/* Fork a Unix child process, and set up to debug it, for GDB.
- Copyright 1990, 1991, 1992, 1993, 1994, 1996 Free Software Foundation, Inc.
+
+ Copyright (C) 1990-2019 Free Software Foundation, Inc.
+
Contributed by Cygnus Support.
-This file is part of GDB.
+ 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 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 3 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.
+ 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. */
+ You should have received a copy of the GNU General Public License
+ along with this program. If not, see <http://www.gnu.org/licenses/>. */
#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 "gdbcmd.h"
#include "terminal.h"
#include "gdbthread.h"
+#include "top.h"
+#include "gdbsupport/job-control.h"
+#include "gdbsupport/filestuff.h"
+#include "nat/fork-inferior.h"
+#include "gdbsupport/common-inferior.h"
-#include <signal.h>
-#ifdef HAVE_UNISTD_H
-#include <unistd.h>
-#endif
-
-#define DEBUGGING 0
+/* The exec-wrapper, if any, that will be used when starting the
+ inferior. */
-/* This just gets used as a default if we can't find SHELL */
-#ifndef SHELL_FILE
-#define SHELL_FILE "/bin/sh"
-#endif
+static char *exec_wrapper = NULL;
-extern char **environ;
+/* See gdbsupport/common-inferior.h. */
-/* 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;
+const char *
+get_exec_wrapper ()
{
- 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;
-
+ return exec_wrapper;
}
-
-/* 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(). */
+/* See nat/fork-inferior.h. */
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;
+gdb_flush_out_err ()
{
- 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
- {
+ gdb_flush (main_ui->m_gdb_stdout);
+ gdb_flush (main_ui->m_gdb_stderr);
+}
- /* 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);
+/* The ui structure that will be saved on 'prefork_hook' and
+ restored on 'postfork_hook'. */
+static struct ui *saved_ui = NULL;
- }
+/* See nat/fork-inferior.h. */
- /* exec is said to fail if the executable is open. */
- close_exec_file ();
+void
+prefork_hook (const char *args)
+{
+ const char *inferior_io_terminal = get_inferior_io_terminal ();
- /* 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;
+ gdb_assert (saved_ui == NULL);
+ /* Retain a copy of our UI, since the child will replace this value
+ and if we're vforked, we have to restore it. */
+ saved_ui = current_ui;
/* 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 */
+/* See nat/fork-inferior.h. */
- /* Now that we have a child process, make it our target, and
- initialize anything target-vector-specific that needs initializing. */
+void
+postfork_hook (pid_t pid)
+{
+ inferior *inf = current_inferior ();
- (*init_trace_fun) (pid);
+ inferior_appeared (inf, 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. */
+ /* Needed for wait_for_inferior stuff. */
+ inferior_ptid = ptid_t (pid);
- /* 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);
+ gdb_assert (saved_ui != NULL);
+ current_ui = saved_ui;
+ saved_ui = NULL;
-#ifdef SOLIB_CREATE_INFERIOR_HOOK
- SOLIB_CREATE_INFERIOR_HOOK (pid);
-#endif
+ new_tty_postfork ();
}
-/* 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.
+/* See nat/fork-inferior.h. */
- 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;
+postfork_child_hook ()
{
- 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));
+ /* 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;
- *followed_child = 0;
- }
+ /* Make sure we switch to main_ui here in order to be able to
+ use the fprintf_unfiltered/warning/error functions. */
+ current_ui = main_ui;
- /* We're the child. */
- else
+ /* Create a new session for the inferior process, if necessary.
+ It will also place the inferior in a separate process group. */
+ if (create_tty_session () <= 0)
{
- 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;
+ /* No session was created, but we still want to run the inferior
+ in a separate process group. */
+ debug_setpgrp = gdb_setpgid ();
+ if (debug_setpgrp == -1)
+ perror (_("setpgrp failed in child"));
}
- /* Discard the handoff sempahore. */
- (void) close (handoff_semaphore[SEM_LISTEN]);
- (void) close (handoff_semaphore[SEM_TALK]);
+ /* Ask the tty subsystem to switch to the one we specified
+ earlier (or to share the current terminal, if none was
+ specified). */
+ new_tty ();
}
-/* Accept NTRAPS traps from the inferior. */
+/* See inferior.h. */
-void
-startup_inferior (ntraps)
- int ntraps;
+ptid_t
+gdb_startup_inferior (pid_t pid, int num_traps)
{
- int pending_execs = ntraps;
- int terminal_initted;
+ ptid_t ptid = startup_inferior (pid, num_traps, NULL, NULL);
- /* 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. */
+ /* Mark all threads non-executing. */
+ set_executing (ptid, 0);
- clear_proceed_status ();
+ return ptid;
+}
- init_wait_for_inferior ();
+/* Implement the "unset exec-wrapper" command. */
- terminal_initted = 0;
+static void
+unset_exec_wrapper_command (const char *args, int from_tty)
+{
+ xfree (exec_wrapper);
+ exec_wrapper = NULL;
+}
- 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;
+static void
+show_startup_with_shell (struct ui_file *file, int from_tty,
+ struct cmd_list_element *c, const char *value)
+{
+ fprintf_filtered (file,
+ _("Use of shell to start subprocesses is %s.\n"),
+ value);
+}
-#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;
+void
+_initialize_fork_child (void)
+{
+ add_setshow_filename_cmd ("exec-wrapper", class_run, &exec_wrapper, _("\
+Set a wrapper for running programs.\n\
+The wrapper prepares the system and environment for the new program."),
+ _("\
+Show the wrapper for running programs."), NULL,
+ NULL, NULL,
+ &setlist, &showlist);
+
+ add_cmd ("exec-wrapper", class_run, unset_exec_wrapper_command,
+ _("Disable use of an execution wrapper."),
+ &unsetlist);
+
+ add_setshow_boolean_cmd ("startup-with-shell", class_support,
+ &startup_with_shell, _("\
+Set use of shell to start subprocesses. The default is on."), _("\
+Show use of shell to start subprocesses."), NULL,
+ NULL,
+ show_startup_with_shell,
+ &setlist, &showlist);
}
projects / deliverable / binutils-gdb.git / blobdiff