[LEDE-DEV] [PATCH 1/2] [ubox] syslog: use realloc to change log buffer size

[Dan Bugnar]

From: Dan Bugnar <danutbug at gmail.com>

Change the log buffer size and copy the messages.

Signed-off-by: Dan Bugnar <danutbug at gmail.com>
---
 log/syslog.c | 37 +++++++++++++++----------------------
 log/syslog.h |  2 +-
 2 files changed, 16 insertions(+), 23 deletions(-)

diff --git a/log/syslog.c b/log/syslog.c
index e8b6774..d6cb868 100644
--- a/log/syslog.c
+++ b/log/syslog.c
@@ -42,7 +42,7 @@
 #define PAD(x) (x % 4) ? (((x) - (x % 4)) + 4) : (x)
 
 static char *log_dev = LOG_DEFAULT_SOCKET;
-static int log_size = LOG_DEFAULT_SIZE;
+static int log_size = 0;
 static struct log_head *log, *log_end, *oldest, *newest;
 static int current_id = 0;
 static regex_t pat_prio;
@@ -237,34 +237,30 @@ log_list(int count, struct log_head *h)
 }
 
 int
-log_buffer_init(int size)
+log_buffer_reinit(int size)
 {
-	struct log_head *_log = malloc(size);
+	if (size <= 0)
+		size = LOG_DEFAULT_SIZE;
+	if (log_size == size)
+		return 0;
+	
+	struct log_head *_log = realloc(log, size);
 
 	if (!_log) {
+		oldest = newest = log = NULL;
 		fprintf(stderr, "Failed to initialize log buffer with size %d\n", log_size);
 		return -1;
 	}
 
-	memset(_log, 0, size);
-
 	if (log && ((log_size + sizeof(struct log_head)) < size)) {
-		struct log_head *start = _log;
-		struct log_head *end = ((void*) _log) + size;
-		struct log_head *l;
-
-		l = log_list(0, NULL);
-		while ((start < end) && l && l->size) {
-			memcpy(start, l, PAD(sizeof(struct log_head) + l->size));
-			start = (struct log_head *) &l->data[PAD(l->size)];
-			l = log_list(0, l);
-		}
-		free(log);
-		newest = start;
+		newest = (_log + (newest - log));
 		newest->size = 0;
-		oldest = log = _log;
+		memset(newest, 0, size - log_size);
+		oldest = (_log + (oldest - log));
+		log = _log;
 		log_end = ((void*) log) + size;
 	} else {
+		memset(_log, 0, size);
 		oldest = newest = log = _log;
 		log_end = ((void*) log) + size;
 	}
@@ -276,13 +272,10 @@ log_buffer_init(int size)
 void
 log_init(int _log_size)
 {
-	if (_log_size > 0)
-		log_size = _log_size;
-
 	regcomp(&pat_prio, "^<([0-9]*)>(.*)", REG_EXTENDED);
 	regcomp(&pat_tstamp, "^\[[ 0]*([0-9]*).([0-9]*)] (.*)", REG_EXTENDED);
 
-	if (log_buffer_init(log_size)) {
+	if (log_buffer_reinit(_log_size)) {
 		fprintf(stderr, "Failed to allocate log memory\n");
 		exit(-1);
 	}
diff --git a/log/syslog.h b/log/syslog.h
index 81a039f..ed5a41b 100644
--- a/log/syslog.h
+++ b/log/syslog.h
@@ -35,7 +35,7 @@ void log_shutdown(void);
 
 typedef void (*log_list_cb)(struct log_head *h);
 struct log_head* log_list(int count, struct log_head *h);
-int log_buffer_init(int size);
+int log_buffer_reinit(int size);
 void log_add(char *buf, int size, int source);
 void ubus_notify_log(struct log_head *l);
 
-- 
2.8.1