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android / platform / external / dbus / refs/heads/nougat-mr2.2-release / . / dbus / dbus-spawn.c
blob: ef00801cc8de917ea04fc2683a49dbbcbef91d07 [file] [log] [blame]
/* -*- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -*- */
/* dbus-spawn.c Wrapper around fork/exec
*
* Copyright (C) 2002, 2003, 2004 Red Hat, Inc.
* Copyright (C) 2003 CodeFactory AB
*
* Licensed under the Academic Free License version 2.1
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*
*/
#include <config.h>
#include "dbus-spawn.h"
#include "dbus-sysdeps-unix.h"
#include "dbus-internals.h"
#include "dbus-test.h"
#include "dbus-protocol.h"
#include <unistd.h>
#include <fcntl.h>
#include <signal.h>
#include <sys/wait.h>
#include <stdlib.h>
#ifdef HAVE_ERRNO_H
#include <errno.h>
#endif
extern char **environ;
/**
* @addtogroup DBusInternalsUtils
* @{
*/
/*
* I'm pretty sure this whole spawn file could be made simpler,
* if you thought about it a bit.
*/
/**
* Enumeration for status of a read()
*/
typedef enum
{
READ_STATUS_OK, /**< Read succeeded */
READ_STATUS_ERROR, /**< Some kind of error */
READ_STATUS_EOF /**< EOF returned */
} ReadStatus;
static ReadStatus
read_ints (int fd,
int *buf,
int n_ints_in_buf,
int *n_ints_read,
DBusError *error)
{
size_t bytes = 0;
ReadStatus retval;
_DBUS_ASSERT_ERROR_IS_CLEAR (error);
retval = READ_STATUS_OK;
while (TRUE)
{
ssize_t chunk;
size_t to_read;
to_read = sizeof (int) * n_ints_in_buf - bytes;
if (to_read == 0)
break;
again:
chunk = read (fd,
((char*)buf) + bytes,
to_read);
if (chunk < 0 && errno == EINTR)
goto again;
if (chunk < 0)
{
dbus_set_error (error,
DBUS_ERROR_SPAWN_FAILED,
"Failed to read from child pipe (%s)",
_dbus_strerror (errno));
retval = READ_STATUS_ERROR;
break;
}
else if (chunk == 0)
{
retval = READ_STATUS_EOF;
break; /* EOF */
}
else /* chunk > 0 */
bytes += chunk;
}
*n_ints_read = (int)(bytes / sizeof(int));
return retval;
}
static ReadStatus
read_pid (int fd,
pid_t *buf,
DBusError *error)
{
size_t bytes = 0;
ReadStatus retval;
_DBUS_ASSERT_ERROR_IS_CLEAR (error);
retval = READ_STATUS_OK;
while (TRUE)
{
ssize_t chunk;
size_t to_read;
to_read = sizeof (pid_t) - bytes;
if (to_read == 0)
break;
again:
chunk = read (fd,
((char*)buf) + bytes,
to_read);
if (chunk < 0 && errno == EINTR)
goto again;
if (chunk < 0)
{
dbus_set_error (error,
DBUS_ERROR_SPAWN_FAILED,
"Failed to read from child pipe (%s)",
_dbus_strerror (errno));
retval = READ_STATUS_ERROR;
break;
}
else if (chunk == 0)
{
retval = READ_STATUS_EOF;
break; /* EOF */
}
else /* chunk > 0 */
bytes += chunk;
}
return retval;
}
/* The implementation uses an intermediate child between the main process
* and the grandchild. The grandchild is our spawned process. The intermediate
* child is a babysitter process; it keeps track of when the grandchild
* exits/crashes, and reaps the grandchild.
*/
/* Messages from children to parents */
enum
{
CHILD_EXITED, /* This message is followed by the exit status int */
CHILD_FORK_FAILED, /* Followed by errno */
CHILD_EXEC_FAILED, /* Followed by errno */
CHILD_PID /* Followed by pid_t */
};
/**
* Babysitter implementation details
*/
struct DBusBabysitter
{
int refcount; /**< Reference count */
char *executable; /**< executable name to use in error messages */
int socket_to_babysitter; /**< Connection to the babysitter process */
int error_pipe_from_child; /**< Connection to the process that does the exec() */
pid_t sitter_pid; /**< PID Of the babysitter */
pid_t grandchild_pid; /**< PID of the grandchild */
DBusWatchList *watches; /**< Watches */
DBusWatch *error_watch; /**< Error pipe watch */
DBusWatch *sitter_watch; /**< Sitter pipe watch */
DBusBabysitterFinishedFunc finished_cb;
void *finished_data;
int errnum; /**< Error number */
int status; /**< Exit status code */
unsigned int have_child_status : 1; /**< True if child status has been reaped */
unsigned int have_fork_errnum : 1; /**< True if we have an error code from fork() */
unsigned int have_exec_errnum : 1; /**< True if we have an error code from exec() */
};
static DBusBabysitter*
_dbus_babysitter_new (void)
{
DBusBabysitter *sitter;
sitter = dbus_new0 (DBusBabysitter, 1);
if (sitter == NULL)
return NULL;
sitter->refcount = 1;
sitter->socket_to_babysitter = -1;
sitter->error_pipe_from_child = -1;
sitter->sitter_pid = -1;
sitter->grandchild_pid = -1;
sitter->watches = _dbus_watch_list_new ();
if (sitter->watches == NULL)
goto failed;
return sitter;
failed:
_dbus_babysitter_unref (sitter);
return NULL;
}
/**
* Increment the reference count on the babysitter object.
*
* @param sitter the babysitter
* @returns the babysitter
*/
DBusBabysitter *
_dbus_babysitter_ref (DBusBabysitter *sitter)
{
_dbus_assert (sitter != NULL);
_dbus_assert (sitter->refcount > 0);
sitter->refcount += 1;
return sitter;
}
static void close_socket_to_babysitter (DBusBabysitter *sitter);
static void close_error_pipe_from_child (DBusBabysitter *sitter);
/**
* Decrement the reference count on the babysitter object.
* When the reference count of the babysitter object reaches
* zero, the babysitter is killed and the child that was being
* babysat gets emancipated.
*
* @param sitter the babysitter
*/
void
_dbus_babysitter_unref (DBusBabysitter *sitter)
{
_dbus_assert (sitter != NULL);
_dbus_assert (sitter->refcount > 0);
sitter->refcount -= 1;
if (sitter->refcount == 0)
{
/* If we haven't forked other babysitters
* since this babysitter and socket were
* created then this close will cause the
* babysitter to wake up from poll with
* a hangup and then the babysitter will
* quit itself.
*/
close_socket_to_babysitter (sitter);
close_error_pipe_from_child (sitter);
if (sitter->sitter_pid > 0)
{
int status;
int ret;
/* It's possible the babysitter died on its own above
* from the close, or was killed randomly
* by some other process, so first try to reap it
*/
ret = waitpid (sitter->sitter_pid, &status, WNOHANG);
/* If we couldn't reap the child then kill it, and
* try again
*/
if (ret == 0)
kill (sitter->sitter_pid, SIGKILL);
again:
if (ret == 0)
ret = waitpid (sitter->sitter_pid, &status, 0);
if (ret < 0)
{
if (errno == EINTR)
goto again;
else if (errno == ECHILD)
_dbus_warn ("Babysitter process not available to be reaped; should not happen\n");
else
_dbus_warn ("Unexpected error %d in waitpid() for babysitter: %s\n",
errno, _dbus_strerror (errno));
}
else
{
_dbus_verbose ("Reaped %ld, waiting for babysitter %ld\n",
(long) ret, (long) sitter->sitter_pid);
if (WIFEXITED (sitter->status))
_dbus_verbose ("Babysitter exited with status %d\n",
WEXITSTATUS (sitter->status));
else if (WIFSIGNALED (sitter->status))
_dbus_verbose ("Babysitter received signal %d\n",
WTERMSIG (sitter->status));
else
_dbus_verbose ("Babysitter exited abnormally\n");
}
sitter->sitter_pid = -1;
}
if (sitter->watches)
_dbus_watch_list_free (sitter->watches);
dbus_free (sitter->executable);
dbus_free (sitter);
}
}
static ReadStatus
read_data (DBusBabysitter *sitter,
int fd)
{
int what;
int got;
DBusError error = DBUS_ERROR_INIT;
ReadStatus r;
r = read_ints (fd, &what, 1, &got, &error);
switch (r)
{
case READ_STATUS_ERROR:
_dbus_warn ("Failed to read data from fd %d: %s\n", fd, error.message);
dbus_error_free (&error);
return r;
case READ_STATUS_EOF:
return r;
case READ_STATUS_OK:
break;
}
if (got == 1)
{
switch (what)
{
case CHILD_EXITED:
case CHILD_FORK_FAILED:
case CHILD_EXEC_FAILED:
{
int arg;
r = read_ints (fd, &arg, 1, &got, &error);
switch (r)
{
case READ_STATUS_ERROR:
_dbus_warn ("Failed to read arg from fd %d: %s\n", fd, error.message);
dbus_error_free (&error);
return r;
case READ_STATUS_EOF:
return r;
case READ_STATUS_OK:
break;
}
if (got == 1)
{
if (what == CHILD_EXITED)
{
sitter->have_child_status = TRUE;
sitter->status = arg;
sitter->errnum = 0;
_dbus_verbose ("recorded child status exited = %d signaled = %d exitstatus = %d termsig = %d\n",
WIFEXITED (sitter->status), WIFSIGNALED (sitter->status),
WEXITSTATUS (sitter->status), WTERMSIG (sitter->status));
}
else if (what == CHILD_FORK_FAILED)
{
sitter->have_fork_errnum = TRUE;
sitter->errnum = arg;
_dbus_verbose ("recorded fork errnum %d\n", sitter->errnum);
}
else if (what == CHILD_EXEC_FAILED)
{
sitter->have_exec_errnum = TRUE;
sitter->errnum = arg;
_dbus_verbose ("recorded exec errnum %d\n", sitter->errnum);
}
}
}
break;
case CHILD_PID:
{
pid_t pid = -1;
r = read_pid (fd, &pid, &error);
switch (r)
{
case READ_STATUS_ERROR:
_dbus_warn ("Failed to read PID from fd %d: %s\n", fd, error.message);
dbus_error_free (&error);
return r;
case READ_STATUS_EOF:
return r;
case READ_STATUS_OK:
break;
}
sitter->grandchild_pid = pid;
_dbus_verbose ("recorded grandchild pid %d\n", sitter->grandchild_pid);
}
break;
default:
_dbus_warn ("Unknown message received from babysitter process\n");
break;
}
}
return r;
}
static void
close_socket_to_babysitter (DBusBabysitter *sitter)
{
_dbus_verbose ("Closing babysitter\n");
if (sitter->sitter_watch != NULL)
{
_dbus_assert (sitter->watches != NULL);
_dbus_watch_list_remove_watch (sitter->watches, sitter->sitter_watch);
_dbus_watch_invalidate (sitter->sitter_watch);
_dbus_watch_unref (sitter->sitter_watch);
sitter->sitter_watch = NULL;
}
if (sitter->socket_to_babysitter >= 0)
{
_dbus_close_socket (sitter->socket_to_babysitter, NULL);
sitter->socket_to_babysitter = -1;
}
}
static void
close_error_pipe_from_child (DBusBabysitter *sitter)
{
_dbus_verbose ("Closing child error\n");
if (sitter->error_watch != NULL)
{
_dbus_assert (sitter->watches != NULL);
_dbus_watch_list_remove_watch (sitter->watches, sitter->error_watch);
_dbus_watch_invalidate (sitter->error_watch);
_dbus_watch_unref (sitter->error_watch);
sitter->error_watch = NULL;
}
if (sitter->error_pipe_from_child >= 0)
{
_dbus_close_socket (sitter->error_pipe_from_child, NULL);
sitter->error_pipe_from_child = -1;
}
}
static void
handle_babysitter_socket (DBusBabysitter *sitter,
int revents)
{
/* Even if we have POLLHUP, we want to keep reading
* data until POLLIN goes away; so this function only
* looks at HUP/ERR if no IN is set.
*/
if (revents & _DBUS_POLLIN)
{
_dbus_verbose ("Reading data from babysitter\n");
if (read_data (sitter, sitter->socket_to_babysitter) != READ_STATUS_OK)
close_socket_to_babysitter (sitter);
}
else if (revents & (_DBUS_POLLERR | _DBUS_POLLHUP))
{
close_socket_to_babysitter (sitter);
}
}
static void
handle_error_pipe (DBusBabysitter *sitter,
int revents)
{
if (revents & _DBUS_POLLIN)
{
_dbus_verbose ("Reading data from child error\n");
if (read_data (sitter, sitter->error_pipe_from_child) != READ_STATUS_OK)
close_error_pipe_from_child (sitter);
}
else if (revents & (_DBUS_POLLERR | _DBUS_POLLHUP))
{
close_error_pipe_from_child (sitter);
}
}
/* returns whether there were any poll events handled */
static dbus_bool_t
babysitter_iteration (DBusBabysitter *sitter,
dbus_bool_t block)
{
DBusPollFD fds[2];
int i;
dbus_bool_t descriptors_ready;
descriptors_ready = FALSE;
i = 0;
if (sitter->error_pipe_from_child >= 0)
{
fds[i].fd = sitter->error_pipe_from_child;
fds[i].events = _DBUS_POLLIN;
fds[i].revents = 0;
++i;
}
if (sitter->socket_to_babysitter >= 0)
{
fds[i].fd = sitter->socket_to_babysitter;
fds[i].events = _DBUS_POLLIN;
fds[i].revents = 0;
++i;
}
if (i > 0)
{
int ret;
do
{
ret = _dbus_poll (fds, i, 0);
}
while (ret < 0 && errno == EINTR);
if (ret == 0 && block)
{
do
{
ret = _dbus_poll (fds, i, -1);
}
while (ret < 0 && errno == EINTR);
}
if (ret > 0)
{
descriptors_ready = TRUE;
while (i > 0)
{
--i;
if (fds[i].fd == sitter->error_pipe_from_child)
handle_error_pipe (sitter, fds[i].revents);
else if (fds[i].fd == sitter->socket_to_babysitter)
handle_babysitter_socket (sitter, fds[i].revents);
}
}
}
return descriptors_ready;
}
/**
* Macro returns #TRUE if the babysitter still has live sockets open to the
* babysitter child or the grandchild.
*/
#define LIVE_CHILDREN(sitter) ((sitter)->socket_to_babysitter >= 0 || (sitter)->error_pipe_from_child >= 0)
/**
* Blocks until the babysitter process gives us the PID of the spawned grandchild,
* then kills the spawned grandchild.
*
* @param sitter the babysitter object
*/
void
_dbus_babysitter_kill_child (DBusBabysitter *sitter)
{
/* be sure we have the PID of the child */
while (LIVE_CHILDREN (sitter) &&
sitter->grandchild_pid == -1)
babysitter_iteration (sitter, TRUE);
_dbus_verbose ("Got child PID %ld for killing\n",
(long) sitter->grandchild_pid);
if (sitter->grandchild_pid == -1)
return; /* child is already dead, or we're so hosed we'll never recover */
kill (sitter->grandchild_pid, SIGKILL);
}
/**
* Checks whether the child has exited, without blocking.
*
* @param sitter the babysitter
*/
dbus_bool_t
_dbus_babysitter_get_child_exited (DBusBabysitter *sitter)
{
/* Be sure we're up-to-date */
while (LIVE_CHILDREN (sitter) &&
babysitter_iteration (sitter, FALSE))
;
/* We will have exited the babysitter when the child has exited */
return sitter->socket_to_babysitter < 0;
}
/**
* Gets the exit status of the child. We do this so implementation specific
* detail is not cluttering up dbus, for example the system launcher code.
* This can only be called if the child has exited, i.e. call
* _dbus_babysitter_get_child_exited(). It returns FALSE if the child
* did not return a status code, e.g. because the child was signaled
* or we failed to ever launch the child in the first place.
*
* @param sitter the babysitter
* @param status the returned status code
* @returns #FALSE on failure
*/
dbus_bool_t
_dbus_babysitter_get_child_exit_status (DBusBabysitter *sitter,
int *status)
{
if (!_dbus_babysitter_get_child_exited (sitter))
_dbus_assert_not_reached ("Child has not exited");
if (!sitter->have_child_status ||
!(WIFEXITED (sitter->status)))
return FALSE;
*status = WEXITSTATUS (sitter->status);
return TRUE;
}
/**
* Sets the #DBusError with an explanation of why the spawned
* child process exited (on a signal, or whatever). If
* the child process has not exited, does nothing (error
* will remain unset).
*
* @param sitter the babysitter
* @param error an error to fill in
*/
void
_dbus_babysitter_set_child_exit_error (DBusBabysitter *sitter,
DBusError *error)
{
if (!_dbus_babysitter_get_child_exited (sitter))
return;
/* Note that if exec fails, we will also get a child status
* from the babysitter saying the child exited,
* so we need to give priority to the exec error
*/
if (sitter->have_exec_errnum)
{
dbus_set_error (error, DBUS_ERROR_SPAWN_EXEC_FAILED,
"Failed to execute program %s: %s",
sitter->executable, _dbus_strerror (sitter->errnum));
}
else if (sitter->have_fork_errnum)
{
dbus_set_error (error, DBUS_ERROR_NO_MEMORY,
"Failed to fork a new process %s: %s",
sitter->executable, _dbus_strerror (sitter->errnum));
}
else if (sitter->have_child_status)
{
if (WIFEXITED (sitter->status))
dbus_set_error (error, DBUS_ERROR_SPAWN_CHILD_EXITED,
"Process %s exited with status %d",
sitter->executable, WEXITSTATUS (sitter->status));
else if (WIFSIGNALED (sitter->status))
dbus_set_error (error, DBUS_ERROR_SPAWN_CHILD_SIGNALED,
"Process %s received signal %d",
sitter->executable, WTERMSIG (sitter->status));
else
dbus_set_error (error, DBUS_ERROR_FAILED,
"Process %s exited abnormally",
sitter->executable);
}
else
{
dbus_set_error (error, DBUS_ERROR_FAILED,
"Process %s exited, reason unknown",
sitter->executable);
}
}
/**
* Sets watch functions to notify us when the
* babysitter object needs to read/write file descriptors.
*
* @param sitter the babysitter
* @param add_function function to begin monitoring a new descriptor.
* @param remove_function function to stop monitoring a descriptor.
* @param toggled_function function to notify when the watch is enabled/disabled
* @param data data to pass to add_function and remove_function.
* @param free_data_function function to be called to free the data.
* @returns #FALSE on failure (no memory)
*/
dbus_bool_t
_dbus_babysitter_set_watch_functions (DBusBabysitter *sitter,
DBusAddWatchFunction add_function,
DBusRemoveWatchFunction remove_function,
DBusWatchToggledFunction toggled_function,
void *data,
DBusFreeFunction free_data_function)
{
return _dbus_watch_list_set_functions (sitter->watches,
add_function,
remove_function,
toggled_function,
data,
free_data_function);
}
static dbus_bool_t
handle_watch (DBusWatch *watch,
unsigned int condition,
void *data)
{
DBusBabysitter *sitter = _dbus_babysitter_ref (data);
int revents;
int fd;
revents = 0;
if (condition & DBUS_WATCH_READABLE)
revents |= _DBUS_POLLIN;
if (condition & DBUS_WATCH_ERROR)
revents |= _DBUS_POLLERR;
if (condition & DBUS_WATCH_HANGUP)
revents |= _DBUS_POLLHUP;
fd = dbus_watch_get_socket (watch);
if (fd == sitter->error_pipe_from_child)
handle_error_pipe (sitter, revents);
else if (fd == sitter->socket_to_babysitter)
handle_babysitter_socket (sitter, revents);
while (LIVE_CHILDREN (sitter) &&
babysitter_iteration (sitter, FALSE))
;
/* fd.o #32992: if the handle_* methods closed their sockets, they previously
* didn't always remove the watches. Check that we don't regress. */
_dbus_assert (sitter->socket_to_babysitter != -1 || sitter->sitter_watch == NULL);
_dbus_assert (sitter->error_pipe_from_child != -1 || sitter->error_watch == NULL);
if (_dbus_babysitter_get_child_exited (sitter) &&
sitter->finished_cb != NULL)
{
sitter->finished_cb (sitter, sitter->finished_data);
sitter->finished_cb = NULL;
}
_dbus_babysitter_unref (sitter);
return TRUE;
}
/** Helps remember which end of the pipe is which */
#define READ_END 0
/** Helps remember which end of the pipe is which */
#define WRITE_END 1
/* Avoids a danger in threaded situations (calling close()
* on a file descriptor twice, and another thread has
* re-opened it since the first close)
*/
static int
close_and_invalidate (int *fd)
{
int ret;
if (*fd < 0)
return -1;
else
{
ret = _dbus_close_socket (*fd, NULL);
*fd = -1;
}
return ret;
}
static dbus_bool_t
make_pipe (int p[2],
DBusError *error)
{
int retval;
#ifdef HAVE_PIPE2
dbus_bool_t cloexec_done;
retval = pipe2 (p, O_CLOEXEC);
cloexec_done = retval >= 0;
/* Check if kernel seems to be too old to know pipe2(). We assume
that if pipe2 is available, O_CLOEXEC is too. */
if (retval < 0 && errno == ENOSYS)
#endif
{
retval = pipe(p);
}
_DBUS_ASSERT_ERROR_IS_CLEAR (error);
if (retval < 0)
{
dbus_set_error (error,
DBUS_ERROR_SPAWN_FAILED,
"Failed to create pipe for communicating with child process (%s)",
_dbus_strerror (errno));
return FALSE;
}
#ifdef HAVE_PIPE2
if (!cloexec_done)
#endif
{
_dbus_fd_set_close_on_exec (p[0]);
_dbus_fd_set_close_on_exec (p[1]);
}
return TRUE;
}
static void
do_write (int fd, const void *buf, size_t count)
{
size_t bytes_written;
int ret;
bytes_written = 0;
again:
ret = write (fd, ((const char*)buf) + bytes_written, count - bytes_written);
if (ret < 0)
{
if (errno == EINTR)
goto again;
else
{
_dbus_warn ("Failed to write data to pipe!\n");
exit (1); /* give up, we suck */
}
}
else
bytes_written += ret;
if (bytes_written < count)
goto again;
}
static void
write_err_and_exit (int fd, int msg)
{
int en = errno;
do_write (fd, &msg, sizeof (msg));
do_write (fd, &en, sizeof (en));
exit (1);
}
static void
write_pid (int fd, pid_t pid)
{
int msg = CHILD_PID;
do_write (fd, &msg, sizeof (msg));
do_write (fd, &pid, sizeof (pid));
}
static void
write_status_and_exit (int fd, int status)
{
int msg = CHILD_EXITED;
do_write (fd, &msg, sizeof (msg));
do_write (fd, &status, sizeof (status));
exit (0);
}
static void
do_exec (int child_err_report_fd,
char **argv,
char **envp,
DBusSpawnChildSetupFunc child_setup,
void *user_data)
{
#ifdef DBUS_BUILD_TESTS
int i, max_open;
#endif
_dbus_verbose_reset ();
_dbus_verbose ("Child process has PID " DBUS_PID_FORMAT "\n",
_dbus_getpid ());
if (child_setup)
(* child_setup) (user_data);
#ifdef DBUS_BUILD_TESTS
max_open = sysconf (_SC_OPEN_MAX);
for (i = 3; i < max_open; i++)
{
int retval;
if (i == child_err_report_fd)
continue;
retval = fcntl (i, F_GETFD);
if (retval != -1 && !(retval & FD_CLOEXEC))
_dbus_warn ("Fd %d did not have the close-on-exec flag set!\n", i);
}
#endif
if (envp == NULL)
{
_dbus_assert (environ != NULL);
envp = environ;
}
execve (argv[0], argv, envp);
/* Exec failed */
write_err_and_exit (child_err_report_fd,
CHILD_EXEC_FAILED);
}
static void
check_babysit_events (pid_t grandchild_pid,
int parent_pipe,
int revents)
{
pid_t ret;
int status;
do
{
ret = waitpid (grandchild_pid, &status, WNOHANG);
/* The man page says EINTR can't happen with WNOHANG,
* but there are reports of it (maybe only with valgrind?)
*/
}
while (ret < 0 && errno == EINTR);
if (ret == 0)
{
_dbus_verbose ("no child exited\n");
; /* no child exited */
}
else if (ret < 0)
{
/* This isn't supposed to happen. */
_dbus_warn ("unexpected waitpid() failure in check_babysit_events(): %s\n",
_dbus_strerror (errno));
exit (1);
}
else if (ret == grandchild_pid)
{
/* Child exited */
_dbus_verbose ("reaped child pid %ld\n", (long) ret);
write_status_and_exit (parent_pipe, status);
}
else
{
_dbus_warn ("waitpid() reaped pid %d that we've never heard of\n",
(int) ret);
exit (1);
}
if (revents & _DBUS_POLLIN)
{
_dbus_verbose ("babysitter got POLLIN from parent pipe\n");
}
if (revents & (_DBUS_POLLERR | _DBUS_POLLHUP))
{
/* Parent is gone, so we just exit */
_dbus_verbose ("babysitter got POLLERR or POLLHUP from parent\n");
exit (0);
}
}
static int babysit_sigchld_pipe = -1;
static void
babysit_signal_handler (int signo)
{
char b = '\0';
again:
if (write (babysit_sigchld_pipe, &b, 1) <= 0)
if (errno == EINTR)
goto again;
}
static void
babysit (pid_t grandchild_pid,
int parent_pipe)
{
int sigchld_pipe[2];
/* We don't exec, so we keep parent state, such as the pid that
* _dbus_verbose() uses. Reset the pid here.
*/
_dbus_verbose_reset ();
/* I thought SIGCHLD would just wake up the poll, but
* that didn't seem to work, so added this pipe.
* Probably the pipe is more likely to work on busted
* operating systems anyhow.
*/
if (pipe (sigchld_pipe) < 0)
{
_dbus_warn ("Not enough file descriptors to create pipe in babysitter process\n");
exit (1);
}
babysit_sigchld_pipe = sigchld_pipe[WRITE_END];
_dbus_set_signal_handler (SIGCHLD, babysit_signal_handler);
write_pid (parent_pipe, grandchild_pid);
check_babysit_events (grandchild_pid, parent_pipe, 0);
while (TRUE)
{
DBusPollFD pfds[2];
pfds[0].fd = parent_pipe;
pfds[0].events = _DBUS_POLLIN;
pfds[0].revents = 0;
pfds[1].fd = sigchld_pipe[READ_END];
pfds[1].events = _DBUS_POLLIN;
pfds[1].revents = 0;
if (_dbus_poll (pfds, _DBUS_N_ELEMENTS (pfds), -1) < 0 && errno != EINTR)
{
_dbus_warn ("_dbus_poll() error: %s\n", strerror (errno));
exit (1);
}
if (pfds[0].revents != 0)
{
check_babysit_events (grandchild_pid, parent_pipe, pfds[0].revents);
}
else if (pfds[1].revents & _DBUS_POLLIN)
{
char b;
if (read (sigchld_pipe[READ_END], &b, 1) == -1)
{
/* ignore */
}
/* do waitpid check */
check_babysit_events (grandchild_pid, parent_pipe, 0);
}
}
exit (1);
}
/**
* Spawns a new process. The executable name and argv[0]
* are the same, both are provided in argv[0]. The child_setup
* function is passed the given user_data and is run in the child
* just before calling exec().
*
* Also creates a "babysitter" which tracks the status of the
* child process, advising the parent if the child exits.
* If the spawn fails, no babysitter is created.
* If sitter_p is #NULL, no babysitter is kept.
*
* @param sitter_p return location for babysitter or #NULL
* @param argv the executable and arguments
* @param env the environment (not used on unix yet)
* @param child_setup function to call in child pre-exec()
* @param user_data user data for setup function
* @param error error object to be filled in if function fails
* @returns #TRUE on success, #FALSE if error is filled in
*/
dbus_bool_t
_dbus_spawn_async_with_babysitter (DBusBabysitter **sitter_p,
char **argv,
char **env,
DBusSpawnChildSetupFunc child_setup,
void *user_data,
DBusError *error)
{
DBusBabysitter *sitter;
int child_err_report_pipe[2] = { -1, -1 };
int babysitter_pipe[2] = { -1, -1 };
pid_t pid;
_DBUS_ASSERT_ERROR_IS_CLEAR (error);
if (sitter_p != NULL)
*sitter_p = NULL;
sitter = NULL;
sitter = _dbus_babysitter_new ();
if (sitter == NULL)
{
dbus_set_error (error, DBUS_ERROR_NO_MEMORY, NULL);
return FALSE;
}
sitter->executable = _dbus_strdup (argv[0]);
if (sitter->executable == NULL)
{
dbus_set_error (error, DBUS_ERROR_NO_MEMORY, NULL);
goto cleanup_and_fail;
}
if (!make_pipe (child_err_report_pipe, error))
goto cleanup_and_fail;
if (!_dbus_full_duplex_pipe (&babysitter_pipe[0], &babysitter_pipe[1], TRUE, error))
goto cleanup_and_fail;
/* Setting up the babysitter is only useful in the parent,
* but we don't want to run out of memory and fail
* after we've already forked, since then we'd leak
* child processes everywhere.
*/
sitter->error_watch = _dbus_watch_new (child_err_report_pipe[READ_END],
DBUS_WATCH_READABLE,
TRUE, handle_watch, sitter, NULL);
if (sitter->error_watch == NULL)
{
dbus_set_error (error, DBUS_ERROR_NO_MEMORY, NULL);
goto cleanup_and_fail;
}
if (!_dbus_watch_list_add_watch (sitter->watches, sitter->error_watch))
{
/* we need to free it early so the destructor won't try to remove it
* without it having been added, which DBusLoop doesn't allow */
_dbus_watch_invalidate (sitter->error_watch);
_dbus_watch_unref (sitter->error_watch);
sitter->error_watch = NULL;
dbus_set_error (error, DBUS_ERROR_NO_MEMORY, NULL);
goto cleanup_and_fail;
}
sitter->sitter_watch = _dbus_watch_new (babysitter_pipe[0],
DBUS_WATCH_READABLE,
TRUE, handle_watch, sitter, NULL);
if (sitter->sitter_watch == NULL)
{
dbus_set_error (error, DBUS_ERROR_NO_MEMORY, NULL);
goto cleanup_and_fail;
}
if (!_dbus_watch_list_add_watch (sitter->watches, sitter->sitter_watch))
{
/* we need to free it early so the destructor won't try to remove it
* without it having been added, which DBusLoop doesn't allow */
_dbus_watch_invalidate (sitter->sitter_watch);
_dbus_watch_unref (sitter->sitter_watch);
sitter->sitter_watch = NULL;
dbus_set_error (error, DBUS_ERROR_NO_MEMORY, NULL);
goto cleanup_and_fail;
}
_DBUS_ASSERT_ERROR_IS_CLEAR (error);
pid = fork ();
if (pid < 0)
{
dbus_set_error (error,
DBUS_ERROR_SPAWN_FORK_FAILED,
"Failed to fork (%s)",
_dbus_strerror (errno));
goto cleanup_and_fail;
}
else if (pid == 0)
{
/* Immediate child, this is the babysitter process. */
int grandchild_pid;
/* 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. */
close_and_invalidate (&child_err_report_pipe[READ_END]);
close_and_invalidate (&babysitter_pipe[0]);
/* Create the child that will exec () */
grandchild_pid = fork ();
if (grandchild_pid < 0)
{
write_err_and_exit (babysitter_pipe[1],
CHILD_FORK_FAILED);
_dbus_assert_not_reached ("Got to code after write_err_and_exit()");
}
else if (grandchild_pid == 0)
{
do_exec (child_err_report_pipe[WRITE_END],
argv,
env,
child_setup, user_data);
_dbus_assert_not_reached ("Got to code after exec() - should have exited on error");
}
else
{
babysit (grandchild_pid, babysitter_pipe[1]);
_dbus_assert_not_reached ("Got to code after babysit()");
}
}
else
{
/* Close the uncared-about ends of the pipes */
close_and_invalidate (&child_err_report_pipe[WRITE_END]);
close_and_invalidate (&babysitter_pipe[1]);
sitter->socket_to_babysitter = babysitter_pipe[0];
babysitter_pipe[0] = -1;
sitter->error_pipe_from_child = child_err_report_pipe[READ_END];
child_err_report_pipe[READ_END] = -1;
sitter->sitter_pid = pid;
if (sitter_p != NULL)
*sitter_p = sitter;
else
_dbus_babysitter_unref (sitter);
dbus_free_string_array (env);
_DBUS_ASSERT_ERROR_IS_CLEAR (error);
return TRUE;
}
cleanup_and_fail:
_DBUS_ASSERT_ERROR_IS_SET (error);
close_and_invalidate (&child_err_report_pipe[READ_END]);
close_and_invalidate (&child_err_report_pipe[WRITE_END]);
close_and_invalidate (&babysitter_pipe[0]);
close_and_invalidate (&babysitter_pipe[1]);
if (sitter != NULL)
_dbus_babysitter_unref (sitter);
return FALSE;
}
void
_dbus_babysitter_set_result_function (DBusBabysitter *sitter,
DBusBabysitterFinishedFunc finished,
void *user_data)
{
sitter->finished_cb = finished;
sitter->finished_data = user_data;
}
/** @} */
#ifdef DBUS_BUILD_TESTS
static char *
get_test_exec (const char *exe,
DBusString *scratch_space)
{
const char *dbus_test_exec;
dbus_test_exec = _dbus_getenv ("DBUS_TEST_EXEC");
if (dbus_test_exec == NULL)
dbus_test_exec = DBUS_TEST_EXEC;
if (!_dbus_string_init (scratch_space))
return NULL;
if (!_dbus_string_append_printf (scratch_space, "%s/%s%s",
dbus_test_exec, exe, DBUS_EXEEXT))
{
_dbus_string_free (scratch_space);
return NULL;
}
return _dbus_string_get_data (scratch_space);
}
static void
_dbus_babysitter_block_for_child_exit (DBusBabysitter *sitter)
{
while (LIVE_CHILDREN (sitter))
babysitter_iteration (sitter, TRUE);
}
static dbus_bool_t
check_spawn_nonexistent (void *data)
{
char *argv[4] = { NULL, NULL, NULL, NULL };
DBusBabysitter *sitter = NULL;
DBusError error = DBUS_ERROR_INIT;
/*** Test launching nonexistent binary */
argv[0] = "/this/does/not/exist/32542sdgafgafdg";
if (_dbus_spawn_async_with_babysitter (&sitter, argv,
NULL, NULL, NULL,
&error))
{
_dbus_babysitter_block_for_child_exit (sitter);
_dbus_babysitter_set_child_exit_error (sitter, &error);
}
if (sitter)
_dbus_babysitter_unref (sitter);
if (!dbus_error_is_set (&error))
{
_dbus_warn ("Did not get an error launching nonexistent executable\n");
return FALSE;
}
if (!(dbus_error_has_name (&error, DBUS_ERROR_NO_MEMORY) ||
dbus_error_has_name (&error, DBUS_ERROR_SPAWN_EXEC_FAILED)))
{
_dbus_warn ("Not expecting error when launching nonexistent executable: %s: %s\n",
error.name, error.message);
dbus_error_free (&error);
return FALSE;
}
dbus_error_free (&error);
return TRUE;
}
static dbus_bool_t
check_spawn_segfault (void *data)
{
char *argv[4] = { NULL, NULL, NULL, NULL };
DBusBabysitter *sitter = NULL;
DBusError error = DBUS_ERROR_INIT;
DBusString argv0;
/*** Test launching segfault binary */
argv[0] = get_test_exec ("test-segfault", &argv0);
if (argv[0] == NULL)
{
/* OOM was simulated, never mind */
return TRUE;
}
if (_dbus_spawn_async_with_babysitter (&sitter, argv,
NULL, NULL, NULL,
&error))
{
_dbus_babysitter_block_for_child_exit (sitter);
_dbus_babysitter_set_child_exit_error (sitter, &error);
}
_dbus_string_free (&argv0);
if (sitter)
_dbus_babysitter_unref (sitter);
if (!dbus_error_is_set (&error))
{
_dbus_warn ("Did not get an error launching segfaulting binary\n");
return FALSE;
}
if (!(dbus_error_has_name (&error, DBUS_ERROR_NO_MEMORY) ||
dbus_error_has_name (&error, DBUS_ERROR_SPAWN_CHILD_SIGNALED)))
{
_dbus_warn ("Not expecting error when launching segfaulting executable: %s: %s\n",
error.name, error.message);
dbus_error_free (&error);
return FALSE;
}
dbus_error_free (&error);
return TRUE;
}
static dbus_bool_t
check_spawn_exit (void *data)
{
char *argv[4] = { NULL, NULL, NULL, NULL };
DBusBabysitter *sitter = NULL;
DBusError error = DBUS_ERROR_INIT;
DBusString argv0;
/*** Test launching exit failure binary */
argv[0] = get_test_exec ("test-exit", &argv0);
if (argv[0] == NULL)
{
/* OOM was simulated, never mind */
return TRUE;
}
if (_dbus_spawn_async_with_babysitter (&sitter, argv,
NULL, NULL, NULL,
&error))
{
_dbus_babysitter_block_for_child_exit (sitter);
_dbus_babysitter_set_child_exit_error (sitter, &error);
}
_dbus_string_free (&argv0);
if (sitter)
_dbus_babysitter_unref (sitter);
if (!dbus_error_is_set (&error))
{
_dbus_warn ("Did not get an error launching binary that exited with failure code\n");
return FALSE;
}
if (!(dbus_error_has_name (&error, DBUS_ERROR_NO_MEMORY) ||
dbus_error_has_name (&error, DBUS_ERROR_SPAWN_CHILD_EXITED)))
{
_dbus_warn ("Not expecting error when launching exiting executable: %s: %s\n",
error.name, error.message);
dbus_error_free (&error);
return FALSE;
}
dbus_error_free (&error);
return TRUE;
}
static dbus_bool_t
check_spawn_and_kill (void *data)
{
char *argv[4] = { NULL, NULL, NULL, NULL };
DBusBabysitter *sitter = NULL;
DBusError error = DBUS_ERROR_INIT;
DBusString argv0;
/*** Test launching sleeping binary then killing it */
argv[0] = get_test_exec ("test-sleep-forever", &argv0);
if (argv[0] == NULL)
{
/* OOM was simulated, never mind */
return TRUE;
}
if (_dbus_spawn_async_with_babysitter (&sitter, argv,
NULL, NULL, NULL,
&error))
{
_dbus_babysitter_kill_child (sitter);
_dbus_babysitter_block_for_child_exit (sitter);
_dbus_babysitter_set_child_exit_error (sitter, &error);
}
_dbus_string_free (&argv0);
if (sitter)
_dbus_babysitter_unref (sitter);
if (!dbus_error_is_set (&error))
{
_dbus_warn ("Did not get an error after killing spawned binary\n");
return FALSE;
}
if (!(dbus_error_has_name (&error, DBUS_ERROR_NO_MEMORY) ||
dbus_error_has_name (&error, DBUS_ERROR_SPAWN_CHILD_SIGNALED)))
{
_dbus_warn ("Not expecting error when killing executable: %s: %s\n",
error.name, error.message);
dbus_error_free (&error);
return FALSE;
}
dbus_error_free (&error);
return TRUE;
}
dbus_bool_t
_dbus_spawn_test (const char *test_data_dir)
{
if (!_dbus_test_oom_handling ("spawn_nonexistent",
check_spawn_nonexistent,
NULL))
return FALSE;
if (!_dbus_test_oom_handling ("spawn_segfault",
check_spawn_segfault,
NULL))
return FALSE;
if (!_dbus_test_oom_handling ("spawn_exit",
check_spawn_exit,
NULL))
return FALSE;
if (!_dbus_test_oom_handling ("spawn_and_kill",
check_spawn_and_kill,
NULL))
return FALSE;
return TRUE;
}
#endif