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src.rivoreo.one / systemd-stable / v239-13 / . / src / basic / process-util.c
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/* SPDX-License-Identifier: LGPL-2.1+ */
#include <ctype.h>
#include <errno.h>
#include <limits.h>
#include <linux/oom.h>
#include <sched.h>
#include <signal.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdio_ext.h>
#include <stdlib.h>
#include <string.h>
#include <sys/mman.h>
#include <sys/mount.h>
#include <sys/personality.h>
#include <sys/prctl.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <syslog.h>
#include <unistd.h>
#if HAVE_VALGRIND_VALGRIND_H
#include <valgrind/valgrind.h>
#endif
#include "alloc-util.h"
#include "architecture.h"
#include "escape.h"
#include "fd-util.h"
#include "fileio.h"
#include "fs-util.h"
#include "ioprio.h"
#include "log.h"
#include "macro.h"
#include "missing.h"
#include "process-util.h"
#include "raw-clone.h"
#include "signal-util.h"
#include "stat-util.h"
#include "string-table.h"
#include "string-util.h"
#include "terminal-util.h"
#include "user-util.h"
#include "util.h"
int get_process_state(pid_t pid) {
const char *p;
char state;
int r;
_cleanup_free_ char *line = NULL;
assert(pid >= 0);
p = procfs_file_alloca(pid, "stat");
r = read_one_line_file(p, &line);
if (r == -ENOENT)
return -ESRCH;
if (r < 0)
return r;
p = strrchr(line, ')');
if (!p)
return -EIO;
p++;
if (sscanf(p, " %c", &state) != 1)
return -EIO;
return (unsigned char) state;
}
int get_process_comm(pid_t pid, char **ret) {
_cleanup_free_ char *escaped = NULL, *comm = NULL;
const char *p;
int r;
assert(ret);
assert(pid >= 0);
escaped = new(char, TASK_COMM_LEN);
if (!escaped)
return -ENOMEM;
p = procfs_file_alloca(pid, "comm");
r = read_one_line_file(p, &comm);
if (r == -ENOENT)
return -ESRCH;
if (r < 0)
return r;
/* Escape unprintable characters, just in case, but don't grow the string beyond the underlying size */
cellescape(escaped, TASK_COMM_LEN, comm);
*ret = TAKE_PTR(escaped);
return 0;
}
int get_process_cmdline(pid_t pid, size_t max_length, bool comm_fallback, char **line) {
_cleanup_fclose_ FILE *f = NULL;
bool space = false;
char *k;
_cleanup_free_ char *ans = NULL;
const char *p;
int c;
assert(line);
assert(pid >= 0);
/* Retrieves a process' command line. Replaces unprintable characters while doing so by whitespace (coalescing
* multiple sequential ones into one). If max_length is != 0 will return a string of the specified size at most
* (the trailing NUL byte does count towards the length here!), abbreviated with a "..." ellipsis. If
* comm_fallback is true and the process has no command line set (the case for kernel threads), or has a
* command line that resolves to the empty string will return the "comm" name of the process instead.
*
* Returns -ESRCH if the process doesn't exist, and -ENOENT if the process has no command line (and
* comm_fallback is false). Returns 0 and sets *line otherwise. */
p = procfs_file_alloca(pid, "cmdline");
f = fopen(p, "re");
if (!f) {
if (errno == ENOENT)
return -ESRCH;
return -errno;
}
(void) __fsetlocking(f, FSETLOCKING_BYCALLER);
if (max_length == 0) {
/* This is supposed to be a safety guard against runaway command lines. */
long l = sysconf(_SC_ARG_MAX);
assert(l > 0);
max_length = l;
}
if (max_length == 1) {
/* If there's only room for one byte, return the empty string */
ans = new0(char, 1);
if (!ans)
return -ENOMEM;
*line = TAKE_PTR(ans);
return 0;
} else {
bool dotdotdot = false;
size_t left;
ans = new(char, max_length);
if (!ans)
return -ENOMEM;
k = ans;
left = max_length;
while ((c = getc(f)) != EOF) {
if (isprint(c)) {
if (space) {
if (left <= 2) {
dotdotdot = true;
break;
}
*(k++) = ' ';
left--;
space = false;
}
if (left <= 1) {
dotdotdot = true;
break;
}
*(k++) = (char) c;
left--;
} else if (k > ans)
space = true;
}
if (dotdotdot) {
if (max_length <= 4) {
k = ans;
left = max_length;
} else {
k = ans + max_length - 4;
left = 4;
/* Eat up final spaces */
while (k > ans && isspace(k[-1])) {
k--;
left++;
}
}
strncpy(k, "...", left-1);
k[left-1] = 0;
} else
*k = 0;
}
/* Kernel threads have no argv[] */
if (isempty(ans)) {
_cleanup_free_ char *t = NULL;
int h;
ans = mfree(ans);
if (!comm_fallback)
return -ENOENT;
h = get_process_comm(pid, &t);
if (h < 0)
return h;
size_t l = strlen(t);
if (l + 3 <= max_length) {
ans = strjoin("[", t, "]");
if (!ans)
return -ENOMEM;
} else if (max_length <= 6) {
ans = new(char, max_length);
if (!ans)
return -ENOMEM;
memcpy(ans, "[...]", max_length-1);
ans[max_length-1] = 0;
} else {
t[max_length - 6] = 0;
/* Chop off final spaces */
delete_trailing_chars(t, WHITESPACE);
ans = strjoin("[", t, "...]");
if (!ans)
return -ENOMEM;
}
*line = TAKE_PTR(ans);
return 0;
}
k = realloc(ans, strlen(ans) + 1);
if (!k)
return -ENOMEM;
ans = NULL;
*line = k;
return 0;
}
int rename_process(const char name[]) {
static size_t mm_size = 0;
static char *mm = NULL;
bool truncated = false;
size_t l;
/* This is a like a poor man's setproctitle(). It changes the comm field, argv[0], and also the glibc's
* internally used name of the process. For the first one a limit of 16 chars applies; to the second one in
* many cases one of 10 (i.e. length of "/sbin/init") — however if we have CAP_SYS_RESOURCES it is unbounded;
* to the third one 7 (i.e. the length of "systemd". If you pass a longer string it will likely be
* truncated.
*
* Returns 0 if a name was set but truncated, > 0 if it was set but not truncated. */
if (isempty(name))
return -EINVAL; /* let's not confuse users unnecessarily with an empty name */
if (!is_main_thread())
return -EPERM; /* Let's not allow setting the process name from other threads than the main one, as we
* cache things without locking, and we make assumptions that PR_SET_NAME sets the
* process name that isn't correct on any other threads */
l = strlen(name);
/* First step, change the comm field. The main thread's comm is identical to the process comm. This means we
* can use PR_SET_NAME, which sets the thread name for the calling thread. */
if (prctl(PR_SET_NAME, name) < 0)
log_debug_errno(errno, "PR_SET_NAME failed: %m");
if (l >= TASK_COMM_LEN) /* Linux process names can be 15 chars at max */
truncated = true;
/* Second step, change glibc's ID of the process name. */
if (program_invocation_name) {
size_t k;
k = strlen(program_invocation_name);
strncpy(program_invocation_name, name, k);
if (l > k)
truncated = true;
}
/* Third step, completely replace the argv[] array the kernel maintains for us. This requires privileges, but
* has the advantage that the argv[] array is exactly what we want it to be, and not filled up with zeros at
* the end. This is the best option for changing /proc/self/cmdline. */
/* Let's not bother with this if we don't have euid == 0. Strictly speaking we should check for the
* CAP_SYS_RESOURCE capability which is independent of the euid. In our own code the capability generally is
* present only for euid == 0, hence let's use this as quick bypass check, to avoid calling mmap() if
* PR_SET_MM_ARG_{START,END} fails with EPERM later on anyway. After all geteuid() is dead cheap to call, but
* mmap() is not. */
if (geteuid() != 0)
log_debug("Skipping PR_SET_MM, as we don't have privileges.");
else if (mm_size < l+1) {
size_t nn_size;
char *nn;
nn_size = PAGE_ALIGN(l+1);
nn = mmap(NULL, nn_size, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0);
if (nn == MAP_FAILED) {
log_debug_errno(errno, "mmap() failed: %m");
goto use_saved_argv;
}
strncpy(nn, name, nn_size);
/* Now, let's tell the kernel about this new memory */
if (prctl(PR_SET_MM, PR_SET_MM_ARG_START, (unsigned long) nn, 0, 0) < 0) {
log_debug_errno(errno, "PR_SET_MM_ARG_START failed, proceeding without: %m");
(void) munmap(nn, nn_size);
goto use_saved_argv;
}
/* And update the end pointer to the new end, too. If this fails, we don't really know what to do, it's
* pretty unlikely that we can rollback, hence we'll just accept the failure, and continue. */
if (prctl(PR_SET_MM, PR_SET_MM_ARG_END, (unsigned long) nn + l + 1, 0, 0) < 0)
log_debug_errno(errno, "PR_SET_MM_ARG_END failed, proceeding without: %m");
if (mm)
(void) munmap(mm, mm_size);
mm = nn;
mm_size = nn_size;
} else {
strncpy(mm, name, mm_size);
/* Update the end pointer, continuing regardless of any failure. */
if (prctl(PR_SET_MM, PR_SET_MM_ARG_END, (unsigned long) mm + l + 1, 0, 0) < 0)
log_debug_errno(errno, "PR_SET_MM_ARG_END failed, proceeding without: %m");
}
use_saved_argv:
/* Fourth step: in all cases we'll also update the original argv[], so that our own code gets it right too if
* it still looks here */
if (saved_argc > 0) {
int i;
if (saved_argv[0]) {
size_t k;
k = strlen(saved_argv[0]);
strncpy(saved_argv[0], name, k);
if (l > k)
truncated = true;
}
for (i = 1; i < saved_argc; i++) {
if (!saved_argv[i])
break;
memzero(saved_argv[i], strlen(saved_argv[i]));
}
}
return !truncated;
}
int is_kernel_thread(pid_t pid) {
_cleanup_free_ char *line = NULL;
unsigned long long flags;
size_t l, i;
const char *p;
char *q;
int r;
if (IN_SET(pid, 0, 1) || pid == getpid_cached()) /* pid 1, and we ourselves certainly aren't a kernel thread */
return 0;
if (!pid_is_valid(pid))
return -EINVAL;
p = procfs_file_alloca(pid, "stat");
r = read_one_line_file(p, &line);
if (r == -ENOENT)
return -ESRCH;
if (r < 0)
return r;
/* Skip past the comm field */
q = strrchr(line, ')');
if (!q)
return -EINVAL;
q++;
/* Skip 6 fields to reach the flags field */
for (i = 0; i < 6; i++) {
l = strspn(q, WHITESPACE);
if (l < 1)
return -EINVAL;
q += l;
l = strcspn(q, WHITESPACE);
if (l < 1)
return -EINVAL;
q += l;
}
/* Skip preceeding whitespace */
l = strspn(q, WHITESPACE);
if (l < 1)
return -EINVAL;
q += l;
/* Truncate the rest */
l = strcspn(q, WHITESPACE);
if (l < 1)
return -EINVAL;
q[l] = 0;
r = safe_atollu(q, &flags);
if (r < 0)
return r;
return !!(flags & PF_KTHREAD);
}
int get_process_capeff(pid_t pid, char **capeff) {
const char *p;
int r;
assert(capeff);
assert(pid >= 0);
p = procfs_file_alloca(pid, "status");
r = get_proc_field(p, "CapEff", WHITESPACE, capeff);
if (r == -ENOENT)
return -ESRCH;
return r;
}
static int get_process_link_contents(const char *proc_file, char **name) {
int r;
assert(proc_file);
assert(name);
r = readlink_malloc(proc_file, name);
if (r == -ENOENT)
return -ESRCH;
if (r < 0)
return r;
return 0;
}
int get_process_exe(pid_t pid, char **name) {
const char *p;
char *d;
int r;
assert(pid >= 0);
p = procfs_file_alloca(pid, "exe");
r = get_process_link_contents(p, name);
if (r < 0)
return r;
d = endswith(*name, " (deleted)");
if (d)
*d = '\0';
return 0;
}
static int get_process_id(pid_t pid, const char *field, uid_t *uid) {
_cleanup_fclose_ FILE *f = NULL;
char line[LINE_MAX];
const char *p;
assert(field);
assert(uid);
if (pid < 0)
return -EINVAL;
p = procfs_file_alloca(pid, "status");
f = fopen(p, "re");
if (!f) {
if (errno == ENOENT)
return -ESRCH;
return -errno;
}
(void) __fsetlocking(f, FSETLOCKING_BYCALLER);
FOREACH_LINE(line, f, return -errno) {
char *l;
l = strstrip(line);
if (startswith(l, field)) {
l += strlen(field);
l += strspn(l, WHITESPACE);
l[strcspn(l, WHITESPACE)] = 0;
return parse_uid(l, uid);
}
}
return -EIO;
}
int get_process_uid(pid_t pid, uid_t *uid) {
if (pid == 0 || pid == getpid_cached()) {
*uid = getuid();
return 0;
}
return get_process_id(pid, "Uid:", uid);
}
int get_process_gid(pid_t pid, gid_t *gid) {
if (pid == 0 || pid == getpid_cached()) {
*gid = getgid();
return 0;
}
assert_cc(sizeof(uid_t) == sizeof(gid_t));
return get_process_id(pid, "Gid:", gid);
}
int get_process_cwd(pid_t pid, char **cwd) {
const char *p;
assert(pid >= 0);
p = procfs_file_alloca(pid, "cwd");
return get_process_link_contents(p, cwd);
}
int get_process_root(pid_t pid, char **root) {
const char *p;
assert(pid >= 0);
p = procfs_file_alloca(pid, "root");
return get_process_link_contents(p, root);
}
int get_process_environ(pid_t pid, char **env) {
_cleanup_fclose_ FILE *f = NULL;
_cleanup_free_ char *outcome = NULL;
int c;
const char *p;
size_t allocated = 0, sz = 0;
assert(pid >= 0);
assert(env);
p = procfs_file_alloca(pid, "environ");
f = fopen(p, "re");
if (!f) {
if (errno == ENOENT)
return -ESRCH;
return -errno;
}
(void) __fsetlocking(f, FSETLOCKING_BYCALLER);
while ((c = fgetc(f)) != EOF) {
if (!GREEDY_REALLOC(outcome, allocated, sz + 5))
return -ENOMEM;
if (c == '\0')
outcome[sz++] = '\n';
else
sz += cescape_char(c, outcome + sz);
}
if (!outcome) {
outcome = strdup("");
if (!outcome)
return -ENOMEM;
} else
outcome[sz] = '\0';
*env = TAKE_PTR(outcome);
return 0;
}
int get_process_ppid(pid_t pid, pid_t *_ppid) {
int r;
_cleanup_free_ char *line = NULL;
long unsigned ppid;
const char *p;
assert(pid >= 0);
assert(_ppid);
if (pid == 0 || pid == getpid_cached()) {
*_ppid = getppid();
return 0;
}
p = procfs_file_alloca(pid, "stat");
r = read_one_line_file(p, &line);
if (r == -ENOENT)
return -ESRCH;
if (r < 0)
return r;
/* Let's skip the pid and comm fields. The latter is enclosed
* in () but does not escape any () in its value, so let's
* skip over it manually */
p = strrchr(line, ')');
if (!p)
return -EIO;
p++;
if (sscanf(p, " "
"%*c " /* state */
"%lu ", /* ppid */
&ppid) != 1)
return -EIO;
if ((long unsigned) (pid_t) ppid != ppid)
return -ERANGE;
*_ppid = (pid_t) ppid;
return 0;
}
int wait_for_terminate(pid_t pid, siginfo_t *status) {
siginfo_t dummy;
assert(pid >= 1);
if (!status)
status = &dummy;
for (;;) {
zero(*status);
if (waitid(P_PID, pid, status, WEXITED) < 0) {
if (errno == EINTR)
continue;
return negative_errno();
}
return 0;
}
}
/*
* Return values:
* < 0 : wait_for_terminate() failed to get the state of the
* process, the process was terminated by a signal, or
* failed for an unknown reason.
* >=0 : The process terminated normally, and its exit code is
* returned.
*
* That is, success is indicated by a return value of zero, and an
* error is indicated by a non-zero value.
*
* A warning is emitted if the process terminates abnormally,
* and also if it returns non-zero unless check_exit_code is true.
*/
int wait_for_terminate_and_check(const char *name, pid_t pid, WaitFlags flags) {
_cleanup_free_ char *buffer = NULL;
siginfo_t status;
int r, prio;
assert(pid > 1);
if (!name) {
r = get_process_comm(pid, &buffer);
if (r < 0)
log_debug_errno(r, "Failed to acquire process name of " PID_FMT ", ignoring: %m", pid);
else
name = buffer;
}
prio = flags & WAIT_LOG_ABNORMAL ? LOG_ERR : LOG_DEBUG;
r = wait_for_terminate(pid, &status);
if (r < 0)
return log_full_errno(prio, r, "Failed to wait for %s: %m", strna(name));
if (status.si_code == CLD_EXITED) {
if (status.si_status != EXIT_SUCCESS)
log_full(flags & WAIT_LOG_NON_ZERO_EXIT_STATUS ? LOG_ERR : LOG_DEBUG,
"%s failed with exit status %i.", strna(name), status.si_status);
else
log_debug("%s succeeded.", name);
return status.si_status;
} else if (IN_SET(status.si_code, CLD_KILLED, CLD_DUMPED)) {
log_full(prio, "%s terminated by signal %s.", strna(name), signal_to_string(status.si_status));
return -EPROTO;
}
log_full(prio, "%s failed due to unknown reason.", strna(name));
return -EPROTO;
}
/*
* Return values:
*
* < 0 : wait_for_terminate_with_timeout() failed to get the state of the process, the process timed out, the process
* was terminated by a signal, or failed for an unknown reason.
*
* >=0 : The process terminated normally with no failures.
*
* Success is indicated by a return value of zero, a timeout is indicated by ETIMEDOUT, and all other child failure
* states are indicated by error is indicated by a non-zero value.
*
* This call assumes SIGCHLD has been blocked already, in particular before the child to wait for has been forked off
* to remain entirely race-free.
*/
int wait_for_terminate_with_timeout(pid_t pid, usec_t timeout) {
sigset_t mask;
int r;
usec_t until;
assert_se(sigemptyset(&mask) == 0);
assert_se(sigaddset(&mask, SIGCHLD) == 0);
/* Drop into a sigtimewait-based timeout. Waiting for the
* pid to exit. */
until = now(CLOCK_MONOTONIC) + timeout;
for (;;) {
usec_t n;
siginfo_t status = {};
struct timespec ts;
n = now(CLOCK_MONOTONIC);
if (n >= until)
break;
r = sigtimedwait(&mask, NULL, timespec_store(&ts, until - n)) < 0 ? -errno : 0;
/* Assuming we woke due to the child exiting. */
if (waitid(P_PID, pid, &status, WEXITED|WNOHANG) == 0) {
if (status.si_pid == pid) {
/* This is the correct child.*/
if (status.si_code == CLD_EXITED)
return (status.si_status == 0) ? 0 : -EPROTO;
else
return -EPROTO;
}
}
/* Not the child, check for errors and proceed appropriately */
if (r < 0) {
switch (r) {
case -EAGAIN:
/* Timed out, child is likely hung. */
return -ETIMEDOUT;
case -EINTR:
/* Received a different signal and should retry */
continue;
default:
/* Return any unexpected errors */
return r;
}
}
}
return -EPROTO;
}
void sigkill_wait(pid_t pid) {
assert(pid > 1);
if (kill(pid, SIGKILL) > 0)
(void) wait_for_terminate(pid, NULL);
}
void sigkill_waitp(pid_t *pid) {
PROTECT_ERRNO;
if (!pid)
return;
if (*pid <= 1)
return;
sigkill_wait(*pid);
}
void sigterm_wait(pid_t pid) {
assert(pid > 1);
if (kill_and_sigcont(pid, SIGTERM) > 0)
(void) wait_for_terminate(pid, NULL);
}
int kill_and_sigcont(pid_t pid, int sig) {
int r;
r = kill(pid, sig) < 0 ? -errno : 0;
/* If this worked, also send SIGCONT, unless we already just sent a SIGCONT, or SIGKILL was sent which isn't
* affected by a process being suspended anyway. */
if (r >= 0 && !IN_SET(sig, SIGCONT, SIGKILL))
(void) kill(pid, SIGCONT);
return r;
}
int getenv_for_pid(pid_t pid, const char *field, char **ret) {
_cleanup_fclose_ FILE *f = NULL;
char *value = NULL;
bool done = false;
const char *path;
size_t l;
assert(pid >= 0);
assert(field);
assert(ret);
if (pid == 0 || pid == getpid_cached()) {
const char *e;
e = getenv(field);
if (!e) {
*ret = NULL;
return 0;
}
value = strdup(e);
if (!value)
return -ENOMEM;
*ret = value;
return 1;
}
path = procfs_file_alloca(pid, "environ");
f = fopen(path, "re");
if (!f) {
if (errno == ENOENT)
return -ESRCH;
return -errno;
}
(void) __fsetlocking(f, FSETLOCKING_BYCALLER);
l = strlen(field);
do {
char line[LINE_MAX];
size_t i;
for (i = 0; i < sizeof(line)-1; i++) {
int c;
c = getc(f);
if (_unlikely_(c == EOF)) {
done = true;
break;
} else if (c == 0)
break;
line[i] = c;
}
line[i] = 0;
if (strneq(line, field, l) && line[l] == '=') {
value = strdup(line + l + 1);
if (!value)
return -ENOMEM;
*ret = value;
return 1;
}
} while (!done);
*ret = NULL;
return 0;
}
bool pid_is_unwaited(pid_t pid) {
/* Checks whether a PID is still valid at all, including a zombie */
if (pid < 0)
return false;
if (pid <= 1) /* If we or PID 1 would be dead and have been waited for, this code would not be running */
return true;
if (pid == getpid_cached())
return true;
if (kill(pid, 0) >= 0)
return true;
return errno != ESRCH;
}
bool pid_is_alive(pid_t pid) {
int r;
/* Checks whether a PID is still valid and not a zombie */
if (pid < 0)
return false;
if (pid <= 1) /* If we or PID 1 would be a zombie, this code would not be running */
return true;
if (pid == getpid_cached())
return true;
r = get_process_state(pid);
if (IN_SET(r, -ESRCH, 'Z'))
return false;
return true;
}
int pid_from_same_root_fs(pid_t pid) {
const char *root;
if (pid < 0)
return false;
if (pid == 0 || pid == getpid_cached())
return true;
root = procfs_file_alloca(pid, "root");
return files_same(root, "/proc/1/root", 0);
}
bool is_main_thread(void) {
static thread_local int cached = 0;
if (_unlikely_(cached == 0))
cached = getpid_cached() == gettid() ? 1 : -1;
return cached > 0;
}
_noreturn_ void freeze(void) {
log_close();
/* Make sure nobody waits for us on a socket anymore */
close_all_fds(NULL, 0);
sync();
/* Let's not freeze right away, but keep reaping zombies. */
for (;;) {
int r;
siginfo_t si = {};
r = waitid(P_ALL, 0, &si, WEXITED);
if (r < 0 && errno != EINTR)
break;
}
/* waitid() failed with an unexpected error, things are really borked. Freeze now! */
for (;;)
pause();
}
bool oom_score_adjust_is_valid(int oa) {
return oa >= OOM_SCORE_ADJ_MIN && oa <= OOM_SCORE_ADJ_MAX;
}
unsigned long personality_from_string(const char *p) {
int architecture;
if (!p)
return PERSONALITY_INVALID;
/* Parse a personality specifier. We use our own identifiers that indicate specific ABIs, rather than just
* hints regarding the register size, since we want to keep things open for multiple locally supported ABIs for
* the same register size. */
architecture = architecture_from_string(p);
if (architecture < 0)
return PERSONALITY_INVALID;
if (architecture == native_architecture())
return PER_LINUX;
#ifdef SECONDARY_ARCHITECTURE
if (architecture == SECONDARY_ARCHITECTURE)
return PER_LINUX32;
#endif
return PERSONALITY_INVALID;
}
const char* personality_to_string(unsigned long p) {
int architecture = _ARCHITECTURE_INVALID;
if (p == PER_LINUX)
architecture = native_architecture();
#ifdef SECONDARY_ARCHITECTURE
else if (p == PER_LINUX32)
architecture = SECONDARY_ARCHITECTURE;
#endif
if (architecture < 0)
return NULL;
return architecture_to_string(architecture);
}
int safe_personality(unsigned long p) {
int ret;
/* So here's the deal, personality() is weirdly defined by glibc. In some cases it returns a failure via errno,
* and in others as negative return value containing an errno-like value. Let's work around this: this is a
* wrapper that uses errno if it is set, and uses the return value otherwise. And then it sets both errno and
* the return value indicating the same issue, so that we are definitely on the safe side.
*
* See https://github.com/systemd/systemd/issues/6737 */
errno = 0;
ret = personality(p);
if (ret < 0) {
if (errno != 0)
return -errno;
errno = -ret;
}
return ret;
}
int opinionated_personality(unsigned long *ret) {
int current;
/* Returns the current personality, or PERSONALITY_INVALID if we can't determine it. This function is a bit
* opinionated though, and ignores all the finer-grained bits and exotic personalities, only distinguishing the
* two most relevant personalities: PER_LINUX and PER_LINUX32. */
current = safe_personality(PERSONALITY_INVALID);
if (current < 0)
return current;
if (((unsigned long) current & 0xffff) == PER_LINUX32)
*ret = PER_LINUX32;
else
*ret = PER_LINUX;
return 0;
}
void valgrind_summary_hack(void) {
#if HAVE_VALGRIND_VALGRIND_H
if (getpid_cached() == 1 && RUNNING_ON_VALGRIND) {
pid_t pid;
pid = raw_clone(SIGCHLD);
if (pid < 0)
log_emergency_errno(errno, "Failed to fork off valgrind helper: %m");
else if (pid == 0)
exit(EXIT_SUCCESS);
else {
log_info("Spawned valgrind helper as PID "PID_FMT".", pid);
(void) wait_for_terminate(pid, NULL);
}
}
#endif
}
int pid_compare_func(const void *a, const void *b) {
const pid_t *p = a, *q = b;
/* Suitable for usage in qsort() */
if (*p < *q)
return -1;
if (*p > *q)
return 1;
return 0;
}
int ioprio_parse_priority(const char *s, int *ret) {
int i, r;
assert(s);
assert(ret);
r = safe_atoi(s, &i);
if (r < 0)
return r;
if (!ioprio_priority_is_valid(i))
return -EINVAL;
*ret = i;
return 0;
}
/* The cached PID, possible values:
*
* == UNSET [0] → cache not initialized yet
* == BUSY [-1] → some thread is initializing it at the moment
* any other → the cached PID
*/
#define CACHED_PID_UNSET ((pid_t) 0)
#define CACHED_PID_BUSY ((pid_t) -1)
static pid_t cached_pid = CACHED_PID_UNSET;
void reset_cached_pid(void) {
/* Invoked in the child after a fork(), i.e. at the first moment the PID changed */
cached_pid = CACHED_PID_UNSET;
}
/* We use glibc __register_atfork() + __dso_handle directly here, as they are not included in the glibc
* headers. __register_atfork() is mostly equivalent to pthread_atfork(), but doesn't require us to link against
* libpthread, as it is part of glibc anyway. */
extern int __register_atfork(void (*prepare) (void), void (*parent) (void), void (*child) (void), void * __dso_handle);
extern void* __dso_handle __attribute__ ((__weak__));
pid_t getpid_cached(void) {
static bool installed = false;
pid_t current_value;
/* getpid_cached() is much like getpid(), but caches the value in local memory, to avoid having to invoke a
* system call each time. This restores glibc behaviour from before 2.24, when getpid() was unconditionally
* cached. Starting with 2.24 getpid() started to become prohibitively expensive when used for detecting when
* objects were used across fork()s. With this caching the old behaviour is somewhat restored.
*
* https://bugzilla.redhat.com/show_bug.cgi?id=1443976
* https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=c579f48edba88380635ab98cb612030e3ed8691e
*/
current_value = __sync_val_compare_and_swap(&cached_pid, CACHED_PID_UNSET, CACHED_PID_BUSY);
switch (current_value) {
case CACHED_PID_UNSET: { /* Not initialized yet, then do so now */
pid_t new_pid;
new_pid = raw_getpid();
if (!installed) {
/* __register_atfork() either returns 0 or -ENOMEM, in its glibc implementation. Since it's
* only half-documented (glibc doesn't document it but LSB does — though only superficially)
* we'll check for errors only in the most generic fashion possible. */
if (__register_atfork(NULL, NULL, reset_cached_pid, __dso_handle) != 0) {
/* OOM? Let's try again later */
cached_pid = CACHED_PID_UNSET;
return new_pid;
}
installed = true;
}
cached_pid = new_pid;
return new_pid;
}
case CACHED_PID_BUSY: /* Somebody else is currently initializing */
return raw_getpid();
default: /* Properly initialized */
return current_value;
}
}
int must_be_root(void) {
if (geteuid() == 0)
return 0;
log_error("Need to be root.");
return -EPERM;
}
int safe_fork_full(
const char *name,
const int except_fds[],
size_t n_except_fds,
ForkFlags flags,
pid_t *ret_pid) {
pid_t original_pid, pid;
sigset_t saved_ss, ss;
bool block_signals = false;
int prio, r;
/* A wrapper around fork(), that does a couple of important initializations in addition to mere forking. Always
* returns the child's PID in *ret_pid. Returns == 0 in the child, and > 0 in the parent. */
prio = flags & FORK_LOG ? LOG_ERR : LOG_DEBUG;
original_pid = getpid_cached();
if (flags & (FORK_RESET_SIGNALS|FORK_DEATHSIG)) {
/* We temporarily block all signals, so that the new child has them blocked initially. This way, we can
* be sure that SIGTERMs are not lost we might send to the child. */
if (sigfillset(&ss) < 0)
return log_full_errno(prio, errno, "Failed to reset signal set: %m");
block_signals = true;
} else if (flags & FORK_WAIT) {
/* Let's block SIGCHLD at least, so that we can safely watch for the child process */
if (sigemptyset(&ss) < 0)
return log_full_errno(prio, errno, "Failed to clear signal set: %m");
if (sigaddset(&ss, SIGCHLD) < 0)
return log_full_errno(prio, errno, "Failed to add SIGCHLD to signal set: %m");
block_signals = true;
}
if (block_signals)
if (sigprocmask(SIG_SETMASK, &ss, &saved_ss) < 0)
return log_full_errno(prio, errno, "Failed to set signal mask: %m");
if (flags & FORK_NEW_MOUNTNS)
pid = raw_clone(SIGCHLD|CLONE_NEWNS);
else
pid = fork();
if (pid < 0) {
r = -errno;
if (block_signals) /* undo what we did above */
(void) sigprocmask(SIG_SETMASK, &saved_ss, NULL);
return log_full_errno(prio, r, "Failed to fork: %m");
}
if (pid > 0) {
/* We are in the parent process */
log_debug("Successfully forked off '%s' as PID " PID_FMT ".", strna(name), pid);
if (flags & FORK_WAIT) {
r = wait_for_terminate_and_check(name, pid, (flags & FORK_LOG ? WAIT_LOG : 0));
if (r < 0)
return r;
if (r != EXIT_SUCCESS) /* exit status > 0 should be treated as failure, too */
return -EPROTO;
}
if (block_signals) /* undo what we did above */
(void) sigprocmask(SIG_SETMASK, &saved_ss, NULL);
if (ret_pid)
*ret_pid = pid;
return 1;
}
/* We are in the child process */
if (flags & FORK_REOPEN_LOG) {
/* Close the logs if requested, before we log anything. And make sure we reopen it if needed. */
log_close();
log_set_open_when_needed(true);
}
if (name) {
r = rename_process(name);
if (r < 0)
log_full_errno(flags & FORK_LOG ? LOG_WARNING : LOG_DEBUG,
r, "Failed to rename process, ignoring: %m");
}
if (flags & FORK_DEATHSIG)
if (prctl(PR_SET_PDEATHSIG, SIGTERM) < 0) {
log_full_errno(prio, errno, "Failed to set death signal: %m");
_exit(EXIT_FAILURE);
}
if (flags & FORK_RESET_SIGNALS) {
r = reset_all_signal_handlers();
if (r < 0) {
log_full_errno(prio, r, "Failed to reset signal handlers: %m");
_exit(EXIT_FAILURE);
}
/* This implicitly undoes the signal mask stuff we did before the fork()ing above */
r = reset_signal_mask();
if (r < 0) {
log_full_errno(prio, r, "Failed to reset signal mask: %m");
_exit(EXIT_FAILURE);
}
} else if (block_signals) { /* undo what we did above */
if (sigprocmask(SIG_SETMASK, &saved_ss, NULL) < 0) {
log_full_errno(prio, errno, "Failed to restore signal mask: %m");
_exit(EXIT_FAILURE);
}
}
if (flags & FORK_DEATHSIG) {
pid_t ppid;
/* Let's see if the parent PID is still the one we started from? If not, then the parent
* already died by the time we set PR_SET_PDEATHSIG, hence let's emulate the effect */
ppid = getppid();
if (ppid == 0)
/* Parent is in a differn't PID namespace. */;
else if (ppid != original_pid) {
log_debug("Parent died early, raising SIGTERM.");
(void) raise(SIGTERM);
_exit(EXIT_FAILURE);
}
}
if (FLAGS_SET(flags, FORK_NEW_MOUNTNS | FORK_MOUNTNS_SLAVE)) {
/* Optionally, make sure we never propagate mounts to the host. */
if (mount(NULL, "/", NULL, MS_SLAVE | MS_REC, NULL) < 0) {
log_full_errno(prio, errno, "Failed to remount root directory as MS_SLAVE: %m");
_exit(EXIT_FAILURE);
}
}
if (flags & FORK_CLOSE_ALL_FDS) {
/* Close the logs here in case it got reopened above, as close_all_fds() would close them for us */
log_close();
r = close_all_fds(except_fds, n_except_fds);
if (r < 0) {
log_full_errno(prio, r, "Failed to close all file descriptors: %m");
_exit(EXIT_FAILURE);
}
}
/* When we were asked to reopen the logs, do so again now */
if (flags & FORK_REOPEN_LOG) {
log_open();
log_set_open_when_needed(false);
}
if (flags & FORK_NULL_STDIO) {
r = make_null_stdio();
if (r < 0) {
log_full_errno(prio, r, "Failed to connect stdin/stdout to /dev/null: %m");
_exit(EXIT_FAILURE);
}
}
if (ret_pid)
*ret_pid = getpid_cached();
return 0;
}
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, except, n_except, FORK_RESET_SIGNALS|FORK_DEATHSIG|FORK_CLOSE_ALL_FDS, 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 because we
* keep an unused copy of stdin around. */
fd = open("/dev/tty", O_WRONLY);
if (fd < 0) {
log_error_errno(errno, "Failed to open /dev/tty: %m");
_exit(EXIT_FAILURE);
}
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);
}
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);
}
int set_oom_score_adjust(int value) {
char t[DECIMAL_STR_MAX(int)];
sprintf(t, "%i", value);
return write_string_file("/proc/self/oom_score_adj", t,
WRITE_STRING_FILE_VERIFY_ON_FAILURE|WRITE_STRING_FILE_DISABLE_BUFFER);
}
static const char *const ioprio_class_table[] = {
[IOPRIO_CLASS_NONE] = "none",
[IOPRIO_CLASS_RT] = "realtime",
[IOPRIO_CLASS_BE] = "best-effort",
[IOPRIO_CLASS_IDLE] = "idle"
};
DEFINE_STRING_TABLE_LOOKUP_WITH_FALLBACK(ioprio_class, int, IOPRIO_N_CLASSES);
static const char *const sigchld_code_table[] = {
[CLD_EXITED] = "exited",
[CLD_KILLED] = "killed",
[CLD_DUMPED] = "dumped",
[CLD_TRAPPED] = "trapped",
[CLD_STOPPED] = "stopped",
[CLD_CONTINUED] = "continued",
};
DEFINE_STRING_TABLE_LOOKUP(sigchld_code, int);
static const char* const sched_policy_table[] = {
[SCHED_OTHER] = "other",
[SCHED_BATCH] = "batch",
[SCHED_IDLE] = "idle",
[SCHED_FIFO] = "fifo",
[SCHED_RR] = "rr"
};
DEFINE_STRING_TABLE_LOOKUP_WITH_FALLBACK(sched_policy, int, INT_MAX);