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glib/glib/gspawn-posix.c
Philip Withnall 6161bbf3e4
gspawn: Add platform-independent top level API file 
This file doesn’t contain any real implementation, it just call the
`impl` functions from the platform-specific files
`gspawn-{posix,win32}.c`.

It serves as a location for the doc comments, introspection annotations
and API preconditions, and will be built on every platform. In
particular, this means that we get consistent GIR output for the
`g_spawn_*()` APIs regardless of whether GLib was built on Linux or
Windows.

Signed-off-by: Philip Withnall <pwithnall@gnome.org>

Helps: #3399
2024-07-15 16:40:55 +01:00

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/* gspawn.c - Process launching
*
* Copyright 2000 Red Hat, Inc.
* g_execvpe implementation based on GNU libc execvp:
* Copyright 1991, 92, 95, 96, 97, 98, 99 Free Software Foundation, Inc.
*
* SPDX-License-Identifier: LGPL-2.1-or-later
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this library; if not, see <http://www.gnu.org/licenses/>.
*/
#include "config.h"
#include <sys/time.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <unistd.h>
#include <errno.h>
#include <fcntl.h>
#include <signal.h>
#include <string.h>
#include <stdlib.h> /* for fdwalk */
#include <dirent.h>
#include <unistd.h>
#ifdef HAVE_SPAWN_H
#include <spawn.h>
#endif /* HAVE_SPAWN_H */
#ifdef HAVE_CRT_EXTERNS_H
#include <crt_externs.h> /* for _NSGetEnviron */
#endif
#ifdef HAVE_SYS_SELECT_H
#include <sys/select.h>
#endif /* HAVE_SYS_SELECT_H */
#ifdef HAVE_SYS_RESOURCE_H
#include <sys/resource.h>
#endif /* HAVE_SYS_RESOURCE_H */
#if defined(__linux__) || defined(__DragonFly__)
#include <sys/syscall.h> /* for syscall and SYS_getdents64 */
#endif
#include "gspawn.h"
#include "gspawn-private.h"
#include "gthread.h"
#include "gtrace-private.h"
#include "glib/gstdio.h"
#include "genviron.h"
#include "gmem.h"
#include "gshell.h"
#include "gstring.h"
#include "gstrfuncs.h"
#include "gtestutils.h"
#include "gutils.h"
#include "glibintl.h"
#include "glib-unix.h"
#if defined(__APPLE__) && defined(HAVE_LIBPROC_H)
#include <libproc.h>
#include <sys/proc_info.h>
#endif
#define INHERITS_OR_NULL_STDIN (G_SPAWN_STDIN_FROM_DEV_NULL | G_SPAWN_CHILD_INHERITS_STDIN)
#define INHERITS_OR_NULL_STDOUT (G_SPAWN_STDOUT_TO_DEV_NULL | G_SPAWN_CHILD_INHERITS_STDOUT)
#define INHERITS_OR_NULL_STDERR (G_SPAWN_STDERR_TO_DEV_NULL | G_SPAWN_CHILD_INHERITS_STDERR)
#define IS_STD_FILENO(_fd) ((_fd >= STDIN_FILENO) && (_fd <= STDERR_FILENO))
#define IS_VALID_FILENO(_fd) (_fd >= 0)
/* posix_spawn() is assumed the fastest way to spawn, but glibc's
* implementation was buggy before glibc 2.24, so avoid it on old versions.
*/
#ifdef HAVE_POSIX_SPAWN
#ifdef __GLIBC__
#if __GLIBC_PREREQ(2,24)
#define POSIX_SPAWN_AVAILABLE
#endif
#else /* !__GLIBC__ */
/* Assume that all non-glibc posix_spawn implementations are fine. */
#define POSIX_SPAWN_AVAILABLE
#endif /* __GLIBC__ */
#endif /* HAVE_POSIX_SPAWN */
#ifdef HAVE__NSGETENVIRON
#define environ (*_NSGetEnviron())
#else
extern char **environ;
#endif
#ifndef O_CLOEXEC
#define O_CLOEXEC 0
#else
#define HAVE_O_CLOEXEC 1
#endif
static gint g_execute (const gchar *file,
gchar **argv,
gchar **argv_buffer,
gsize argv_buffer_len,
gchar **envp,
const gchar *search_path,
gchar *search_path_buffer,
gsize search_path_buffer_len);
static gboolean fork_exec (gboolean intermediate_child,
const gchar *working_directory,
const gchar * const *argv,
const gchar * const *envp,
gboolean close_descriptors,
gboolean search_path,
gboolean search_path_from_envp,
gboolean stdout_to_null,
gboolean stderr_to_null,
gboolean child_inherits_stdin,
gboolean file_and_argv_zero,
gboolean cloexec_pipes,
GSpawnChildSetupFunc child_setup,
gpointer user_data,
GPid *child_pid,
gint *stdin_pipe_out,
gint *stdout_pipe_out,
gint *stderr_pipe_out,
gint stdin_fd,
gint stdout_fd,
gint stderr_fd,
const gint *source_fds,
const gint *target_fds,
gsize n_fds,
GError **error);
G_DEFINE_QUARK (g-exec-error-quark, g_spawn_error)
G_DEFINE_QUARK (g-spawn-exit-error-quark, g_spawn_exit_error)
/* Some versions of OS X define READ_OK in public headers */
#undef READ_OK
typedef enum
{
READ_FAILED = 0, /* FALSE */
READ_OK,
READ_EOF
} ReadResult;
static ReadResult
read_data (GString *str,
gint fd,
GError **error)
{
gssize bytes;
gchar buf[4096];
again:
bytes = read (fd, buf, 4096);
if (bytes == 0)
return READ_EOF;
else if (bytes > 0)
{
g_string_append_len (str, buf, bytes);
return READ_OK;
}
else if (errno == EINTR)
goto again;
else
{
int errsv = errno;
g_set_error (error,
G_SPAWN_ERROR,
G_SPAWN_ERROR_READ,
_("Failed to read data from child process (%s)"),
g_strerror (errsv));
return READ_FAILED;
}
}
gboolean
g_spawn_sync_impl (const gchar *working_directory,
gchar **argv,
gchar **envp,
GSpawnFlags flags,
GSpawnChildSetupFunc child_setup,
gpointer user_data,
gchar **standard_output,
gchar **standard_error,
gint *wait_status,
GError **error)
{
gint outpipe = -1;
gint errpipe = -1;
GPid pid;
gint ret;
GString *outstr = NULL;
GString *errstr = NULL;
gboolean failed;
gint status;
g_return_val_if_fail (argv != NULL, FALSE);
g_return_val_if_fail (argv[0] != NULL, FALSE);
g_return_val_if_fail (!(flags & G_SPAWN_DO_NOT_REAP_CHILD), FALSE);
g_return_val_if_fail (standard_output == NULL ||
!(flags & G_SPAWN_STDOUT_TO_DEV_NULL), FALSE);
g_return_val_if_fail (standard_error == NULL ||
!(flags & G_SPAWN_STDERR_TO_DEV_NULL), FALSE);
/* Just to ensure segfaults if callers try to use
* these when an error is reported.
*/
if (standard_output)
*standard_output = NULL;
if (standard_error)
*standard_error = NULL;
if (!fork_exec (FALSE,
working_directory,
(const gchar * const *) argv,
(const gchar * const *) envp,
!(flags & G_SPAWN_LEAVE_DESCRIPTORS_OPEN),
(flags & G_SPAWN_SEARCH_PATH) != 0,
(flags & G_SPAWN_SEARCH_PATH_FROM_ENVP) != 0,
(flags & G_SPAWN_STDOUT_TO_DEV_NULL) != 0,
(flags & G_SPAWN_STDERR_TO_DEV_NULL) != 0,
(flags & G_SPAWN_CHILD_INHERITS_STDIN) != 0,
(flags & G_SPAWN_FILE_AND_ARGV_ZERO) != 0,
(flags & G_SPAWN_CLOEXEC_PIPES) != 0,
child_setup,
user_data,
&pid,
NULL,
standard_output ? &outpipe : NULL,
standard_error ? &errpipe : NULL,
-1, -1, -1,
NULL, NULL, 0,
error))
return FALSE;
/* Read data from child. */
failed = FALSE;
if (outpipe >= 0)
{
outstr = g_string_new (NULL);
}
if (errpipe >= 0)
{
errstr = g_string_new (NULL);
}
/* Read data until we get EOF on both pipes. */
while (!failed &&
(outpipe >= 0 ||
errpipe >= 0))
{
/* Any negative FD in the array is ignored, so we can use a fixed length.
* We can use UNIX FDs here without worrying about Windows HANDLEs because
* the Windows implementation is entirely in gspawn-win32.c. */
GPollFD fds[] =
{
{ outpipe, G_IO_IN | G_IO_HUP | G_IO_ERR, 0 },
{ errpipe, G_IO_IN | G_IO_HUP | G_IO_ERR, 0 },
};
ret = g_poll (fds, G_N_ELEMENTS (fds), -1 /* no timeout */);
if (ret < 0)
{
int errsv = errno;
if (errno == EINTR)
continue;
failed = TRUE;
g_set_error (error,
G_SPAWN_ERROR,
G_SPAWN_ERROR_READ,
_("Unexpected error in reading data from a child process (%s)"),
g_strerror (errsv));
break;
}
if (outpipe >= 0 && fds[0].revents != 0)
{
switch (read_data (outstr, outpipe, error))
{
case READ_FAILED:
failed = TRUE;
break;
case READ_EOF:
g_clear_fd (&outpipe, NULL);
break;
default:
break;
}
if (failed)
break;
}
if (errpipe >= 0 && fds[1].revents != 0)
{
switch (read_data (errstr, errpipe, error))
{
case READ_FAILED:
failed = TRUE;
break;
case READ_EOF:
g_clear_fd (&errpipe, NULL);
break;
default:
break;
}
if (failed)
break;
}
}
/* These should only be open still if we had an error. */
g_clear_fd (&outpipe, NULL);
g_clear_fd (&errpipe, NULL);
/* Wait for child to exit, even if we have
* an error pending.
*/
again:
ret = waitpid (pid, &status, 0);
if (ret < 0)
{
if (errno == EINTR)
goto again;
else if (errno == ECHILD)
{
if (wait_status)
{
g_warning ("In call to g_spawn_sync(), wait status of a child process was requested but ECHILD was received by waitpid(). See the documentation of g_child_watch_source_new() for possible causes.");
}
else
{
/* We don't need the wait status. */
}
}
else
{
if (!failed) /* avoid error pileups */
{
int errsv = errno;
failed = TRUE;
g_set_error (error,
G_SPAWN_ERROR,
G_SPAWN_ERROR_READ,
_("Unexpected error in waitpid() (%s)"),
g_strerror (errsv));
}
}
}
if (failed)
{
if (outstr)
g_string_free (outstr, TRUE);
if (errstr)
g_string_free (errstr, TRUE);
return FALSE;
}
else
{
if (wait_status)
*wait_status = status;
if (standard_output)
*standard_output = g_string_free (outstr, FALSE);
if (standard_error)
*standard_error = g_string_free (errstr, FALSE);
return TRUE;
}
}
gboolean
g_spawn_async_with_pipes_and_fds_impl (const gchar *working_directory,
const gchar * const *argv,
const gchar * const *envp,
GSpawnFlags flags,
GSpawnChildSetupFunc child_setup,
gpointer user_data,
gint stdin_fd,
gint stdout_fd,
gint stderr_fd,
const gint *source_fds,
const gint *target_fds,
gsize n_fds,
GPid *child_pid_out,
gint *stdin_pipe_out,
gint *stdout_pipe_out,
gint *stderr_pipe_out,
GError **error)
{
g_return_val_if_fail (argv != NULL, FALSE);
g_return_val_if_fail (argv[0] != NULL, FALSE);
/* can’t both inherit and set pipes to /dev/null */
g_return_val_if_fail ((flags & INHERITS_OR_NULL_STDIN) != INHERITS_OR_NULL_STDIN, FALSE);
g_return_val_if_fail ((flags & INHERITS_OR_NULL_STDOUT) != INHERITS_OR_NULL_STDOUT, FALSE);
g_return_val_if_fail ((flags & INHERITS_OR_NULL_STDERR) != INHERITS_OR_NULL_STDERR, FALSE);
/* can’t use pipes and stdin/stdout/stderr FDs */
g_return_val_if_fail (stdin_pipe_out == NULL || stdin_fd < 0, FALSE);
g_return_val_if_fail (stdout_pipe_out == NULL || stdout_fd < 0, FALSE);
g_return_val_if_fail (stderr_pipe_out == NULL || stderr_fd < 0, FALSE);
if ((flags & INHERITS_OR_NULL_STDIN) != 0)
stdin_pipe_out = NULL;
if ((flags & INHERITS_OR_NULL_STDOUT) != 0)
stdout_pipe_out = NULL;
if ((flags & INHERITS_OR_NULL_STDERR) != 0)
stderr_pipe_out = NULL;
return fork_exec (!(flags & G_SPAWN_DO_NOT_REAP_CHILD),
working_directory,
(const gchar * const *) argv,
(const gchar * const *) envp,
!(flags & G_SPAWN_LEAVE_DESCRIPTORS_OPEN),
(flags & G_SPAWN_SEARCH_PATH) != 0,
(flags & G_SPAWN_SEARCH_PATH_FROM_ENVP) != 0,
(flags & G_SPAWN_STDOUT_TO_DEV_NULL) != 0,
(flags & G_SPAWN_STDERR_TO_DEV_NULL) != 0,
(flags & G_SPAWN_CHILD_INHERITS_STDIN) != 0,
(flags & G_SPAWN_FILE_AND_ARGV_ZERO) != 0,
(flags & G_SPAWN_CLOEXEC_PIPES) != 0,
child_setup,
user_data,
child_pid_out,
stdin_pipe_out,
stdout_pipe_out,
stderr_pipe_out,
stdin_fd,
stdout_fd,
stderr_fd,
source_fds,
target_fds,
n_fds,
error);
}
gboolean
g_spawn_check_wait_status_impl (gint wait_status,
GError **error)
{
gboolean ret = FALSE;
if (WIFEXITED (wait_status))
{
if (WEXITSTATUS (wait_status) != 0)
{
g_set_error (error, G_SPAWN_EXIT_ERROR, WEXITSTATUS (wait_status),
_("Child process exited with code %ld"),
(long) WEXITSTATUS (wait_status));
goto out;
}
}
else if (WIFSIGNALED (wait_status))
{
g_set_error (error, G_SPAWN_ERROR, G_SPAWN_ERROR_FAILED,
_("Child process killed by signal %ld"),
(long) WTERMSIG (wait_status));
goto out;
}
else if (WIFSTOPPED (wait_status))
{
g_set_error (error, G_SPAWN_ERROR, G_SPAWN_ERROR_FAILED,
_("Child process stopped by signal %ld"),
(long) WSTOPSIG (wait_status));
goto out;
}
else
{
g_set_error (error, G_SPAWN_ERROR, G_SPAWN_ERROR_FAILED,
_("Child process exited abnormally"));
goto out;
}
ret = TRUE;
out:
return ret;
}
/* This function is called between fork() and exec() and hence must be
* async-signal-safe (see signal-safety(7)). */
static gssize
write_all (gint fd, gconstpointer vbuf, gsize to_write)
{
gchar *buf = (gchar *) vbuf;
while (to_write > 0)
{
gssize count = write (fd, buf, to_write);
if (count < 0)
{
if (errno != EINTR)
return FALSE;
}
else
{
to_write -= count;
buf += count;
}
}
return TRUE;
}
/* This function is called between fork() and exec() and hence must be
* async-signal-safe (see signal-safety(7)). */
G_NORETURN
static void
write_err_and_exit (gint fd, gint msg)
{
gint en = errno;
write_all (fd, &msg, sizeof(msg));
write_all (fd, &en, sizeof(en));
_exit (1);
}
/* This function is called between fork() and exec() and hence must be
* async-signal-safe (see signal-safety(7)). */
static void
set_cloexec (int fd)
{
fcntl (fd, F_SETFD, FD_CLOEXEC);
}
/* This function is called between fork() and exec() and hence must be
* async-signal-safe (see signal-safety(7)). */
static void
unset_cloexec (int fd)
{
int flags;
int result;
flags = fcntl (fd, F_GETFD, 0);
if (flags != -1)
{
int errsv;
flags &= (~FD_CLOEXEC);
do
{
result = fcntl (fd, F_SETFD, flags);
errsv = errno;
}
while (result == -1 && errsv == EINTR);
}
}
/* This function is called between fork() and exec() and hence must be
* async-signal-safe (see signal-safety(7)). */
static int
dupfd_cloexec (int old_fd, int new_fd_min)
{
int fd, errsv;
#ifdef F_DUPFD_CLOEXEC
do
{
fd = fcntl (old_fd, F_DUPFD_CLOEXEC, new_fd_min);
errsv = errno;
}
while (fd == -1 && errsv == EINTR);
#else
/* OS X Snow Lion and earlier don't have F_DUPFD_CLOEXEC:
* https://bugzilla.gnome.org/show_bug.cgi?id=710962
*/
int result, flags;
do
{
fd = fcntl (old_fd, F_DUPFD, new_fd_min);
errsv = errno;
}
while (fd == -1 && errsv == EINTR);
flags = fcntl (fd, F_GETFD, 0);
if (flags != -1)
{
flags |= FD_CLOEXEC;
do
{
result = fcntl (fd, F_SETFD, flags);
errsv = errno;
}
while (result == -1 && errsv == EINTR);
}
#endif
return fd;
}
/* This function is called between fork() and exec() and hence must be
* async-signal-safe (see signal-safety(7)). */
static gint
safe_dup2 (gint fd1, gint fd2)
{
gint ret;
do
ret = dup2 (fd1, fd2);
while (ret < 0 && (errno == EINTR || errno == EBUSY));
return ret;
}
/* This function is called between fork() and exec() and hence must be
* async-signal-safe (see signal-safety(7)). */
static gboolean
relocate_fd_out_of_standard_range (gint *fd)
{
gint ret = -1;
const int min_fileno = STDERR_FILENO + 1;
do
ret = fcntl (*fd, F_DUPFD, min_fileno);
while (ret < 0 && errno == EINTR);
/* Note we don't need to close the old fd, because the caller is expected
* to close fds in the standard range itself.
*/
if (ret >= min_fileno)
{
*fd = ret;
return TRUE;
}
return FALSE;
}
/* This function is called between fork() and exec() and hence must be
* async-signal-safe (see signal-safety(7)). */
static gint
safe_open (const char *path, gint mode)
{
gint ret;
do
ret = open (path, mode);
while (ret < 0 && errno == EINTR);
return ret;
}
enum
{
CHILD_CHDIR_FAILED,
CHILD_EXEC_FAILED,
CHILD_OPEN_FAILED,
CHILD_DUPFD_FAILED,
CHILD_FORK_FAILED,
CHILD_CLOSE_FAILED,
};
/* This function is called between fork() and exec() and hence must be
* async-signal-safe (see signal-safety(7)) until it calls exec().
*
* All callers must guarantee that @argv and @argv[0] are non-NULL. */
static void
do_exec (gint child_err_report_fd,
gint stdin_fd,
gint stdout_fd,
gint stderr_fd,
gint *source_fds,
const gint *target_fds,
gsize n_fds,
const gchar *working_directory,
const gchar * const *argv,
gchar **argv_buffer,
gsize argv_buffer_len,
const gchar * const *envp,
gboolean close_descriptors,
const gchar *search_path,
gchar *search_path_buffer,
gsize search_path_buffer_len,
gboolean stdout_to_null,
gboolean stderr_to_null,
gboolean child_inherits_stdin,
gboolean file_and_argv_zero,
GSpawnChildSetupFunc child_setup,
gpointer user_data)
{
gsize i;
gint max_target_fd = 0;
if (working_directory && chdir (working_directory) < 0)
write_err_and_exit (child_err_report_fd,
CHILD_CHDIR_FAILED);
/* It's possible the caller assigned stdin to an fd with a
* file number that is supposed to be reserved for
* stdout or stderr.
*
* If so, move it up out of the standard range, so it doesn't
* cause a conflict.
*/
if (IS_STD_FILENO (stdin_fd) && stdin_fd != STDIN_FILENO)
{
int old_fd = stdin_fd;
if (!relocate_fd_out_of_standard_range (&stdin_fd))
write_err_and_exit (child_err_report_fd, CHILD_DUPFD_FAILED);
if (stdout_fd == old_fd)
stdout_fd = stdin_fd;
if (stderr_fd == old_fd)
stderr_fd = stdin_fd;
}
/* Redirect pipes as required
*
* There are two cases where we don't need to do the redirection
* 1. Where the associated file descriptor is cleared/invalid
* 2. When the associated file descriptor is already given the
* correct file number.
*/
if (IS_VALID_FILENO (stdin_fd) && stdin_fd != STDIN_FILENO)
{
if (safe_dup2 (stdin_fd, 0) < 0)
write_err_and_exit (child_err_report_fd,
CHILD_DUPFD_FAILED);
set_cloexec (stdin_fd);
}
else if (!child_inherits_stdin)
{
/* Keep process from blocking on a read of stdin */
gint read_null = safe_open ("/dev/null", O_RDONLY);
if (read_null < 0)
write_err_and_exit (child_err_report_fd,
CHILD_OPEN_FAILED);
if (safe_dup2 (read_null, 0) < 0)
write_err_and_exit (child_err_report_fd,
CHILD_DUPFD_FAILED);
g_clear_fd (&read_null, NULL);
}
/* Like with stdin above, it's possible the caller assigned
* stdout to an fd with a file number that's intruding on the
* standard range.
*
* If so, move it out of the way, too.
*/
if (IS_STD_FILENO (stdout_fd) && stdout_fd != STDOUT_FILENO)
{
int old_fd = stdout_fd;
if (!relocate_fd_out_of_standard_range (&stdout_fd))
write_err_and_exit (child_err_report_fd, CHILD_DUPFD_FAILED);
if (stderr_fd == old_fd)
stderr_fd = stdout_fd;
}
if (IS_VALID_FILENO (stdout_fd) && stdout_fd != STDOUT_FILENO)
{
if (safe_dup2 (stdout_fd, 1) < 0)
write_err_and_exit (child_err_report_fd,
CHILD_DUPFD_FAILED);
set_cloexec (stdout_fd);
}
else if (stdout_to_null)
{
gint write_null = safe_open ("/dev/null", O_WRONLY);
if (write_null < 0)
write_err_and_exit (child_err_report_fd,
CHILD_OPEN_FAILED);
if (safe_dup2 (write_null, 1) < 0)
write_err_and_exit (child_err_report_fd,
CHILD_DUPFD_FAILED);
g_clear_fd (&write_null, NULL);
}
if (IS_STD_FILENO (stderr_fd) && stderr_fd != STDERR_FILENO)
{
if (!relocate_fd_out_of_standard_range (&stderr_fd))
write_err_and_exit (child_err_report_fd, CHILD_DUPFD_FAILED);
}
/* Like with stdin/stdout above, it's possible the caller assigned
* stderr to an fd with a file number that's intruding on the
* standard range.
*
* Make sure it's out of the way, also.
*/
if (IS_VALID_FILENO (stderr_fd) && stderr_fd != STDERR_FILENO)
{
if (safe_dup2 (stderr_fd, 2) < 0)
write_err_and_exit (child_err_report_fd,
CHILD_DUPFD_FAILED);
set_cloexec (stderr_fd);
}
else if (stderr_to_null)
{
gint write_null = safe_open ("/dev/null", O_WRONLY);
if (write_null < 0)
write_err_and_exit (child_err_report_fd,
CHILD_OPEN_FAILED);
if (safe_dup2 (write_null, 2) < 0)
write_err_and_exit (child_err_report_fd,
CHILD_DUPFD_FAILED);
g_clear_fd (&write_null, NULL);
}
/* Close all file descriptors but stdin, stdout and stderr, and any of source_fds,
* before we exec. Note that this includes
* child_err_report_fd, which keeps the parent from blocking
* forever on the other end of that pipe.
*/
if (close_descriptors)
{
if (child_setup == NULL && n_fds == 0)
{
if (safe_dup2 (child_err_report_fd, 3) < 0)
write_err_and_exit (child_err_report_fd, CHILD_DUPFD_FAILED);
set_cloexec (3);
if (g_closefrom (4) < 0)
write_err_and_exit (child_err_report_fd, CHILD_CLOSE_FAILED);
child_err_report_fd = 3;
}
else
{
if (g_fdwalk_set_cloexec (3) < 0)
write_err_and_exit (child_err_report_fd, CHILD_CLOSE_FAILED);
}
}
else
{
/* We need to do child_err_report_fd anyway */
set_cloexec (child_err_report_fd);
}
/*
* Work through the @source_fds and @target_fds mapping.
*
* Based on code originally derived from
* gnome-terminal:src/terminal-screen.c:terminal_screen_child_setup(),
* used under the LGPLv2+ with permission from author. (The code has
* since migrated to vte:src/spawn.cc:SpawnContext::exec and is no longer
* terribly similar to what we have here.)
*/
if (n_fds > 0)
{
for (i = 0; i < n_fds; i++)
max_target_fd = MAX (max_target_fd, target_fds[i]);
if (max_target_fd == G_MAXINT)
{
errno = EINVAL;
write_err_and_exit (child_err_report_fd, CHILD_DUPFD_FAILED);
}
/* If we're doing remapping fd assignments, we need to handle
* the case where the user has specified e.g. 5 -> 4, 4 -> 6.
* We do this by duping all source fds, taking care to ensure the new
* fds are larger than any target fd to avoid introducing new conflicts.
*/
for (i = 0; i < n_fds; i++)
{
if (source_fds[i] != target_fds[i])
{
source_fds[i] = dupfd_cloexec (source_fds[i], max_target_fd + 1);
if (source_fds[i] < 0)
write_err_and_exit (child_err_report_fd, CHILD_DUPFD_FAILED);
}
}
for (i = 0; i < n_fds; i++)
{
/* For basic fd assignments (where source == target), we can just
* unset FD_CLOEXEC.
*/
if (source_fds[i] == target_fds[i])
{
unset_cloexec (source_fds[i]);
}
else
{
/* If any of the @target_fds conflict with @child_err_report_fd,
* dup it so it doesn’t get conflated.
*/
if (target_fds[i] == child_err_report_fd)
{
child_err_report_fd = dupfd_cloexec (child_err_report_fd, max_target_fd + 1);
if (child_err_report_fd < 0)
write_err_and_exit (child_err_report_fd, CHILD_DUPFD_FAILED);
}
if (safe_dup2 (source_fds[i], target_fds[i]) < 0)
write_err_and_exit (child_err_report_fd, CHILD_DUPFD_FAILED);
g_clear_fd (&source_fds[i], NULL);
}
}
}
/* Call user function just before we exec */
if (child_setup)
{
(* child_setup) (user_data);
}
g_execute (argv[0],
(gchar **) (file_and_argv_zero ? argv + 1 : argv),
argv_buffer, argv_buffer_len,
(gchar **) envp, search_path, search_path_buffer, search_path_buffer_len);
/* Exec failed */
write_err_and_exit (child_err_report_fd,
CHILD_EXEC_FAILED);
}
static gboolean
read_ints (int fd,
gint* buf,
gint n_ints_in_buf,
gint *n_ints_read,
GError **error)
{
gsize bytes = 0;
while (TRUE)
{
gssize chunk;
if (bytes >= sizeof(gint)*2)
break; /* give up, who knows what happened, should not be
* possible.
*/
again:
chunk = read (fd,
((gchar*)buf) + bytes,
sizeof(gint) * n_ints_in_buf - bytes);
if (chunk < 0 && errno == EINTR)
goto again;
if (chunk < 0)
{
int errsv = errno;
/* Some weird shit happened, bail out */
g_set_error (error,
G_SPAWN_ERROR,
G_SPAWN_ERROR_FAILED,
_("Failed to read from child pipe (%s)"),
g_strerror (errsv));
return FALSE;
}
else if (chunk == 0)
break; /* EOF */
else /* chunk > 0 */
bytes += chunk;
}
*n_ints_read = (gint)(bytes / sizeof(gint));
return TRUE;
}
#ifdef POSIX_SPAWN_AVAILABLE
static gboolean
do_posix_spawn (const gchar * const *argv,
const gchar * const *envp,
gboolean search_path,
gboolean stdout_to_null,
gboolean stderr_to_null,
gboolean child_inherits_stdin,
gboolean file_and_argv_zero,
GPid *child_pid,
gint *child_close_fds,
gint stdin_fd,
gint stdout_fd,
gint stderr_fd,
const gint *source_fds,
const gint *target_fds,
gsize n_fds)
{
pid_t pid;
gint *duped_source_fds = NULL;
gint max_target_fd = 0;
const gchar * const *argv_pass;
posix_spawnattr_t attr;
posix_spawn_file_actions_t file_actions;
gint parent_close_fds[3];
gsize num_parent_close_fds = 0;
GSList *child_close = NULL;
GSList *elem;
sigset_t mask;
gsize i;
int r;
g_assert (argv != NULL && argv[0] != NULL);
if (*argv[0] == '\0')
{
/* We check the simple case first. */
return ENOENT;
}
r = posix_spawnattr_init (&attr);
if (r != 0)
return r;
if (child_close_fds)
{
int i = -1;
while (child_close_fds[++i] != -1)
child_close = g_slist_prepend (child_close,
GINT_TO_POINTER (child_close_fds[i]));
}
r = posix_spawnattr_setflags (&attr, POSIX_SPAWN_SETSIGDEF);
if (r != 0)
goto out_free_spawnattr;
/* Reset some signal handlers that we may use */
sigemptyset (&mask);
sigaddset (&mask, SIGCHLD);
sigaddset (&mask, SIGINT);
sigaddset (&mask, SIGTERM);
sigaddset (&mask, SIGHUP);
r = posix_spawnattr_setsigdefault (&attr, &mask);
if (r != 0)
goto out_free_spawnattr;
r = posix_spawn_file_actions_init (&file_actions);
if (r != 0)
goto out_free_spawnattr;
/* Redirect pipes as required */
if (stdin_fd >= 0)
{
r = posix_spawn_file_actions_adddup2 (&file_actions, stdin_fd, 0);
if (r != 0)
goto out_close_fds;
if (!g_slist_find (child_close, GINT_TO_POINTER (stdin_fd)))
child_close = g_slist_prepend (child_close, GINT_TO_POINTER (stdin_fd));
}
else if (!child_inherits_stdin)
{
/* Keep process from blocking on a read of stdin */
gint read_null = safe_open ("/dev/null", O_RDONLY | O_CLOEXEC);
g_assert (read_null != -1);
parent_close_fds[num_parent_close_fds++] = read_null;
#ifndef HAVE_O_CLOEXEC
fcntl (read_null, F_SETFD, FD_CLOEXEC);
#endif
r = posix_spawn_file_actions_adddup2 (&file_actions, read_null, 0);
if (r != 0)
goto out_close_fds;
}
if (stdout_fd >= 0)
{
r = posix_spawn_file_actions_adddup2 (&file_actions, stdout_fd, 1);
if (r != 0)
goto out_close_fds;
if (!g_slist_find (child_close, GINT_TO_POINTER (stdout_fd)))
child_close = g_slist_prepend (child_close, GINT_TO_POINTER (stdout_fd));
}
else if (stdout_to_null)
{
gint write_null = safe_open ("/dev/null", O_WRONLY | O_CLOEXEC);
g_assert (write_null != -1);
parent_close_fds[num_parent_close_fds++] = write_null;
#ifndef HAVE_O_CLOEXEC
fcntl (write_null, F_SETFD, FD_CLOEXEC);
#endif
r = posix_spawn_file_actions_adddup2 (&file_actions, write_null, 1);
if (r != 0)
goto out_close_fds;
}
if (stderr_fd >= 0)
{
r = posix_spawn_file_actions_adddup2 (&file_actions, stderr_fd, 2);
if (r != 0)
goto out_close_fds;
if (!g_slist_find (child_close, GINT_TO_POINTER (stderr_fd)))
child_close = g_slist_prepend (child_close, GINT_TO_POINTER (stderr_fd));
}
else if (stderr_to_null)
{
gint write_null = safe_open ("/dev/null", O_WRONLY | O_CLOEXEC);
g_assert (write_null != -1);
parent_close_fds[num_parent_close_fds++] = write_null;
#ifndef HAVE_O_CLOEXEC
fcntl (write_null, F_SETFD, FD_CLOEXEC);
#endif
r = posix_spawn_file_actions_adddup2 (&file_actions, write_null, 2);
if (r != 0)
goto out_close_fds;
}
/* If source_fds[i] != target_fds[i], we need to handle the case
* where the user has specified, e.g., 5 -> 4, 4 -> 6. We do this
* by duping the source fds, taking care to ensure the new fds are
* larger than any target fd to avoid introducing new conflicts.
*
* If source_fds[i] == target_fds[i], then we just need to leak
* the fd into the child process, which we *could* do by temporarily
* unsetting CLOEXEC and then setting it again after we spawn if
* it was originally set. POSIX requires that the addup2 action unset
* CLOEXEC if source and target are identical, so you'd think doing it
* manually wouldn't be needed, but unfortunately as of 2021 many
* libcs still don't do so. Example nonconforming libcs:
* Bionic: https://android.googlesource.com/platform/bionic/+/f6e5b582604715729b09db3e36a7aeb8c24b36a4/libc/bionic/spawn.cpp#71
* uclibc-ng: https://cgit.uclibc-ng.org/cgi/cgit/uclibc-ng.git/tree/librt/spawn.c?id=7c36bcae09d66bbaa35cbb02253ae0556f42677e#n88
*
* Anyway, unsetting CLOEXEC ourselves would open a small race window
* where the fd could be inherited into a child process if another
* thread spawns something at the same time, because we have not
* called fork() and are multithreaded here. This race is avoidable by
* using dupfd_cloexec, which we already have to do to handle the
* source_fds[i] != target_fds[i] case. So let's always do it!
*/
for (i = 0; i < n_fds; i++)
max_target_fd = MAX (max_target_fd, target_fds[i]);
if (max_target_fd == G_MAXINT)
goto out_close_fds;
duped_source_fds = g_new (gint, n_fds);
for (i = 0; i < n_fds; i++)
duped_source_fds[i] = -1; /* initialise in case dupfd_cloexec() fails below */
for (i = 0; i < n_fds; i++)
{
duped_source_fds[i] = dupfd_cloexec (source_fds[i], max_target_fd + 1);
if (duped_source_fds[i] < 0)
goto out_close_fds;
}
for (i = 0; i < n_fds; i++)
{
r = posix_spawn_file_actions_adddup2 (&file_actions, duped_source_fds[i], target_fds[i]);
if (r != 0)
goto out_close_fds;
}
/* Intentionally close the fds in the child as the last file action,
* having been careful not to add the same fd to this list twice.
*
* This is important to allow (e.g.) for the same fd to be passed as stdout
* and stderr (we must not close it before we have dupped it in both places,
* and we must not attempt to close it twice).
*/
for (elem = child_close; elem != NULL; elem = elem->next)
{
r = posix_spawn_file_actions_addclose (&file_actions,
GPOINTER_TO_INT (elem->data));
if (r != 0)
goto out_close_fds;
}
argv_pass = file_and_argv_zero ? argv + 1 : argv;
if (envp == NULL)
envp = (const gchar * const *) environ;
/* Don't search when it contains a slash. */
if (!search_path || strchr (argv[0], '/') != NULL)
r = posix_spawn (&pid, argv[0], &file_actions, &attr, (char * const *) argv_pass, (char * const *) envp);
else
r = posix_spawnp (&pid, argv[0], &file_actions, &attr, (char * const *) argv_pass, (char * const *) envp);
if (r == 0 && child_pid != NULL)
*child_pid = pid;
out_close_fds:
for (i = 0; i < num_parent_close_fds; i++)
g_clear_fd (&parent_close_fds[i], NULL);
if (duped_source_fds != NULL)
{
for (i = 0; i < n_fds; i++)
g_clear_fd (&duped_source_fds[i], NULL);
g_free (duped_source_fds);
}
posix_spawn_file_actions_destroy (&file_actions);
out_free_spawnattr:
posix_spawnattr_destroy (&attr);
g_slist_free (child_close);
return r;
}
#endif /* POSIX_SPAWN_AVAILABLE */
static gboolean
source_fds_collide_with_pipe (const GUnixPipe *pipefd,
const int *source_fds,
gsize n_fds,
GError **error)
{
return (_g_spawn_invalid_source_fd (pipefd->fds[G_UNIX_PIPE_END_READ], source_fds, n_fds, error) ||
_g_spawn_invalid_source_fd (pipefd->fds[G_UNIX_PIPE_END_WRITE], source_fds, n_fds, error));
}
static gboolean
fork_exec (gboolean intermediate_child,
const gchar *working_directory,
const gchar * const *argv,
const gchar * const *envp,
gboolean close_descriptors,
gboolean search_path,
gboolean search_path_from_envp,
gboolean stdout_to_null,
gboolean stderr_to_null,
gboolean child_inherits_stdin,
gboolean file_and_argv_zero,
gboolean cloexec_pipes,
GSpawnChildSetupFunc child_setup,
gpointer user_data,
GPid *child_pid,
gint *stdin_pipe_out,
gint *stdout_pipe_out,
gint *stderr_pipe_out,
gint stdin_fd,
gint stdout_fd,
gint stderr_fd,
const gint *source_fds,
const gint *target_fds,
gsize n_fds,
GError **error)
{
GPid pid = -1;
GUnixPipe child_err_report_pipe = G_UNIX_PIPE_INIT;
GUnixPipe child_pid_report_pipe = G_UNIX_PIPE_INIT;
guint pipe_flags = cloexec_pipes ? O_CLOEXEC : 0;
gint status;
const gchar *chosen_search_path;
gchar *search_path_buffer = NULL;
gchar *search_path_buffer_heap = NULL;
gsize search_path_buffer_len = 0;
gchar **argv_buffer = NULL;
gchar **argv_buffer_heap = NULL;
gsize argv_buffer_len = 0;
GUnixPipe stdin_pipe = G_UNIX_PIPE_INIT;
GUnixPipe stdout_pipe = G_UNIX_PIPE_INIT;
GUnixPipe stderr_pipe = G_UNIX_PIPE_INIT;
gint child_close_fds[4] = { -1, -1, -1, -1 };
gint n_child_close_fds = 0;
gint *source_fds_copy = NULL;
g_assert (argv != NULL && argv[0] != NULL);
g_assert (stdin_pipe_out == NULL || stdin_fd < 0);
g_assert (stdout_pipe_out == NULL || stdout_fd < 0);
g_assert (stderr_pipe_out == NULL || stderr_fd < 0);
/* If pipes have been requested, open them */
if (stdin_pipe_out != NULL)
{
if (!g_unix_pipe_open (&stdin_pipe, pipe_flags, error))
goto cleanup_and_fail;
if (source_fds_collide_with_pipe (&stdin_pipe, source_fds, n_fds, error))
goto cleanup_and_fail;
child_close_fds[n_child_close_fds++] = g_unix_pipe_get (&stdin_pipe, G_UNIX_PIPE_END_WRITE);
stdin_fd = g_unix_pipe_get (&stdin_pipe, G_UNIX_PIPE_END_READ);
}
if (stdout_pipe_out != NULL)
{
if (!g_unix_pipe_open (&stdout_pipe, pipe_flags, error))
goto cleanup_and_fail;
if (source_fds_collide_with_pipe (&stdout_pipe, source_fds, n_fds, error))
goto cleanup_and_fail;
child_close_fds[n_child_close_fds++] = g_unix_pipe_get (&stdout_pipe, G_UNIX_PIPE_END_READ);
stdout_fd = g_unix_pipe_get (&stdout_pipe, G_UNIX_PIPE_END_WRITE);
}
if (stderr_pipe_out != NULL)
{
if (!g_unix_pipe_open (&stderr_pipe, pipe_flags, error))
goto cleanup_and_fail;
if (source_fds_collide_with_pipe (&stderr_pipe, source_fds, n_fds, error))
goto cleanup_and_fail;
child_close_fds[n_child_close_fds++] = g_unix_pipe_get (&stderr_pipe, G_UNIX_PIPE_END_READ);
stderr_fd = g_unix_pipe_get (&stderr_pipe, G_UNIX_PIPE_END_WRITE);
}
child_close_fds[n_child_close_fds++] = -1;
#ifdef POSIX_SPAWN_AVAILABLE
if (!intermediate_child && working_directory == NULL && !close_descriptors &&
!search_path_from_envp && child_setup == NULL)
{
g_trace_mark (G_TRACE_CURRENT_TIME, 0,
"GLib", "posix_spawn",
"%s", argv[0]);
status = do_posix_spawn (argv,
envp,
search_path,
stdout_to_null,
stderr_to_null,
child_inherits_stdin,
file_and_argv_zero,
child_pid,
child_close_fds,
stdin_fd,
stdout_fd,
stderr_fd,
source_fds,
target_fds,
n_fds);
if (status == 0)
goto success;
if (status != ENOEXEC)
{
g_set_error (error,
G_SPAWN_ERROR,
G_SPAWN_ERROR_FAILED,
_("Failed to spawn child process “%s” (%s)"),
argv[0],
g_strerror (status));
goto cleanup_and_fail;
}
/* posix_spawn is not intended to support script execution. It does in
* some situations on some glibc versions, but that will be fixed.
* So if it fails with ENOEXEC, we fall through to the regular
* gspawn codepath so that script execution can be attempted,
* per standard gspawn behaviour. */
g_debug ("posix_spawn failed (ENOEXEC), fall back to regular gspawn");
}
else
{
g_trace_mark (G_TRACE_CURRENT_TIME, 0,
"GLib", "fork",
"posix_spawn avoided %s%s%s%s%s",
!intermediate_child ? "" : "(automatic reaping requested) ",
working_directory == NULL ? "" : "(workdir specified) ",
!close_descriptors ? "" : "(fd close requested) ",
!search_path_from_envp ? "" : "(using envp for search path) ",
child_setup == NULL ? "" : "(child_setup specified) ");
}
#endif /* POSIX_SPAWN_AVAILABLE */
/* Choose a search path. This has to be done before calling fork()
* as getenv() isn’t async-signal-safe (see `man 7 signal-safety`). */
chosen_search_path = NULL;
if (search_path_from_envp)
chosen_search_path = g_environ_getenv ((gchar **) envp, "PATH");
if (search_path && chosen_search_path == NULL)
chosen_search_path = g_getenv ("PATH");
if ((search_path || search_path_from_envp) && chosen_search_path == NULL)
{
/* There is no 'PATH' in the environment. The default
* * search path in libc is the current directory followed by
* * the path 'confstr' returns for '_CS_PATH'.
* */
/* In GLib we put . last, for security, and don't use the
* * unportable confstr(); UNIX98 does not actually specify
* * what to search if PATH is unset. POSIX may, dunno.
* */
chosen_search_path = "/bin:/usr/bin:.";
}
if (search_path || search_path_from_envp)
g_assert (chosen_search_path != NULL);
else
g_assert (chosen_search_path == NULL);
/* Allocate a buffer which the fork()ed child can use to assemble potential
* paths for the binary to exec(), combining the argv[0] and elements from
* the chosen_search_path. This can’t be done in the child because malloc()
* (or alloca()) are not async-signal-safe (see `man 7 signal-safety`).
*
* Add 2 for the nul terminator and a leading `/`. */
if (chosen_search_path != NULL)
{
search_path_buffer_len = strlen (chosen_search_path) + strlen (argv[0]) + 2;
if (search_path_buffer_len < 4000)
{
/* Prefer small stack allocations to avoid valgrind leak warnings
* in forked child. The 4000B cutoff is arbitrary. */
search_path_buffer = g_alloca (search_path_buffer_len);
}
else
{
search_path_buffer_heap = g_malloc (search_path_buffer_len);
search_path_buffer = search_path_buffer_heap;
}
}
if (search_path || search_path_from_envp)
g_assert (search_path_buffer != NULL);
else
g_assert (search_path_buffer == NULL);
/* And allocate a buffer which is 2 elements longer than @argv, so that if
* script_execute() has to be called later on, it can build a wrapper argv
* array in this buffer. */
argv_buffer_len = g_strv_length ((gchar **) argv) + 2;
if (argv_buffer_len < 4000 / sizeof (gchar *))
{
/* Prefer small stack allocations to avoid valgrind leak warnings
* in forked child. The 4000B cutoff is arbitrary. */
argv_buffer = g_newa (gchar *, argv_buffer_len);
}
else
{
argv_buffer_heap = g_new (gchar *, argv_buffer_len);
argv_buffer = argv_buffer_heap;
}
/* And one to hold a copy of @source_fds for later manipulation in do_exec(). */
source_fds_copy = g_new (int, n_fds);
if (n_fds > 0)
memcpy (source_fds_copy, source_fds, sizeof (*source_fds) * n_fds);
if (!g_unix_pipe_open (&child_err_report_pipe, pipe_flags, error))
goto cleanup_and_fail;
if (source_fds_collide_with_pipe (&child_err_report_pipe, source_fds, n_fds, error))
goto cleanup_and_fail;
if (intermediate_child)
{
if (!g_unix_pipe_open (&child_pid_report_pipe, pipe_flags, error))
goto cleanup_and_fail;
if (source_fds_collide_with_pipe (&child_pid_report_pipe, source_fds, n_fds, error))
goto cleanup_and_fail;
}
pid = fork ();
if (pid < 0)
{
int errsv = errno;
g_set_error (error,
G_SPAWN_ERROR,
G_SPAWN_ERROR_FORK,
_("Failed to fork (%s)"),
g_strerror (errsv));
goto cleanup_and_fail;
}
else if (pid == 0)
{
/* Immediate child. This may or may not be the child that
* actually execs the new process.
*/
/* Reset some signal handlers that we may use */
signal (SIGCHLD, SIG_DFL);
signal (SIGINT, SIG_DFL);
signal (SIGTERM, SIG_DFL);
signal (SIGHUP, SIG_DFL);
/* Be sure we crash if the parent exits
* and we write to the err_report_pipe
*/
signal (SIGPIPE, SIG_DFL);
/* Close the parent's end of the pipes;
* not needed in the close_descriptors case,
* though
*/
g_unix_pipe_close (&child_err_report_pipe, G_UNIX_PIPE_END_READ, NULL);
g_unix_pipe_close (&child_pid_report_pipe, G_UNIX_PIPE_END_READ, NULL);
if (child_close_fds[0] != -1)
{
int i = -1;
while (child_close_fds[++i] != -1)
g_clear_fd (&child_close_fds[i], NULL);
}
if (intermediate_child)
{
/* We need to fork an intermediate child that launches the
* final child. The purpose of the intermediate child
* is to exit, so we can waitpid() it immediately.
* Then the grandchild will not become a zombie.
*/
GPid grandchild_pid;
grandchild_pid = fork ();
if (grandchild_pid < 0)
{
/* report -1 as child PID */
write_all (g_unix_pipe_get (&child_pid_report_pipe, G_UNIX_PIPE_END_WRITE),
&grandchild_pid, sizeof(grandchild_pid));
write_err_and_exit (g_unix_pipe_get (&child_err_report_pipe, G_UNIX_PIPE_END_WRITE),
CHILD_FORK_FAILED);
}
else if (grandchild_pid == 0)
{
g_unix_pipe_close (&child_pid_report_pipe, G_UNIX_PIPE_END_WRITE, NULL);
do_exec (g_unix_pipe_get (&child_err_report_pipe, G_UNIX_PIPE_END_WRITE),
stdin_fd,
stdout_fd,
stderr_fd,
source_fds_copy,
target_fds,
n_fds,
working_directory,
argv,
argv_buffer,
argv_buffer_len,
envp,
close_descriptors,
chosen_search_path,
search_path_buffer,
search_path_buffer_len,
stdout_to_null,
stderr_to_null,
child_inherits_stdin,
file_and_argv_zero,
child_setup,
user_data);
}
else
{
write_all (g_unix_pipe_get (&child_pid_report_pipe, G_UNIX_PIPE_END_WRITE),
&grandchild_pid, sizeof(grandchild_pid));
g_unix_pipe_close (&child_pid_report_pipe, G_UNIX_PIPE_END_WRITE, NULL);
_exit (0);
}
}
else
{
/* Just run the child.
*/
do_exec (g_unix_pipe_get (&child_err_report_pipe, G_UNIX_PIPE_END_WRITE),
stdin_fd,
stdout_fd,
stderr_fd,
source_fds_copy,
target_fds,
n_fds,
working_directory,
argv,
argv_buffer,
argv_buffer_len,
envp,
close_descriptors,
chosen_search_path,
search_path_buffer,
search_path_buffer_len,
stdout_to_null,
stderr_to_null,
child_inherits_stdin,
file_and_argv_zero,
child_setup,
user_data);
}
}
else
{
/* Parent */
gint buf[2];
gint n_ints = 0;
/* Close the uncared-about ends of the pipes */
g_unix_pipe_close (&child_err_report_pipe, G_UNIX_PIPE_END_WRITE, NULL);
g_unix_pipe_close (&child_pid_report_pipe, G_UNIX_PIPE_END_WRITE, NULL);
/* If we had an intermediate child, reap it */
if (intermediate_child)
{
wait_again:
if (waitpid (pid, &status, 0) < 0)
{
if (errno == EINTR)
goto wait_again;
else if (errno == ECHILD)
; /* do nothing, child already reaped */
else
g_warning ("waitpid() should not fail in 'fork_exec'");
}
}
if (!read_ints (g_unix_pipe_get (&child_err_report_pipe, G_UNIX_PIPE_END_READ),
buf, 2, &n_ints,
error))
goto cleanup_and_fail;
if (n_ints >= 2)
{
/* Error from the child. */
switch (buf[0])
{
case CHILD_CHDIR_FAILED:
g_set_error (error,
G_SPAWN_ERROR,
G_SPAWN_ERROR_CHDIR,
_("Failed to change to directory “%s” (%s)"),
working_directory,
g_strerror (buf[1]));
break;
case CHILD_EXEC_FAILED:
g_set_error (error,
G_SPAWN_ERROR,
_g_spawn_exec_err_to_g_error (buf[1]),
_("Failed to execute child process “%s” (%s)"),
argv[0],
g_strerror (buf[1]));
break;
case CHILD_OPEN_FAILED:
g_set_error (error,
G_SPAWN_ERROR,
G_SPAWN_ERROR_FAILED,
_("Failed to open file to remap file descriptor (%s)"),
g_strerror (buf[1]));
break;
case CHILD_DUPFD_FAILED:
g_set_error (error,
G_SPAWN_ERROR,
G_SPAWN_ERROR_FAILED,
_("Failed to duplicate file descriptor for child process (%s)"),
g_strerror (buf[1]));
break;
case CHILD_FORK_FAILED:
g_set_error (error,
G_SPAWN_ERROR,
G_SPAWN_ERROR_FORK,
_("Failed to fork child process (%s)"),
g_strerror (buf[1]));
break;
case CHILD_CLOSE_FAILED:
g_set_error (error,
G_SPAWN_ERROR,
G_SPAWN_ERROR_FAILED,
_("Failed to close file descriptor for child process (%s)"),
g_strerror (buf[1]));
break;
default:
g_set_error (error,
G_SPAWN_ERROR,
G_SPAWN_ERROR_FAILED,
_("Unknown error executing child process “%s”"),
argv[0]);
break;
}
goto cleanup_and_fail;
}
/* Get child pid from intermediate child pipe. */
if (intermediate_child)
{
n_ints = 0;
if (!read_ints (g_unix_pipe_get (&child_pid_report_pipe, G_UNIX_PIPE_END_READ),
buf, 1, &n_ints, error))
goto cleanup_and_fail;
if (n_ints < 1)
{
int errsv = errno;
g_set_error (error,
G_SPAWN_ERROR,
G_SPAWN_ERROR_FAILED,
_("Failed to read enough data from child pid pipe (%s)"),
g_strerror (errsv));
goto cleanup_and_fail;
}
else
{
/* we have the child pid */
pid = buf[0];
}
}
/* Success against all odds! return the information */
g_unix_pipe_close (&child_err_report_pipe, G_UNIX_PIPE_END_READ, NULL);
g_unix_pipe_close (&child_pid_report_pipe, G_UNIX_PIPE_END_READ, NULL);
g_free (search_path_buffer_heap);
g_free (argv_buffer_heap);
g_free (source_fds_copy);
if (child_pid)
*child_pid = pid;
goto success;
}
success:
/* Close the uncared-about ends of the pipes */
g_unix_pipe_close (&stdin_pipe, G_UNIX_PIPE_END_READ, NULL);
g_unix_pipe_close (&stdout_pipe, G_UNIX_PIPE_END_WRITE, NULL);
g_unix_pipe_close (&stderr_pipe, G_UNIX_PIPE_END_WRITE, NULL);
if (stdin_pipe_out != NULL)
*stdin_pipe_out = g_unix_pipe_steal (&stdin_pipe, G_UNIX_PIPE_END_WRITE);
if (stdout_pipe_out != NULL)
*stdout_pipe_out = g_unix_pipe_steal (&stdout_pipe, G_UNIX_PIPE_END_READ);
if (stderr_pipe_out != NULL)
*stderr_pipe_out = g_unix_pipe_steal (&stderr_pipe, G_UNIX_PIPE_END_READ);
return TRUE;
cleanup_and_fail:
/* There was an error from the Child, reap the child to avoid it being
a zombie.
*/
if (pid > 0)
{
wait_failed:
if (waitpid (pid, NULL, 0) < 0)
{
if (errno == EINTR)
goto wait_failed;
else if (errno == ECHILD)
; /* do nothing, child already reaped */
else
g_warning ("waitpid() should not fail in 'fork_exec'");
}
}
g_unix_pipe_clear (&stdin_pipe);
g_unix_pipe_clear (&stdout_pipe);
g_unix_pipe_clear (&stderr_pipe);
g_unix_pipe_clear (&child_err_report_pipe);
g_unix_pipe_clear (&child_pid_report_pipe);
g_clear_pointer (&search_path_buffer_heap, g_free);
g_clear_pointer (&argv_buffer_heap, g_free);
g_clear_pointer (&source_fds_copy, g_free);
return FALSE;
}
/* Based on execvp from GNU C Library */
/* This function is called between fork() and exec() and hence must be
* async-signal-safe (see signal-safety(7)) until it calls exec(). */
static gboolean
script_execute (const gchar *file,
gchar **argv,
gchar **argv_buffer,
gsize argv_buffer_len,
gchar **envp)
{
/* Count the arguments. */
gsize argc = 0;
while (argv[argc])
++argc;
/* Construct an argument list for the shell. */
if (argc + 2 > argv_buffer_len)
return FALSE;
argv_buffer[0] = (char *) "/bin/sh";
argv_buffer[1] = (char *) file;
while (argc > 0)
{
argv_buffer[argc + 1] = argv[argc];
--argc;
}
/* Execute the shell. */
if (envp)
execve (argv_buffer[0], argv_buffer, envp);
else
execv (argv_buffer[0], argv_buffer);
return TRUE;
}
/* This function is called between fork() and exec() and hence must be
* async-signal-safe (see signal-safety(7)). */
static gchar*
my_strchrnul (const gchar *str, gchar c)
{
gchar *p = (gchar*) str;
while (*p && (*p != c))
++p;
return p;
}
/* This function is called between fork() and exec() and hence must be
* async-signal-safe (see signal-safety(7)) until it calls exec(). */
static gint
g_execute (const gchar *file,
gchar **argv,
gchar **argv_buffer,
gsize argv_buffer_len,
gchar **envp,
const gchar *search_path,
gchar *search_path_buffer,
gsize search_path_buffer_len)
{
if (file == NULL || *file == '\0')
{
/* We check the simple case first. */
errno = ENOENT;
return -1;
}
if (search_path == NULL || strchr (file, '/') != NULL)
{
/* Don't search when it contains a slash. */
if (envp)
execve (file, argv, envp);
else
execv (file, argv);
if (errno == ENOEXEC &&
!script_execute (file, argv, argv_buffer, argv_buffer_len, envp))
{
errno = ENOMEM;
return -1;
}
}
else
{
gboolean got_eacces = 0;
const gchar *path, *p;
gchar *name;
gsize len;
gsize pathlen;
path = search_path;
len = strlen (file) + 1;
pathlen = strlen (path);
name = search_path_buffer;
if (search_path_buffer_len < pathlen + len + 1)
{
errno = ENOMEM;
return -1;
}
/* Copy the file name at the top, including '\0' */
memcpy (name + pathlen + 1, file, len);
name = name + pathlen;
/* And add the slash before the filename */
*name = '/';
p = path;
do
{
char *startp;
path = p;
p = my_strchrnul (path, ':');
if (p == path)
/* Two adjacent colons, or a colon at the beginning or the end
* of 'PATH' means to search the current directory.
*/
startp = name + 1;
else
startp = memcpy (name - (p - path), path, p - path);
/* Try to execute this name. If it works, execv will not return. */
if (envp)
execve (startp, argv, envp);
else
execv (startp, argv);
if (errno == ENOEXEC &&
!script_execute (startp, argv, argv_buffer, argv_buffer_len, envp))
{
errno = ENOMEM;
return -1;
}
switch (errno)
{
case EACCES:
/* Record the we got a 'Permission denied' error. If we end
* up finding no executable we can use, we want to diagnose
* that we did find one but were denied access.
*/
got_eacces = TRUE;
G_GNUC_FALLTHROUGH;
case ENOENT:
#ifdef ESTALE
case ESTALE:
#endif
#ifdef ENOTDIR
case ENOTDIR:
#endif
/* Those errors indicate the file is missing or not executable
* by us, in which case we want to just try the next path
* directory.
*/
break;
case ENODEV:
case ETIMEDOUT:
/* Some strange filesystems like AFS return even
* stranger error numbers. They cannot reasonably mean anything
* else so ignore those, too.
*/
break;
default:
/* Some other error means we found an executable file, but
* something went wrong executing it; return the error to our
* caller.
*/
return -1;
}
}
while (*p++ != '\0');
/* We tried every element and none of them worked. */
if (got_eacces)
/* At least one failure was due to permissions, so report that
* error.
*/
errno = EACCES;
}
/* Return the error from the last attempt (probably ENOENT). */
return -1;
}
void
g_spawn_close_pid_impl (GPid pid)
{
/* no-op */
}
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