mixer.c: Fix doxygen \file description.

[paraslash.git] / daemon.c

diff --git a/daemon.c b/daemon.c
index 478b0f47acc94d3098cc17576599032f007b43ca..a4e2f3193730d456ce9908eb55888cdb759154e0 100644 (file)
--- a/daemon.c
+++ b/daemon.c
@@ -1,8 +1,4 @@
-/*
- * Copyright (C) 1997 Andre Noll <maan@tuebingen.mpg.de>
- *
- * Licensed under the GPL v2. For licencing details see COPYING.
- */
+/* Copyright (C) 1997 Andre Noll <maan@tuebingen.mpg.de>, see file COPYING. */

 
 /** \file daemon.c Some helpers for programs that detach from the console. */
 
 
 /** \file daemon.c Some helpers for programs that detach from the console. */
 


@@ -34,6 +30,13 @@ struct daemon {
        char *hostname;
        /** Used for colored log messages. */
        char log_colors[NUM_LOGLEVELS][COLOR_MAXLEN];
        char *hostname;
        /** Used for colored log messages. */
        char log_colors[NUM_LOGLEVELS][COLOR_MAXLEN];

+       char *old_cwd;
+       /*
+        * If these pointers are non-NULL, the functions are called from
+        * daemon_log() before and after writing each log message.
+        */
+       void (*pre_log_hook)(void);
+       void (*post_log_hook)(void);

 };
 
 static struct daemon the_daemon, *me = &the_daemon;
 };
 
 static struct daemon the_daemon, *me = &the_daemon;


@@ -54,12 +57,12 @@ static void daemon_set_default_log_colors(void)
                color_parse_or_die(default_log_colors[i], me->log_colors[i]);
 }
 
                color_parse_or_die(default_log_colors[i], me->log_colors[i]);
 }
 

-/*
+/**

  * Set the color for one loglevel.
  *
  * Set the color for one loglevel.
  *

- * arg must be of the form "ll:[fg [bg]] [attr]".
+ * \param arg Must be of the form "ll:[fg [bg]] [attr]".

  */
  */

-static void daemon_set_log_color_or_die(char const *arg)
+void daemon_set_log_color_or_die(const char *arg)

 {
        char *p = strchr(arg, ':');
        int ret, ll;
 {
        char *p = strchr(arg, ':');
        int ret, ll;


@@ -74,7 +77,7 @@ static void daemon_set_log_color_or_die(char const *arg)
        color_parse_or_die(p, me->log_colors[ll]);
        return;
 err:
        color_parse_or_die(p, me->log_colors[ll]);
        return;
 err:

-       PARA_EMERG_LOG("%s: color syntax error\n", arg);
+       PARA_EMERG_LOG("%s: invalid color argument\n", arg);

        exit(EXIT_FAILURE);
 }
 
        exit(EXIT_FAILURE);
 }
 


@@ -85,36 +88,31 @@ err:
  * \param color_arg_auto The value for automatic color detection.
  * \param color_arg_no The value to disable colored log messages.
  * \param logfile_given In auto mode colors are disabled if this value is true.
  * \param color_arg_auto The value for automatic color detection.
  * \param color_arg_no The value to disable colored log messages.
  * \param logfile_given In auto mode colors are disabled if this value is true.

- * \param log_color_argv Color specifiers given to --log-color.
- * \param argc Number of color specifiers in \a log_color_argv.

  *
  *

- * If \a color_arg equals \a color_arg_no, color mode is disabled, i.e., calls
- * to \a para_log() will not produce colored output. If \a color_arg == \a
- * color_arg_auto, the function autodetects whether to activate colors.
- * Otherwise color mode is enabled.
+ * If color_arg equals color_arg_no, color mode is disabled. That is, calls to
+ * para_log() will not produce colored output. If color_arg equals
+ * color_arg_auto, the function detects automatically whether to activate
+ * colors. Otherwise color mode is enabled.
+ *
+ * If color mode is to be enabled, the default colors are set for each
+ * loglevel. They can be overwritten by calling daemon_set_log_color_or_die().

  *
  *

- * If color mode is to be enabled, the strings in \a log_color_argv are parsed
- * and the color scheme is updated accordingly. For each loglevel, the default
- * colors apply if there is no log_color_argv for this loglevel.
+ * \return Whether colors have been enabled by the function.

  */
  */

-void daemon_init_colors_or_die(int color_arg, int color_arg_auto,
-               int color_arg_no, bool logfile_given, char **log_color_argv,
-               int argc)
+bool daemon_init_colors_or_die(int color_arg, int color_arg_auto,
+               int color_arg_no, bool logfile_given)

 {
 {

-       int i;
-

        if (color_arg == color_arg_no)
        if (color_arg == color_arg_no)

-               return;
+               return false;

        if (color_arg == color_arg_auto) {
                if (logfile_given)
        if (color_arg == color_arg_auto) {
                if (logfile_given)

-                       return;
+                       return false;

                if (!isatty(STDERR_FILENO))
                if (!isatty(STDERR_FILENO))

-                       return;
+                       return false;

        }
        daemon_set_flag(DF_COLOR_LOG);
        daemon_set_default_log_colors();
        }
        daemon_set_flag(DF_COLOR_LOG);
        daemon_set_default_log_colors();

-       for (i = 0; i < argc; i++)
-               daemon_set_log_color_or_die(log_color_argv[i]);
+       return true;

 }
 
 /**
 }
 
 /**


@@ -122,11 +120,16 @@ void daemon_init_colors_or_die(int color_arg, int color_arg_auto,
  *
  * \param logfile_name The full path of the logfile.
  */
  *
  * \param logfile_name The full path of the logfile.
  */

-void daemon_set_logfile(char *logfile_name)
+void daemon_set_logfile(const char *logfile_name)

 {
        free(me->logfile_name);
        me->logfile_name = NULL;
 {
        free(me->logfile_name);
        me->logfile_name = NULL;

-       if (logfile_name)
+       if (!logfile_name)
+               return;
+       if (me->old_cwd && logfile_name[0] != '/')
+               me->logfile_name = make_message("%s/%s", me->old_cwd,
+                       logfile_name);
+       else

                me->logfile_name = para_strdup(logfile_name);
 }
 
                me->logfile_name = para_strdup(logfile_name);
 }
 


@@ -135,7 +138,7 @@ void daemon_set_logfile(char *logfile_name)
  *
  * \param loglevel The smallest level that should be logged.
  */
  *
  * \param loglevel The smallest level that should be logged.
  */

-void daemon_set_loglevel(char *loglevel)
+void daemon_set_loglevel(const char *loglevel)

 {
        int ret = get_loglevel_by_name(loglevel);
 
 {
        int ret = get_loglevel_by_name(loglevel);
 


@@ -143,6 +146,28 @@ void daemon_set_loglevel(char *loglevel)
        me->loglevel = ret;
 }
 
        me->loglevel = ret;
 }
 

+/**
+ * Register functions to be called before and after a message is logged.
+ *
+ * \param pre_log_hook Called before the message is logged.
+ * \param post_log_hook Called after the message is logged.
+ *
+ * The purpose of this function is to provide a primitive for multi-threaded
+ * applications to serialize the access to the log facility, preventing
+ * interleaving log messages. This can be achieved by having the pre-log hook
+ * acquire a lock which blocks the other threads on the attempt to log a
+ * message at the same time.  The post-log hook is responsible for releasing
+ * the lock.
+ *
+ * If these hooks are unnecessary, for example because the application is
+ * single-threaded, this function does not need to be called.
+ */
+void daemon_set_hooks(void (*pre_log_hook)(void), void (*post_log_hook)(void))
+{
+       me->pre_log_hook = pre_log_hook;
+       me->post_log_hook = post_log_hook;
+}
+

 /**
  * Set one of the daemon config flags.
  *
 /**
  * Set one of the daemon config flags.
  *


@@ -160,10 +185,6 @@ static bool daemon_test_flag(unsigned flag)
        return me->flags & flag;
 }
 
        return me->flags & flag;
 }
 

-static void dummy_sighandler(__a_unused int s)
-{
-}
-

 /**
  * Do the usual stuff to become a daemon.
  *
 /**
  * Do the usual stuff to become a daemon.
  *


@@ -171,33 +192,46 @@ static void dummy_sighandler(__a_unused int s)
  *
  * Fork, become session leader, cd to /, and dup fd 0, 1, 2 to /dev/null. If \a
  * parent_waits is false, the parent process terminates immediately.
  *
  * Fork, become session leader, cd to /, and dup fd 0, 1, 2 to /dev/null. If \a
  * parent_waits is false, the parent process terminates immediately.

- * Otherwise, it calls pause() to sleep until it receives \p SIGTERM or \p
- * SIGCHLD and exits successfully thereafter. This behaviour is useful if the
- * daemon process should not detach from the console until the child process
- * has completed its setup.
+ * Otherwise, a pipe is created prior to the fork() and the parent tries to
+ * read a single byte from the reading end of the pipe. The child is supposed
+ * to write to the writing end of the pipe after it completed its setup
+ * procedure successfully. This behaviour is useful to let the parent process
+ * die with an error if the child process aborts early, since in this case the
+ * read() will return non-positive.
+ *
+ * \return This function either succeeds or calls exit(3). If parent_waits is
+ * true, the return value is the file descriptor of the writing end of the
+ * pipe. Otherwise the function returns zero.

  *
  * \sa fork(2), setsid(2), dup(2), pause(2).
  */
  *
  * \sa fork(2), setsid(2), dup(2), pause(2).
  */

-void daemonize(bool parent_waits)
+int daemonize(bool parent_waits)

 {
        pid_t pid;
 {
        pid_t pid;

-       int null;
+       int null, pipe_fd[2];

 
 

-       PARA_INFO_LOG("daemonizing\n");
+       if (parent_waits && pipe(pipe_fd) < 0)
+               goto err;
+       PARA_INFO_LOG("subsequent log messages go to %s\n", me->logfile_name?
+                me->logfile_name : "/dev/null");

        pid = fork();
        if (pid < 0)
                goto err;
        pid = fork();
        if (pid < 0)
                goto err;

-       if (pid) {
+       if (pid) { /* parent exits */

                if (parent_waits) {
                if (parent_waits) {

-                       signal(SIGTERM, dummy_sighandler);
-                       signal(SIGCHLD, dummy_sighandler);
-                       pause();
+                       char c;
+                       close(pipe_fd[1]);
+                       exit(read(pipe_fd[0], &c, 1) <= 0?
+                               EXIT_FAILURE : EXIT_SUCCESS);

                }
                }

-               exit(EXIT_SUCCESS); /* parent exits */
+               exit(EXIT_SUCCESS);

        }
        }

+       if (parent_waits)
+               close(pipe_fd[0]);

        /* become session leader */
        if (setsid() < 0)
                goto err;
        /* become session leader */
        if (setsid() < 0)
                goto err;

+       me->old_cwd = getcwd(NULL, 0);

        if (chdir("/") < 0)
                goto err;
        null = open("/dev/null", O_RDWR);
        if (chdir("/") < 0)
                goto err;
        null = open("/dev/null", O_RDWR);


@@ -210,7 +244,7 @@ void daemonize(bool parent_waits)
        if (dup2(null, STDERR_FILENO) < 0)
                goto err;
        close(null);
        if (dup2(null, STDERR_FILENO) < 0)
                goto err;
        close(null);

-       return;
+       return parent_waits? pipe_fd[1] : 0;

 err:
        PARA_EMERG_LOG("fatal: %s\n", strerror(errno));
        exit(EXIT_FAILURE);
 err:
        PARA_EMERG_LOG("fatal: %s\n", strerror(errno));
        exit(EXIT_FAILURE);


@@ -235,15 +269,18 @@ void daemon_close_log(void)
  */
 void daemon_open_log_or_die(void)
 {
  */
 void daemon_open_log_or_die(void)
 {

-       daemon_close_log();
+       FILE *new_log;
+

        if (!me->logfile_name)
                return;
        if (!me->logfile_name)
                return;

-       me->logfile = fopen(me->logfile_name, "a");
-       if (!me->logfile) {
+       new_log = fopen(me->logfile_name, "a");
+       if (!new_log) {

                PARA_EMERG_LOG("can not open %s: %s\n", me->logfile_name,
                        strerror(errno));
                exit(EXIT_FAILURE);
        }
                PARA_EMERG_LOG("can not open %s: %s\n", me->logfile_name,
                        strerror(errno));
                exit(EXIT_FAILURE);
        }

+       daemon_close_log();
+       me->logfile = new_log;

        /* equivalent to setlinebuf(), but portable */
        setvbuf(me->logfile, NULL, _IOLBF, 0);
 }
        /* equivalent to setlinebuf(), but portable */
        setvbuf(me->logfile, NULL, _IOLBF, 0);
 }


@@ -371,8 +408,6 @@ time_t daemon_get_uptime(const struct timeval *current_time)
  * \param current_time See a \ref daemon_get_uptime().
  *
  * \return A dynamically allocated string of the form "days:hours:minutes".
  * \param current_time See a \ref daemon_get_uptime().
  *
  * \return A dynamically allocated string of the form "days:hours:minutes".

- *
- * \sa server_uptime.

  */
 __malloc char *daemon_get_uptime_str(const struct timeval *current_time)
 {
  */
 __malloc char *daemon_get_uptime_str(const struct timeval *current_time)
 {


@@ -402,6 +437,8 @@ __printf_2_3 void daemon_log(int ll, const char* fmt,...)
                return;
 
        fp = me->logfile? me->logfile : stderr;
                return;
 
        fp = me->logfile? me->logfile : stderr;

+       if (me->pre_log_hook)
+               me->pre_log_hook();

        color = daemon_test_flag(DF_COLOR_LOG)? me->log_colors[ll] : NULL;
        if (color)
                fprintf(fp, "%s", color);
        color = daemon_test_flag(DF_COLOR_LOG)? me->log_colors[ll] : NULL;
        if (color)
                fprintf(fp, "%s", color);


@@ -434,4 +471,6 @@ __printf_2_3 void daemon_log(int ll, const char* fmt,...)
        va_end(argp);
        if (color)
                fprintf(fp, "%s", COLOR_RESET);
        va_end(argp);
        if (color)
                fprintf(fp, "%s", COLOR_RESET);

+       if (me->post_log_hook)
+               me->post_log_hook();

 }
 }