[Qemu-devel] [PATCH 16/20] vmdk: push vmdk_read_desc up to caller

[Paolo Bonzini <pbonzini@redhat.com>]

Currently, we just try reading a VMDK file as both image and descriptor.
This makes it hard to choose which of the two attempts gave the best error.
We'll decide in advance if the file looks like an image or a descriptor,
and this patch is the first step to that end.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 block/vmdk.c | 54 ++++++++++++++++++++++++++++++------------------------
 1 file changed, 30 insertions(+), 24 deletions(-)

diff --git a/block/vmdk.c b/block/vmdk.c
index 58f4c34..74a0bac 100644
--- a/block/vmdk.c
+++ b/block/vmdk.c
@@ -526,8 +526,8 @@ static int vmdk_open_vmfs_sparse(BlockDriverState *bs,
     return ret;
 }
 
-static int vmdk_open_desc_file(BlockDriverState *bs, int flags,
-                               uint64_t desc_offset, Error **errp);
+static int vmdk_open_desc_file(BlockDriverState *bs, int flags, char *buf,
+                               Error **errp);
 
 static char *vmdk_read_desc(BlockDriverState *file, uint64_t desc_offset,
                             Error **errp)
@@ -575,7 +575,13 @@ static int vmdk_open_vmdk4(BlockDriverState *bs,
     if (header.capacity == 0) {
         uint64_t desc_offset = le64_to_cpu(header.desc_offset);
         if (desc_offset) {
-            return vmdk_open_desc_file(bs, flags, desc_offset << 9, errp);
+            char *buf = vmdk_read_desc(file, desc_offset << 9, errp);
+            if (!buf) {
+                return -EINVAL;
+            }
+            ret = vmdk_open_desc_file(bs, flags, buf, errp);
+            g_free(buf);
+            return ret;
         }
     }
 
@@ -726,16 +732,12 @@ static int vmdk_parse_description(const char *desc, const char *opt_name,
 
 /* Open an extent file and append to bs array */
 static int vmdk_open_sparse(BlockDriverState *bs,
-                            BlockDriverState *file,
-                            int flags, Error **errp)
+                            BlockDriverState *file, int flags,
+                            char *buf, Error **errp)
 {
     uint32_t magic;
 
-    if (bdrv_pread(file, 0, &magic, sizeof(magic)) != sizeof(magic)) {
-        return -EIO;
-    }
-
-    magic = be32_to_cpu(magic);
+    magic = ldl_be_p(buf);
     switch (magic) {
         case VMDK3_MAGIC:
             return vmdk_open_vmfs_sparse(bs, file, flags, errp);
@@ -819,7 +821,12 @@ static int vmdk_parse_extents(const char *desc, BlockDriverState *bs,
             extent->flat_start_offset = flat_offset << 9;
         } else if (!strcmp(type, "SPARSE") || !strcmp(type, "VMFSSPARSE")) {
             /* SPARSE extent and VMFSSPARSE extent are both "COWD" sparse file*/
-            ret = vmdk_open_sparse(bs, extent_file, bs->open_flags, errp);
+            char *buf = vmdk_read_desc(extent_file, 0, errp);
+            if (!buf) {
+                ret = -EINVAL;
+            } else {
+                ret = vmdk_open_sparse(bs, extent_file, bs->open_flags, buf, errp);
+            }
             if (ret) {
                 bdrv_unref(extent_file);
                 return ret;
@@ -843,20 +850,13 @@ next_line:
     return 0;
 }
 
-static int vmdk_open_desc_file(BlockDriverState *bs, int flags,
-                               uint64_t desc_offset, Error **errp)
+static int vmdk_open_desc_file(BlockDriverState *bs, int flags, char *buf,
+                               Error **errp)
 {
     int ret;
-    char *buf;
     char ct[128];
     BDRVVmdkState *s = bs->opaque;
 
-    buf = vmdk_read_desc(bs->file, desc_offset, errp);
-    if (!buf) {
-        return -EINVAL;
-        goto exit;
-    }
-
     if (vmdk_parse_description(buf, "createType", ct, sizeof(ct))) {
         ret = -EMEDIUMTYPE;
         goto exit;
@@ -874,20 +874,25 @@ static int vmdk_open_desc_file(BlockDriverState *bs, int flags,
     s->desc_offset = 0;
     ret = vmdk_parse_extents(buf, bs, bs->file->filename, errp);
 exit:
-    g_free(buf);
     return ret;
 }
 
 static int vmdk_open(BlockDriverState *bs, QDict *options, int flags,
                      Error **errp)
 {
+    char *buf = NULL;
     int ret;
     BDRVVmdkState *s = bs->opaque;
 
-    if (vmdk_open_sparse(bs, bs->file, flags, errp) == 0) {
+    buf = vmdk_read_desc(bs->file, 0, errp);
+    if (!buf) {
+        return -EINVAL;
+    }
+
+    if (vmdk_open_sparse(bs, bs->file, flags, buf, errp) == 0) {
         s->desc_offset = 0x200;
     } else {
-        ret = vmdk_open_desc_file(bs, flags, 0, errp);
+        ret = vmdk_open_desc_file(bs, flags, buf, errp);
         if (ret) {
             goto fail;
         }
@@ -906,10 +911,11 @@ static int vmdk_open(BlockDriverState *bs, QDict *options, int flags,
               QERR_BLOCK_FORMAT_FEATURE_NOT_SUPPORTED,
               "vmdk", bs->device_name, "live migration");
     migrate_add_blocker(s->migration_blocker);
-
+    g_free(buf);
     return 0;
 
 fail:
+    g_free(buf);
     g_free(s->create_type);
     s->create_type = NULL;
     vmdk_free_extents(bs);
-- 
1.8.5.3