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|
/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
/***
This file is part of systemd.
Copyright 2010 ProFUSION embedded systems
systemd is free software; you can redistribute it and/or modify it
under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation; either version 2.1 of the License, or
(at your option) any later version.
systemd is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License
along with systemd; If not, see <http://www.gnu.org/licenses/>.
***/
#include <sys/wait.h>
#include <signal.h>
#include <errno.h>
#include "util.h"
#include "def.h"
#include "killall.h"
#define TIMEOUT_USEC (5 * USEC_PER_SEC)
static bool ignore_proc(pid_t pid) {
char buf[PATH_MAX];
FILE *f;
char c;
size_t count;
uid_t uid;
int r;
/* We are PID 1, let's not commit suicide */
if (pid == 1)
return true;
r = get_process_uid(pid, &uid);
if (r < 0)
return true; /* not really, but better safe than sorry */
/* Non-root processes otherwise are always subject to be killed */
if (uid != 0)
return false;
snprintf(buf, sizeof(buf), "/proc/%lu/cmdline", (unsigned long) pid);
char_array_0(buf);
f = fopen(buf, "re");
if (!f)
return true; /* not really, but has the desired effect */
count = fread(&c, 1, 1, f);
fclose(f);
/* Kernel threads have an empty cmdline */
if (count <= 0)
return true;
/* Processes with argv[0][0] = '@' we ignore from the killing
* spree.
*
* http://www.freedesktop.org/wiki/Software/systemd/RootStorageDaemons */
if (count == 1 && c == '@')
return true;
return false;
}
static void wait_for_children(int n_processes, sigset_t *mask) {
usec_t until;
assert(mask);
until = now(CLOCK_MONOTONIC) + TIMEOUT_USEC;
for (;;) {
struct timespec ts;
int k;
usec_t n;
for (;;) {
pid_t pid = waitpid(-1, NULL, WNOHANG);
if (pid == 0)
break;
if (pid < 0 && errno == ECHILD)
return;
if (n_processes > 0)
if (--n_processes == 0)
return;
}
n = now(CLOCK_MONOTONIC);
if (n >= until)
return;
timespec_store(&ts, until - n);
if ((k = sigtimedwait(mask, NULL, &ts)) != SIGCHLD) {
if (k < 0 && errno != EAGAIN) {
log_error("sigtimedwait() failed: %m");
return;
}
if (k >= 0)
log_warning("sigtimedwait() returned unexpected signal.");
}
}
}
static int killall(int sig) {
DIR *dir;
struct dirent *d;
unsigned int n_processes = 0;
dir = opendir("/proc");
if (!dir)
return -errno;
while ((d = readdir(dir))) {
pid_t pid;
if (d->d_type != DT_DIR &&
d->d_type != DT_UNKNOWN)
continue;
if (parse_pid(d->d_name, &pid) < 0)
continue;
if (ignore_proc(pid))
continue;
if (kill(pid, sig) >= 0)
n_processes++;
else if (errno != ENOENT)
log_warning("Could not kill %d: %m", pid);
}
closedir(dir);
return n_processes;
}
void broadcast_signal(int sig) {
sigset_t mask, oldmask;
int n_processes;
assert_se(sigemptyset(&mask) == 0);
assert_se(sigaddset(&mask, SIGCHLD) == 0);
assert_se(sigprocmask(SIG_BLOCK, &mask, &oldmask) == 0);
if (kill(-1, SIGSTOP) < 0 && errno != ESRCH)
log_warning("kill(-1, SIGSTOP) failed: %m");
n_processes = killall(sig);
if (kill(-1, SIGCONT) < 0 && errno != ESRCH)
log_warning("kill(-1, SIGCONT) failed: %m");
if (n_processes <= 0)
goto finish;
wait_for_children(n_processes, &mask);
finish:
sigprocmask(SIG_SETMASK, &oldmask, NULL);
}
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