mirror of
https://github.com/morgan9e/systemd
synced 2026-04-15 08:56:15 +09:00
85f660d46b
This is useful for situations where an array of FDs is to be passed into a child process (i.e. by passing it through safe_fork). This function can be called in the child (before calling exec) to pack the FDs to all be next to each-other starting from SD_LISTEN_FDS_START (i.e. 3)
606 lines
21 KiB
C
606 lines
21 KiB
C
/* SPDX-License-Identifier: LGPL-2.1-or-later */
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#include <dirent.h>
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#include <errno.h>
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#include <sys/prctl.h>
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#include <sys/types.h>
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#include <unistd.h>
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#include <stdio.h>
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#include "alloc-util.h"
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#include "conf-files.h"
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#include "env-file.h"
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#include "env-util.h"
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#include "errno-util.h"
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#include "escape.h"
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#include "exec-util.h"
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#include "fd-util.h"
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#include "fileio.h"
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#include "hashmap.h"
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#include "macro.h"
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#include "missing_syscall.h"
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#include "path-util.h"
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#include "process-util.h"
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#include "serialize.h"
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#include "set.h"
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#include "signal-util.h"
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#include "stat-util.h"
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#include "string-table.h"
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#include "string-util.h"
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#include "strv.h"
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#include "terminal-util.h"
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#include "tmpfile-util.h"
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#define EXIT_SKIP_REMAINING 77
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/* Put this test here for a lack of better place */
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assert_cc(EAGAIN == EWOULDBLOCK);
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static int do_spawn(const char *path, char *argv[], int stdout_fd, pid_t *pid, bool set_systemd_exec_pid) {
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pid_t _pid;
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int r;
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if (null_or_empty_path(path) > 0) {
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log_debug("%s is empty (a mask).", path);
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return 0;
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}
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r = safe_fork("(direxec)", FORK_DEATHSIG_SIGTERM|FORK_LOG|FORK_RLIMIT_NOFILE_SAFE, &_pid);
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if (r < 0)
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return r;
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if (r == 0) {
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char *_argv[2];
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if (stdout_fd >= 0) {
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r = rearrange_stdio(STDIN_FILENO, TAKE_FD(stdout_fd), STDERR_FILENO);
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if (r < 0)
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_exit(EXIT_FAILURE);
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}
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if (set_systemd_exec_pid) {
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r = setenv_systemd_exec_pid(false);
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if (r < 0)
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log_warning_errno(r, "Failed to set $SYSTEMD_EXEC_PID, ignoring: %m");
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}
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if (!argv) {
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_argv[0] = (char*) path;
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_argv[1] = NULL;
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argv = _argv;
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} else
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argv[0] = (char*) path;
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execv(path, argv);
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log_error_errno(errno, "Failed to execute %s: %m", path);
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_exit(EXIT_FAILURE);
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}
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*pid = _pid;
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return 1;
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}
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static int do_execute(
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char* const* paths,
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const char *root,
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usec_t timeout,
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gather_stdout_callback_t const callbacks[_STDOUT_CONSUME_MAX],
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void* const callback_args[_STDOUT_CONSUME_MAX],
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int output_fd,
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char *argv[],
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char *envp[],
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ExecDirFlags flags) {
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_cleanup_hashmap_free_free_ Hashmap *pids = NULL;
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bool parallel_execution;
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int r;
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/* We fork this all off from a child process so that we can somewhat cleanly make
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* use of SIGALRM to set a time limit.
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*
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* We attempt to perform parallel execution if configured by the user, however
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* if `callbacks` is nonnull, execution must be serial.
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*/
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parallel_execution = FLAGS_SET(flags, EXEC_DIR_PARALLEL) && !callbacks;
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if (parallel_execution) {
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pids = hashmap_new(NULL);
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if (!pids)
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return log_oom();
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}
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/* Abort execution of this process after the timeout. We simply rely on SIGALRM as
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* default action terminating the process, and turn on alarm(). */
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if (timeout != USEC_INFINITY)
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alarm(DIV_ROUND_UP(timeout, USEC_PER_SEC));
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STRV_FOREACH(e, envp)
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if (putenv(*e) != 0)
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return log_error_errno(errno, "Failed to set environment variable: %m");
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STRV_FOREACH(path, paths) {
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_cleanup_free_ char *t = NULL;
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_cleanup_close_ int fd = -EBADF;
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pid_t pid;
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t = path_join(root, *path);
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if (!t)
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return log_oom();
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if (callbacks) {
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_cleanup_free_ char *bn = NULL;
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r = path_extract_filename(*path, &bn);
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if (r < 0)
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return log_error_errno(r, "Failed to extract filename from path '%s': %m", *path);
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fd = open_serialization_fd(bn);
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if (fd < 0)
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return log_error_errno(fd, "Failed to open serialization file: %m");
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}
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if (DEBUG_LOGGING) {
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_cleanup_free_ char *args = NULL;
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if (argv)
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args = quote_command_line(strv_skip(argv, 1), SHELL_ESCAPE_EMPTY);
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log_debug("About to execute %s%s%s", t, argv ? " " : "", argv ? strnull(args) : "");
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}
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r = do_spawn(t, argv, fd, &pid, FLAGS_SET(flags, EXEC_DIR_SET_SYSTEMD_EXEC_PID));
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if (r <= 0)
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continue;
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if (parallel_execution) {
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r = hashmap_put(pids, PID_TO_PTR(pid), t);
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if (r < 0)
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return log_oom();
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t = NULL;
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} else {
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bool skip_remaining = false;
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r = wait_for_terminate_and_check(t, pid, WAIT_LOG_ABNORMAL);
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if (r < 0)
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return r;
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if (r > 0) {
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if (FLAGS_SET(flags, EXEC_DIR_SKIP_REMAINING) && r == EXIT_SKIP_REMAINING) {
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log_info("%s succeeded with exit status %i, not executing remaining executables.", *path, r);
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skip_remaining = true;
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} else if (FLAGS_SET(flags, EXEC_DIR_IGNORE_ERRORS))
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log_warning("%s failed with exit status %i, ignoring.", *path, r);
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else {
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log_error("%s failed with exit status %i.", *path, r);
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return r;
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}
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}
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if (callbacks) {
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if (lseek(fd, 0, SEEK_SET) < 0)
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return log_error_errno(errno, "Failed to seek on serialization fd: %m");
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r = callbacks[STDOUT_GENERATE](TAKE_FD(fd), callback_args[STDOUT_GENERATE]);
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if (r < 0)
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return log_error_errno(r, "Failed to process output from %s: %m", *path);
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}
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if (skip_remaining)
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break;
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}
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}
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if (callbacks) {
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r = callbacks[STDOUT_COLLECT](output_fd, callback_args[STDOUT_COLLECT]);
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if (r < 0)
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return log_error_errno(r, "Callback two failed: %m");
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}
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while (!hashmap_isempty(pids)) {
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_cleanup_free_ char *t = NULL;
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pid_t pid;
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pid = PTR_TO_PID(hashmap_first_key(pids));
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assert(pid > 0);
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t = hashmap_remove(pids, PID_TO_PTR(pid));
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assert(t);
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r = wait_for_terminate_and_check(t, pid, WAIT_LOG);
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if (r < 0)
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return r;
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if (!FLAGS_SET(flags, EXEC_DIR_IGNORE_ERRORS) && r > 0)
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return r;
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}
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return 0;
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}
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int execute_strv(
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const char *name,
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char* const* paths,
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const char *root,
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usec_t timeout,
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gather_stdout_callback_t const callbacks[_STDOUT_CONSUME_MAX],
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void* const callback_args[_STDOUT_CONSUME_MAX],
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char *argv[],
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char *envp[],
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ExecDirFlags flags) {
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_cleanup_close_ int fd = -EBADF;
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pid_t executor_pid;
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int r;
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assert(!FLAGS_SET(flags, EXEC_DIR_PARALLEL | EXEC_DIR_SKIP_REMAINING));
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if (strv_isempty(paths))
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return 0;
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if (callbacks) {
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assert(name);
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assert(callback_args);
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assert(callbacks[STDOUT_GENERATE]);
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assert(callbacks[STDOUT_COLLECT]);
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assert(callbacks[STDOUT_CONSUME]);
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fd = open_serialization_fd(name);
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if (fd < 0)
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return log_error_errno(fd, "Failed to open serialization file: %m");
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}
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/* Executes all binaries in the directories serially or in parallel and waits for
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* them to finish. Optionally a timeout is applied. If a file with the same name
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* exists in more than one directory, the earliest one wins. */
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r = safe_fork("(sd-exec-strv)", FORK_RESET_SIGNALS|FORK_DEATHSIG_SIGTERM|FORK_LOG, &executor_pid);
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if (r < 0)
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return r;
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if (r == 0) {
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r = do_execute(paths, root, timeout, callbacks, callback_args, fd, argv, envp, flags);
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_exit(r < 0 ? EXIT_FAILURE : r);
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}
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r = wait_for_terminate_and_check("(sd-exec-strv)", executor_pid, 0);
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if (r < 0)
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return r;
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if (!FLAGS_SET(flags, EXEC_DIR_IGNORE_ERRORS) && r > 0)
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return r;
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if (!callbacks)
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return 0;
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if (lseek(fd, 0, SEEK_SET) < 0)
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return log_error_errno(errno, "Failed to rewind serialization fd: %m");
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r = callbacks[STDOUT_CONSUME](TAKE_FD(fd), callback_args[STDOUT_CONSUME]);
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if (r < 0)
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return log_error_errno(r, "Failed to parse returned data: %m");
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return 0;
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}
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int execute_directories(
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const char* const* directories,
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usec_t timeout,
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gather_stdout_callback_t const callbacks[_STDOUT_CONSUME_MAX],
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void* const callback_args[_STDOUT_CONSUME_MAX],
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char *argv[],
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char *envp[],
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ExecDirFlags flags) {
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_cleanup_strv_free_ char **paths = NULL;
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_cleanup_free_ char *name = NULL;
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int r;
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assert(!strv_isempty((char**) directories));
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r = conf_files_list_strv(&paths, NULL, NULL, CONF_FILES_EXECUTABLE|CONF_FILES_REGULAR|CONF_FILES_FILTER_MASKED, directories);
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if (r < 0)
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return log_error_errno(r, "Failed to enumerate executables: %m");
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if (strv_isempty(paths)) {
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log_debug("No executables found.");
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return 0;
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}
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if (callbacks) {
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r = path_extract_filename(directories[0], &name);
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if (r < 0)
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return log_error_errno(r, "Failed to extract file name from '%s': %m", directories[0]);
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}
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return execute_strv(name, paths, NULL, timeout, callbacks, callback_args, argv, envp, flags);
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}
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static int gather_environment_generate(int fd, void *arg) {
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char ***env = ASSERT_PTR(arg);
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_cleanup_fclose_ FILE *f = NULL;
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_cleanup_strv_free_ char **new = NULL;
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int r;
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/* Read a series of VAR=value assignments from fd, use them to update the list of
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* variables in env. Also update the exported environment.
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*
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* fd is always consumed, even on error.
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*/
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f = fdopen(fd, "r");
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if (!f) {
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safe_close(fd);
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return -errno;
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}
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r = load_env_file_pairs(f, NULL, &new);
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if (r < 0)
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return r;
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STRV_FOREACH_PAIR(x, y, new) {
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if (!env_name_is_valid(*x)) {
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log_warning("Invalid variable assignment \"%s=...\", ignoring.", *x);
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continue;
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}
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r = strv_env_assign(env, *x, *y);
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if (r < 0)
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return r;
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if (setenv(*x, *y, true) < 0)
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return -errno;
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}
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return 0;
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}
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static int gather_environment_collect(int fd, void *arg) {
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_cleanup_fclose_ FILE *f = NULL;
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char ***env = ASSERT_PTR(arg);
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int r;
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/* Write out a series of env=cescape(VAR=value) assignments to fd. */
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f = fdopen(fd, "w");
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if (!f) {
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safe_close(fd);
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return -errno;
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}
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r = serialize_strv(f, "env", *env);
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if (r < 0)
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return r;
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r = fflush_and_check(f);
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if (r < 0)
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return r;
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return 0;
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}
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static int gather_environment_consume(int fd, void *arg) {
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_cleanup_fclose_ FILE *f = NULL;
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char ***env = ASSERT_PTR(arg);
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int r = 0;
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/* Read a series of env=cescape(VAR=value) assignments from fd into env. */
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f = fdopen(fd, "r");
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if (!f) {
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safe_close(fd);
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return -errno;
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}
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for (;;) {
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_cleanup_free_ char *line = NULL;
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const char *v;
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int k;
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k = read_line(f, LONG_LINE_MAX, &line);
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if (k < 0)
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return k;
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if (k == 0)
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break;
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v = startswith(line, "env=");
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if (!v) {
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log_debug("Serialization line \"%s\" unexpectedly didn't start with \"env=\".", line);
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if (r == 0)
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r = -EINVAL;
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continue;
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}
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k = deserialize_environment(v, env);
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if (k < 0) {
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log_debug_errno(k, "Invalid serialization line \"%s\": %m", line);
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if (r == 0)
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r = k;
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}
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}
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return r;
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}
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int exec_command_flags_from_strv(char **ex_opts, ExecCommandFlags *flags) {
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ExecCommandFlags ex_flag, ret_flags = 0;
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assert(flags);
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STRV_FOREACH(opt, ex_opts) {
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ex_flag = exec_command_flags_from_string(*opt);
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if (ex_flag < 0)
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return ex_flag;
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ret_flags |= ex_flag;
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}
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*flags = ret_flags;
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return 0;
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}
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int exec_command_flags_to_strv(ExecCommandFlags flags, char ***ex_opts) {
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_cleanup_strv_free_ char **ret_opts = NULL;
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ExecCommandFlags it = flags;
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const char *str;
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int r;
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assert(ex_opts);
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if (flags < 0)
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return flags;
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for (unsigned i = 0; it != 0; it &= ~(1 << i), i++)
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if (FLAGS_SET(flags, (1 << i))) {
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str = exec_command_flags_to_string(1 << i);
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if (!str)
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return -EINVAL;
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r = strv_extend(&ret_opts, str);
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if (r < 0)
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return r;
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}
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*ex_opts = TAKE_PTR(ret_opts);
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return 0;
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}
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const gather_stdout_callback_t gather_environment[] = {
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gather_environment_generate,
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gather_environment_collect,
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gather_environment_consume,
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};
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static const char* const exec_command_strings[] = {
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"ignore-failure", /* EXEC_COMMAND_IGNORE_FAILURE */
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"privileged", /* EXEC_COMMAND_FULLY_PRIVILEGED */
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"no-setuid", /* EXEC_COMMAND_NO_SETUID */
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"ambient", /* EXEC_COMMAND_AMBIENT_MAGIC */
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"no-env-expand", /* EXEC_COMMAND_NO_ENV_EXPAND */
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};
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const char* exec_command_flags_to_string(ExecCommandFlags i) {
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for (size_t idx = 0; idx < ELEMENTSOF(exec_command_strings); idx++)
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if (i == (1 << idx))
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return exec_command_strings[idx];
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return NULL;
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}
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ExecCommandFlags exec_command_flags_from_string(const char *s) {
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ssize_t idx;
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idx = string_table_lookup(exec_command_strings, ELEMENTSOF(exec_command_strings), s);
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if (idx < 0)
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return _EXEC_COMMAND_FLAGS_INVALID;
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else
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return 1 << idx;
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}
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int fexecve_or_execve(int executable_fd, const char *executable, char *const argv[], char *const envp[]) {
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/* Refuse invalid fds, regardless if fexecve() use is enabled or not */
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if (executable_fd < 0)
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return -EBADF;
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/* Block any attempts on exploiting Linux' liberal argv[] handling, i.e. CVE-2021-4034 and suchlike */
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if (isempty(executable) || strv_isempty(argv))
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return -EINVAL;
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#if ENABLE_FEXECVE
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execveat(executable_fd, "", argv, envp, AT_EMPTY_PATH);
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if (IN_SET(errno, ENOSYS, ENOENT) || ERRNO_IS_PRIVILEGE(errno))
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/* Old kernel or a script or an overzealous seccomp filter? Let's fall back to execve().
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*
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* fexecve(3): "If fd refers to a script (i.e., it is an executable text file that names a
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* script interpreter with a first line that begins with the characters #!) and the
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* close-on-exec flag has been set for fd, then fexecve() fails with the error ENOENT. This
|
|
* error occurs because, by the time the script interpreter is executed, fd has already been
|
|
* closed because of the close-on-exec flag. Thus, the close-on-exec flag can't be set on fd
|
|
* if it refers to a script."
|
|
*
|
|
* Unfortunately, if we unset close-on-exec, the script will be executed just fine, but (at
|
|
* least in case of bash) the script name, $0, will be shown as /dev/fd/nnn, which breaks
|
|
* scripts which make use of $0. Thus, let's fall back to execve() in this case.
|
|
*/
|
|
#endif
|
|
execve(executable, argv, envp);
|
|
return -errno;
|
|
}
|
|
|
|
int fork_agent(const char *name, const int except[], size_t n_except, pid_t *ret_pid, const char *path, ...) {
|
|
bool stdout_is_tty, stderr_is_tty;
|
|
size_t n, i;
|
|
va_list ap;
|
|
char **l;
|
|
int r;
|
|
|
|
assert(path);
|
|
|
|
/* Spawns a temporary TTY agent, making sure it goes away when we go away */
|
|
|
|
r = safe_fork_full(name,
|
|
NULL,
|
|
(int*) except, /* safe_fork_full only changes except if you pass in FORK_PACK_FDS, which we don't */
|
|
n_except,
|
|
FORK_RESET_SIGNALS|FORK_DEATHSIG_SIGTERM|FORK_CLOSE_ALL_FDS|FORK_REOPEN_LOG|FORK_RLIMIT_NOFILE_SAFE,
|
|
ret_pid);
|
|
if (r < 0)
|
|
return r;
|
|
if (r > 0)
|
|
return 0;
|
|
|
|
/* In the child: */
|
|
|
|
stdout_is_tty = isatty(STDOUT_FILENO);
|
|
stderr_is_tty = isatty(STDERR_FILENO);
|
|
|
|
if (!stdout_is_tty || !stderr_is_tty) {
|
|
int fd;
|
|
|
|
/* Detach from stdout/stderr and reopen /dev/tty for them. This is important to ensure that
|
|
* when systemctl is started via popen() or a similar call that expects to read EOF we
|
|
* actually do generate EOF and not delay this indefinitely by keeping an unused copy of
|
|
* stdin around. */
|
|
fd = open("/dev/tty", O_WRONLY);
|
|
if (fd < 0) {
|
|
if (errno != ENXIO) {
|
|
log_error_errno(errno, "Failed to open /dev/tty: %m");
|
|
_exit(EXIT_FAILURE);
|
|
}
|
|
|
|
/* If we get ENXIO here we have no controlling TTY even though stdout/stderr are
|
|
* connected to a TTY. That's a weird setup, but let's handle it gracefully: let's
|
|
* skip the forking of the agents, given the TTY setup is not in order. */
|
|
} else {
|
|
if (!stdout_is_tty && dup2(fd, STDOUT_FILENO) < 0) {
|
|
log_error_errno(errno, "Failed to dup2 /dev/tty: %m");
|
|
_exit(EXIT_FAILURE);
|
|
}
|
|
|
|
if (!stderr_is_tty && dup2(fd, STDERR_FILENO) < 0) {
|
|
log_error_errno(errno, "Failed to dup2 /dev/tty: %m");
|
|
_exit(EXIT_FAILURE);
|
|
}
|
|
|
|
fd = safe_close_above_stdio(fd);
|
|
}
|
|
}
|
|
|
|
/* Count arguments */
|
|
va_start(ap, path);
|
|
for (n = 0; va_arg(ap, char*); n++)
|
|
;
|
|
va_end(ap);
|
|
|
|
/* Allocate strv */
|
|
l = newa(char*, n + 1);
|
|
|
|
/* Fill in arguments */
|
|
va_start(ap, path);
|
|
for (i = 0; i <= n; i++)
|
|
l[i] = va_arg(ap, char*);
|
|
va_end(ap);
|
|
|
|
execv(path, l);
|
|
_exit(EXIT_FAILURE);
|
|
}
|