X-Git-Url: http://git.tuebingen.mpg.de/?p=paraslash.git;a=blobdiff_plain;f=daemon.c;h=bfa81487430f62dc7417db6ba6e0c6d53c008051;hp=392d2b4e02f654126fe69249390a9caad429dbc5;hb=99f21f0b6ecf29f949cdbce285e241a2e3ef3093;hpb=cf1b5fd816348658393b7c2583b67560b17f30a2

diff --git a/daemon.c b/daemon.c
index 392d2b4e..bfa81487 100644
--- 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. */
 
@@ -34,6 +30,13 @@ struct daemon {
 	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;
@@ -121,7 +124,12 @@ void daemon_set_logfile(const char *logfile_name)
 {
 	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);
 }
 
@@ -138,6 +146,12 @@ void daemon_set_loglevel(const char *loglevel)
 	me->loglevel = ret;
 }
 
+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.
  *
@@ -155,10 +169,6 @@ static bool daemon_test_flag(unsigned flag)
 	return me->flags & flag;
 }
 
-static void dummy_sighandler(__a_unused int s)
-{
-}
-
 /**
  * Do the usual stuff to become a daemon.
  *
@@ -166,34 +176,46 @@ 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.
- * 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).
  */
-void daemonize(bool parent_waits)
+int daemonize(bool parent_waits)
 {
 	pid_t pid;
-	int null;
+	int null, pipe_fd[2];
 
+	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;
-	if (pid) {
+	if (pid) { /* parent exits */
 		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;
+	me->old_cwd = getcwd(NULL, 0);
 	if (chdir("/") < 0)
 		goto err;
 	null = open("/dev/null", O_RDWR);
@@ -206,7 +228,7 @@ void daemonize(bool parent_waits)
 	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);
@@ -231,15 +253,18 @@ void daemon_close_log(void)
  */
 void daemon_open_log_or_die(void)
 {
-	daemon_close_log();
+	FILE *new_log;
+
 	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);
 	}
+	daemon_close_log();
+	me->logfile = new_log;
 	/* equivalent to setlinebuf(), but portable */
 	setvbuf(me->logfile, NULL, _IOLBF, 0);
 }
@@ -367,8 +392,6 @@ 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".
- *
- * \sa server_uptime.
  */
 __malloc char *daemon_get_uptime_str(const struct timeval *current_time)
 {
@@ -398,6 +421,8 @@ __printf_2_3 void daemon_log(int ll, const char* fmt,...)
 		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);
@@ -430,4 +455,6 @@ __printf_2_3 void daemon_log(int ll, const char* fmt,...)
 	va_end(argp);
 	if (color)
 		fprintf(fp, "%s", COLOR_RESET);
+	if (me->post_log_hook)
+		me->post_log_hook();
 }