Add logging functionality

This is logging functionality for weston compositor.

It handles:
messages coming from libwayland-server from wl_log()
messages from weston itself, from weston_log()

Introduce --log option, to specify log file path on the command line.
When the path is incorrect, or on weston_log_file_destroy(), fall
back to stderr.

src/Makefile.am

@@ -11,6 +11,8 @@ weston_CFLAGS = $(GCC_CFLAGS) $(COMPOSITOR_CFLAGS)
 weston_LDADD = $(COMPOSITOR_LIBS) $(DLOPEN_LIBS) -lm ../shared/libshared.la
 
 weston_SOURCES =				\
+	log.c					\
+	log.h					\
 	compositor.c				\
 	compositor.h				\
 	filter.c				\

src/compositor.c

@@ -48,6 +48,7 @@
 #include <wayland-server.h>
 #include "compositor.h"
 #include "../shared/os-compatibility.h"
+#include "log.h"
 
 static struct wl_list child_process_list;
 static jmp_buf segv_jmp_buf;
@@ -3105,6 +3106,7 @@ int main(int argc, char *argv[])
 	char *backend = NULL;
 	char *shell = NULL;
 	char *module = NULL;
+	char *log = NULL;
 	int32_t idle_time = 300;
 	int32_t xserver = 0;
 	char *socket_name = NULL;
@@ -3125,6 +3127,7 @@ int main(int argc, char *argv[])
 		{ WESTON_OPTION_INTEGER, "idle-time", 'i', &idle_time },
 		{ WESTON_OPTION_BOOLEAN, "xserver", 0, &xserver },
 		{ WESTON_OPTION_STRING, "module", 0, &module },
+		{ WESTON_OPTION_STRING, "log", 0, &log },
 	};
 
 	argc = parse_options(core_options,
@@ -3135,6 +3138,8 @@ int main(int argc, char *argv[])
 		exit(EXIT_FAILURE);
 	}
 
+	weston_log_file_open(log);
+
 	display = wl_display_create();
 
 	loop = wl_display_get_event_loop(display);
@@ -3237,5 +3242,7 @@ int main(int argc, char *argv[])
 	ec->destroy(ec);
 	wl_display_destroy(display);
 
+	weston_log_file_close();
+
 	return ret;
 }

src/log.c

@@ -0,0 +1,115 @@
+/*
+ * Copyright © 2012 Martin Minarik
+ *
+ * Permission to use, copy, modify, distribute, and sell this software and
+ * its documentation for any purpose is hereby granted without fee, provided
+ * that the above copyright notice appear in all copies and that both that
+ * copyright notice and this permission notice appear in supporting
+ * documentation, and that the name of the copyright holders not be used in
+ * advertising or publicity pertaining to distribution of the software
+ * without specific, written prior permission.  The copyright holders make
+ * no representations about the suitability of this software for any
+ * purpose.  It is provided "as is" without express or implied warranty.
+ *
+ * THE COPYRIGHT HOLDERS DISCLAIM ALL WARRANTIES WITH REGARD TO THIS
+ * SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND
+ * FITNESS, IN NO EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE FOR ANY
+ * SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER
+ * RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF
+ * CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
+ * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#include <stdio.h>
+#include <stdarg.h>
+#include <stdlib.h>
+#include <string.h>
+#include <time.h>
+
+#include <wayland-server.h>
+#include <wayland-util.h>
+
+#include "log.h"
+
+static FILE *weston_logfile = NULL;
+
+static char cached_timestamp[21];
+static int cached_tv_sec = 0;
+
+static int weston_log_timestamp(void)
+{
+	struct timespec tp;
+	unsigned int time;
+
+	clock_gettime(CLOCK_REALTIME, &tp);
+	time = (tp.tv_sec * 1000000L) + (tp.tv_nsec / 1000);
+
+	if (cached_tv_sec != tp.tv_sec) {
+		char string[26];
+		struct tm *lt = localtime(&tp.tv_sec);
+
+		cached_tv_sec = tp.tv_sec;
+
+		strftime (string,24,"%Y-%m-%d %H:%M:%S", lt);
+		strncpy (cached_timestamp, string, 20);
+	}
+
+	return fprintf(weston_logfile, "[%s.%03u] ", cached_timestamp, tp.tv_nsec/1000000);
+}
+
+static int weston_log_print(const char *fmt, va_list arg)
+{
+	int l;
+	l = vfprintf(weston_logfile, fmt, arg);
+	fflush(weston_logfile);
+	return l;
+}
+
+static void
+custom_handler(const char *fmt, va_list arg)
+{
+	weston_log_timestamp();
+	fprintf(weston_logfile, "libwayland: ");
+	weston_log_print(fmt, arg);
+}
+
+void
+weston_log_file_open(const char *filename)
+{
+	wl_log_set_handler_server(custom_handler);
+
+	weston_logfile = fopen(filename, "a");
+	if (weston_logfile == NULL)
+		weston_logfile = stderr;
+}
+
+void
+weston_log_file_close()
+{
+	if (weston_logfile != stderr)
+		fclose(weston_logfile);
+	weston_logfile = stderr;
+}
+
+WL_EXPORT int
+weston_log(const char *fmt, ...)
+{
+	int l;
+	va_list argp;
+	va_start(argp, fmt);
+	l = weston_log_timestamp();
+	l += weston_log_print(fmt, argp);
+	va_end(argp);
+	return l;
+}
+
+WL_EXPORT int
+weston_log_continue(const char *fmt, ...)
+{
+	int l;
+	va_list argp;
+	va_start(argp, fmt);
+	l = weston_log_print(fmt, argp);
+	va_end(argp);
+	return l;
+}

src/log.h

@@ -0,0 +1,32 @@
+/*
+ * Copyright © 2012 Martin Minarik
+ *
+ * Permission to use, copy, modify, distribute, and sell this software and
+ * its documentation for any purpose is hereby granted without fee, provided
+ * that the above copyright notice appear in all copies and that both that
+ * copyright notice and this permission notice appear in supporting
+ * documentation, and that the name of the copyright holders not be used in
+ * advertising or publicity pertaining to distribution of the software
+ * without specific, written prior permission.  The copyright holders make
+ * no representations about the suitability of this software for any
+ * purpose.  It is provided "as is" without express or implied warranty.
+ *
+ * THE COPYRIGHT HOLDERS DISCLAIM ALL WARRANTIES WITH REGARD TO THIS
+ * SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND
+ * FITNESS, IN NO EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE FOR ANY
+ * SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER
+ * RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF
+ * CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
+ * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#ifndef _WAYLAND_SYSTEM_LOG_H_
+#define _WAYLAND_SYSTEM_LOG_H_
+
+void weston_log_file_open(const char *filename);
+void weston_log_file_close(void);
+
+int weston_log(const char *fmt, ...);
+int weston_log_continue(const char *fmt, ...);
+
+#endif