1 /* SPDX-License-Identifier: LGPL-2.1+ */
3 This file is part of systemd.
5 Copyright 2010 Lennart Poettering
7 systemd is free software; you can redistribute it and/or modify it
8 under the terms of the GNU Lesser General Public License as published by
9 the Free Software Foundation; either version 2.1 of the License, or
10 (at your option) any later version.
12 systemd is distributed in the hope that it will be useful, but
13 WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 Lesser General Public License for more details.
17 You should have received a copy of the GNU Lesser General Public License
18 along with systemd; If not, see <http://www.gnu.org/licenses/>.
24 #include <linux/oom.h>
29 #include <stdio_ext.h>
33 #include <sys/personality.h>
34 #include <sys/prctl.h>
35 #include <sys/types.h>
39 #if HAVE_VALGRIND_VALGRIND_H
40 #include <valgrind/valgrind.h>
43 #include "alloc-util.h"
44 //#include "architecture.h"
53 #include "process-util.h"
54 #include "raw-clone.h"
55 #include "signal-util.h"
56 //#include "stat-util.h"
57 #include "string-table.h"
58 #include "string-util.h"
59 //#include "terminal-util.h"
60 #include "user-util.h"
63 int get_process_state(pid_t pid) {
67 _cleanup_free_ char *line = NULL;
71 p = procfs_file_alloca(pid, "stat");
73 r = read_one_line_file(p, &line);
79 p = strrchr(line, ')');
85 if (sscanf(p, " %c", &state) != 1)
88 return (unsigned char) state;
91 int get_process_comm(pid_t pid, char **name) {
98 p = procfs_file_alloca(pid, "comm");
100 r = read_one_line_file(p, name);
107 int get_process_cmdline(pid_t pid, size_t max_length, bool comm_fallback, char **line) {
108 _cleanup_fclose_ FILE *f = NULL;
110 char *k, *ans = NULL;
117 /* Retrieves a process' command line. Replaces unprintable characters while doing so by whitespace (coalescing
118 * multiple sequential ones into one). If max_length is != 0 will return a string of the specified size at most
119 * (the trailing NUL byte does count towards the length here!), abbreviated with a "..." ellipsis. If
120 * comm_fallback is true and the process has no command line set (the case for kernel threads), or has a
121 * command line that resolves to the empty string will return the "comm" name of the process instead.
123 * Returns -ESRCH if the process doesn't exist, and -ENOENT if the process has no command line (and
124 * comm_fallback is false). Returns 0 and sets *line otherwise. */
126 p = procfs_file_alloca(pid, "cmdline");
135 (void) __fsetlocking(f, FSETLOCKING_BYCALLER);
137 if (max_length == 1) {
139 /* If there's only room for one byte, return the empty string */
147 } else if (max_length == 0) {
148 size_t len = 0, allocated = 0;
150 while ((c = getc(f)) != EOF) {
152 if (!GREEDY_REALLOC(ans, allocated, len+3)) {
174 bool dotdotdot = false;
177 ans = new(char, max_length);
183 while ((c = getc(f)) != EOF) {
210 if (max_length <= 4) {
214 k = ans + max_length - 4;
217 /* Eat up final spaces */
218 while (k > ans && isspace(k[-1])) {
224 strncpy(k, "...", left-1);
230 /* Kernel threads have no argv[] */
232 _cleanup_free_ char *t = NULL;
240 h = get_process_comm(pid, &t);
245 ans = strjoin("[", t, "]");
251 if (l + 3 <= max_length)
252 ans = strjoin("[", t, "]");
253 else if (max_length <= 6) {
255 ans = new(char, max_length);
259 memcpy(ans, "[...]", max_length-1);
260 ans[max_length-1] = 0;
264 t[max_length - 6] = 0;
266 /* Chop off final spaces */
268 while (e > t && isspace(e[-1]))
272 ans = strjoin("[", t, "...]");
283 int rename_process(const char name[]) {
284 static size_t mm_size = 0;
285 static char *mm = NULL;
286 bool truncated = false;
289 /* This is a like a poor man's setproctitle(). It changes the comm field, argv[0], and also the glibc's
290 * internally used name of the process. For the first one a limit of 16 chars applies; to the second one in
291 * many cases one of 10 (i.e. length of "/sbin/init") — however if we have CAP_SYS_RESOURCES it is unbounded;
292 * to the third one 7 (i.e. the length of "systemd". If you pass a longer string it will likely be
295 * Returns 0 if a name was set but truncated, > 0 if it was set but not truncated. */
298 return -EINVAL; /* let's not confuse users unnecessarily with an empty name */
300 if (!is_main_thread())
301 return -EPERM; /* Let's not allow setting the process name from other threads than the main one, as we
302 * cache things without locking, and we make assumptions that PR_SET_NAME sets the
303 * process name that isn't correct on any other threads */
307 /* First step, change the comm field. The main thread's comm is identical to the process comm. This means we
308 * can use PR_SET_NAME, which sets the thread name for the calling thread. */
309 if (prctl(PR_SET_NAME, name) < 0)
310 log_debug_errno(errno, "PR_SET_NAME failed: %m");
311 if (l > 15) /* Linux process names can be 15 chars at max */
314 /* Second step, change glibc's ID of the process name. */
315 if (program_invocation_name) {
318 k = strlen(program_invocation_name);
319 strncpy(program_invocation_name, name, k);
324 /* Third step, completely replace the argv[] array the kernel maintains for us. This requires privileges, but
325 * has the advantage that the argv[] array is exactly what we want it to be, and not filled up with zeros at
326 * the end. This is the best option for changing /proc/self/cmdline. */
328 /* Let's not bother with this if we don't have euid == 0. Strictly speaking we should check for the
329 * CAP_SYS_RESOURCE capability which is independent of the euid. In our own code the capability generally is
330 * present only for euid == 0, hence let's use this as quick bypass check, to avoid calling mmap() if
331 * PR_SET_MM_ARG_{START,END} fails with EPERM later on anyway. After all geteuid() is dead cheap to call, but
334 log_debug("Skipping PR_SET_MM, as we don't have privileges.");
335 else if (mm_size < l+1) {
339 nn_size = PAGE_ALIGN(l+1);
340 nn = mmap(NULL, nn_size, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0);
341 if (nn == MAP_FAILED) {
342 log_debug_errno(errno, "mmap() failed: %m");
346 strncpy(nn, name, nn_size);
348 /* Now, let's tell the kernel about this new memory */
349 if (prctl(PR_SET_MM, PR_SET_MM_ARG_START, (unsigned long) nn, 0, 0) < 0) {
350 log_debug_errno(errno, "PR_SET_MM_ARG_START failed, proceeding without: %m");
351 (void) munmap(nn, nn_size);
355 /* And update the end pointer to the new end, too. If this fails, we don't really know what to do, it's
356 * pretty unlikely that we can rollback, hence we'll just accept the failure, and continue. */
357 if (prctl(PR_SET_MM, PR_SET_MM_ARG_END, (unsigned long) nn + l + 1, 0, 0) < 0)
358 log_debug_errno(errno, "PR_SET_MM_ARG_END failed, proceeding without: %m");
361 (void) munmap(mm, mm_size);
366 strncpy(mm, name, mm_size);
368 /* Update the end pointer, continuing regardless of any failure. */
369 if (prctl(PR_SET_MM, PR_SET_MM_ARG_END, (unsigned long) mm + l + 1, 0, 0) < 0)
370 log_debug_errno(errno, "PR_SET_MM_ARG_END failed, proceeding without: %m");
374 /* Fourth step: in all cases we'll also update the original argv[], so that our own code gets it right too if
375 * it still looks here */
377 if (saved_argc > 0) {
383 k = strlen(saved_argv[0]);
384 strncpy(saved_argv[0], name, k);
389 for (i = 1; i < saved_argc; i++) {
393 memzero(saved_argv[i], strlen(saved_argv[i]));
400 int is_kernel_thread(pid_t pid) {
401 _cleanup_free_ char *line = NULL;
402 unsigned long long flags;
408 if (IN_SET(pid, 0, 1) || pid == getpid_cached()) /* pid 1, and we ourselves certainly aren't a kernel thread */
410 if (!pid_is_valid(pid))
413 p = procfs_file_alloca(pid, "stat");
414 r = read_one_line_file(p, &line);
420 /* Skip past the comm field */
421 q = strrchr(line, ')');
426 /* Skip 6 fields to reach the flags field */
427 for (i = 0; i < 6; i++) {
428 l = strspn(q, WHITESPACE);
433 l = strcspn(q, WHITESPACE);
439 /* Skip preceeding whitespace */
440 l = strspn(q, WHITESPACE);
445 /* Truncate the rest */
446 l = strcspn(q, WHITESPACE);
451 r = safe_atollu(q, &flags);
455 return !!(flags & PF_KTHREAD);
458 #if 0 /// UNNEEDED by elogind
459 int get_process_capeff(pid_t pid, char **capeff) {
466 p = procfs_file_alloca(pid, "status");
468 r = get_proc_field(p, "CapEff", WHITESPACE, capeff);
476 static int get_process_link_contents(const char *proc_file, char **name) {
482 r = readlink_malloc(proc_file, name);
491 int get_process_exe(pid_t pid, char **name) {
498 p = procfs_file_alloca(pid, "exe");
499 r = get_process_link_contents(p, name);
503 d = endswith(*name, " (deleted)");
510 #if 0 /// UNNEEDED by elogind
511 static int get_process_id(pid_t pid, const char *field, uid_t *uid) {
512 _cleanup_fclose_ FILE *f = NULL;
522 p = procfs_file_alloca(pid, "status");
530 (void) __fsetlocking(f, FSETLOCKING_BYCALLER);
532 FOREACH_LINE(line, f, return -errno) {
537 if (startswith(l, field)) {
539 l += strspn(l, WHITESPACE);
541 l[strcspn(l, WHITESPACE)] = 0;
543 return parse_uid(l, uid);
550 int get_process_uid(pid_t pid, uid_t *uid) {
552 if (pid == 0 || pid == getpid_cached()) {
557 return get_process_id(pid, "Uid:", uid);
560 int get_process_gid(pid_t pid, gid_t *gid) {
562 if (pid == 0 || pid == getpid_cached()) {
567 assert_cc(sizeof(uid_t) == sizeof(gid_t));
568 return get_process_id(pid, "Gid:", gid);
571 int get_process_cwd(pid_t pid, char **cwd) {
576 p = procfs_file_alloca(pid, "cwd");
578 return get_process_link_contents(p, cwd);
581 int get_process_root(pid_t pid, char **root) {
586 p = procfs_file_alloca(pid, "root");
588 return get_process_link_contents(p, root);
591 int get_process_environ(pid_t pid, char **env) {
592 _cleanup_fclose_ FILE *f = NULL;
593 _cleanup_free_ char *outcome = NULL;
596 size_t allocated = 0, sz = 0;
601 p = procfs_file_alloca(pid, "environ");
610 (void) __fsetlocking(f, FSETLOCKING_BYCALLER);
612 while ((c = fgetc(f)) != EOF) {
613 if (!GREEDY_REALLOC(outcome, allocated, sz + 5))
617 outcome[sz++] = '\n';
619 sz += cescape_char(c, outcome + sz);
623 outcome = strdup("");
629 *env = TAKE_PTR(outcome);
634 int get_process_ppid(pid_t pid, pid_t *_ppid) {
636 _cleanup_free_ char *line = NULL;
643 if (pid == 0 || pid == getpid_cached()) {
648 p = procfs_file_alloca(pid, "stat");
649 r = read_one_line_file(p, &line);
655 /* Let's skip the pid and comm fields. The latter is enclosed
656 * in () but does not escape any () in its value, so let's
657 * skip over it manually */
659 p = strrchr(line, ')');
671 if ((long unsigned) (pid_t) ppid != ppid)
674 *_ppid = (pid_t) ppid;
680 int wait_for_terminate(pid_t pid, siginfo_t *status) {
691 if (waitid(P_PID, pid, status, WEXITED) < 0) {
696 return negative_errno();
705 * < 0 : wait_for_terminate() failed to get the state of the
706 * process, the process was terminated by a signal, or
707 * failed for an unknown reason.
708 * >=0 : The process terminated normally, and its exit code is
711 * That is, success is indicated by a return value of zero, and an
712 * error is indicated by a non-zero value.
714 * A warning is emitted if the process terminates abnormally,
715 * and also if it returns non-zero unless check_exit_code is true.
717 int wait_for_terminate_and_check(const char *name, pid_t pid, WaitFlags flags) {
718 _cleanup_free_ char *buffer = NULL;
725 r = get_process_comm(pid, &buffer);
727 log_debug_errno(r, "Failed to acquire process name of " PID_FMT ", ignoring: %m", pid);
732 prio = flags & WAIT_LOG_ABNORMAL ? LOG_ERR : LOG_DEBUG;
734 r = wait_for_terminate(pid, &status);
736 return log_full_errno(prio, r, "Failed to wait for %s: %m", strna(name));
738 if (status.si_code == CLD_EXITED) {
739 if (status.si_status != EXIT_SUCCESS)
740 log_full(flags & WAIT_LOG_NON_ZERO_EXIT_STATUS ? LOG_ERR : LOG_DEBUG,
741 "%s failed with exit status %i.", strna(name), status.si_status);
743 log_debug("%s succeeded.", name);
745 return status.si_status;
747 } else if (IN_SET(status.si_code, CLD_KILLED, CLD_DUMPED)) {
749 log_full(prio, "%s terminated by signal %s.", strna(name), signal_to_string(status.si_status));
753 log_full(prio, "%s failed due to unknown reason.", strna(name));
759 * < 0 : wait_for_terminate_with_timeout() failed to get the state of the
760 * process, the process timed out, the process was terminated by a
761 * signal, or failed for an unknown reason.
762 * >=0 : The process terminated normally with no failures.
764 * Success is indicated by a return value of zero, a timeout is indicated
765 * by ETIMEDOUT, and all other child failure states are indicated by error
766 * is indicated by a non-zero value.
768 int wait_for_terminate_with_timeout(pid_t pid, usec_t timeout) {
773 assert_se(sigemptyset(&mask) == 0);
774 assert_se(sigaddset(&mask, SIGCHLD) == 0);
776 /* Drop into a sigtimewait-based timeout. Waiting for the
778 until = now(CLOCK_MONOTONIC) + timeout;
781 siginfo_t status = {};
784 n = now(CLOCK_MONOTONIC);
788 r = sigtimedwait(&mask, NULL, timespec_store(&ts, until - n)) < 0 ? -errno : 0;
789 /* Assuming we woke due to the child exiting. */
790 if (waitid(P_PID, pid, &status, WEXITED|WNOHANG) == 0) {
791 if (status.si_pid == pid) {
792 /* This is the correct child.*/
793 if (status.si_code == CLD_EXITED)
794 return (status.si_status == 0) ? 0 : -EPROTO;
799 /* Not the child, check for errors and proceed appropriately */
803 /* Timed out, child is likely hung. */
806 /* Received a different signal and should retry */
809 /* Return any unexpected errors */
818 #if 0 /// UNNEEDED by elogind
819 void sigkill_wait(pid_t pid) {
822 if (kill(pid, SIGKILL) > 0)
823 (void) wait_for_terminate(pid, NULL);
826 void sigkill_waitp(pid_t *pid) {
838 void sigterm_wait(pid_t pid) {
841 if (kill_and_sigcont(pid, SIGTERM) > 0)
842 (void) wait_for_terminate(pid, NULL);
845 int kill_and_sigcont(pid_t pid, int sig) {
848 r = kill(pid, sig) < 0 ? -errno : 0;
850 /* If this worked, also send SIGCONT, unless we already just sent a SIGCONT, or SIGKILL was sent which isn't
851 * affected by a process being suspended anyway. */
852 if (r >= 0 && !IN_SET(sig, SIGCONT, SIGKILL))
853 (void) kill(pid, SIGCONT);
858 int getenv_for_pid(pid_t pid, const char *field, char **ret) {
859 _cleanup_fclose_ FILE *f = NULL;
869 if (pid == 0 || pid == getpid_cached()) {
886 path = procfs_file_alloca(pid, "environ");
888 f = fopen(path, "re");
896 (void) __fsetlocking(f, FSETLOCKING_BYCALLER);
904 for (i = 0; i < sizeof(line)-1; i++) {
908 if (_unlikely_(c == EOF)) {
918 if (strneq(line, field, l) && line[l] == '=') {
919 value = strdup(line + l + 1);
933 bool pid_is_unwaited(pid_t pid) {
934 /* Checks whether a PID is still valid at all, including a zombie */
939 if (pid <= 1) /* If we or PID 1 would be dead and have been waited for, this code would not be running */
942 if (pid == getpid_cached())
945 if (kill(pid, 0) >= 0)
948 return errno != ESRCH;
951 bool pid_is_alive(pid_t pid) {
954 /* Checks whether a PID is still valid and not a zombie */
959 if (pid <= 1) /* If we or PID 1 would be a zombie, this code would not be running */
962 if (pid == getpid_cached())
965 r = get_process_state(pid);
966 if (IN_SET(r, -ESRCH, 'Z'))
972 #if 0 /// UNNEEDED by elogind
973 int pid_from_same_root_fs(pid_t pid) {
979 if (pid == 0 || pid == getpid_cached())
982 root = procfs_file_alloca(pid, "root");
984 return files_same(root, "/proc/1/root", 0);
988 bool is_main_thread(void) {
989 static thread_local int cached = 0;
991 if (_unlikely_(cached == 0))
992 cached = getpid_cached() == gettid() ? 1 : -1;
997 #if 0 /// UNNEEDED by elogind
998 _noreturn_ void freeze(void) {
1002 /* Make sure nobody waits for us on a socket anymore */
1003 close_all_fds(NULL, 0);
1007 /* Let's not freeze right away, but keep reaping zombies. */
1012 r = waitid(P_ALL, 0, &si, WEXITED);
1013 if (r < 0 && errno != EINTR)
1017 /* waitid() failed with an unexpected error, things are really borked. Freeze now! */
1022 bool oom_score_adjust_is_valid(int oa) {
1023 return oa >= OOM_SCORE_ADJ_MIN && oa <= OOM_SCORE_ADJ_MAX;
1026 unsigned long personality_from_string(const char *p) {
1030 return PERSONALITY_INVALID;
1032 /* Parse a personality specifier. We use our own identifiers that indicate specific ABIs, rather than just
1033 * hints regarding the register size, since we want to keep things open for multiple locally supported ABIs for
1034 * the same register size. */
1036 architecture = architecture_from_string(p);
1037 if (architecture < 0)
1038 return PERSONALITY_INVALID;
1040 if (architecture == native_architecture())
1042 #ifdef SECONDARY_ARCHITECTURE
1043 if (architecture == SECONDARY_ARCHITECTURE)
1047 return PERSONALITY_INVALID;
1050 const char* personality_to_string(unsigned long p) {
1051 int architecture = _ARCHITECTURE_INVALID;
1054 architecture = native_architecture();
1055 #ifdef SECONDARY_ARCHITECTURE
1056 else if (p == PER_LINUX32)
1057 architecture = SECONDARY_ARCHITECTURE;
1060 if (architecture < 0)
1063 return architecture_to_string(architecture);
1066 int safe_personality(unsigned long p) {
1069 /* So here's the deal, personality() is weirdly defined by glibc. In some cases it returns a failure via errno,
1070 * and in others as negative return value containing an errno-like value. Let's work around this: this is a
1071 * wrapper that uses errno if it is set, and uses the return value otherwise. And then it sets both errno and
1072 * the return value indicating the same issue, so that we are definitely on the safe side.
1074 * See https://github.com/systemd/systemd/issues/6737 */
1077 ret = personality(p);
1088 int opinionated_personality(unsigned long *ret) {
1091 /* Returns the current personality, or PERSONALITY_INVALID if we can't determine it. This function is a bit
1092 * opinionated though, and ignores all the finer-grained bits and exotic personalities, only distinguishing the
1093 * two most relevant personalities: PER_LINUX and PER_LINUX32. */
1095 current = safe_personality(PERSONALITY_INVALID);
1099 if (((unsigned long) current & 0xffff) == PER_LINUX32)
1107 void valgrind_summary_hack(void) {
1108 #if HAVE_VALGRIND_VALGRIND_H
1109 if (getpid_cached() == 1 && RUNNING_ON_VALGRIND) {
1111 pid = raw_clone(SIGCHLD);
1113 log_emergency_errno(errno, "Failed to fork off valgrind helper: %m");
1117 log_info("Spawned valgrind helper as PID "PID_FMT".", pid);
1118 (void) wait_for_terminate(pid, NULL);
1124 int pid_compare_func(const void *a, const void *b) {
1125 const pid_t *p = a, *q = b;
1127 /* Suitable for usage in qsort() */
1136 int ioprio_parse_priority(const char *s, int *ret) {
1142 r = safe_atoi(s, &i);
1146 if (!ioprio_priority_is_valid(i))
1154 /* The cached PID, possible values:
1156 * == UNSET [0] → cache not initialized yet
1157 * == BUSY [-1] → some thread is initializing it at the moment
1158 * any other → the cached PID
1161 #define CACHED_PID_UNSET ((pid_t) 0)
1162 #define CACHED_PID_BUSY ((pid_t) -1)
1164 static pid_t cached_pid = CACHED_PID_UNSET;
1166 void reset_cached_pid(void) {
1167 /* Invoked in the child after a fork(), i.e. at the first moment the PID changed */
1168 cached_pid = CACHED_PID_UNSET;
1171 /* We use glibc __register_atfork() + __dso_handle directly here, as they are not included in the glibc
1172 * headers. __register_atfork() is mostly equivalent to pthread_atfork(), but doesn't require us to link against
1173 * libpthread, as it is part of glibc anyway. */
1175 extern int __register_atfork(void (*prepare) (void), void (*parent) (void), void (*child) (void), void * __dso_handle);
1176 extern void* __dso_handle __attribute__ ((__weak__));
1177 #endif // ifdef __GLIBC__
1179 pid_t getpid_cached(void) {
1180 static bool installed = false;
1181 pid_t current_value;
1183 /* getpid_cached() is much like getpid(), but caches the value in local memory, to avoid having to invoke a
1184 * system call each time. This restores glibc behaviour from before 2.24, when getpid() was unconditionally
1185 * cached. Starting with 2.24 getpid() started to become prohibitively expensive when used for detecting when
1186 * objects were used across fork()s. With this caching the old behaviour is somewhat restored.
1188 * https://bugzilla.redhat.com/show_bug.cgi?id=1443976
1189 * https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=c579f48edba88380635ab98cb612030e3ed8691e
1192 current_value = __sync_val_compare_and_swap(&cached_pid, CACHED_PID_UNSET, CACHED_PID_BUSY);
1194 switch (current_value) {
1196 case CACHED_PID_UNSET: { /* Not initialized yet, then do so now */
1199 new_pid = raw_getpid();
1202 /* __register_atfork() either returns 0 or -ENOMEM, in its glibc implementation. Since it's
1203 * only half-documented (glibc doesn't document it but LSB does — though only superficially)
1204 * we'll check for errors only in the most generic fashion possible. */
1206 if (__register_atfork(NULL, NULL, reset_cached_pid, __dso_handle) != 0) {
1207 /* OOM? Let's try again later */
1208 cached_pid = CACHED_PID_UNSET;
1215 cached_pid = new_pid;
1219 case CACHED_PID_BUSY: /* Somebody else is currently initializing */
1220 return raw_getpid();
1222 default: /* Properly initialized */
1223 return current_value;
1227 int must_be_root(void) {
1232 log_error("Need to be root.");
1238 const int except_fds[],
1239 size_t n_except_fds,
1243 pid_t original_pid, pid;
1244 sigset_t saved_ss, ss;
1245 bool block_signals = false;
1248 /* A wrapper around fork(), that does a couple of important initializations in addition to mere forking. Always
1249 * returns the child's PID in *ret_pid. Returns == 0 in the child, and > 0 in the parent. */
1251 prio = flags & FORK_LOG ? LOG_ERR : LOG_DEBUG;
1253 original_pid = getpid_cached();
1255 if (flags & (FORK_RESET_SIGNALS|FORK_DEATHSIG)) {
1257 /* We temporarily block all signals, so that the new child has them blocked initially. This way, we can
1258 * be sure that SIGTERMs are not lost we might send to the child. */
1260 if (sigfillset(&ss) < 0)
1261 return log_full_errno(prio, errno, "Failed to reset signal set: %m");
1263 block_signals = true;
1265 } else if (flags & FORK_WAIT) {
1267 /* Let's block SIGCHLD at least, so that we can safely watch for the child process */
1269 if (sigemptyset(&ss) < 0)
1270 return log_full_errno(prio, errno, "Failed to clear signal set: %m");
1272 if (sigaddset(&ss, SIGCHLD) < 0)
1273 return log_full_errno(prio, errno, "Failed to add SIGCHLD to signal set: %m");
1275 block_signals = true;
1279 if (sigprocmask(SIG_SETMASK, &ss, &saved_ss) < 0)
1280 return log_full_errno(prio, errno, "Failed to set signal mask: %m");
1282 if (flags & FORK_NEW_MOUNTNS)
1283 pid = raw_clone(SIGCHLD|CLONE_NEWNS);
1289 if (block_signals) /* undo what we did above */
1290 (void) sigprocmask(SIG_SETMASK, &saved_ss, NULL);
1292 return log_full_errno(prio, r, "Failed to fork: %m");
1295 /* We are in the parent process */
1297 log_debug("Successfully forked off '%s' as PID " PID_FMT ".", strna(name), pid);
1299 if (flags & FORK_WAIT) {
1300 r = wait_for_terminate_and_check(name, pid, (flags & FORK_LOG ? WAIT_LOG : 0));
1303 if (r != EXIT_SUCCESS) /* exit status > 0 should be treated as failure, too */
1307 if (block_signals) /* undo what we did above */
1308 (void) sigprocmask(SIG_SETMASK, &saved_ss, NULL);
1316 /* We are in the child process */
1318 if (flags & FORK_REOPEN_LOG) {
1319 /* Close the logs if requested, before we log anything. And make sure we reopen it if needed. */
1321 log_set_open_when_needed(true);
1325 r = rename_process(name);
1327 log_full_errno(flags & FORK_LOG ? LOG_WARNING : LOG_DEBUG,
1328 r, "Failed to rename process, ignoring: %m");
1331 if (flags & FORK_DEATHSIG)
1332 if (prctl(PR_SET_PDEATHSIG, SIGTERM) < 0) {
1333 log_full_errno(prio, errno, "Failed to set death signal: %m");
1334 _exit(EXIT_FAILURE);
1337 if (flags & FORK_RESET_SIGNALS) {
1338 r = reset_all_signal_handlers();
1340 log_full_errno(prio, r, "Failed to reset signal handlers: %m");
1341 _exit(EXIT_FAILURE);
1344 /* This implicitly undoes the signal mask stuff we did before the fork()ing above */
1345 r = reset_signal_mask();
1347 log_full_errno(prio, r, "Failed to reset signal mask: %m");
1348 _exit(EXIT_FAILURE);
1350 } else if (block_signals) { /* undo what we did above */
1351 if (sigprocmask(SIG_SETMASK, &saved_ss, NULL) < 0) {
1352 log_full_errno(prio, errno, "Failed to restore signal mask: %m");
1353 _exit(EXIT_FAILURE);
1357 if (flags & FORK_DEATHSIG) {
1359 /* Let's see if the parent PID is still the one we started from? If not, then the parent
1360 * already died by the time we set PR_SET_PDEATHSIG, hence let's emulate the effect */
1364 /* Parent is in a differn't PID namespace. */;
1365 else if (ppid != original_pid) {
1366 log_debug("Parent died early, raising SIGTERM.");
1367 (void) raise(SIGTERM);
1368 _exit(EXIT_FAILURE);
1372 if (flags & FORK_CLOSE_ALL_FDS) {
1373 /* Close the logs here in case it got reopened above, as close_all_fds() would close them for us */
1376 r = close_all_fds(except_fds, n_except_fds);
1378 log_full_errno(prio, r, "Failed to close all file descriptors: %m");
1379 _exit(EXIT_FAILURE);
1383 /* When we were asked to reopen the logs, do so again now */
1384 if (flags & FORK_REOPEN_LOG) {
1386 log_set_open_when_needed(false);
1389 if (flags & FORK_NULL_STDIO) {
1390 r = make_null_stdio();
1392 log_full_errno(prio, r, "Failed to connect stdin/stdout to /dev/null: %m");
1393 _exit(EXIT_FAILURE);
1398 *ret_pid = getpid_cached();
1403 int fork_agent(const char *name, const int except[], unsigned n_except, pid_t *ret_pid, const char *path, ...) {
1404 bool stdout_is_tty, stderr_is_tty;
1412 /* Spawns a temporary TTY agent, making sure it goes away when we go away */
1414 r = safe_fork_full(name, except, n_except, FORK_RESET_SIGNALS|FORK_DEATHSIG|FORK_CLOSE_ALL_FDS, ret_pid);
1422 stdout_is_tty = isatty(STDOUT_FILENO);
1423 stderr_is_tty = isatty(STDERR_FILENO);
1425 if (!stdout_is_tty || !stderr_is_tty) {
1428 /* Detach from stdout/stderr. and reopen
1429 * /dev/tty for them. This is important to
1430 * ensure that when systemctl is started via
1431 * popen() or a similar call that expects to
1432 * read EOF we actually do generate EOF and
1433 * not delay this indefinitely by because we
1434 * keep an unused copy of stdin around. */
1435 fd = open("/dev/tty", O_WRONLY);
1437 log_error_errno(errno, "Failed to open /dev/tty: %m");
1438 _exit(EXIT_FAILURE);
1441 if (!stdout_is_tty && dup2(fd, STDOUT_FILENO) < 0) {
1442 log_error_errno(errno, "Failed to dup2 /dev/tty: %m");
1443 _exit(EXIT_FAILURE);
1446 if (!stderr_is_tty && dup2(fd, STDERR_FILENO) < 0) {
1447 log_error_errno(errno, "Failed to dup2 /dev/tty: %m");
1448 _exit(EXIT_FAILURE);
1451 safe_close_above_stdio(fd);
1454 /* Count arguments */
1456 for (n = 0; va_arg(ap, char*); n++)
1461 l = alloca(sizeof(char *) * (n + 1));
1463 /* Fill in arguments */
1465 for (i = 0; i <= n; i++)
1466 l[i] = va_arg(ap, char*);
1470 _exit(EXIT_FAILURE);
1473 #if 0 /// UNNEEDED by elogind
1474 static const char *const ioprio_class_table[] = {
1475 [IOPRIO_CLASS_NONE] = "none",
1476 [IOPRIO_CLASS_RT] = "realtime",
1477 [IOPRIO_CLASS_BE] = "best-effort",
1478 [IOPRIO_CLASS_IDLE] = "idle"
1481 DEFINE_STRING_TABLE_LOOKUP_WITH_FALLBACK(ioprio_class, int, IOPRIO_N_CLASSES);
1483 static const char *const sigchld_code_table[] = {
1484 [CLD_EXITED] = "exited",
1485 [CLD_KILLED] = "killed",
1486 [CLD_DUMPED] = "dumped",
1487 [CLD_TRAPPED] = "trapped",
1488 [CLD_STOPPED] = "stopped",
1489 [CLD_CONTINUED] = "continued",
1492 DEFINE_STRING_TABLE_LOOKUP(sigchld_code, int);
1494 static const char* const sched_policy_table[] = {
1495 [SCHED_OTHER] = "other",
1496 [SCHED_BATCH] = "batch",
1497 [SCHED_IDLE] = "idle",
1498 [SCHED_FIFO] = "fifo",
1502 DEFINE_STRING_TABLE_LOOKUP_WITH_FALLBACK(sched_policy, int, INT_MAX);