libs/log.[ch]: Implement stderr logging.

* Export log_level as global variable; remove getter and setter.
* Fix memory leak in log_open().
* Move FVWM3_LOGFILE_DEFAULT to defaults.h.

doc/fvwm3_manpage_source.adoc

@@ -4,6 +4,7 @@
 [*-c* _config-command_]
 [*-d* _displayname_]
 [*-f* _config-file_]
+[*-o* _logfile_]
 [*-s* [_screen_num_]]
 [*-v*]
 [other options]
@@ -81,6 +82,11 @@ Causes fvwm to read _config-file_ instead of _~/.fvwm/config_ as its
 initialization file. _$FVWM_USERDIR_ can also be used to change location
 of default user directory _~/.fvwm_.
 
+*-o* _logfile_::
+
+Write log messages to _logfile_.  If _logfile_ is '-', log to the
+console.  (Does not turn on logging, see the *-v* option.)
+
 *-h* | *--help*::
 
 A short usage description is printed.
@@ -241,7 +247,7 @@ save a few bits of memory.
 Enables stack ring debugging. This option is only intended for internal
 debugging and should only be used by developers.
 
-*-v*::
+*-v* | *--verbose*::
 
 Enables debug logging. Writes in append mode to fvwm log file, which is
 ~/.fvwm/fvwm3-output.log by default. See ENVIRONMENT section on how to

fvwm/expand.c

@@ -1140,7 +1140,7 @@ static signed int expand_vars_extended(
 		break;
 	case VAR_DEBUG_LOG_STATE:
 		is_numeric = True;
-		val = log_get_level();
+		val = lib_log_level;
 		break;
 	default:
 		/* unknown variable - try to find it in the environment */

fvwm/fvwm3.c

@@ -1242,10 +1242,12 @@ static void usage(int is_verbose)
 		   " -I vis-id:    use visual <vis-id>\n"
 		   " -l colors:    try to use no more than <colors> colors\n"
 		   " -L:           strict color limit\n"
+                   " -o logfile:   output file or '-' for stderr\n"
 		   " -P:           visual palette\n"
 		   " -r:           replace running window manager\n"
 		   " -s [screen]:  manage a single screen\n"
 		   " -S:           static palette\n"
+		   " -v:           verbose log output\n"
 		   " -V:           print version information\n"
 		);
 	fprintf(stderr, "Try 'man %s' for more information.\n",
@@ -1802,6 +1804,7 @@ int main(int argc, char **argv)
 			   fvwm_userdir);
 	}
 
+	set_log_file(NULL);
 	for (i = 1; i < argc; i++)
 	{
 		if (strcmp(argv[i], "-debug_stack_ring") == 0 ||
@@ -2043,10 +2046,21 @@ int main(int argc, char **argv)
 			free(Fvwm_SupportInfo);
 			exit(0);
 		}
-		else if (strcmp(argv[i], "-v") == 0)
+		else if (
+			strcmp(argv[i], "-v") == 0 ||
+			strcmp(argv[i], "--verbose") == 0)
 		{
-			log_set_level(1);
-			log_open(fvwm_userdir);
+			lib_log_level = 1;
+		}
+		else if (strcmp(argv[i], "-o") == 0 ||
+			 strcmp(argv[i], "--output-file") == 0)
+		{
+			if (++i >= argc)
+			{
+				usage(0);
+				exit(1);
+			}
+			set_log_file(argv[i]);
 		}
 		else
 		{
@@ -2056,6 +2070,7 @@ int main(int argc, char **argv)
 			exit(1);
 		}
 	}
+	log_open(fvwm_userdir);
 
 	InstallSignals();
 

libs/defaults.h

@@ -10,6 +10,9 @@
 #ifndef FVWMLIB_DEFAULTS_H
 #define FVWMLIB_DEFAULTS_H
 
+/*** logging ***/
+#define FVWM3_LOGFILE_DEFAULT "fvwm3-output.log"
+
 /*** event handling ***/
 #define CLOCK_SKEW_MS                  30000 /* ms */
 

libs/log.c

@@ -31,51 +31,64 @@
 #include "getpwuid.h"
 #include "log.h"
 
+static char	*log_file_name;
 static FILE	*log_file;
-static int	 log_level;
+int	lib_log_level = 0;
 
-static void	 log_vwrite(const char *, const char *, va_list);
-
-/* Set log level. */
 void
-log_set_level(int ll)
+set_log_file(char *name)
 {
-	log_level = ll;
-}
+	if (log_file_name != NULL)
+	{
+		free(log_file_name);
+		log_file_name = NULL;
+	}
+	if (name != NULL)
+	{
+		log_file_name = fxstrdup(name);
+	}
 
-/* Get log level. */
-int log_get_level(void)
-{
-	return log_level;
 }
 
 /* Open logging to file. */
 void
 log_open(const char *fvwm_userdir)
 {
-	char *path, *logfile_env;
-
-	xasprintf(&path, "%s/%s", fvwm_userdir, FVWM3_LOGFILE_DEFAULT);
+	char *path, *file_name;
 
-	logfile_env = getenv("FVWM3_LOGFILE");
-	if (logfile_env != NULL) {
-		const char	*expanded_path;
+	if (lib_log_level == 0)
+		return;
+	if (log_file_name != NULL &&
+	    log_file_name[0] == '-' && log_file_name[1] == 0) {
+		log_file = stderr;
+		return;
+	}
+	if ((file_name = log_file_name) == NULL)
+		file_name = getenv("FVWM3_LOGFILE");
 
-		expanded_path = expand_path(logfile_env);
+	if (file_name != NULL)
+	{
+		char	*expanded_path;
 
+		expanded_path = expand_path(file_name);
 		if (expanded_path[0] == '/')
-			path = fxstrdup(expanded_path);
+		{
+			path = expanded_path;
+		}
 		else
+		{
 			xasprintf(&path, "%s/%s", fvwm_userdir, expanded_path);
-		free((char *)expanded_path);
+			free((char *)expanded_path);
+		}
+	}
+	else
+	{
+		xasprintf(&path, "%s/%s", fvwm_userdir, FVWM3_LOGFILE_DEFAULT);
 	}
 
-	if (log_level == 0)
-		return;
 	log_close();
 
-	log_file = fopen(path, "a");
-	if (log_file == NULL) {
+	if ((log_file = fopen(path, "a")) == NULL) {
 		free(path);
 		return;
 	}
@@ -89,13 +102,13 @@ log_open(const char *fvwm_userdir)
 void
 log_toggle(const char *fvwm_userdir)
 {
-	if (log_level == 0) {
-		log_level = 1;
+	if (lib_log_level == 0) {
+		lib_log_level = 1;
 		log_open(fvwm_userdir);
 		fvwm_debug(NULL, "log opened (because of SIGUSR2)");
 	} else {
 		fvwm_debug(NULL, "log closed (because of SIGUSR2)");
-		log_level = 0;
+		lib_log_level = 0;
 		log_close();
 	}
 }
@@ -104,7 +117,7 @@ log_toggle(const char *fvwm_userdir)
 void
 log_close(void)
 {
-	if (log_file != NULL)
+	if (log_file != NULL && log_file != stderr)
 		fclose(log_file);
 	log_file = NULL;
 }

libs/log.h

@@ -2,10 +2,10 @@
 #define FVWMLIB_LOG_H
 
 #define printflike(a, b) __attribute__ ((format (printf, a, b)))
-#define FVWM3_LOGFILE_DEFAULT "fvwm3-output.log"
 
-void	log_set_level(int);
-int	log_get_level(void);
+extern int	lib_log_level;
+
+void	set_log_file(char *name);
 void	log_open(const char *);
 void	log_toggle(const char *);
 void	log_close(void);