block/dmg: extract processing of resource forks

Besides the offset, also read the resource length. This length is now
used in the extracted function to verify the end of the resource fork
against "count" from the resource fork.

Signed-off-by: Peter Wu <peter@lekensteyn.nl>

1 files changed, 59 insertions, 31 deletions

diff --git a/block/dmg.c b/block/dmg.c
index 6dc6dbb711..7f49388f29 100644
--- a/block/dmg.c
+++ b/block/dmg.c
@@ -278,38 +278,13 @@ fail:
     return ret;
 }
 
-static int dmg_open(BlockDriverState *bs, QDict *options, int flags,
-                    Error **errp)
+static int dmg_read_resource_fork(BlockDriverState *bs, DmgHeaderState *ds,
+                                  uint64_t info_begin, uint64_t info_length)
 {
-    BDRVDMGState *s = bs->opaque;
-    DmgHeaderState ds;
-    uint64_t info_begin, info_end;
-    uint32_t count, tmp;
-    int64_t offset;
     int ret;
-
-    bs->read_only = 1;
-    s->n_chunks = 0;
-    s->offsets = s->lengths = s->sectors = s->sectorcounts = NULL;
-    ds.last_in_offset = 0;
-    ds.last_out_offset = 0;
-    ds.max_compressed_size = 1;
-    ds.max_sectors_per_chunk = 1;
-
-    /* locate the UDIF trailer */
-    offset = dmg_find_koly_offset(bs->file);
-    if (offset < 0) {
-        ret = offset;
-        goto fail;
-    }
-
-    ret = read_uint64(bs, offset + 0x28, &info_begin);
-    if (ret < 0) {
-        goto fail;
-    } else if (info_begin == 0) {
-        ret = -EINVAL;
-        goto fail;
-    }
+    uint32_t count, tmp;
+    uint64_t info_end;
+    uint64_t offset;
 
     ret = read_uint32(bs, info_begin, &tmp);
     if (ret < 0) {
@@ -326,6 +301,10 @@ static int dmg_open(BlockDriverState *bs, QDict *options, int flags,
         ret = -EINVAL;
         goto fail;
     }
+    if (count > info_length) {
+        ret = -EINVAL;
+        goto fail;
+    }
     info_end = info_begin + count;
 
     /* begin of mish block */
@@ -342,12 +321,61 @@ static int dmg_open(BlockDriverState *bs, QDict *options, int flags,
         }
         offset += 4;
 
-        ret = dmg_read_mish_block(bs, &ds, offset, count);
+        ret = dmg_read_mish_block(bs, ds, offset, count);
         if (ret < 0) {
             goto fail;
         }
         offset += count;
     }
+    return 0;
+
+fail:
+    return ret;
+}
+
+static int dmg_open(BlockDriverState *bs, QDict *options, int flags,
+                    Error **errp)
+{
+    BDRVDMGState *s = bs->opaque;
+    DmgHeaderState ds;
+    uint64_t rsrc_fork_offset, rsrc_fork_length;
+    int64_t offset;
+    int ret;
+
+    bs->read_only = 1;
+    s->n_chunks = 0;
+    s->offsets = s->lengths = s->sectors = s->sectorcounts = NULL;
+    ds.last_in_offset = 0;
+    ds.last_out_offset = 0;
+    ds.max_compressed_size = 1;
+    ds.max_sectors_per_chunk = 1;
+
+    /* locate the UDIF trailer */
+    offset = dmg_find_koly_offset(bs->file);
+    if (offset < 0) {
+        ret = offset;
+        goto fail;
+    }
+
+    /* offset of resource fork (RsrcForkOffset) */
+    ret = read_uint64(bs, offset + 0x28, &rsrc_fork_offset);
+    if (ret < 0) {
+        goto fail;
+    }
+    ret = read_uint64(bs, offset + 0x30, &rsrc_fork_length);
+    if (ret < 0) {
+        goto fail;
+    }
+    if (rsrc_fork_offset != 0 && rsrc_fork_length != 0) {
+        ret = dmg_read_resource_fork(bs, &ds,
+                                     rsrc_fork_offset, rsrc_fork_length);
+        if (ret < 0) {
+            goto fail;
+        }
+    } else {
+        ret = -EINVAL;
+        goto fail;
+    }
 
     /* initialize zlib engine */
     s->compressed_chunk = qemu_try_blockalign(bs->file,