From: Jo-Philipp Wich <jow@openwrt.org>
Date: Wed, 24 Jul 2013 18:10:09 +0000 (+0200)
Subject: block: use dynamically sized probe buffer in libblkid-tiny
X-Git-Url: http://git.archive.openwrt.org/?p=project%2Fubox.git;a=commitdiff_plain;h=0ce8e1b704b22d218d98524addcb59f466544fda

block: use dynamically sized probe buffer in libblkid-tiny

This fixes label extraction on vfat partitions with large cluster sizes,
the previous statically sized buffer of 4096 bytes was too small.
---

diff --git a/libblkid-tiny/libblkid-tiny.c b/libblkid-tiny/libblkid-tiny.c
index bd86c41..623ef69 100644
--- a/libblkid-tiny/libblkid-tiny.c
+++ b/libblkid-tiny/libblkid-tiny.c
@@ -13,6 +13,7 @@
 int blkid_debug_mask = 0;
 
 static unsigned char *probe_buffer;
+static unsigned int probe_buffer_size = 0;
 
 int get_linux_version (void)
 {
@@ -80,17 +81,24 @@ unsigned char *blkid_probe_get_buffer(blkid_probe pr,
 				blkid_loff_t off, blkid_loff_t len)
 {
 	int ret;
+	unsigned char *buf;
 
-	if (len > 4096) {
-		fprintf(stderr, "probe buffer too small %d\n", (int) len);
-		return NULL;
-	}
+	if (len > probe_buffer_size) {
+		buf = realloc(probe_buffer, len);
+
+		if (!buf) {
+			fprintf(stderr, "failed to allocate %d byte buffer\n",
+			        (int)len);
 
-	if (!probe_buffer) {
-		probe_buffer = malloc(4096);
-		memset(probe_buffer, 0, 4096);
+			return NULL;
+		}
+
+		probe_buffer = buf;
+		probe_buffer_size = len;
 	}
 
+	memset(probe_buffer, 0, probe_buffer_size);
+
 	lseek(pr->fd, off, SEEK_SET);
 	ret = read(pr->fd, probe_buffer, len);