vmdk: Fix creating big description file

The buffer for description file was 4096 which only covers a few
hundred of extents. This changes the buffer to dynamic allocated with
g_strdup_printf in order to support bigger cases.

Signed-off-by: Fam Zheng <famz@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>

block/vmdk.c

@@ -1596,15 +1596,15 @@ static int vmdk_create(const char *filename, QEMUOptionParameter *options,
                        Error **errp)
 {
     int fd, idx = 0;
-    char desc[BUF_SIZE];
+    char *desc = NULL;
     int64_t total_size = 0, filesize;
     const char *adapter_type = NULL;
     const char *backing_file = NULL;
     const char *fmt = NULL;
     int flags = 0;
     int ret = 0;
     bool flat, split, compress;
-    char ext_desc_lines[BUF_SIZE] = "";
+    GString *ext_desc_lines;
     char path[PATH_MAX], prefix[PATH_MAX], postfix[PATH_MAX];
     const int64_t split_size = 0x80000000;  /* VMDK has constant split size */
     const char *desc_extent_line;
@@ -1632,8 +1632,11 @@ static int vmdk_create(const char *filename, QEMUOptionParameter *options,
         "ddb.geometry.sectors = \"63\"\n"
         "ddb.adapterType = \"%s\"\n";
 
+    ext_desc_lines = g_string_new(NULL);
+
     if (filename_decompose(filename, path, prefix, postfix, PATH_MAX, errp)) {
-        return -EINVAL;
+        ret = -EINVAL;
+        goto exit;
     }
     /* Read out options */
     while (options && options->name) {
@@ -1659,7 +1662,8 @@ static int vmdk_create(const char *filename, QEMUOptionParameter *options,
                strcmp(adapter_type, "lsilogic") &&
                strcmp(adapter_type, "legacyESX")) {
         error_setg(errp, "Unknown adapter type: '%s'", adapter_type);
-        return -EINVAL;
+        ret = -EINVAL;
+        goto exit;
     }
     if (strcmp(adapter_type, "ide") != 0) {
         /* that's the number of heads with which vmware operates when
@@ -1675,7 +1679,8 @@ static int vmdk_create(const char *filename, QEMUOptionParameter *options,
                strcmp(fmt, "twoGbMaxExtentFlat") &&
                strcmp(fmt, "streamOptimized")) {
         error_setg(errp, "Unknown subformat: '%s'", fmt);
-        return -EINVAL;
+        ret = -EINVAL;
+        goto exit;
     }
     split = !(strcmp(fmt, "twoGbMaxExtentFlat") &&
               strcmp(fmt, "twoGbMaxExtentSparse"));
@@ -1689,22 +1694,25 @@ static int vmdk_create(const char *filename, QEMUOptionParameter *options,
     }
     if (flat && backing_file) {
         error_setg(errp, "Flat image can't have backing file");
-        return -ENOTSUP;
+        ret = -ENOTSUP;
+        goto exit;
     }
     if (flat && zeroed_grain) {
         error_setg(errp, "Flat image can't enable zeroed grain");
-        return -ENOTSUP;
+        ret = -ENOTSUP;
+        goto exit;
     }
     if (backing_file) {
         BlockDriverState *bs = bdrv_new("");
         ret = bdrv_open(bs, backing_file, NULL, BDRV_O_NO_BACKING, NULL, errp);
         if (ret != 0) {
             bdrv_unref(bs);
-            return ret;
+            goto exit;
         }
         if (strcmp(bs->drv->format_name, "vmdk")) {
             bdrv_unref(bs);
-            return -EINVAL;
+            ret = -EINVAL;
+            goto exit;
         }
         parent_cid = vmdk_read_cid(bs, 0);
         bdrv_unref(bs);
@@ -1738,25 +1746,27 @@ static int vmdk_create(const char *filename, QEMUOptionParameter *options,
 
         if (vmdk_create_extent(ext_filename, size,
                                flat, compress, zeroed_grain)) {
-            return -EINVAL;
+            ret = -EINVAL;
+            goto exit;
         }
         filesize -= size;
 
         /* Format description line */
         snprintf(desc_line, sizeof(desc_line),
                     desc_extent_line, size / 512, desc_filename);
-        pstrcat(ext_desc_lines, sizeof(ext_desc_lines), desc_line);
+        g_string_append(ext_desc_lines, desc_line);
     }
     /* generate descriptor file */
-    snprintf(desc, sizeof(desc), desc_template,
-            (unsigned int)time(NULL),
-            parent_cid,
-            fmt,
-            parent_desc_line,
-            ext_desc_lines,
-            (flags & BLOCK_FLAG_COMPAT6 ? 6 : 4),
-            total_size / (int64_t)(63 * number_heads * 512), number_heads,
-                adapter_type);
+    desc = g_strdup_printf(desc_template,
+                           (unsigned int)time(NULL),
+                           parent_cid,
+                           fmt,
+                           parent_desc_line,
+                           ext_desc_lines->str,
+                           (flags & BLOCK_FLAG_COMPAT6 ? 6 : 4),
+                           total_size / (int64_t)(63 * number_heads * 512),
+                           number_heads,
+                           adapter_type);
     if (split || flat) {
         fd = qemu_open(filename,
                        O_WRONLY | O_CREAT | O_TRUNC | O_BINARY | O_LARGEFILE,
@@ -1767,21 +1777,25 @@ static int vmdk_create(const char *filename, QEMUOptionParameter *options,
                        0644);
     }
     if (fd < 0) {
-        return -errno;
+        ret = -errno;
+        goto exit;
     }
     /* the descriptor offset = 0x200 */
     if (!split && !flat && 0x200 != lseek(fd, 0x200, SEEK_SET)) {
         ret = -errno;
-        goto exit;
+        goto close_exit;
     }
     ret = qemu_write_full(fd, desc, strlen(desc));
     if (ret != strlen(desc)) {
         ret = -errno;
-        goto exit;
+        goto close_exit;
     }
     ret = 0;
-exit:
+close_exit:
     qemu_close(fd);
+exit:
+    g_free(desc);
+    g_string_free(ext_desc_lines, true);
     return ret;
 }
 

tests/qemu-iotests/059

@@ -75,6 +75,11 @@ echo
 echo "=== Testing monolithicFlat with zeroed_grain ==="
 IMGOPTS="subformat=monolithicFlat,zeroed_grain=on" _make_test_img 2G
 
+echo
+echo "=== Testing big twoGbMaxExtentFlat ==="
+IMGOPTS="subformat=twoGbMaxExtentFlat" _make_test_img 1000G
+$QEMU_IMG info $TEST_IMG | _filter_testdir | sed -e 's/cid: [0-9]*/cid: XXXXXXXX/'
+
 echo
 echo "=== Testing version 3 ==="
 _use_sample_img iotest-version3.vmdk.bz2