Initial revision

1 files changed, 616 insertions, 0 deletions

diff --git a/gdb/fork-child.c b/gdb/fork-child.c
new file mode 100644
index 00000000000..f3504bc6409
--- /dev/null
+++ b/gdb/fork-child.c
@@ -0,0 +1,616 @@
+/* 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
+
+#define DEBUGGING 0
+
+/* This just gets used as a default if we can't find SHELL */
+#ifndef SHELL_FILE
+#define SHELL_FILE "/bin/sh"
+#endif
+
+extern char **environ;
+
+/* This function breaks up an argument string into an argument
+ * vector suitable for passing to execvp().
+ * E.g., on "run a b c d" this routine would get as input
+ * the string "a b c d", and as output it would fill in argv with
+ * the four arguments "a", "b", "c", "d".
+ */
+static void
+breakup_args (
+	       scratch,
+	       argv)
+     char *scratch;
+     char **argv;
+{
+  char *cp = scratch;
+
+#if DEBUGGING
+  printf ("breakup_args: input = %s\n", scratch);
+#endif
+  for (;;)
+    {
+
+      /* Scan past leading separators */
+      while (*cp == ' ' || *cp == '\t' || *cp == '\n')
+	{
+	  cp++;
+	}
+
+      /* Break if at end of string */
+      if (*cp == '\0')
+	break;
+
+      /* Take an arg */
+      *argv++ = cp;
+
+      /* Scan for next arg separator */
+      cp = strchr (cp, ' ');
+      if (cp == NULL)
+	cp = strchr (cp, '\t');
+      if (cp == NULL)
+	cp = strchr (cp, '\n');
+
+      /* No separators => end of string => break */
+      if (cp == NULL)
+	break;
+
+      /* Replace the separator with a terminator */
+      *cp++ = '\0';
+    }
+
+  /* execv requires a null-terminated arg vector */
+  *argv = NULL;
+
+}
+
+
+/* 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,
+	       pre_trace_fun, shell_file)
+     char *exec_file;
+     char *allargs;
+     char **env;
+     void (*traceme_fun) PARAMS ((void));
+     void (*init_trace_fun) PARAMS ((int));
+     void (*pre_trace_fun) PARAMS ((void));
+     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;
+  int shell = 0;
+  char **argv;
+  char *tryname;
+
+  /* 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);
+
+  /* STARTUP_WITH_SHELL is defined in inferior.h.
+   * If 0, we'll just do a fork/exec, no shell, so don't
+   * bother figuring out what shell.
+   */
+  if (STARTUP_WITH_SHELL)
+    {
+      /* Figure out what shell to start up the user program under. */
+      if (shell_file == NULL)
+	shell_file = getenv ("SHELL");
+      if (shell_file == NULL)
+	shell_file = default_shell_file;
+      shell = 1;
+    }
+
+#if DEBUGGING
+  printf ("shell is %s\n", shell_file);
+#endif
+
+  /* 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
+
+  if (!shell)
+    {
+      /* We're going to call execvp. Create argv */
+      /* Largest case: every other character is a separate arg */
+#if DEBUGGING
+      printf ("allocating argv, length = %d\n",
+	      (
+		(strlen (allargs) + 1) / (unsigned) 2
+		+ 2
+	      ) * sizeof (*argv)
+	);
+#endif
+      argv = (char **) xmalloc (((strlen (allargs) + 1) / (unsigned) 2 + 2) * sizeof (*argv));
+      argv[0] = exec_file;
+      breakup_args (allargs, &argv[1]);
+
+    }
+  else
+    {
+
+      /* We're going to call a shell */
+
+      /* Now add exec_file, quoting as necessary.  */
+
+      char *p;
+      int need_to_quote;
+
+      strcat (shell_command, "exec ");
+
+      /* 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 there's any initialization of the target layers that must happen
+   to prepare to handle the child we're about fork, do it now...
+   */
+  if (pre_trace_fun != NULL)
+    (*pre_trace_fun) ();
+
+#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) ();
+      /* The call above set this process (the "child") as debuggable
+       * by the original gdb process (the "parent").  Since processes
+       * (unlike people) can have only one parent, if you are
+       * debugging gdb itself (and your debugger is thus _already_ the
+       * controller/parent for this child),  code from here on out
+       * is undebuggable.  Indeed, you probably got an error message
+       * saying "not parent".  Sorry--you'll have to use print statements!
+       */
+
+      /* 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;
+
+      /* If we decided above to start up with a shell,
+       * we exec the shell,
+       * "-c" says to interpret the next arg as a shell command
+       * to execute, and this command is "exec <target-program> <args>".
+       * "-f" means "fast startup" to the c-shell, which means
+       * don't do .cshrc file. Doing .cshrc may cause fork/exec
+       * events which will confuse debugger start-up code.
+       */
+      if (shell)
+	{
+#if 0
+
+	  /* HP change is problematic. The -f option has different meanings
+	   for different shells. It is particularly inappropriate for
+	   bourne shells. */
+	  execlp (shell_file, shell_file, "-f", "-c", shell_command, (char *) 0);
+#else
+	  execlp (shell_file, shell_file, "-c", shell_command, (char *) 0);
+#endif
+
+
+	  /* If we get here, it's an error */
+	  fprintf_unfiltered (gdb_stderr, "Cannot exec %s: %s.\n", shell_file,
+			      safe_strerror (errno));
+	  gdb_flush (gdb_stderr);
+	  _exit (0177);
+	}
+      else
+	{
+	  /* Otherwise, we directly exec the target program with execvp. */
+	  int i;
+	  char *errstring;
+#if DEBUGGING
+	  printf ("about to exec target, exec_file = %s\n", exec_file);
+	  i = 0;
+	  while (argv[i] != NULL)
+	    {
+	      printf ("strlen(argv[%d]) is %d\n", i, strlen (argv[i]));
+	      printf ("argv[%d] is %s\n", i, argv[i]);
+	      i++;
+	    }
+#endif
+	  execvp (exec_file, argv);
+
+	  /* If we get here, it's an error */
+	  errstring = safe_strerror (errno);
+	  fprintf_unfiltered (gdb_stderr, "Cannot exec %s ", exec_file);
+
+	  i = 1;
+	  while (argv[i] != NULL)
+	    {
+	      if (i != 1)
+		fprintf_unfiltered (gdb_stderr, " ");
+	      fprintf_unfiltered (gdb_stderr, "%s", argv[i]);
+	      i++;
+	    }
+	  fprintf_unfiltered (gdb_stderr, ".\n");
+	  /* This extra info seems to be useless
+        fprintf_unfiltered (gdb_stderr, "Got error %s.\n", errstring);
+         */
+	  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.  */
+
+  /* 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
+}
+
+/* An inferior Unix process CHILD_PID has been created by a call to
+   fork() (or variants like vfork).  It is presently stopped, and waiting
+   to be resumed.  clone_and_follow_inferior will fork the debugger,
+   and that clone will "follow" (attach to) CHILD_PID.  The original copy
+   of the debugger will not touch CHILD_PID again.
+
+   Also, the original debugger will set FOLLOWED_CHILD FALSE, while the
+   clone will set it TRUE.
+   */
+void
+clone_and_follow_inferior (child_pid, followed_child)
+     int child_pid;
+     int *followed_child;
+{
+  extern int auto_solib_add;
+
+  int debugger_pid;
+  int status;
+  char pid_spelling[100];	/* Arbitrary but sufficient length. */
+
+  /* This semaphore is used to coordinate the two debuggers' handoff
+     of CHILD_PID.  The original debugger will detach from CHILD_PID,
+     and then the clone debugger will attach to it.  (It must be done
+     this way because on some targets, only one process at a time can
+     trace another.  Thus, the original debugger must relinquish its
+     tracing rights before the clone can pick them up.)
+     */
+#define SEM_TALK (1)
+#define SEM_LISTEN (0)
+  int handoff_semaphore[2];	/* Original "talks" to [1], clone "listens" to [0] */
+  int talk_value = 99;
+  int listen_value;
+
+  /* Set debug_fork then attach to the child while it sleeps, to debug. */
+  static int debug_fork = 0;
+
+  /* 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);
+
+  /* Open the semaphore pipes.
+     */
+  status = pipe (handoff_semaphore);
+  if (status < 0)
+    error ("error getting pipe for handoff semaphore");
+
+  /* Clone the debugger. */
+#if defined(USG) && !defined(HAVE_VFORK)
+  debugger_pid = fork ();
+#else
+  if (debug_fork)
+    debugger_pid = fork ();
+  else
+    debugger_pid = vfork ();
+#endif
+
+  if (debugger_pid < 0)
+    perror_with_name ("fork");
+
+  /* Are we the original debugger?  If so, we must relinquish all claims
+   to CHILD_PID. */
+  if (debugger_pid != 0)
+    {
+      char signal_spelling[100];/* Arbitrary but sufficient length */
+
+      /* Detach from CHILD_PID.  Deliver a "stop" signal when we do, though,
+       so that it remains stopped until the clone debugger can attach
+       to it.
+       */
+      detach_breakpoints (child_pid);
+
+      sprintf (signal_spelling, "%d", target_signal_to_host (TARGET_SIGNAL_STOP));
+      target_require_detach (child_pid, signal_spelling, 1);
+
+      /* Notify the clone debugger that it should attach to CHILD_PID. */
+      write (handoff_semaphore[SEM_TALK], &talk_value, sizeof (talk_value));
+
+      *followed_child = 0;
+    }
+
+  /* We're the child. */
+  else
+    {
+      if (debug_fork)
+	sleep (debug_fork);
+
+      /* The child (i.e., the cloned debugger) must now attach to
+         CHILD_PID.  inferior_pid is presently set to the parent process
+         of the fork, while CHILD_PID should be the child process of the
+         fork.
+
+         Wait until the original debugger relinquishes control of CHILD_PID,
+         though.
+         */
+      read (handoff_semaphore[SEM_LISTEN], &listen_value, sizeof (listen_value));
+
+      /* Note that we DON'T want to actually detach from inferior_pid,
+         because that would allow it to run free.  The original
+         debugger wants to retain control of the process.  So, we
+         just reset inferior_pid to CHILD_PID, and then ensure that all
+         breakpoints are really set in CHILD_PID.
+         */
+      target_mourn_inferior ();
+
+      /* Ask the tty subsystem to switch to the one we specified earlier
+         (or to share the current terminal, if none was specified).  */
+
+      new_tty ();
+
+      dont_repeat ();
+      sprintf (pid_spelling, "%d", child_pid);
+      target_require_attach (pid_spelling, 1);
+
+      /* Perform any necessary cleanup, after attachment.  (This form
+         of attaching can behave differently on some targets than the
+         standard method, where a process formerly not under debugger
+         control was suddenly attached to..)
+         */
+      target_post_follow_inferior_by_clone ();
+
+      *followed_child = 1;
+    }
+
+  /* Discard the handoff sempahore. */
+  (void) close (handoff_semaphore[SEM_LISTEN]);
+  (void) close (handoff_semaphore[SEM_TALK]);
+}
+
+/* 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;
+
+  if (STARTUP_WITH_SHELL)
+    inferior_ignoring_startup_exec_events = ntraps;
+  else
+    inferior_ignoring_startup_exec_events = 0;
+  inferior_ignoring_leading_exec_events =
+    target_reported_exec_events_per_exec_call () - 1;
+
+#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;
+	    }
+
+	  pending_execs = pending_execs - 1;
+	  if (0 == pending_execs)
+	    break;
+
+	  resume (0, TARGET_SIGNAL_0);	/* Just make it go on */
+	}
+    }
+#endif /* STARTUP_INFERIOR */
+  stop_soon_quietly = 0;
+}