Block signals to avoid fork /signal races.
This commit is contained in:
parent
fef5d0af59
commit
ad04517623
2
TODO
2
TODO
@ -1,3 +1,3 @@
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- stop using signal() and convert everything to sigaction()
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- ensure all forks block, restore and unblock signals. needs review
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- add support somehow for optional translations
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@ -34,7 +34,6 @@
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#include <sys/stat.h>
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#include <errno.h>
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#include <signal.h>
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#include <stdbool.h>
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#include <string.h>
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@ -134,7 +133,7 @@ bool rc_conf_yesno (const char *var);
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char **env_filter (void);
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char **env_config (void);
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bool service_plugable (const char *service);
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void signal_setup (int sig, void (*handler)(int));
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int signal_setup (int sig, void (*handler)(int));
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/* basename_c never modifies the argument. As such, if there is a trailing
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* slash then an empty string is returned. */
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@ -32,6 +32,7 @@
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const char librc_copyright[] = "Copyright (c) 2007-2008 Roy Marples";
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#include "librc.h"
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#include <signal.h>
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#define SOFTLEVEL RC_SVCDIR "/softlevel"
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@ -575,6 +576,10 @@ static pid_t _exec_service (const char *service, const char *arg)
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char *file;
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char *fifo;
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pid_t pid = -1;
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sigset_t empty;
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sigset_t full;
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sigset_t old;
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struct sigaction sa;
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file = rc_service_resolve (service);
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if (! exists (file)) {
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@ -593,13 +598,37 @@ static pid_t _exec_service (const char *service, const char *arg)
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return (-1);
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}
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if ((pid = vfork ()) == 0) {
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/* We need to block signals until we have forked */
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memset (&sa, 0, sizeof (sa));
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sa.sa_handler = SIG_DFL;
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sigemptyset (&sa.sa_mask);
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sigemptyset (&empty);
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sigfillset (&full);
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sigprocmask (SIG_SETMASK, &full, &old);
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if ((pid = fork ()) == 0) {
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/* Restore default handlers */
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sigaction (SIGCHLD, &sa, NULL);
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sigaction (SIGHUP, &sa, NULL);
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sigaction (SIGINT, &sa, NULL);
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sigaction (SIGQUIT, &sa, NULL);
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sigaction (SIGTERM, &sa, NULL);
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sigaction (SIGUSR1, &sa, NULL);
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sigaction (SIGWINCH, &sa, NULL);
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/* Unmask signals */
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sigprocmask (SIG_SETMASK, &empty, NULL);
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/* Safe to run now */
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execl (file, file, arg, (char *) NULL);
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fprintf (stderr, "unable to exec `%s': %s\n", file, strerror (errno));
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fprintf (stderr, "unable to exec `%s': %s\n",
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file, strerror (errno));
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unlink (fifo);
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_exit (EXIT_FAILURE);
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}
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sigprocmask (SIG_SETMASK, &old, NULL);
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free (fifo);
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free (file);
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@ -432,13 +432,12 @@ bool service_plugable (const char *service)
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return (allow);
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}
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void signal_setup (int sig, void (*handler)(int))
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int signal_setup (int sig, void (*handler)(int))
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{
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struct sigaction sa;
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memset (&sa, 0, sizeof (sa));
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sa.sa_handler = handler;
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sigemptyset (&sa.sa_mask);
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if (sigaction (sig, &sa, NULL) == -1)
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eerrorx ("sigaction: %s", strerror (errno));
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sa.sa_handler = handler;
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return (sigaction (sig, &sa, NULL));
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}
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@ -143,84 +143,110 @@ int rc_waitpid (pid_t pid)
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void rc_plugin_run (rc_hook_t hook, const char *value)
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{
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plugin_t *plugin = plugins;
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struct sigaction sa;
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sigset_t empty;
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sigset_t full;
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sigset_t old;
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/* Don't run plugins if we're in one */
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if (rc_in_plugin)
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return;
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/* We need to block signals until we have forked */
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memset (&sa, 0, sizeof (sa));
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sa.sa_handler = SIG_DFL;
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sigemptyset (&sa.sa_mask);
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sigemptyset (&empty);
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sigfillset (&full);
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while (plugin) {
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if (plugin->hook) {
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int i;
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int flags;
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int pfd[2];
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pid_t pid;
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int i;
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int flags;
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int pfd[2];
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pid_t pid;
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char *buffer;
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char *token;
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char *p;
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ssize_t nr;
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/* We create a pipe so that plugins can affect our environment
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* vars, which in turn influence our scripts. */
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if (pipe (pfd) == -1) {
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eerror ("pipe: %s", strerror (errno));
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return;
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}
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if (! plugin->hook) {
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plugin = plugin->next;
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continue;
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}
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/* Stop any scripts from inheriting us.
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* This is actually quite important as without this, the splash
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* plugin will probably hang when running in silent mode. */
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for (i = 0; i < 2; i++)
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if ((flags = fcntl (pfd[i], F_GETFD, 0)) < 0 ||
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fcntl (pfd[i], F_SETFD, flags | FD_CLOEXEC) < 0)
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eerror ("fcntl: %s", strerror (errno));
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/* We create a pipe so that plugins can affect our environment
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* vars, which in turn influence our scripts. */
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if (pipe (pfd) == -1) {
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eerror ("pipe: %s", strerror (errno));
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return;
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}
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/* We run the plugin in a new process so we never crash
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* or otherwise affected by it */
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if ((pid = fork ()) == -1) {
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eerror ("fork: %s", strerror (errno));
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return;
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}
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/* Stop any scripts from inheriting us.
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* This is actually quite important as without this, the splash
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* plugin will probably hang when running in silent mode. */
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for (i = 0; i < 2; i++)
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if ((flags = fcntl (pfd[i], F_GETFD, 0)) < 0 ||
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fcntl (pfd[i], F_SETFD, flags | FD_CLOEXEC) < 0)
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eerror ("fcntl: %s", strerror (errno));
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if (pid == 0) {
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int retval;
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sigprocmask (SIG_SETMASK, &full, &old);
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rc_in_plugin = true;
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close (pfd[0]);
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rc_environ_fd = fdopen (pfd[1], "w");
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retval = plugin->hook (hook, value);
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fclose (rc_environ_fd);
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rc_environ_fd = NULL;
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/* We run the plugin in a new process so we never crash
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* or otherwise affected by it */
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if ((pid = fork ()) == -1) {
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eerror ("fork: %s", strerror (errno));
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break;
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}
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/* Just in case the plugin sets this to false */
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rc_in_plugin = true;
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exit (retval);
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} else {
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char *buffer;
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char *token;
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char *p;
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ssize_t nr;
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if (pid == 0) {
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int retval;
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close (pfd[1]);
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buffer = xmalloc (sizeof (char) * BUFSIZ);
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memset (buffer, 0, BUFSIZ);
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/* Restore default handlers */
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sigaction (SIGCHLD, &sa, NULL);
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sigaction (SIGHUP, &sa, NULL);
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sigaction (SIGINT, &sa, NULL);
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sigaction (SIGQUIT, &sa, NULL);
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sigaction (SIGTERM, &sa, NULL);
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sigaction (SIGUSR1, &sa, NULL);
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sigaction (SIGWINCH, &sa, NULL);
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sigprocmask (SIG_SETMASK, &old, NULL);
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rc_in_plugin = true;
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close (pfd[0]);
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rc_environ_fd = fdopen (pfd[1], "w");
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retval = plugin->hook (hook, value);
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fclose (rc_environ_fd);
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rc_environ_fd = NULL;
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while ((nr = read (pfd[0], buffer, BUFSIZ)) > 0) {
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p = buffer;
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while (*p && p - buffer < nr) {
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token = strsep (&p, "=");
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if (token) {
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unsetenv (token);
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if (*p) {
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setenv (token, p, 1);
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p += strlen (p) + 1;
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} else
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p++;
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}
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}
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/* Just in case the plugin sets this to false */
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rc_in_plugin = true;
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exit (retval);
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}
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sigprocmask (SIG_SETMASK, &old, NULL);
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close (pfd[1]);
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buffer = xmalloc (sizeof (char) * BUFSIZ);
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memset (buffer, 0, BUFSIZ);
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while ((nr = read (pfd[0], buffer, BUFSIZ)) > 0) {
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p = buffer;
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while (*p && p - buffer < nr) {
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token = strsep (&p, "=");
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if (token) {
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unsetenv (token);
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if (*p) {
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setenv (token, p, 1);
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p += strlen (p) + 1;
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} else
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p++;
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}
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free (buffer);
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close (pfd[0]);
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rc_waitpid (pid);
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}
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}
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free (buffer);
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close (pfd[0]);
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rc_waitpid (pid);
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plugin = plugin->next;
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}
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}
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16
src/rc/rc.c
16
src/rc/rc.c
@ -663,6 +663,7 @@ int main (int argc, char **argv)
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int opt;
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bool parallel;
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int regen = 0;
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pid_t pid;
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applet = basename_c (argv[0]);
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atexit (cleanup);
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@ -994,7 +995,7 @@ int main (int argc, char **argv)
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/* We always stop the service when in these runlevels */
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if (going_down) {
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pid_t pid = rc_service_stop (service);
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pid = rc_service_stop (service);
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if (pid > 0 && ! parallel)
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rc_waitpid (pid);
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continue;
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@ -1060,11 +1061,10 @@ int main (int argc, char **argv)
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/* After all that we can finally stop the blighter! */
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if (! found) {
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pid_t pid;
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pid = rc_service_stop (service);
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if ((pid = rc_service_stop (service)) > 0) {
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if (pid > 0) {
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add_pid (pid);
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if (! parallel) {
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rc_waitpid (pid);
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remove_pid (pid);
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@ -1136,9 +1136,7 @@ int main (int argc, char **argv)
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#endif
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STRLIST_FOREACH (start_services, service, i) {
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if (rc_service_state (service) & RC_SERVICE_STOPPED) {
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pid_t pid;
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if (rc_service_state (service) & RC_SERVICE_STOPPED) {
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if (! interactive)
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interactive = want_interactive ();
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@ -1160,8 +1158,10 @@ interactive_option:
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}
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}
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pid = rc_service_start (service);
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/* Remember the pid if we're running in parallel */
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if ((pid = rc_service_start (service)) > 0) {
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if (pid > 0) {
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add_pid (pid);
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if (! parallel) {
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@ -432,8 +432,6 @@ static bool svc_exec (const char *arg1, const char *arg2)
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eerrorx ("%s: vfork: %s", service, strerror (errno));
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if (service_pid == 0) {
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if (slave_tty >= 0) {
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/* Hmmm, this shouldn't work in a vfork, but it does which is
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* good for us */
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close (master_tty);
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dup2 (slave_tty, 1);
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