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[libvirt] [PATCH 1/4] storage: factor out large integer reads



This makes code easier to read, by avoiding lines longer than
80 columns and removing the repetition from the callers.

* src/util/virstoragefile.c (virRead64BE, virRead64LE)
(virRead32BE, virRead32LE): New helper functions.
(qedGetHeaderUL, qedGetHeaderULL): Delete in favor of more generic
name.
(qcow2GetBackingStoreFormat, qcowXGetBackingStore)
(qedGetBackingStore, virStorageFileMatchesVersion)
(virStorageFileGetMetadataInternal): Use them.
---
 src/util/virstoragefile.c | 159 +++++++++++++++++++++-------------------------
 1 file changed, 72 insertions(+), 87 deletions(-)

diff --git a/src/util/virstoragefile.c b/src/util/virstoragefile.c
index 6e2d61e..e7ab226 100644
--- a/src/util/virstoragefile.c
+++ b/src/util/virstoragefile.c
@@ -208,6 +208,58 @@ static struct FileTypeInfo const fileTypeInfo[] = {
 };
 verify(ARRAY_CARDINALITY(fileTypeInfo) == VIR_STORAGE_FILE_LAST);

+/* Read 8 bytes at BUF as a big-endian 64-bit number.  Caller is
+   responsible to avoid reading beyond array bounds.  */
+static unsigned long long
+virRead64BE(const unsigned char *buf)
+{
+    return (((uint64_t)buf[0] << 56) |
+            ((uint64_t)buf[1] << 48) |
+            ((uint64_t)buf[2] << 40) |
+            ((uint64_t)buf[3] << 32) |
+            ((uint64_t)buf[4] << 24) |
+            ((uint64_t)buf[5] << 16) |
+            ((uint64_t)buf[6] << 8) |
+            (uint64_t)buf[7]);
+}
+
+/* Read 8 bytes at BUF as a little-endian 64-bit number.  Caller is
+   responsible to avoid reading beyond array bounds.  */
+static unsigned long long
+virRead64LE(const unsigned char *buf)
+{
+    return ((uint64_t)buf[0] |
+            ((uint64_t)buf[1] << 8) |
+            ((uint64_t)buf[2] << 16) |
+            ((uint64_t)buf[3] << 24) |
+            ((uint64_t)buf[4] << 32) |
+            ((uint64_t)buf[5] << 40) |
+            ((uint64_t)buf[6] << 48) |
+            ((uint64_t)buf[7] << 56));
+}
+
+/* Read 4 bytes at BUF as a big-endian 32-bit number.  Caller is
+   responsible to avoid reading beyond array bounds.  */
+static unsigned int
+virRead32BE(const unsigned char *buf)
+{
+    return ((buf[0] << 24) |
+            (buf[1] << 16) |
+            (buf[2] << 8) |
+            buf[3]);
+}
+
+/* Read 4 bytes at BUF as a little-endian 32-bit number.  Caller is
+   responsible to avoid reading beyond array bounds.  */
+static unsigned int
+virRead32LE(const unsigned char *buf)
+{
+    return (buf[0] |
+            (buf[1] << 8) |
+            (buf[2] << 16) |
+            (buf[3] << 24));
+}
+
 static int
 cowGetBackingStore(char **res,
                    int *format,
@@ -255,16 +307,8 @@ qcow2GetBackingStoreFormat(int *format,
      */
     while (offset < (buf_size-8) &&
            offset < (extension_end-8)) {
-        unsigned int magic =
-            (buf[offset] << 24) +
-            (buf[offset+1] << 16) +
-            (buf[offset+2] << 8) +
-            (buf[offset+3]);
-        unsigned int len =
-            (buf[offset+4] << 24) +
-            (buf[offset+5] << 16) +
-            (buf[offset+6] << 8) +
-            (buf[offset+7]);
+        unsigned int magic = virRead32BE(buf + offset);
+        unsigned int len = virRead32BE(buf + offset + 4);

         offset += 8;

@@ -312,20 +356,10 @@ qcowXGetBackingStore(char **res,

     if (buf_size < QCOWX_HDR_BACKING_FILE_OFFSET+8+4)
         return BACKING_STORE_INVALID;
-    offset = (((unsigned long long)buf[QCOWX_HDR_BACKING_FILE_OFFSET] << 56)
-              | ((unsigned long long)buf[QCOWX_HDR_BACKING_FILE_OFFSET+1] << 48)
-              | ((unsigned long long)buf[QCOWX_HDR_BACKING_FILE_OFFSET+2] << 40)
-              | ((unsigned long long)buf[QCOWX_HDR_BACKING_FILE_OFFSET+3] << 32)
-              | ((unsigned long long)buf[QCOWX_HDR_BACKING_FILE_OFFSET+4] << 24)
-              | ((unsigned long long)buf[QCOWX_HDR_BACKING_FILE_OFFSET+5] << 16)
-              | ((unsigned long long)buf[QCOWX_HDR_BACKING_FILE_OFFSET+6] << 8)
-              | buf[QCOWX_HDR_BACKING_FILE_OFFSET+7]); /* QCowHeader.backing_file_offset */
+    offset = virRead64BE(buf + QCOWX_HDR_BACKING_FILE_OFFSET);
     if (offset > buf_size)
         return BACKING_STORE_INVALID;
-    size = ((buf[QCOWX_HDR_BACKING_FILE_SIZE] << 24)
-            | (buf[QCOWX_HDR_BACKING_FILE_SIZE+1] << 16)
-            | (buf[QCOWX_HDR_BACKING_FILE_SIZE+2] << 8)
-            | buf[QCOWX_HDR_BACKING_FILE_SIZE+3]); /* QCowHeader.backing_file_size */
+    size = virRead32BE(buf + QCOWX_HDR_BACKING_FILE_SIZE);
     if (size == 0) {
         if (format)
             *format = VIR_STORAGE_FILE_NONE;
@@ -468,28 +502,6 @@ cleanup:
     return ret;
 }

-static unsigned long
-qedGetHeaderUL(const unsigned char *loc)
-{
-    return (((unsigned long)loc[3] << 24) |
-            ((unsigned long)loc[2] << 16) |
-            ((unsigned long)loc[1] << 8) |
-            ((unsigned long)loc[0] << 0));
-}
-
-static unsigned long long
-qedGetHeaderULL(const unsigned char *loc)
-{
-    return (((unsigned long long)loc[7] << 56) |
-            ((unsigned long long)loc[6] << 48) |
-            ((unsigned long long)loc[5] << 40) |
-            ((unsigned long long)loc[4] << 32) |
-            ((unsigned long long)loc[3] << 24) |
-            ((unsigned long long)loc[2] << 16) |
-            ((unsigned long long)loc[1] << 8) |
-            ((unsigned long long)loc[0] << 0));
-}
-
 static int
 qedGetBackingStore(char **res,
                    int *format,
@@ -503,7 +515,7 @@ qedGetBackingStore(char **res,
     /* Check if this image has a backing file */
     if (buf_size < QED_HDR_FEATURES_OFFSET+8)
         return BACKING_STORE_INVALID;
-    flags = qedGetHeaderULL(buf + QED_HDR_FEATURES_OFFSET);
+    flags = virRead64LE(buf + QED_HDR_FEATURES_OFFSET);
     if (!(flags & QED_F_BACKING_FILE)) {
         *format = VIR_STORAGE_FILE_NONE;
         return BACKING_STORE_OK;
@@ -512,10 +524,10 @@ qedGetBackingStore(char **res,
     /* Parse the backing file */
     if (buf_size < QED_HDR_BACKING_FILE_OFFSET+8)
         return BACKING_STORE_INVALID;
-    offset = qedGetHeaderUL(buf + QED_HDR_BACKING_FILE_OFFSET);
+    offset = virRead32LE(buf + QED_HDR_BACKING_FILE_OFFSET);
     if (offset > buf_size)
         return BACKING_STORE_INVALID;
-    size = qedGetHeaderUL(buf + QED_HDR_BACKING_FILE_SIZE);
+    size = virRead32LE(buf + QED_HDR_BACKING_FILE_SIZE);
     if (size == 0)
         return BACKING_STORE_OK;
     if (offset + size > buf_size || offset + size < offset)
@@ -633,19 +645,10 @@ virStorageFileMatchesVersion(int format,
     if ((fileTypeInfo[format].versionOffset + 4) > buflen)
         return false;

-    if (fileTypeInfo[format].endian == LV_LITTLE_ENDIAN) {
-        version =
-            (buf[fileTypeInfo[format].versionOffset+3] << 24) |
-            (buf[fileTypeInfo[format].versionOffset+2] << 16) |
-            (buf[fileTypeInfo[format].versionOffset+1] << 8) |
-            (buf[fileTypeInfo[format].versionOffset]);
-    } else {
-        version =
-            (buf[fileTypeInfo[format].versionOffset] << 24) |
-            (buf[fileTypeInfo[format].versionOffset+1] << 16) |
-            (buf[fileTypeInfo[format].versionOffset+2] << 8) |
-            (buf[fileTypeInfo[format].versionOffset+3]);
-    }
+    if (fileTypeInfo[format].endian == LV_LITTLE_ENDIAN)
+        version = virRead32LE(buf + fileTypeInfo[format].versionOffset);
+    else
+        version = virRead32BE(buf + fileTypeInfo[format].versionOffset);

     VIR_DEBUG("Compare detected version %d vs expected version %d",
               version, fileTypeInfo[format].versionNumber);
@@ -687,29 +690,15 @@ virStorageFileGetMetadataFromBuf(int format,
         if ((fileTypeInfo[format].sizeOffset + 8) > buflen)
             return 1;

-        if (fileTypeInfo[format].endian == LV_LITTLE_ENDIAN) {
-            meta->capacity =
-                ((unsigned long long)buf[fileTypeInfo[format].sizeOffset+7] << 56) |
-                ((unsigned long long)buf[fileTypeInfo[format].sizeOffset+6] << 48) |
-                ((unsigned long long)buf[fileTypeInfo[format].sizeOffset+5] << 40) |
-                ((unsigned long long)buf[fileTypeInfo[format].sizeOffset+4] << 32) |
-                ((unsigned long long)buf[fileTypeInfo[format].sizeOffset+3] << 24) |
-                ((unsigned long long)buf[fileTypeInfo[format].sizeOffset+2] << 16) |
-                ((unsigned long long)buf[fileTypeInfo[format].sizeOffset+1] << 8) |
-                ((unsigned long long)buf[fileTypeInfo[format].sizeOffset]);
-        } else {
-            meta->capacity =
-                ((unsigned long long)buf[fileTypeInfo[format].sizeOffset] << 56) |
-                ((unsigned long long)buf[fileTypeInfo[format].sizeOffset+1] << 48) |
-                ((unsigned long long)buf[fileTypeInfo[format].sizeOffset+2] << 40) |
-                ((unsigned long long)buf[fileTypeInfo[format].sizeOffset+3] << 32) |
-                ((unsigned long long)buf[fileTypeInfo[format].sizeOffset+4] << 24) |
-                ((unsigned long long)buf[fileTypeInfo[format].sizeOffset+5] << 16) |
-                ((unsigned long long)buf[fileTypeInfo[format].sizeOffset+6] << 8) |
-                ((unsigned long long)buf[fileTypeInfo[format].sizeOffset+7]);
-        }
+        if (fileTypeInfo[format].endian == LV_LITTLE_ENDIAN)
+            meta->capacity = virRead64LE(buf +
+                                         fileTypeInfo[format].sizeOffset);
+        else
+            meta->capacity = virRead64BE(buf +
+                                         fileTypeInfo[format].sizeOffset);
         /* Avoid unlikely, but theoretically possible overflow */
-        if (meta->capacity > (ULLONG_MAX / fileTypeInfo[format].sizeMultiplier))
+        if (meta->capacity > (ULLONG_MAX /
+                              fileTypeInfo[format].sizeMultiplier))
             return 1;
         meta->capacity *= fileTypeInfo[format].sizeMultiplier;
     }
@@ -717,11 +706,7 @@ virStorageFileGetMetadataFromBuf(int format,
     if (fileTypeInfo[format].qcowCryptOffset != -1) {
         int crypt_format;

-        crypt_format =
-            (buf[fileTypeInfo[format].qcowCryptOffset] << 24) |
-            (buf[fileTypeInfo[format].qcowCryptOffset+1] << 16) |
-            (buf[fileTypeInfo[format].qcowCryptOffset+2] << 8) |
-            (buf[fileTypeInfo[format].qcowCryptOffset+3]);
+        crypt_format = virRead32BE(buf + fileTypeInfo[format].qcowCryptOffset);
         meta->encrypted = crypt_format != 0;
     }

-- 
1.8.1


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