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274 lines
8.3 KiB
C
274 lines
8.3 KiB
C
/* Fork a Unix child process, and set up to debug it, for GDB.
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Copyright 1990, 1991, 1992 Free Software Foundation, Inc.
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Contributed by Cygnus Support.
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This file is part of GDB.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */
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#include "defs.h"
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#include "frame.h" /* required by inferior.h */
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#include "inferior.h"
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#include "target.h"
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#include "wait.h"
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#include "gdbcore.h"
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#include "terminal.h" /* For #ifdef TIOCGPGRP and new_tty */
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#include <signal.h>
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#ifdef SET_STACK_LIMIT_HUGE
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#include <sys/time.h>
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#include <sys/resource.h>
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extern int original_stack_limit;
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#endif /* SET_STACK_LIMIT_HUGE */
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extern char **environ;
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/* Start an inferior Unix child process and sets inferior_pid to its pid.
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EXEC_FILE is the file to run.
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ALLARGS is a string containing the arguments to the program.
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ENV is the environment vector to pass. Errors reported with error(). */
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#ifndef SHELL_FILE
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#define SHELL_FILE "/bin/sh"
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#endif
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void
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fork_inferior (exec_file, allargs, env, traceme_fun, init_trace_fun)
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char *exec_file;
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char *allargs;
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char **env;
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void (*traceme_fun) PARAMS ((void));
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void (*init_trace_fun) PARAMS ((int));
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{
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int pid;
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char *shell_command;
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char *shell_file;
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static char default_shell_file[] = SHELL_FILE;
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int len;
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int pending_execs;
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/* Set debug_fork then attach to the child while it sleeps, to debug. */
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static int debug_fork = 0;
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/* This is set to the result of setpgrp, which if vforked, will be visible
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to you in the parent process. It's only used by humans for debugging. */
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static int debug_setpgrp = 657473;
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char **save_our_env;
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/* If no exec file handed to us, get it from the exec-file command -- with
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a good, common error message if none is specified. */
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if (exec_file == 0)
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exec_file = get_exec_file(1);
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/* The user might want tilde-expansion, and in general probably wants
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the program to behave the same way as if run from
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his/her favorite shell. So we let the shell run it for us.
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FIXME, this should probably search the local environment (as
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modified by the setenv command), not the env gdb inherited. */
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shell_file = getenv ("SHELL");
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if (shell_file == NULL)
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shell_file = default_shell_file;
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/* Multiplying the length of exec_file by 4 is to account for the fact
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that it may expand when quoted; it is a worst-case number based on
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every character being '. */
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len = 5 + 4 * strlen (exec_file) + 1 + strlen (allargs) + 1 + /*slop*/ 12;
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/* If desired, concat something onto the front of ALLARGS.
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SHELL_COMMAND is the result. */
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#ifdef SHELL_COMMAND_CONCAT
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shell_command = (char *) alloca (strlen (SHELL_COMMAND_CONCAT) + len);
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strcpy (shell_command, SHELL_COMMAND_CONCAT);
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#else
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shell_command = (char *) alloca (len);
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shell_command[0] = '\0';
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#endif
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strcat (shell_command, "exec ");
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/* Now add exec_file, quoting as necessary. Quoting in this style is
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said to work with all shells. */
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{
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char *p;
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strcat (shell_command, "'");
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for (p = exec_file; *p != '\0'; ++p)
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{
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if (*p == '\'')
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strcat (shell_command, "'\\''");
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else
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strncat (shell_command, p, 1);
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}
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strcat (shell_command, "'");
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}
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strcat (shell_command, " ");
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strcat (shell_command, allargs);
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/* exec is said to fail if the executable is open. */
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close_exec_file ();
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/* Retain a copy of our environment variables, since the child will
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replace the value of environ and if we're vforked, we have to
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restore it. */
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save_our_env = environ;
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/* Tell the terminal handling subsystem what tty we plan to run on;
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it will just record the information for later. */
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new_tty_prefork (inferior_io_terminal);
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/* It is generally good practice to flush any possible pending stdio
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output prior to doing a fork, to avoid the possibility of both the
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parent and child flushing the same data after the fork. */
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fflush (stdout);
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fflush (stderr);
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#if defined(USG) && !defined(HAVE_VFORK)
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pid = fork ();
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#else
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if (debug_fork)
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pid = fork ();
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else
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pid = vfork ();
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#endif
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if (pid < 0)
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perror_with_name ("vfork");
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if (pid == 0)
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{
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if (debug_fork)
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sleep (debug_fork);
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#ifdef TIOCGPGRP
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/* Run inferior in a separate process group. */
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#ifdef NEED_POSIX_SETPGID
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debug_setpgrp = setpgid (0, 0);
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#else
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#if defined(USG) && !defined(SETPGRP_ARGS)
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debug_setpgrp = setpgrp ();
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#else
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debug_setpgrp = setpgrp (getpid (), getpid ());
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#endif /* USG */
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#endif /* NEED_POSIX_SETPGID */
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if (debug_setpgrp == -1)
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perror("setpgrp failed in child");
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#endif /* TIOCGPGRP */
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#ifdef SET_STACK_LIMIT_HUGE
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/* Reset the stack limit back to what it was. */
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{
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struct rlimit rlim;
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getrlimit (RLIMIT_STACK, &rlim);
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rlim.rlim_cur = original_stack_limit;
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setrlimit (RLIMIT_STACK, &rlim);
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}
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#endif /* SET_STACK_LIMIT_HUGE */
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/* Ask the tty subsystem to switch to the one we specified earlier
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(or to share the current terminal, if none was specified). */
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new_tty ();
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/* Changing the signal handlers for the inferior after
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a vfork can also change them for the superior, so we don't mess
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with signals here. See comments in
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initialize_signals for how we get the right signal handlers
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for the inferior. */
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/* "Trace me, Dr. Memory!" */
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(*traceme_fun) ();
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/* There is no execlpe call, so we have to set the environment
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for our child in the global variable. If we've vforked, this
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clobbers the parent, but environ is restored a few lines down
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in the parent. By the way, yes we do need to look down the
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path to find $SHELL. Rich Pixley says so, and I agree. */
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environ = env;
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execlp (shell_file, shell_file, "-c", shell_command, (char *)0);
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fprintf (stderr, "Cannot exec %s: %s.\n", shell_file,
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safe_strerror (errno));
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fflush (stderr);
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_exit (0177);
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}
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/* Restore our environment in case a vforked child clob'd it. */
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environ = save_our_env;
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/* Now that we have a child process, make it our target, and
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initialize anything target-vector-specific that needs initializing. */
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(*init_trace_fun)(pid);
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#ifdef CREATE_INFERIOR_HOOK
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CREATE_INFERIOR_HOOK (pid);
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#endif
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/* The process was started by the fork that created it,
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but it will have stopped one instruction after execing the shell.
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Here we must get it up to actual execution of the real program. */
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inferior_pid = pid; /* Needed for wait_for_inferior stuff below */
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clear_proceed_status ();
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/* We will get a trace trap after one instruction.
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Continue it automatically. Eventually (after shell does an exec)
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it will get another trace trap. Then insert breakpoints and continue. */
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#ifdef START_INFERIOR_TRAPS_EXPECTED
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pending_execs = START_INFERIOR_TRAPS_EXPECTED;
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#else
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pending_execs = 2;
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#endif
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init_wait_for_inferior ();
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/* Set up the "saved terminal modes" of the inferior
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based on what modes we are starting it with. */
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target_terminal_init ();
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/* Install inferior's terminal modes. */
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target_terminal_inferior ();
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while (1)
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{
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stop_soon_quietly = 1; /* Make wait_for_inferior be quiet */
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wait_for_inferior ();
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if (stop_signal != SIGTRAP)
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{
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/* Let shell child handle its own signals in its own way */
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/* FIXME, what if child has exit()ed? Must exit loop somehow */
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resume (0, stop_signal);
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}
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else
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{
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/* We handle SIGTRAP, however; it means child did an exec. */
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if (0 == --pending_execs)
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break;
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resume (0, 0); /* Just make it go on */
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}
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}
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stop_soon_quietly = 0;
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/* We are now in the child process of interest, having exec'd the
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correct program, and are poised at the first instruction of the
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new program. */
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#ifdef SOLIB_CREATE_INFERIOR_HOOK
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SOLIB_CREATE_INFERIOR_HOOK (pid);
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#endif
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}
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