From 18e86fbee105f594beaacf00069dc43a6551b428 Mon Sep 17 00:00:00 2001
From: Timo Kokkonen <timo.t.kokkonen@iki.fi>
Date: Fri, 30 Nov 2012 18:11:01 +0200
Subject: [PATCH] debug: Add support for log files

A new command line argument --logfile or -l is now supported for
logging purposes.

Signed-off-by: Timo Kokkonen <timo.t.kokkonen@iki.fi>
---
 debug.c | 37 +++++++++++++++++++++++++++++++++++--
 debug.h |  2 ++
 main.c  |  7 ++++++-
 3 files changed, 43 insertions(+), 3 deletions(-)

diff --git a/debug.c b/debug.c
index 6c7042e..55fdd14 100644
--- a/debug.c
+++ b/debug.c
@@ -1,3 +1,6 @@
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
 #include <time.h>
 #include <unistd.h>
 #include <stdarg.h>
@@ -18,6 +21,7 @@ const char normal_color[] = {
 };
 
 int trace_level = 1;
+int logfile_fd = STDERR_FILENO;
 
 static const char *assign_color(int color)
 {
@@ -38,7 +42,9 @@ void print_trace(const char *file, int line, int color, int l,
 	time_t t = time(0);
 	char time[32];
 	char trace[1024];
+	char all_trace[1538];
 	const char *color_str = assign_color(color);
+	int ret;
 
 	if (l > trace_level)
 		return;
@@ -49,9 +55,36 @@ void print_trace(const char *file, int line, int color, int l,
 
 	strftime(time, sizeof(time), "%d.%m.%Y %T", localtime(&t));
 
-	fprintf(stderr, "%s%s [%5d.%d] %s:%d %s %s",
+	ret = snprintf(all_trace, sizeof(all_trace),
+		"%s%s [%5d.%d] %s:%d %s %s",
 		color_str, time,
 		getpid(), get_parent_count(),
 		file, line, normal_color, trace);
-	fflush(stderr);
+
+	ret = write(logfile_fd, all_trace, ret);
+	/*
+	 * If write failed, well, not much point in trying to print a
+	 * trace about it.. So we just ignore the return value
+	 */
+}
+
+int open_log_file(const char *logfile)
+{
+	int fd;
+
+	pr_info("Switching logging to file: %s\n", logfile);
+
+	fd = open(logfile, O_WRONLY | O_CREAT | O_APPEND, 0666);
+	if (fd < 0) {
+		pr_err("Failed to open logfile %s: %m\n", logfile);
+		return fd;
+	}
+
+	if (logfile_fd != STDERR_FILENO)
+		close(logfile_fd);
+	logfile_fd = fd;
+
+	pr_info("Opened file %s for logging\n", logfile);
+
+	return 0;
 }
diff --git a/debug.h b/debug.h
index 54e81a2..1dd11f9 100644
--- a/debug.h
+++ b/debug.h
@@ -12,4 +12,6 @@ print_trace(const char *file, int line, int color, int l,
 #define pr_err(arg...)  print_trace(__FILE__, __LINE__, 1, 0, arg)
 #define pr_info(arg...) print_trace(__FILE__, __LINE__, 2, 1, arg)
 
+int open_log_file(const char *logfile);
+
 #endif
diff --git a/main.c b/main.c
index 75eddf3..55e1ef3 100644
--- a/main.c
+++ b/main.c
@@ -25,9 +25,10 @@ int read_args(int argc, char *argv[], struct user_options *opts)
 	static struct option long_options[] = {
 		{ .val = 'j', .has_arg = 1, .name = "jobs", },
 		{ .val = 'c', .has_arg = 1, .name = "config", },
+		{ .val = 'l', .has_arg = 1, .name = "log-file", },
 		{ },
 	};
-	char short_options[] = "j:c:";
+	char short_options[] = "j:c:l:";
 
 	while (1) {
 		c = getopt_long(argc, argv, short_options, long_options,
@@ -45,6 +46,10 @@ int read_args(int argc, char *argv[], struct user_options *opts)
 			opts->config_file = optarg;
 			break;
 
+		case 'l':
+			open_log_file(optarg);
+			break;
+
 		case '?':
 			return -1;
 		}
-- 
2.44.0