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/*
* This file is part of mpv.
*
* mpv 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.
*
* mpv 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 mpv. If not, see <http://www.gnu.org/licenses/>.
*/
#include <spawn.h>
#include <poll.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <fcntl.h>
#include <errno.h>
#include <signal.h>
#include "osdep/subprocess.h"
#include "osdep/io.h"
#include "common/common.h"
#include "stream/stream.h"
extern char **environ;
// A silly helper: automatically skips entries with negative FDs
static int sparse_poll(struct pollfd *fds, int num_fds, int timeout)
{
struct pollfd p_fds[10];
int map[10];
if (num_fds > MP_ARRAY_SIZE(p_fds))
return -1;
int p_num_fds = 0;
for (int n = 0; n < num_fds; n++) {
map[n] = -1;
if (fds[n].fd < 0)
continue;
map[n] = p_num_fds;
p_fds[p_num_fds++] = fds[n];
}
int r = poll(p_fds, p_num_fds, timeout);
for (int n = 0; n < num_fds; n++)
fds[n].revents = (map[n] < 0 && r >= 0) ? 0 : p_fds[map[n]].revents;
return r;
}
int mp_subprocess(char **args, struct mp_cancel *cancel, void *ctx,
subprocess_read_cb on_stdout, subprocess_read_cb on_stderr,
char **error)
{
posix_spawn_file_actions_t fa;
bool fa_destroy = false;
int status = -1;
int p_stdout[2] = {-1, -1};
int p_stderr[2] = {-1, -1};
int devnull = -1;
pid_t pid = -1;
bool spawned = false;
bool killed_by_us = false;
if (on_stdout && mp_make_cloexec_pipe(p_stdout) < 0)
goto done;
if (on_stderr && mp_make_cloexec_pipe(p_stderr) < 0)
goto done;
devnull = open("/dev/null", O_RDONLY | O_CLOEXEC);
if (devnull < 0)
goto done;
if (posix_spawn_file_actions_init(&fa))
goto done;
fa_destroy = true;
// redirect stdin/stdout/stderr
if (posix_spawn_file_actions_adddup2(&fa, devnull, 0))
goto done;
if (p_stdout[1] >= 0 && posix_spawn_file_actions_adddup2(&fa, p_stdout[1], 1))
goto done;
if (p_stderr[1] >= 0 && posix_spawn_file_actions_adddup2(&fa, p_stderr[1], 2))
goto done;
if (posix_spawnp(&pid, args[0], &fa, NULL, args, environ)) {
pid = -1;
goto done;
}
spawned = true;
close(p_stdout[1]);
p_stdout[1] = -1;
close(p_stderr[1]);
p_stderr[1] = -1;
close(devnull);
devnull = -1;
int *read_fds[2] = {&p_stdout[0], &p_stderr[0]};
subprocess_read_cb read_cbs[2] = {on_stdout, on_stderr};
while (p_stdout[0] >= 0 || p_stderr[0] >= 0) {
struct pollfd fds[] = {
{.events = POLLIN, .fd = *read_fds[0]},
{.events = POLLIN, .fd = *read_fds[1]},
{.events = POLLIN, .fd = cancel ? mp_cancel_get_fd(cancel) : -1},
};
if (sparse_poll(fds, MP_ARRAY_SIZE(fds), -1) < 0 && errno != EINTR)
break;
for (int n = 0; n < 2; n++) {
if (fds[n].revents) {
char buf[4096];
ssize_t r = read(*read_fds[n], buf, sizeof(buf));
if (r < 0 && errno == EINTR)
continue;
if (r > 0 && read_cbs[n])
read_cbs[n](ctx, buf, r);
if (r <= 0) {
close(*read_fds[n]);
*read_fds[n] = -1;
}
}
}
if (fds[2].revents) {
kill(pid, SIGKILL);
killed_by_us = true;
break;
}
}
// Note: it can happen that a child process closes the pipe, but does not
// terminate yet. In this case, we would have to run waitpid() in
// a separate thread and use pthread_cancel(), or use other weird
// and laborious tricks. So this isn't handled yet.
while (waitpid(pid, &status, 0) < 0 && errno == EINTR) {}
done:
if (fa_destroy)
posix_spawn_file_actions_destroy(&fa);
close(p_stdout[0]);
close(p_stdout[1]);
close(p_stderr[0]);
close(p_stderr[1]);
close(devnull);
if (!spawned || (WIFEXITED(status) && WEXITSTATUS(status) == 127)) {
*error = "init";
status = -1;
} else if (WIFEXITED(status)) {
*error = NULL;
status = WEXITSTATUS(status);
} else {
*error = "killed";
status = killed_by_us ? MP_SUBPROCESS_EKILLED_BY_US : -1;
}
return status;
}
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