Signed-off-by: Nikolai Barybin <nikolai.barybin@virtuozzo.com>
---
 src/storage_file/storage_file_probe.c | 53 +++++++++++++++++++++++++--
 1 file changed, 49 insertions(+), 4 deletions(-)

diff --git a/src/storage_file/storage_file_probe.c b/src/storage_file/storage_file_probe.c
index 4792b9fdff..21430d18aa 100644
--- a/src/storage_file/storage_file_probe.c
+++ b/src/storage_file/storage_file_probe.c
@@ -106,6 +106,7 @@ qcow2GetClusterSize(const char *buf,
                     size_t buf_size);
 static int qcowXGetBackingStore(char **, int *,
                                 const char *, size_t);
+static int qcowXGetDataFile(char **, char *, int, size_t);
 static int qcow2GetFeatures(virBitmap **features, int format,
                             char *buf, ssize_t len);
 static int vmdk4GetBackingStore(char **, int *,
@@ -127,6 +128,7 @@ qedGetBackingStore(char **, int *, const char *, size_t);
 
 #define QCOW2_HDR_EXTENSION_END 0
 #define QCOW2_HDR_EXTENSION_BACKING_FORMAT 0xE2792ACA
+#define QCOW2_HDR_EXTENSION_DATA_FILE_NAME 0x44415441
 
 #define QCOW2v3_HDR_FEATURES_INCOMPATIBLE (QCOW2_HDR_TOTAL_SIZE)
 #define QCOW2v3_HDR_FEATURES_COMPATIBLE (QCOW2v3_HDR_FEATURES_INCOMPATIBLE+8)
@@ -314,7 +316,7 @@ static struct FileTypeInfo const fileTypeInfo[] = {
         qcow2EncryptionInfo,
         qcow2GetClusterSize,
         qcowXGetBackingStore,
-        NULL,
+        qcowXGetDataFile,
         qcow2GetFeatures
     },
     [VIR_STORAGE_FILE_QED] = {
@@ -361,7 +363,7 @@ enum qcow2IncompatibleFeature {
 static const virStorageFileFeature qcow2IncompatibleFeatureArray[] = {
     VIR_STORAGE_FILE_FEATURE_LAST, /* QCOW2_INCOMPATIBLE_FEATURE_DIRTY */
     VIR_STORAGE_FILE_FEATURE_LAST, /* QCOW2_INCOMPATIBLE_FEATURE_CORRUPT */
-    VIR_STORAGE_FILE_FEATURE_LAST, /* QCOW2_INCOMPATIBLE_FEATURE_DATA_FILE */
+    VIR_STORAGE_FILE_FEATURE_DATA_FILE, /* QCOW2_INCOMPATIBLE_FEATURE_DATA_FILE */
     VIR_STORAGE_FILE_FEATURE_LAST, /* QCOW2_INCOMPATIBLE_FEATURE_COMPRESSION */
     VIR_STORAGE_FILE_FEATURE_EXTENDED_L2, /* QCOW2_INCOMPATIBLE_FEATURE_EXTL2 */
 };
@@ -393,7 +395,8 @@ cowGetBackingStore(char **res,
 static int
 qcow2GetExtensions(const char *buf,
                    size_t buf_size,
-                   int *backingFormat)
+                   int *backingFormat,
+                   char **dataFilePath)
 {
     size_t offset;
     size_t extension_start;
@@ -488,6 +491,17 @@ qcow2GetExtensions(const char *buf,
             break;
         }
 
+        case QCOW2_HDR_EXTENSION_DATA_FILE_NAME: {
+            g_autofree char *tmp = NULL;
+            if (!dataFilePath)
+                break;
+
+            *(char **)dataFilePath = g_new0(char, len + 1);
+            memcpy(*(char **)dataFilePath, buf + offset, len);
+            (*((char **)dataFilePath))[len] = '\0';
+            break;
+        }
+
         case QCOW2_HDR_EXTENSION_END:
             return 0;
         }
@@ -554,9 +568,34 @@ qcowXGetBackingStore(char **res,
     memcpy(*res, buf + offset, size);
     (*res)[size] = '\0';
 
-    if (qcow2GetExtensions(buf, buf_size, format) < 0)
+    if (qcow2GetExtensions(buf, buf_size, format, NULL) < 0)
+        return 0;
+
+    return 0;
+}
+
+
+static int
+qcowXGetDataFile(char **res,
+                 char *buf,
+                 int format,
+                 size_t buf_size)
+{
+    virBitmap *features = NULL;
+    char *filename = NULL;
+    *res = NULL;
+
+    if (buf_size < QCOW2v3_HDR_FEATURES_INCOMPATIBLE + 8)
         return 0;
 
+    ignore_value(qcow2GetFeatures(&features, format, buf, buf_size));
+    if (features && virBitmapIsBitSet(features, VIR_STORAGE_FILE_FEATURE_DATA_FILE)) {
+        if (qcow2GetExtensions(buf, buf_size, NULL, &filename) < 0)
+            return 0;
+
+        *res = g_strdup(filename);
+    }
+
     return 0;
 }
 
@@ -963,6 +1002,12 @@ virStorageFileProbeGetMetadata(virStorageSource *meta,
         meta->backingStoreRawFormat = format;
     }
 
+    VIR_FREE(meta->dataFileRaw);
+    if (fileTypeInfo[meta->format].getDataFile != NULL) {
+        fileTypeInfo[meta->format].getDataFile(&meta->dataFileRaw,
+                                               buf, meta->format, len);
+    }
+
     g_clear_pointer(&meta->features, virBitmapFree);
     if (fileTypeInfo[meta->format].getFeatures != NULL &&
         fileTypeInfo[meta->format].getFeatures(&meta->features, meta->format, buf, len) < 0)
-- 
2.43.5

On Sat, Sep 07, 2024 at 17:15:21 +0300, Nikolai Barybin via Devel wrote:
> Signed-off-by: Nikolai Barybin <nikolai.barybin@virtuozzo.com>
> ---
>  src/storage_file/storage_file_probe.c | 53 +++++++++++++++++++++++++--
>  1 file changed, 49 insertions(+), 4 deletions(-)
> 
> diff --git a/src/storage_file/storage_file_probe.c b/src/storage_file/storage_file_probe.c
> index 4792b9fdff..21430d18aa 100644
> --- a/src/storage_file/storage_file_probe.c
> +++ b/src/storage_file/storage_file_probe.c
> @@ -106,6 +106,7 @@ qcow2GetClusterSize(const char *buf,
>                      size_t buf_size);
>  static int qcowXGetBackingStore(char **, int *,
>                                  const char *, size_t);
> +static int qcowXGetDataFile(char **, char *, int, size_t);

data file is a qcow2 only feature so calling this 'qcowX' makes no sense
as it won't be reused.

>  static int qcow2GetFeatures(virBitmap **features, int format,
>                              char *buf, ssize_t len);
>  static int vmdk4GetBackingStore(char **, int *,
> @@ -393,7 +395,8 @@ cowGetBackingStore(char **res,
>  static int
>  qcow2GetExtensions(const char *buf,
>                     size_t buf_size,
> -                   int *backingFormat)
> +                   int *backingFormat,
> +                   char **dataFilePath)
>  {
>      size_t offset;
>      size_t extension_start;
> @@ -488,6 +491,17 @@ qcow2GetExtensions(const char *buf,
>              break;
>          }
>  
> +        case QCOW2_HDR_EXTENSION_DATA_FILE_NAME: {
> +            g_autofree char *tmp = NULL;

'tmp' is unused.

> +            if (!dataFilePath)
> +                break;
> +
> +            *(char **)dataFilePath = g_new0(char, len + 1);

No need for that amount of typecasts since 'dataFilePath' is aready 'char
**'

> +            memcpy(*(char **)dataFilePath, buf + offset, len);

same here.

> +            (*((char **)dataFilePath))[len] = '\0';

This is not needed as g_new0 allocates a zeroed-out buffer.

> +            break;
> +        }
> +
>          case QCOW2_HDR_EXTENSION_END:
>              return 0;
>          }
> @@ -554,9 +568,34 @@ qcowXGetBackingStore(char **res,
>      memcpy(*res, buf + offset, size);
>      (*res)[size] = '\0';
>  
> -    if (qcow2GetExtensions(buf, buf_size, format) < 0)
> +    if (qcow2GetExtensions(buf, buf_size, format, NULL) < 0)
> +        return 0;
> +
> +    return 0;
> +}
> +
> +
> +static int
> +qcowXGetDataFile(char **res,
> +                 char *buf,
> +                 int format,
> +                 size_t buf_size)
> +{
> +    virBitmap *features = NULL;
> +    char *filename = NULL;
> +    *res = NULL;
> +
> +    if (buf_size < QCOW2v3_HDR_FEATURES_INCOMPATIBLE + 8)
>          return 0;
>  
> +    ignore_value(qcow2GetFeatures(&features, format, buf, buf_size));

'qcowXGetDataFile' gets called one block before 'qcow2GetFeatures' would
be called via

  'fileTypeInfo[meta->format].getFeatures(&meta->features,'

but here you do it again. Restrucutre the code so that iut doesn't need
to do this twice.

> +    if (features && virBitmapIsBitSet(features, VIR_STORAGE_FILE_FEATURE_DATA_FILE)) {
> +        if (qcow2GetExtensions(buf, buf_size, NULL, &filename) < 0)

So 'filename' will be filled with an allocated buffer ...

> +            return 0;
> +
> +        *res = g_strdup(filename);

... you'll dup it (which is wasteful) and then leak the original.

> +    }
> +
>      return 0;
>  }
>  
> @@ -963,6 +1002,12 @@ virStorageFileProbeGetMetadata(virStorageSource *meta,
>          meta->backingStoreRawFormat = format;
>      }
>  
> +    VIR_FREE(meta->dataFileRaw);
> +    if (fileTypeInfo[meta->format].getDataFile != NULL) {
> +        fileTypeInfo[meta->format].getDataFile(&meta->dataFileRaw,
> +                                               buf, meta->format, len);
> +    }
> +
>      g_clear_pointer(&meta->features, virBitmapFree);
>      if (fileTypeInfo[meta->format].getFeatures != NULL &&
>          fileTypeInfo[meta->format].getFeatures(&meta->features, meta->format, buf, len) < 0)
> -- 
> 2.43.5
>