/* Fork a Unix child process, and set up to debug it, for GDB.
- Copyright (C) 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1998, 1999, 2000,
- 2001, 2004, 2005, 2006, 2007 Free Software Foundation, Inc.
+ Copyright (C) 1990-2020 Free Software Foundation, Inc.
Contributed by Cygnus Support.
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
+ 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,
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., 51 Franklin Street, Fifth Floor,
- Boston, MA 02110-1301, USA. */
+ 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 "gdb_wait.h"
-#include "gdb_vfork.h"
-#include "gdbcore.h"
+#include "gdbcmd.h"
#include "terminal.h"
#include "gdbthread.h"
-#include "command.h" /* for dont_repeat () */
-#include "solib.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>
+/* 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. */
-/* Break up SCRATCH into an argument vector suitable for passing to
- execvp and store it in ARGV. 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 (char *scratch, char **argv)
+const char *
+get_exec_wrapper ()
{
- char *cp = scratch;
-
- 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';
- }
-
- /* Null-terminate the vector. */
- *argv = NULL;
+ return exec_wrapper;
}
-/* When executing a command under the given shell, return non-zero if
- the '!' character should be escaped when embedded in a quoted
- command-line argument. */
+/* See nat/fork-inferior.h. */
-static int
-escape_bang_in_quoted_argument (const char *shell_file)
+void
+gdb_flush_out_err ()
{
- const int shell_file_len = strlen (shell_file);
+ gdb_flush (main_ui->m_gdb_stdout);
+ gdb_flush (main_ui->m_gdb_stderr);
+}
- /* Bang should be escaped only in C Shells. For now, simply check
- that the shell name ends with 'csh', which covers at least csh
- and tcsh. This should be good enough for now. */
+/* The ui structure that will be saved on 'prefork_hook' and
+ restored on 'postfork_hook'. */
+static struct ui *saved_ui = NULL;
- if (shell_file_len < 3)
- return 0;
+/* See nat/fork-inferior.h. */
- if (shell_file[shell_file_len - 3] == 'c'
- && shell_file[shell_file_len - 2] == 's'
- && shell_file[shell_file_len - 1] == 'h')
- return 1;
+void
+prefork_hook (const char *args)
+{
+ const char *inferior_io_terminal = get_inferior_io_terminal ();
- return 0;
-}
+ 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;
-/* Start an inferior Unix child process and sets inferior_ptid 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. */
+ /* 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);
+}
-/* This function is NOT reentrant. Some of the variables have been
- made static to ensure that they survive the vfork call. */
+/* See nat/fork-inferior.h. */
void
-fork_inferior (char *exec_file_arg, char *allargs, char **env,
- void (*traceme_fun) (void), void (*init_trace_fun) (int),
- void (*pre_trace_fun) (void), char *shell_file_arg)
+postfork_hook (pid_t pid)
{
- 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;
- static char *shell_file;
- static char *exec_file;
- char **save_our_env;
- int shell = 0;
- static char **argv;
- const char *inferior_io_terminal = get_inferior_io_terminal ();
+ inferior *inf = current_inferior ();
- /* If no exec file handed to us, get it from the exec-file command
- -- with a good, common error message if none is specified. */
- exec_file = exec_file_arg;
- if (exec_file == 0)
- exec_file = get_exec_file (1);
-
- /* STARTUP_WITH_SHELL is defined in inferior.h. If 0,e we'll just
- do a fork/exec, no shell, so don't bother figuring out what
- shell. */
- shell_file = shell_file_arg;
- 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;
- }
+ inferior_appeared (inf, pid);
- /* 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 argument vector.
- Calculate an upper bound on the length of the vector by
- assuming that every other character is a separate
- argument. */
- int argc = (strlen (allargs) + 1) / 2 + 2;
- argv = (char **) xmalloc (argc * 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;
- const int escape_bang = escape_bang_in_quoted_argument (shell_file);
-
- 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 ' ':
- 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 if (*p == '!' && escape_bang)
- 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);
- }
+ /* Needed for wait_for_inferior stuff. */
+ inferior_ptid = ptid_t (pid);
- /* On some systems an exec will fail if the executable is open. */
- close_exec_file ();
+ gdb_assert (saved_ui != NULL);
+ current_ui = saved_ui;
+ saved_ui = NULL;
- /* 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;
+ new_tty_postfork ();
+}
- /* 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);
+/* See nat/fork-inferior.h. */
- /* 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) ();
-
- /* Create the child process. Since the child process is going to
- exec(3) shortly afterwards, try to reduce the overhead by
- calling vfork(2). However, if PRE_TRACE_FUN is non-null, it's
- likely that this optimization won't work since there's too much
- work to do between the vfork(2) and the exec(3). This is known
- to be the case on ttrace(2)-based HP-UX, where some handshaking
- between parent and child needs to happen between fork(2) and
- exec(2). However, since the parent is suspended in the vforked
- state, this doesn't work. Also note that the vfork(2) call might
- actually be a call to fork(2) due to the fact that autoconf will
- ``#define vfork fork'' on certain platforms. */
- if (pre_trace_fun || debug_fork)
- pid = fork ();
- else
- pid = vfork ();
-
- if (pid < 0)
- perror_with_name (("vfork"));
-
- if (pid == 0)
- {
- if (debug_fork)
- sleep (debug_fork);
+void
+postfork_child_hook ()
+{
+ /* 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;
+
+ /* 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;
- /* Run inferior in a separate process group. */
+ /* 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)
+ {
+ /* 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");
-
- /* 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)
- {
- execlp (shell_file, shell_file, "-c", shell_command, (char *) 0);
-
- /* 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;
-
- 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");
-#if 0
- /* This extra info seems to be useless. */
- fprintf_unfiltered (gdb_stderr, "Got error %s.\n", errstring);
-#endif
- gdb_flush (gdb_stderr);
- _exit (0177);
- }
+ perror (_("setpgrp failed in child"));
}
- /* Restore our environment in case a vforked child clob'd it. */
- environ = save_our_env;
+ /* Ask the tty subsystem to switch to the one we specified
+ earlier (or to share the current terminal, if none was
+ specified). */
+ new_tty ();
+}
- init_thread_list ();
+/* See inferior.h. */
- /* Needed for wait_for_inferior stuff below. */
- inferior_ptid = pid_to_ptid (pid);
+ptid_t
+gdb_startup_inferior (pid_t pid, int num_traps)
+{
+ inferior *inf = current_inferior ();
+ process_stratum_target *proc_target = inf->process_target ();
- /* Now that we have a child process, make it our target, and
- initialize anything target-vector-specific that needs
- initializing. */
- (*init_trace_fun) (pid);
+ ptid_t ptid = startup_inferior (proc_target, pid, num_traps, NULL, NULL);
- /* 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. */
+ /* Mark all threads non-executing. */
+ set_executing (proc_target, ptid, 0);
- /* Allow target dependent 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);
+ return ptid;
}
-/* Accept NTRAPS traps from the inferior. */
+/* Implement the "unset exec-wrapper" command. */
-void
-startup_inferior (int ntraps)
+static void
+unset_exec_wrapper_command (const char *args, int from_tty)
{
- int pending_execs = ntraps;
- int terminal_initted = 0;
-
- /* 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 ();
+ 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);
+}
- while (1)
- {
- /* Make wait_for_inferior be quiet. */
- stop_soon = STOP_QUIETLY;
- 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 exited? 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 (--pending_execs == 0)
- break;
-
- resume (0, TARGET_SIGNAL_0); /* Just make it go on. */
- }
- }
- stop_soon = NO_STOP_QUIETLY;
+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