X-Git-Url: http://git.tuebingen.mpg.de/?p=paraslash.git;a=blobdiff_plain;f=daemon.c;h=a4e2f3193730d456ce9908eb55888cdb759154e0;hp=4e15824f350989ea7d695d0c995bbc2160656b11;hb=HEAD;hpb=10a62b85c43319d9cdefd7d04823aaed47b3817e

diff --git a/daemon.c b/daemon.c
index 4e15824f..d8f598be 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;
@@ -55,24 +58,30 @@ 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)
 {
+	unsigned ll;
+	const char * const sev[] = {SEVERITIES};
 	char *p = strchr(arg, ':');
-	int ret, ll;
 
 	if (!p)
 		goto err;
-	ret = get_loglevel_by_name(arg);
-	if (ret < 0)
-		goto err;
-	ll = ret;
-	p++;
-	color_parse_or_die(p, me->log_colors[ll]);
-	return;
+	for (ll = 0; ll < NUM_LOGLEVELS; ll++) {
+		const char *name = sev[ll];
+		/*
+		 * Parse only the first part of the string so that, for
+		 * example, the argument "info:something_else" is recognized.
+		 * Note that the string comparison is performed
+		 * case-insensitively.
+		 */
+		if (strncasecmp(arg, name, strlen(name)))
+			continue;
+		return color_parse_or_die(p + 1, me->log_colors[ll]);
+	}
 err:
 	PARA_EMERG_LOG("%s: invalid color argument\n", arg);
 	exit(EXIT_FAILURE);
@@ -121,21 +130,61 @@ 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 new log level.
+ */
+void daemon_set_loglevel(int loglevel)
+{
+	assert(loglevel >= 0);
+	assert(loglevel < NUM_LOGLEVELS);
+	me->loglevel = loglevel;
+}
+
+/**
+ * Get the current log level of the daemon.
  *
- * \param loglevel The smallest level that should be logged.
+ * \return Greater or equal than zero and less than NUM_LOGLEVELS. This
+ * function never fails.
  */
-void daemon_set_loglevel(const char *loglevel)
+int daemon_get_loglevel(void)
 {
-	int ret = get_loglevel_by_name(loglevel);
+	return me->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;
 }
 
 /**
@@ -201,6 +250,7 @@ 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);
@@ -232,21 +282,24 @@ void daemon_close_log(void)
 }
 
 /**
- * fopen() the logfile in append mode.
+ * Open the logfile in append mode.
  *
- * \return Either succeeds or exits.
+ * This function either succeeds or exits.
  */
 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);
 }
@@ -403,6 +456,8 @@ __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);
@@ -435,4 +490,6 @@ __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();
 }