Changeset d5309df7 in mainline for uspace/srv/bd/qcow_bd/qcow_bd.c

Timestamp:

2021-09-14T06:37:21Z (3 years ago)

Author:

Erik Kučák <riko98@…>

Children:

2ce943a

Parents:

bdad846

Message:

Fixed problem with big endian

File:

• uspace/srv/bd/qcow_bd/qcow_bd.c (modified) (6 diffs)

uspace/srv/bd/qcow_bd/qcow_bd.c

@@ -48 +48 @@
 static bd_srvs_t bd_srvs;
 static fibril_mutex_t dev_lock;
+static bool isLittleEndian();
 static void print_usage(void);
 static errno_t qcow_bd_init(const char *fname);
@@ -176 +177 @@
 }
 
+/* Return 0 for if this system uses big endian, 1 for little endian. */
+static bool isLittleEndian() {
+    volatile uint32_t i = 0x01234567;
+    return (*((uint8_t*)(&i))) == 0x67;
+}
+
 static errno_t qcow_bd_init(const char *fname)
 {
@@ -219 +226 @@
 
         /* Swap values to big-endian */
-        header.magic = __builtin_bswap32(header.magic);
-        header.version = __builtin_bswap32(header.version);
-        header.backing_file_offset = __builtin_bswap64(header.backing_file_offset);
-        header.backing_file_size = __builtin_bswap32(header.backing_file_size);
-        header.mtime = __builtin_bswap32(header.mtime);
-        header.size = __builtin_bswap64(header.size);
-        header.crypt_method = __builtin_bswap32(header.crypt_method);
-        header.l1_table_offset = __builtin_bswap64(header.l1_table_offset);
+        if (isLittleEndian()) {
+                header.magic = __builtin_bswap32(header.magic);
+                header.version = __builtin_bswap32(header.version);
+                header.backing_file_offset = __builtin_bswap64(header.backing_file_offset);
+                header.backing_file_size = __builtin_bswap32(header.backing_file_size);
+                header.mtime = __builtin_bswap32(header.mtime);
+                header.size = __builtin_bswap64(header.size);
+                header.crypt_method = __builtin_bswap32(header.crypt_method);
+                header.l1_table_offset = __builtin_bswap64(header.l1_table_offset);
+        }
 
         if (ferror(img)) {
@@ -234 +243 @@
 
         /* Verify all values from file header */
-        if (header.magic == QCOW_MAGIC)
-                initialize_state();
+        if (header.magic != QCOW_MAGIC) {
+                fprintf(stderr, "File is not in QCOW format!\n");
+                fclose(img);
+                return ENOTSUP;
+        }
+
+        initialize_state();
 
         if (header.version != QCOW_VERSION) {
@@ -295 +309 @@
         }
 
-        l2_table_reference = __builtin_bswap64(l2_table_reference);
+        if (isLittleEndian())
+                l2_table_reference = __builtin_bswap64(l2_table_reference);
 
         if (l2_table_reference & QCOW_OFLAG_COMPRESSED) {
@@ -325 +340 @@
         }
 
-        cluster_reference = __builtin_bswap64(cluster_reference);
+        if (isLittleEndian())
+                cluster_reference = __builtin_bswap64(cluster_reference);
 
         if (cluster_reference & QCOW_OFLAG_COMPRESSED) {