	187	pid = vfork ();
	188	#endif
	189
	190	if (pid < 0)
	191	perror_with_name ("vfork");
	192
	193	if (pid == 0)
	194	{
	195	if (debug_fork)
	196	sleep (debug_fork);
	197
3fbdd536	198	/* Run inferior in a separate process group. */
c2e247c4	199	debug_setpgrp = gdb_setpgid ();
3fbdd536 JG	200	if (debug_setpgrp == -1)
3fbdd536 JG	201	perror("setpgrp failed in child");
3fbdd536 JG	202
	203	#ifdef SET_STACK_LIMIT_HUGE
	204	/* Reset the stack limit back to what it was. */
	205	{
	206	struct rlimit rlim;
	207
	208	getrlimit (RLIMIT_STACK, &rlim);
	209	rlim.rlim_cur = original_stack_limit;
	210	setrlimit (RLIMIT_STACK, &rlim);
	211	}
	212	#endif /* SET_STACK_LIMIT_HUGE */
	213
	214	/* Ask the tty subsystem to switch to the one we specified earlier
	215	(or to share the current terminal, if none was specified). */
	216
	217	new_tty ();
	218
	219	/* Changing the signal handlers for the inferior after
	220	a vfork can also change them for the superior, so we don't mess
	221	with signals here. See comments in
	222	initialize_signals for how we get the right signal handlers
	223	for the inferior. */
	224
	225	/* "Trace me, Dr. Memory!" */
	226	(*traceme_fun) ();
	227
	228	/* There is no execlpe call, so we have to set the environment
	229	for our child in the global variable. If we've vforked, this
	230	clobbers the parent, but environ is restored a few lines down
	231	in the parent. By the way, yes we do need to look down the
	232	path to find $SHELL. Rich Pixley says so, and I agree. */
	233	environ = env;
	234	execlp (shell_file, shell_file, "-c", shell_command, (char *)0);
	235
199b2450	236	fprintf_unfiltered (gdb_stderr, "Cannot exec %s: %s.\n", shell_file,
3fbdd536	237	safe_strerror (errno));
199b2450	238	gdb_flush (gdb_stderr);
3fbdd536 JG	239	_exit (0177);
	240	}
	241
	242	/* Restore our environment in case a vforked child clob'd it. */
	243	environ = save_our_env;
	244
de43d7d0 SG	245	init_thread_list();
de43d7d0 SG	246
bc28a06c JK	247	inferior_pid = pid; /* Needed for wait_for_inferior stuff below */
bc28a06c JK	248
3fbdd536 JG	249	/* Now that we have a child process, make it our target, and
	250	initialize anything target-vector-specific that needs initializing. */
	251	(*init_trace_fun)(pid);
	252
bc28a06c JK	253	/* We are now in the child process of interest, having exec'd the
	254	correct program, and are poised at the first instruction of the
	255	new program. */
	256	#ifdef SOLIB_CREATE_INFERIOR_HOOK
	257	SOLIB_CREATE_INFERIOR_HOOK (pid);
	258	#endif
	259	}
	260
	261	/* Accept NTRAPS traps from the inferior. */
	262
	263	void
	264	startup_inferior (ntraps)
	265	int ntraps;
	266	{
	267	int pending_execs = ntraps;
	268	int terminal_initted;
	269
5d76c8e6 JK	270	/* The process was started by the fork that created it,
	271	but it will have stopped one instruction after execing the shell.
	272	Here we must get it up to actual execution of the real program. */
3fbdd536	273
3fbdd536 JG	274	clear_proceed_status ();
3fbdd536 JG	275
3fbdd536 JG	276	init_wait_for_inferior ();
3fbdd536 JG	277
01dfd415	278	terminal_initted = 0;
3fbdd536 JG	279
	280	while (1)
	281	{
	282	stop_soon_quietly = 1; /* Make wait_for_inferior be quiet */
	283	wait_for_inferior ();
67ac9759	284	if (stop_signal != TARGET_SIGNAL_TRAP)
3fbdd536 JG	285	{
	286	/* Let shell child handle its own signals in its own way */
	287	/* FIXME, what if child has exit()ed? Must exit loop somehow */
	288	resume (0, stop_signal);
	289	}
	290	else
	291	{
	292	/* We handle SIGTRAP, however; it means child did an exec. */
01dfd415 JK	293	if (!terminal_initted)
	294	{
	295	/* Now that the child has exec'd we know it has already set its
	296	process group. On POSIX systems, tcsetpgrp will fail with
	297	EPERM if we try it before the child's setpgid. */
	298
	299	/* Set up the "saved terminal modes" of the inferior
	300	based on what modes we are starting it with. */
	301	target_terminal_init ();
	302
	303	/* Install inferior's terminal modes. */
	304	target_terminal_inferior ();
	305
	306	terminal_initted = 1;
	307	}
3fbdd536 JG	308	if (0 == --pending_execs)
3fbdd536 JG	309	break;
67ac9759	310	resume (0, TARGET_SIGNAL_0); /* Just make it go on */
3fbdd536 JG	311	}
	312	}
	313	stop_soon_quietly = 0;
3fbdd536	314	}