win32_capture: Enlarge FSCTL_QUERY_FILE_LAYOUT buffer when needed
authorEric Biggers <ebiggers3@gmail.com>
Fri, 4 Mar 2016 02:57:47 +0000 (20:57 -0600)
committerEric Biggers <ebiggers3@gmail.com>
Fri, 4 Mar 2016 03:19:49 +0000 (21:19 -0600)
32768 bytes is not always enough.

src/win32_capture.c

index d4512e0..e9f4df0 100644 (file)
@@ -2405,7 +2405,7 @@ load_files_from_mft(const wchar_t *path, struct ntfs_inode_map *inode_map)
                         QUERY_FILE_LAYOUT_INCLUDE_STREAMS_WITH_NO_CLUSTERS_ALLOCATED,
                .FilterType = QUERY_FILE_LAYOUT_FILTER_TYPE_NONE,
        };
-       const size_t outsize = 32768;
+       size_t outsize = 32768;
        QUERY_FILE_LAYOUT_OUTPUT *out = NULL;
        int ret;
        NTSTATUS status;
@@ -2417,27 +2417,38 @@ load_files_from_mft(const wchar_t *path, struct ntfs_inode_map *inode_map)
                goto out;
        }
 
-       out = MALLOC(outsize);
-       if (!out) {
-               ret = WIMLIB_ERR_NOMEM;
-               goto out;
-       }
+       for (;;) {
+               /* Allocate a buffer for the output of the ioctl.  */
+               out = MALLOC(outsize);
+               if (!out) {
+                       ret = WIMLIB_ERR_NOMEM;
+                       goto out;
+               }
 
-       while (NT_SUCCESS(status = winnt_fsctl(h, FSCTL_QUERY_FILE_LAYOUT,
-                                              &in, sizeof(in),
-                                              out, outsize, NULL)))
-       {
-               const FILE_LAYOUT_ENTRY *file =
-                       (const void *)out + out->FirstFileOffset;
-               for (;;) {
-                       ret = load_one_file(file, inode_map);
-                       if (ret)
-                               goto out;
-                       if (file->NextFileOffset == 0)
-                               break;
-                       file = (const void *)file + file->NextFileOffset;
+               /* Execute FSCTL_QUERY_FILE_LAYOUT until it fails.  */
+               while (NT_SUCCESS(status = winnt_fsctl(h,
+                                                      FSCTL_QUERY_FILE_LAYOUT,
+                                                      &in, sizeof(in),
+                                                      out, outsize, NULL)))
+               {
+                       const FILE_LAYOUT_ENTRY *file =
+                               (const void *)out + out->FirstFileOffset;
+                       for (;;) {
+                               ret = load_one_file(file, inode_map);
+                               if (ret)
+                                       goto out;
+                               if (file->NextFileOffset == 0)
+                                       break;
+                               file = (const void *)file + file->NextFileOffset;
+                       }
+                       in.Flags &= ~QUERY_FILE_LAYOUT_RESTART;
                }
-               in.Flags &= ~QUERY_FILE_LAYOUT_RESTART;
+
+               /* Enlarge the buffer if needed.  */
+               if (status != STATUS_BUFFER_TOO_SMALL)
+                       break;
+               FREE(out);
+               outsize *= 2;
        }
 
        /* Normally, FSCTL_QUERY_FILE_LAYOUT fails with STATUS_END_OF_FILE after