Validate VBR checksum before other checks.

git-svn-id: http://exfat.googlecode.com/svn/trunk@394 60bc1c72-a15a-11de-b98f-4500b42dc123

diff --git a/libexfat/mount.c b/libexfat/mount.c
index 3606ad6..c161372 100644 (file)
--- a/libexfat/mount.c
+++ b/libexfat/mount.c
@@ -207,49 +207,51 @@ int exfat_mount(struct exfat* ef, const char* spec, const char* options)
                exfat_error("exFAT file system is not found");
                return -EIO;
        }
-       if (ef->sb->version.major != 1 || ef->sb->version.minor != 0)
+       ef->zero_cluster = malloc(CLUSTER_SIZE(*ef->sb));
+       if (ef->zero_cluster == NULL)
        {
                exfat_close(ef->dev);
-               exfat_error("unsupported exFAT version: %hhu.%hhu",
-                               ef->sb->version.major, ef->sb->version.minor);
                free(ef->sb);
-               return -EIO;
+               exfat_error("failed to allocate zero sector");
+               return -ENOMEM;
        }
-       if (ef->sb->fat_count != 1)
+       /* use zero_cluster as a temporary buffer for VBR checksum verification */
+       if (verify_vbr_checksum(ef->dev, ef->zero_cluster,
+                       SECTOR_SIZE(*ef->sb)) != 0)
        {
+               free(ef->zero_cluster);
                exfat_close(ef->dev);
-               exfat_error("unsupported FAT count: %hhu", ef->sb->fat_count);
                free(ef->sb);
                return -EIO;
        }
-       /* officially exFAT supports cluster size up to 32 MB */
-       if ((int) ef->sb->sector_bits + (int) ef->sb->spc_bits > 25)
+       memset(ef->zero_cluster, 0, CLUSTER_SIZE(*ef->sb));
+       if (ef->sb->version.major != 1 || ef->sb->version.minor != 0)
        {
+               free(ef->zero_cluster);
                exfat_close(ef->dev);
-               exfat_error("too big cluster size: 2^%d",
-                               (int) ef->sb->sector_bits + (int) ef->sb->spc_bits);
+               exfat_error("unsupported exFAT version: %hhu.%hhu",
+                               ef->sb->version.major, ef->sb->version.minor);
                free(ef->sb);
                return -EIO;
        }
-
-       ef->zero_cluster = malloc(CLUSTER_SIZE(*ef->sb));
-       if (ef->zero_cluster == NULL)
+       if (ef->sb->fat_count != 1)
        {
+               free(ef->zero_cluster);
                exfat_close(ef->dev);
+               exfat_error("unsupported FAT count: %hhu", ef->sb->fat_count);
                free(ef->sb);
-               exfat_error("failed to allocate zero sector");
-               return -ENOMEM;
+               return -EIO;
        }
-       /* use zero_cluster as a temporary buffer for VBR checksum verification */
-       if (verify_vbr_checksum(ef->dev, ef->zero_cluster,
-                       SECTOR_SIZE(*ef->sb)) != 0)
+       /* officially exFAT supports cluster size up to 32 MB */
+       if ((int) ef->sb->sector_bits + (int) ef->sb->spc_bits > 25)
        {
                free(ef->zero_cluster);
                exfat_close(ef->dev);
+               exfat_error("too big cluster size: 2^%d",
+                               (int) ef->sb->sector_bits + (int) ef->sb->spc_bits);
                free(ef->sb);
                return -EIO;
        }
-       memset(ef->zero_cluster, 0, CLUSTER_SIZE(*ef->sb));
 
        ef->root = malloc(sizeof(struct exfat_node));
        if (ef->root == NULL)