crtools: add options to specified a log file

Signed-off-by: Andrey Vagin <avagin@openvz.org>
Acked-by: Pavel Emelyanov <xemul@parallels.com>
Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>

crtools.c

@@ -253,8 +253,9 @@ int main(int argc, char *argv[])
 	int ret = -1;
 	int opt, idx;
 	int action = -1;
+	int log_inited = 0;
 
-	static const char short_opts[] = "drskf:p:t:hcD:";
+	static const char short_opts[] = "drskf:p:t:hcD:o:";
 	static const struct option long_opts[] = {
 		{ "dump",	no_argument, NULL, 'd' },
 		{ "restore",	no_argument, NULL, 'r' },
@@ -262,9 +263,6 @@ int main(int argc, char *argv[])
 		{ NULL,		no_argument, NULL, 0 }
 	};
 
-	if (init_logging())
-		return 1;
-
 	BUILD_BUG_ON(PAGE_SIZE != PAGE_IMAGE_SIZE);
 
 	if (argc < 3)
@@ -311,12 +309,20 @@ int main(int argc, char *argv[])
 				return 1;
 			}
 			break;
+		case 'o':
+			if (init_logging(optarg))
+				return 1;
+			log_inited = 1;
+			break;
 		case 'h':
 		default:
 			goto usage;
 		}
 	}
 
+	if (!log_inited && init_logging(NULL))
+		return 1;
+
 	if (getcwd(image_dir, sizeof(image_dir)) < 0) {
 		pr_perror("can't get currect directory\n");
 		return 1;

include/util.h

@@ -15,7 +15,7 @@
 #include "compiler.h"
 #include "types.h"
 
-extern int init_logging(void);
+extern int init_logging(const char *file_name);
 extern void deinit_logging(void);
 extern void printk(const char *format, ...);
 

util.c

@@ -42,9 +42,18 @@
 
 static int logfd = STDERR_FILENO;
 
-int init_logging(void)
+int init_logging(const char *name)
 {
 	struct rlimit rlimit;
+	int fd = STDERR_FILENO;
+
+	if (name) {
+		fd = open(name, O_CREAT | O_WRONLY);
+		if (fd == -1) {
+			pr_perror("Can't create log file %s\n", name);
+			return 1;
+		}
+	}
 
 	if (getrlimit(RLIMIT_NOFILE, &rlimit)) {
 		pr_err("can't get rlimit: %m\n");
@@ -52,7 +61,7 @@ int init_logging(void)
 	}
 
 	logfd = rlimit.rlim_cur - 1;
-	if (dup2(2, logfd) < 0) {
+	if (dup2(fd, logfd) < 0) {
 		pr_err("can't duplicate descriptor 2->%d: %m\n", logfd);
 		return 1;
 	}