From: Peter Krempa <pkrempa@redhat.com>
Date: Wed, 28 May 2025 15:18:36 +0000 (+0200)
Subject: storage_file_probe: Refactor qcowXGetBackingStore into specific callbacks for qcow... 
X-Git-Tag: v11.5.0-rc1~95
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=7758ddc107735fe62e75100f44e78ed8936fa25d;p=thirdparty%2Flibvirt.git

storage_file_probe: Refactor qcowXGetBackingStore into specific callbacks for qcow and qcow2

Change qcowXGetBackingStore to use the new function prototype which
fills virStorageSource directly. Convert the copying of the backing file
string from 'g_new0' + 'memcpy' to 'g_strndup' as we treat it as a
string.

Introduce qcowGetImageSpecific (as a wrapper for qcowXGetBackingStore)
and qcow2GetImageSpecific. The latter of the two will be used to collect
all the qcow2-specific code later on, but for now it just parses the
backing store and the format.

Signed-off-by: Peter Krempa <pkrempa@redhat.com>
Reviewed-by: Ján Tomko <jtomko@redhat.com>
---

diff --git a/src/storage_file/storage_file_probe.c b/src/storage_file/storage_file_probe.c
index e741bccd44..ce8ba4b884 100644
--- a/src/storage_file/storage_file_probe.c
+++ b/src/storage_file/storage_file_probe.c
@@ -106,11 +106,17 @@ static int
 cowGetImageSpecific(virStorageSource *meta,
                     const char *buf,
                     size_t buf_size);
+static int
+qcowGetImageSpecific(virStorageSource *meta,
+                     const char *buf,
+                     size_t buf_size);
+static int
+qcow2GetImageSpecific(virStorageSource *meta,
+                      const char *buf,
+                      size_t buf_size);
 static unsigned long long
 qcow2GetClusterSize(const char *buf,
                     size_t buf_size);
-static int qcowXGetBackingStore(char **, int *,
-                                const char *, size_t);
 static int qcow2GetDataFile(char **, virBitmap *, char *, size_t);
 static int qcow2GetFeatures(virBitmap **features, int format,
                             char *buf, ssize_t len);
@@ -316,7 +322,7 @@ static struct FileTypeInfo const fileTypeInfo[] = {
         LV_BIG_ENDIAN, 4, 4, {1},
         QCOWX_HDR_IMAGE_SIZE, 8, 1,
         qcow1EncryptionInfo,
-        NULL, qcowXGetBackingStore, NULL, NULL, NULL
+        NULL,  NULL, NULL, NULL, qcowGetImageSpecific
     },
     [VIR_STORAGE_FILE_QCOW2] = {
         0, "QFI",
@@ -324,10 +330,10 @@ static struct FileTypeInfo const fileTypeInfo[] = {
         QCOWX_HDR_IMAGE_SIZE, 8, 1,
         qcow2EncryptionInfo,
         qcow2GetClusterSize,
-        qcowXGetBackingStore,
+        NULL,
         qcow2GetDataFile,
         qcow2GetFeatures,
-        NULL
+        qcow2GetImageSpecific
     },
     [VIR_STORAGE_FILE_QED] = {
         /* https://wiki.qemu.org/Features/QED */
@@ -545,45 +551,66 @@ qcow2GetClusterSize(const char *buf,
 
 
 static int
-qcowXGetBackingStore(char **res,
-                     int *format,
+qcowXGetBackingStore(virStorageSource *meta,
                      const char *buf,
                      size_t buf_size)
 {
     unsigned long long offset;
     unsigned int size;
 
-    *res = NULL;
-    *format = VIR_STORAGE_FILE_AUTO;
+    g_clear_pointer(&meta->backingStoreRaw, g_free);
+    meta->backingStoreRawFormat = VIR_STORAGE_FILE_AUTO;
 
     if (buf_size < QCOWX_HDR_BACKING_FILE_OFFSET+8+4)
         return 0;
 
     offset = virReadBufInt64BE(buf + QCOWX_HDR_BACKING_FILE_OFFSET);
-    if (offset > buf_size)
-        return 0;
+    size = virReadBufInt32BE(buf + QCOWX_HDR_BACKING_FILE_SIZE);
 
-    if (offset == 0) {
-        *format = VIR_STORAGE_FILE_NONE;
+    if (offset == 0 || size == 0) {
+        meta->backingStoreRawFormat = VIR_STORAGE_FILE_NONE;
         return 0;
     }
 
-    size = virReadBufInt32BE(buf + QCOWX_HDR_BACKING_FILE_SIZE);
-    if (size == 0) {
-        *format = VIR_STORAGE_FILE_NONE;
+    if (offset > buf_size)
         return 0;
-    }
     if (size > 1023)
         return 0;
     if (offset + size > buf_size || offset + size < offset)
         return 0;
-    *res = g_new0(char, size + 1);
-    memcpy(*res, buf + offset, size);
-    (*res)[size] = '\0';
 
-    if (qcow2GetExtensions(buf, buf_size, format, NULL) < 0)
+    meta->backingStoreRaw = g_strndup(buf + offset, size);
+
+    return 0;
+}
+
+
+static int
+qcowGetImageSpecific(virStorageSource *meta,
+                     const char *buf,
+                     size_t buf_size)
+{
+    return qcowXGetBackingStore(meta, buf, buf_size);
+}
+
+
+static int
+qcow2GetImageSpecific(virStorageSource *meta,
+                      const char *buf,
+                      size_t buf_size)
+{
+    int format;
+
+    if (qcowXGetBackingStore(meta, buf, buf_size) < 0)
+        return -1;
+
+    format = meta->backingStoreRawFormat;
+
+    if (qcow2GetExtensions(buf, buf_size, &format, NULL) < 0)
         return 0;
 
+    meta->backingStoreRawFormat = format;
+
     return 0;
 }