X-Git-Url: http://git.tuebingen.mpg.de/?a=blobdiff_plain;f=daemon.c;h=04dbc122386274110975bb155a5686ef9520f940;hb=a0cd2ac59b891751067512dce77cf6223104932f;hp=e47639bc42864cc4881d5992bb567e902f4752ac;hpb=767a4a54c967bc4b80bd14d02e89fe91acd848dd;p=paraslash.git

diff --git a/daemon.c b/daemon.c
index e47639bc..04dbc122 100644
--- a/daemon.c
+++ b/daemon.c
@@ -30,6 +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;
@@ -51,9 +58,9 @@ static void daemon_set_default_log_colors(void)
 }
 
 /**
- * Set the color for one loglevel.
+ * Set the color for log messages of the given severity level.
  *
- * \param arg Must be of the form "ll:[fg [bg]] [attr]".
+ * \param arg Must be of the form "severity:[fg [bg]] [attr]".
  */
 void daemon_set_log_color_or_die(const char *arg)
 {
@@ -117,21 +124,51 @@ 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);
 }
 
 /**
- * Suppress log messages with severity lower than the given loglevel.
+ * Control the verbosity for logging.
+ *
+ * This instructs the daemon to not log subsequent messages whose severity is
+ * lower than the given value.
  *
- * \param loglevel The smallest level that should be logged.
+ * \param loglevel The new log level.
  */
-void daemon_set_loglevel(const char *loglevel)
+void daemon_set_loglevel(int loglevel)
 {
-	int ret = get_loglevel_by_name(loglevel);
+	assert(loglevel >= 0);
+	assert(loglevel < NUM_LOGLEVELS);
+	me->loglevel = loglevel;
 
-	assert(ret >= 0);
-	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;
 }
 
 /**
@@ -197,6 +234,7 @@ int daemonize(bool parent_waits)
 	/* 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);
@@ -234,15 +272,18 @@ 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);
 }
@@ -399,6 +440,8 @@ __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);
@@ -431,4 +474,6 @@ __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();
 }