X-Git-Url: http://git.onelab.eu/?a=blobdiff_plain;f=lib%2Fdaemon.c;h=4c7c8e16ae3f2f9b6760185e86dfa00258c5be56;hb=3834bcf2bf9106114bca70264b7a0bdb7351ff80;hp=91e0404e9c1e912a8ca9801c4874ced9663b2cec;hpb=2bf9d87ae3aa946ef93cb923e560beb582f5b655;p=sliver-openvswitch.git

diff --git a/lib/daemon.c b/lib/daemon.c
index 91e0404e9..4c7c8e16a 100644
--- a/lib/daemon.c
+++ b/lib/daemon.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2008, 2009, 2010 Nicira Networks.
+ * Copyright (c) 2014 Nicira, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -13,116 +13,19 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-
 #include <config.h>
 #include "daemon.h"
+#include "daemon-private.h"
 #include <errno.h>
 #include <fcntl.h>
-#include <signal.h>
-#include <stdlib.h>
-#include <string.h>
-#include <sys/resource.h>
-#include <sys/wait.h>
-#include <sys/stat.h>
 #include <unistd.h>
-#include "command-line.h"
-#include "fatal-signal.h"
-#include "dirs.h"
-#include "lockfile.h"
-#include "process.h"
-#include "socket-util.h"
-#include "timeval.h"
-#include "util.h"
 #include "vlog.h"
 
-VLOG_DEFINE_THIS_MODULE(daemon)
-
-/* --detach: Should we run in the background? */
-static bool detach;
-
-/* --pidfile: Name of pidfile (null if none). */
-static char *pidfile;
-
-/* Device and inode of pidfile, so we can avoid reopening it. */
-static dev_t pidfile_dev;
-static ino_t pidfile_ino;
-
-/* --overwrite-pidfile: Create pidfile even if one already exists and is
-   locked? */
-static bool overwrite_pidfile;
-
-/* --no-chdir: Should we chdir to "/"? */
-static bool chdir_ = true;
-
-/* File descriptor used by daemonize_start() and daemonize_complete(). */
-static int daemonize_fd = -1;
-
-/* --monitor: Should a supervisory process monitor the daemon and restart it if
- * it dies due to an error signal? */
-static bool monitor;
-
-/* Returns the file name that would be used for a pidfile if 'name' were
- * provided to set_pidfile().  The caller must free the returned string. */
-char *
-make_pidfile_name(const char *name)
-{
-    return (!name
-            ? xasprintf("%s/%s.pid", ovs_rundir, program_name)
-            : abs_file_name(ovs_rundir, name));
-}
-
-/* Sets up a following call to daemonize() to create a pidfile named 'name'.
- * If 'name' begins with '/', then it is treated as an absolute path.
- * Otherwise, it is taken relative to RUNDIR, which is $(prefix)/var/run by
- * default.
- *
- * If 'name' is null, then program_name followed by ".pid" is used. */
-void
-set_pidfile(const char *name)
-{
-    free(pidfile);
-    pidfile = make_pidfile_name(name);
-}
-
-/* Returns an absolute path to the configured pidfile, or a null pointer if no
- * pidfile is configured.  The caller must not modify or free the returned
- * string. */
-const char *
-get_pidfile(void)
-{
-    return pidfile;
-}
-
-/* Sets that we do not chdir to "/". */
-void
-set_no_chdir(void)
-{
-    chdir_ = false;
-}
+VLOG_DEFINE_THIS_MODULE(daemon);
 
-/* Will we chdir to "/" as part of daemonizing? */
-bool
-is_chdir_enabled(void)
-{
-    return chdir_;
-}
-
-/* Normally, die_if_already_running() will terminate the program with a message
- * if a locked pidfile already exists.  If this function is called,
- * die_if_already_running() will merely log a warning. */
-void
-ignore_existing_pidfile(void)
-{
-    overwrite_pidfile = true;
-}
-
-/* Sets up a following call to daemonize() to detach from the foreground
- * session, running this process in the background.  */
-void
-set_detach(void)
-{
-    detach = true;
-}
+/* For each of the standard file descriptors, whether to replace it by
+ * /dev/null (if false) or keep it for the daemon to use (if true). */
+static bool save_fds[3];
 
 /* Will daemonize() really detach? */
 bool
@@ -131,117 +34,6 @@ get_detach(void)
     return detach;
 }
 
-/* Sets up a following call to daemonize() to fork a supervisory process to
- * monitor the daemon and restart it if it dies due to an error signal.  */
-void
-daemon_set_monitor(void)
-{
-    monitor = true;
-}
-
-/* If a pidfile has been configured and that pidfile already exists and is
- * locked by a running process, returns the pid of the running process.
- * Otherwise, returns 0. */
-static pid_t
-already_running(void)
-{
-    pid_t pid = 0;
-    if (pidfile) {
-        int fd = open(pidfile, O_RDWR);
-        if (fd >= 0) {
-            struct flock lck;
-            lck.l_type = F_WRLCK;
-            lck.l_whence = SEEK_SET;
-            lck.l_start = 0;
-            lck.l_len = 0;
-            if (fcntl(fd, F_GETLK, &lck) != -1 && lck.l_type != F_UNLCK) {
-                pid = lck.l_pid;
-            }
-            close(fd);
-        }
-    }
-    return pid;
-}
-
-/* If a locked pidfile exists, issue a warning message and, unless
- * ignore_existing_pidfile() has been called, terminate the program. */
-void
-die_if_already_running(void)
-{
-    pid_t pid = already_running();
-    if (pid) {
-        if (!overwrite_pidfile) {
-            ovs_fatal(0, "%s: already running as pid %ld",
-                      get_pidfile(), (long int) pid);
-        } else {
-            VLOG_WARN("%s: %s already running as pid %ld",
-                      get_pidfile(), program_name, (long int) pid);
-        }
-    }
-}
-
-/* If a pidfile has been configured, creates it and stores the running
- * process's pid in it.  Ensures that the pidfile will be deleted when the
- * process exits. */
-static void
-make_pidfile(void)
-{
-    if (pidfile) {
-        /* Create pidfile via temporary file, so that observers never see an
-         * empty pidfile or an unlocked pidfile. */
-        long int pid = getpid();
-        char *tmpfile;
-        int fd;
-
-        tmpfile = xasprintf("%s.tmp%ld", pidfile, pid);
-        fatal_signal_add_file_to_unlink(tmpfile);
-        fd = open(tmpfile, O_CREAT | O_WRONLY | O_TRUNC, 0666);
-        if (fd >= 0) {
-            struct flock lck;
-            lck.l_type = F_WRLCK;
-            lck.l_whence = SEEK_SET;
-            lck.l_start = 0;
-            lck.l_len = 0;
-            if (fcntl(fd, F_SETLK, &lck) != -1) {
-                char *text = xasprintf("%ld\n", pid);
-                if (write(fd, text, strlen(text)) == strlen(text)) {
-                    fatal_signal_add_file_to_unlink(pidfile);
-                    if (rename(tmpfile, pidfile) < 0) {
-                        VLOG_ERR("failed to rename \"%s\" to \"%s\": %s",
-                                 tmpfile, pidfile, strerror(errno));
-                        fatal_signal_remove_file_to_unlink(pidfile);
-                        close(fd);
-                    } else {
-                        /* Keep 'fd' open to retain the lock. */
-                        struct stat s;
-
-                        if (!fstat(fd, &s)) {
-                            pidfile_dev = s.st_dev;
-                            pidfile_ino = s.st_ino;
-                        } else {
-                            VLOG_ERR("%s: fstat failed: %s",
-                                     pidfile, strerror(errno));
-                        }
-                    }
-                    free(text);
-                } else {
-                    VLOG_ERR("%s: write failed: %s", tmpfile, strerror(errno));
-                    close(fd);
-                }
-            } else {
-                VLOG_ERR("%s: fcntl failed: %s", tmpfile, strerror(errno));
-                close(fd);
-            }
-        } else {
-            VLOG_ERR("%s: create failed: %s", tmpfile, strerror(errno));
-        }
-        fatal_signal_remove_file_to_unlink(tmpfile);
-        free(tmpfile);
-    }
-    free(pidfile);
-    pidfile = NULL;
-}
-
 /* If configured with set_pidfile() or set_detach(), creates the pid file and
  * detaches from the foreground session.  */
 void
@@ -251,326 +43,78 @@ daemonize(void)
     daemonize_complete();
 }
 
-static pid_t
-fork_and_wait_for_startup(int *fdp)
-{
-    int fds[2];
-    pid_t pid;
-
-    if (pipe(fds) < 0) {
-        ovs_fatal(errno, "pipe failed");
-    }
-
-    pid = fork();
-    if (pid > 0) {
-        /* Running in parent process. */
-        char c;
-
-        close(fds[1]);
-        fatal_signal_fork();
-        if (read(fds[0], &c, 1) != 1) {
-            int retval;
-            int status;
-
-            do {
-                retval = waitpid(pid, &status, 0);
-            } while (retval == -1 && errno == EINTR);
-
-            if (retval == pid
-                && WIFEXITED(status)
-                && WEXITSTATUS(status)) {
-                /* Child exited with an error.  Convey the same error to
-                 * our parent process as a courtesy. */
-                exit(WEXITSTATUS(status));
-            }
-
-            ovs_fatal(errno, "fork child failed to signal startup");
-        }
-        close(fds[0]);
-        *fdp = -1;
-    } else if (!pid) {
-        /* Running in child process. */
-        close(fds[0]);
-        time_postfork();
-        lockfile_postfork();
-        *fdp = fds[1];
-    } else {
-        ovs_fatal(errno, "could not fork");
-    }
-
-    return pid;
-}
-
-static void
-fork_notify_startup(int fd)
-{
-    if (fd != -1) {
-        size_t bytes_written;
-        int error;
-
-        error = write_fully(fd, "", 1, &bytes_written);
-        if (error) {
-            ovs_fatal(error, "could not write to pipe");
-        }
-
-        close(fd);
-    }
-}
-
-static bool
-should_restart(int status)
+/* Sets up a following call to daemonize() to create a pidfile named 'name'.
+ * If 'name' begins with '/' (or contains ':' in windows), then it is treated
+ * as an absolute path. Otherwise, it is taken relative to RUNDIR,
+ * which is $(prefix)/var/run by default.
+ *
+ * If 'name' is null, then program_name followed by ".pid" is used. */
+void
+set_pidfile(const char *name)
 {
-    if (WIFSIGNALED(status)) {
-        static const int error_signals[] = {
-            SIGABRT, SIGALRM, SIGBUS, SIGFPE, SIGILL, SIGPIPE, SIGSEGV,
-            SIGXCPU, SIGXFSZ
-        };
-
-        size_t i;
-
-        for (i = 0; i < ARRAY_SIZE(error_signals); i++) {
-            if (error_signals[i] == WTERMSIG(status)) {
-                return true;
-            }
-        }
-    }
-    return false;
+    assert_single_threaded();
+    free(pidfile);
+    pidfile = make_pidfile_name(name);
 }
 
-static void
-monitor_daemon(pid_t daemon_pid)
-{
-    /* XXX Should log daemon's stderr output at startup time. */
-    const char *saved_program_name;
-    time_t last_restart;
-    char *status_msg;
-    int crashes;
-
-    saved_program_name = program_name;
-    program_name = xasprintf("monitor(%s)", program_name);
-    status_msg = xstrdup("healthy");
-    last_restart = TIME_MIN;
-    crashes = 0;
-    for (;;) {
-        int retval;
-        int status;
-
-        proctitle_set("%s: monitoring pid %lu (%s)",
-                      saved_program_name, (unsigned long int) daemon_pid,
-                      status_msg);
-
-        do {
-            retval = waitpid(daemon_pid, &status, 0);
-        } while (retval == -1 && errno == EINTR);
-
-        if (retval == -1) {
-            ovs_fatal(errno, "waitpid failed");
-        } else if (retval == daemon_pid) {
-            char *s = process_status_msg(status);
-            if (should_restart(status)) {
-                free(status_msg);
-                status_msg = xasprintf("%d crashes: pid %lu died, %s",
-                                       ++crashes,
-                                       (unsigned long int) daemon_pid, s);
-                free(s);
-
-                if (WCOREDUMP(status)) {
-                    /* Disable further core dumps to save disk space. */
-                    struct rlimit r;
-
-                    r.rlim_cur = 0;
-                    r.rlim_max = 0;
-                    if (setrlimit(RLIMIT_CORE, &r) == -1) {
-                        VLOG_WARN("failed to disable core dumps: %s",
-                                  strerror(errno));
-                    }
-                }
-
-                /* Throttle restarts to no more than once every 10 seconds. */
-                if (time(NULL) < last_restart + 10) {
-                    VLOG_WARN("%s, waiting until 10 seconds since last "
-                              "restart", status_msg);
-                    for (;;) {
-                        time_t now = time(NULL);
-                        time_t wakeup = last_restart + 10;
-                        if (now >= wakeup) {
-                            break;
-                        }
-                        sleep(wakeup - now);
-                    }
-                }
-                last_restart = time(NULL);
-
-                VLOG_ERR("%s, restarting", status_msg);
-                daemon_pid = fork_and_wait_for_startup(&daemonize_fd);
-                if (!daemon_pid) {
-                    break;
-                }
-            } else {
-                VLOG_INFO("pid %lu died, %s, exiting",
-                          (unsigned long int) daemon_pid, s);
-                free(s);
-                exit(0);
-            }
+/* A daemon doesn't normally have any use for the file descriptors for stdin,
+ * stdout, and stderr after it detaches.  To keep these file descriptors from
+ * e.g. holding an SSH session open, by default detaching replaces each of
+ * these file descriptors by /dev/null.  But a few daemons expect the user to
+ * redirect stdout or stderr to a file, in which case it is desirable to keep
+ * these file descriptors.  This function, therefore, disables replacing 'fd'
+ * by /dev/null when the daemon detaches. */
+void
+daemon_save_fd(int fd)
+{
+    ovs_assert(fd == STDIN_FILENO ||
+               fd == STDOUT_FILENO ||
+               fd == STDERR_FILENO);
+    save_fds[fd] = true;
+}
+
+/* Returns a readable and writable fd for /dev/null, if successful, otherwise
+ * a negative errno value.  The caller must not close the returned fd (because
+ * the same fd will be handed out to subsequent callers). */
+static int
+get_null_fd(void)
+{
+    static int null_fd;
+#ifndef _WIN32
+    char *device = "/dev/null";
+#else
+    char *device = "nul";
+#endif
+
+    if (!null_fd) {
+        null_fd = open(device, O_RDWR);
+        if (null_fd < 0) {
+            int error = errno;
+            VLOG_ERR("could not open %s: %s", device, ovs_strerror(error));
+            null_fd = -error;
         }
     }
-    free(status_msg);
 
-    /* Running in new daemon process. */
-    proctitle_restore();
-    free((char *) program_name);
-    program_name = saved_program_name;
+    return null_fd;
 }
 
-/* Close stdin, stdout, stderr.  If we're started from e.g. an SSH session,
- * then this keeps us from holding that session open artificially. */
-static void
+/* Close standard file descriptors (except any that the client has requested we
+ * leave open by calling daemon_save_fd()).  If we're started from e.g. an SSH
+ * session, then this keeps us from holding that session open artificially. */
+void
 close_standard_fds(void)
 {
     int null_fd = get_null_fd();
     if (null_fd >= 0) {
-        dup2(null_fd, STDIN_FILENO);
-        dup2(null_fd, STDOUT_FILENO);
-        dup2(null_fd, STDERR_FILENO);
-    }
-}
-
-/* If daemonization is configured, then starts daemonization, by forking and
- * returning in the child process.  The parent process hangs around until the
- * child lets it know either that it completed startup successfully (by calling
- * daemon_complete()) or that it failed to start up (by exiting with a nonzero
- * exit code). */
-void
-daemonize_start(void)
-{
-    daemonize_fd = -1;
-
-    if (detach) {
-        if (fork_and_wait_for_startup(&daemonize_fd) > 0) {
-            /* Running in parent process. */
-            exit(0);
-        }
-        /* Running in daemon or monitor process. */
-    }
-
-    if (monitor) {
-        int saved_daemonize_fd = daemonize_fd;
-        pid_t daemon_pid;
-
-        daemon_pid = fork_and_wait_for_startup(&daemonize_fd);
-        if (daemon_pid > 0) {
-            /* Running in monitor process. */
-            fork_notify_startup(saved_daemonize_fd);
-            close_standard_fds();
-            monitor_daemon(daemon_pid);
-        }
-        /* Running in daemon process. */
-    }
-
-    make_pidfile();
-
-    /* Make sure that the unixctl commands for vlog get registered in a
-     * daemon, even before the first log message. */
-    vlog_init();
-}
-
-/* If daemonization is configured, then this function notifies the parent
- * process that the child process has completed startup successfully. */
-void
-daemonize_complete(void)
-{
-    fork_notify_startup(daemonize_fd);
-
-    if (detach) {
-        setsid();
-        if (chdir_) {
-            ignore(chdir("/"));
-        }
-        close_standard_fds();
-    }
-}
-
-void
-daemon_usage(void)
-{
-    printf(
-        "\nDaemon options:\n"
-        "  --detach                run in background as daemon\n"
-        "  --no-chdir              do not chdir to '/'\n"
-        "  --pidfile[=FILE]        create pidfile (default: %s/%s.pid)\n"
-        "  --overwrite-pidfile     with --pidfile, start even if already "
-                                   "running\n",
-        ovs_rundir, program_name);
-}
-
-/* Opens and reads a PID from 'pidfile'.  Returns the nonnegative PID if
- * successful, otherwise a negative errno value. */
-pid_t
-read_pidfile(const char *pidfile)
-{
-    char line[128];
-    struct flock lck;
-    struct stat s;
-    FILE *file;
-    int error;
-
-    if ((pidfile_ino || pidfile_dev)
-        && !stat(pidfile, &s)
-        && s.st_ino == pidfile_ino && s.st_dev == pidfile_dev) {
-        /* It's our own pidfile.  We can't afford to open it, because closing
-         * *any* fd for a file that a process has locked also releases all the
-         * locks on that file.
-         *
-         * Fortunately, we know the associated pid anyhow: */
-        return getpid();
-    }
-
-    file = fopen(pidfile, "r");
-    if (!file) {
-        error = errno;
-        VLOG_WARN("%s: open: %s", pidfile, strerror(error));
-        goto error;
-    }
-
-    lck.l_type = F_WRLCK;
-    lck.l_whence = SEEK_SET;
-    lck.l_start = 0;
-    lck.l_len = 0;
-    if (fcntl(fileno(file), F_GETLK, &lck)) {
-        error = errno;
-        VLOG_WARN("%s: fcntl: %s", pidfile, strerror(error));
-        goto error;
-    }
-    if (lck.l_type == F_UNLCK) {
-        error = ESRCH;
-        VLOG_WARN("%s: pid file is not locked", pidfile);
-        goto error;
-    }
+        int fd;
 
-    if (!fgets(line, sizeof line, file)) {
-        if (ferror(file)) {
-            error = errno;
-            VLOG_WARN("%s: read: %s", pidfile, strerror(error));
-        } else {
-            error = ESRCH;
-            VLOG_WARN("%s: read: unexpected end of file", pidfile);
+        for (fd = 0; fd < 3; fd++) {
+            if (!save_fds[fd]) {
+                dup2(null_fd, fd);
+            }
         }
-        goto error;
     }
 
-    if (lck.l_pid != strtoul(line, NULL, 10)) {
-        error = ESRCH;
-        VLOG_WARN("l_pid (%ld) != %s pid (%s)",
-                   (long int) lck.l_pid, pidfile, line);
-        goto error;
-    }
-
-    fclose(file);
-    return lck.l_pid;
-
-error:
-    if (file) {
-        fclose(file);
-    }
-    return -error;
+    /* Disable logging to stderr to avoid wasting CPU time. */
+    vlog_set_levels(NULL, VLF_CONSOLE, VLL_OFF);
 }