X-Git-Url: http://git.onelab.eu/?a=blobdiff_plain;f=lib%2Fdaemon.c;h=4c7c8e16ae3f2f9b6760185e86dfa00258c5be56;hb=HEAD;hp=c4effa9b0b91c425326b29e365a94febe0631da7;hpb=95440284bdf8ac9a94c3e119d011d76acab577a7;p=sliver-openvswitch.git

diff --git a/lib/daemon.c b/lib/daemon.c
index c4effa9b0..4c7c8e16a 100644
--- a/lib/daemon.c
+++ b/lib/daemon.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2008, 2009 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.
@@ -13,101 +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 <stdlib.h>
-#include <string.h>
-#include <sys/wait.h>
 #include <unistd.h>
-#include "fatal-signal.h"
-#include "dirs.h"
-#include "lockfile.h"
-#include "timeval.h"
-#include "util.h"
-
-#define THIS_MODULE VLM_daemon
 #include "vlog.h"
 
-/* Should we run in the background? */
-static bool detach;
-
-/* Name of pidfile (null if none). */
-static char *pidfile;
-
-/* Create pidfile even if one already exists and is locked? */
-static bool overwrite_pidfile;
-
-/* Should we chdir to "/"? */
-static bool chdir_ = true;
-
-/* File descriptors used by daemonize_start() and daemonize_complete(). */
-static int daemonize_fds[2];
-
-/* 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)
-            : *name == '/' ? xstrdup(name)
-            : xasprintf("%s/%s", 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;
-}
-
-/* Will we chdir to "/" as part of daemonizing? */
-bool
-is_chdir_enabled(void)
-{
-    return chdir_;
-}
+VLOG_DEFINE_THIS_MODULE(daemon);
 
-/* 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
@@ -116,100 +34,6 @@ get_detach(void)
     return detach;
 }
 
-/* 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'
- * pid init.  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. */
-                    }
-                    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
@@ -219,147 +43,78 @@ daemonize(void)
     daemonize_complete();
 }
 
-/* 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). */
+/* 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
-daemonize_start(void)
+set_pidfile(const char *name)
 {
-    if (detach) {
-        pid_t pid;
-
-        if (pipe(daemonize_fds) < 0) {
-            ovs_fatal(errno, "pipe failed");
-        }
-
-        pid = fork();
-        if (pid > 0) {
-            /* Running in parent process. */
-            char c;
-
-            close(daemonize_fds[1]);
-            fatal_signal_fork();
-            if (read(daemonize_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, "daemon child failed to signal startup");
-            }
-            exit(0);
-        } else if (!pid) {
-            /* Running in child process. */
-            close(daemonize_fds[0]);
-            make_pidfile();
-            time_postfork();
-            lockfile_postfork();
-        } else {
-            ovs_fatal(errno, "could not fork");
-        }
-    } else {
-        make_pidfile();
-    }
+    assert_single_threaded();
+    free(pidfile);
+    pidfile = make_pidfile_name(name);
 }
 
-/* If daemonization is configured, then this function notifies the parent
- * process that the child process has completed startup successfully. */
+/* 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
-daemonize_complete(void)
-{
-    if (detach) {
-        char c = 0;
-
-        ignore(write(daemonize_fds[1], &c, 1));
-        close(daemonize_fds[1]);
-        setsid();
-        if (chdir_) {
-            ignore(chdir("/"));
+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;
         }
     }
-}
 
-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);
+    return null_fd;
 }
 
-/* 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)
+/* 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)
 {
-    char line[128];
-    struct flock lck;
-    FILE *file;
-    int error;
-
-    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 null_fd = get_null_fd();
+    if (null_fd >= 0) {
+        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);
 }