[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 "serial.h" /* For job_control.  */
#include "terminal.h"		/* For new_tty */

#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;

/* 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.  Errors reported with error().  */

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

void
fork_inferior (exec_file, allargs, env, traceme_fun, init_trace_fun)
     char *exec_file;
     char *allargs;
     char **env;
     void (*traceme_fun) PARAMS ((void));
     void (*init_trace_fun) PARAMS ((int));
{
  int pid;
  char *shell_command;
  char *shell_file;
  static char default_shell_file[] = SHELL_FILE;
  int len;
  int pending_execs;
  /* 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, this should probably search the local environment (as
     modified by the setenv command), not the env gdb inherited.  */
  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. */

  fflush (stdout);
  fflush (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 (stderr, "Cannot exec %s: %s.\n", shell_file,
	       safe_strerror (errno));
      fflush (stderr);
      _exit (0177);
    }

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

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

#ifdef CREATE_INFERIOR_HOOK
  CREATE_INFERIOR_HOOK (pid);
#endif  

/* 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.  */

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

  clear_proceed_status ();

  /* We will get a trace trap after one instruction.
     Continue it automatically.  Eventually (after shell does an exec)
     it will get another trace trap.  Then insert breakpoints and continue.  */

#ifdef START_INFERIOR_TRAPS_EXPECTED
  pending_execs = START_INFERIOR_TRAPS_EXPECTED;
#else
  pending_execs = 2;
#endif

  init_wait_for_inferior ();

  /* 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 ();

  while (1)
    {
      stop_soon_quietly = 1;	/* Make wait_for_inferior be quiet */
      wait_for_inferior ();
      if (stop_signal != SIGTRAP)
	{
	  /* 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 (0 == --pending_execs)
	    break;
	  resume (0, 0);		/* Just make it go on */
	}
    }
  stop_soon_quietly = 0;

  /* 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
}
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"
c2e247c4 JK	27	#include "serial.h" /* For job_control. */
c2e247c4 JK	28	#include "terminal.h" /* For new_tty */
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
	41	/* Start an inferior Unix child process and sets inferior_pid to its pid.
	42	EXEC_FILE is the file to run.
	43	ALLARGS is a string containing the arguments to the program.
	44	ENV is the environment vector to pass. Errors reported with error(). */
	45
	46	#ifndef SHELL_FILE
	47	#define SHELL_FILE "/bin/sh"
	48	#endif
	49
	50	void
	51	fork_inferior (exec_file, allargs, env, traceme_fun, init_trace_fun)
	52	char *exec_file;
	53	char *allargs;
	54	char **env;
	55	void (*traceme_fun) PARAMS ((void));
	56	void (*init_trace_fun) PARAMS ((int));
	57	{
	58	int pid;
	59	char *shell_command;
	60	char *shell_file;
	61	static char default_shell_file[] = SHELL_FILE;
	62	int len;
	63	int pending_execs;
	64	/* Set debug_fork then attach to the child while it sleeps, to debug. */
	65	static int debug_fork = 0;
	66	/* This is set to the result of setpgrp, which if vforked, will be visible
	67	to you in the parent process. It's only used by humans for debugging. */
	68	static int debug_setpgrp = 657473;
	69	char **save_our_env;
	70
	71	/* If no exec file handed to us, get it from the exec-file command -- with
	72	a good, common error message if none is specified. */
	73	if (exec_file == 0)
	74	exec_file = get_exec_file(1);
	75
	76	/* The user might want tilde-expansion, and in general probably wants
	77	the program to behave the same way as if run from
	78	his/her favorite shell. So we let the shell run it for us.
	79	FIXME, this should probably search the local environment (as
	80	modified by the setenv command), not the env gdb inherited. */
	81	shell_file = getenv ("SHELL");
	82	if (shell_file == NULL)
	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
	174	fflush (stdout);
	175	fflush (stderr);
	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 JG	198
	199	#ifdef SET_STACK_LIMIT_HUGE
	200	/* Reset the stack limit back to what it was. */
	201	{
	202	struct rlimit rlim;
	203
	204	getrlimit (RLIMIT_STACK, &rlim);
	205	rlim.rlim_cur = original_stack_limit;
	206	setrlimit (RLIMIT_STACK, &rlim);
	207	}
	208	#endif /* SET_STACK_LIMIT_HUGE */
	209
	210	/* Ask the tty subsystem to switch to the one we specified earlier
	211	(or to share the current terminal, if none was specified). */
	212
	213	new_tty ();
	214
	215	/* Changing the signal handlers for the inferior after
	216	a vfork can also change them for the superior, so we don't mess
	217	with signals here. See comments in
	218	initialize_signals for how we get the right signal handlers
	219	for the inferior. */
	220
	221	/* "Trace me, Dr. Memory!" */
	222	(*traceme_fun) ();
	223
	224	/* There is no execlpe call, so we have to set the environment
	225	for our child in the global variable. If we've vforked, this
	226	clobbers the parent, but environ is restored a few lines down
	227	in the parent. By the way, yes we do need to look down the
	228	path to find $SHELL. Rich Pixley says so, and I agree. */
	229	environ = env;
	230	execlp (shell_file, shell_file, "-c", shell_command, (char *)0);
	231
	232	fprintf (stderr, "Cannot exec %s: %s.\n", shell_file,
	233	safe_strerror (errno));
	234	fflush (stderr);
	235	_exit (0177);
	236	}
	237
	238	/* Restore our environment in case a vforked child clob'd it. */
	239	environ = save_our_env;
	240
	241	/* Now that we have a child process, make it our target, and
	242	initialize anything target-vector-specific that needs initializing. */
	243	(*init_trace_fun)(pid);
	244
	245	#ifdef CREATE_INFERIOR_HOOK
	246	CREATE_INFERIOR_HOOK (pid);
	247	#endif
	248
	249	/* The process was started by the fork that created it,
	250	but it will have stopped one instruction after execing the shell.
	251	Here we must get it up to actual execution of the real program. */
	252
	253	inferior_pid = pid; /* Needed for wait_for_inferior stuff below */
	254
	255	clear_proceed_status ();
	256
	257	/* We will get a trace trap after one instruction.
	258	Continue it automatically. Eventually (after shell does an exec)
	259	it will get another trace trap. Then insert breakpoints and continue. */
	260
	261	#ifdef START_INFERIOR_TRAPS_EXPECTED
262	pending_execs = START_INFERIOR_TRAPS_EXPECTED;
263	#else
264	pending_execs = 2;
265	#endif
266
267	init_wait_for_inferior ();
268
269	/* Set up the "saved terminal modes" of the inferior
270	based on what modes we are starting it with. */
271	target_terminal_init ();
272
273	/* Install inferior's terminal modes. */
274	target_terminal_inferior ();
275
276	while (1)
277	{
278	stop_soon_quietly = 1; /* Make wait_for_inferior be quiet */
279	wait_for_inferior ();
280	if (stop_signal != SIGTRAP)
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. */
289	if (0 == --pending_execs)
290	break;
291	resume (0, 0); /* Just make it go on */
292	}
293	}
294	stop_soon_quietly = 0;
295
296	/* We are now in the child process of interest, having exec'd the
297	correct program, and are poised at the first instruction of the
298	new program. */
299	#ifdef SOLIB_CREATE_INFERIOR_HOOK
300	SOLIB_CREATE_INFERIOR_HOOK (pid);
301	#endif
302	}