Fix decoding of empty Metadata Blocks, that don't have

even the Metadata Flags field. Earlier the code allowed
such files; now they are prohibited as the file format
specification requires.

diff --git a/src/liblzma/common/metadata_decoder.c b/src/liblzma/common/metadata_decoder.c
index 8ff4e25..579b0a5 100644 (file)
--- a/src/liblzma/common/metadata_decoder.c
+++ b/src/liblzma/common/metadata_decoder.c
@@ -127,6 +127,8 @@ process(lzma_coder *coder, lzma_allocator *allocator)
                if (coder->buffer[coder->buffer_pos] & 0x70)
                        return LZMA_HEADER_ERROR;
 
+               coder->todo_count = 0;
+
                // If Size of Header Metadata is present, prepare the
                // variable for variable-length integer decoding. Otherwise
                // set it to LZMA_VLI_VALUE_UNKNOWN to indicate that the
@@ -535,7 +537,7 @@ metadata_decoder_init(lzma_next_coder *next, lzma_allocator *allocator,
        metadata->extra = NULL;
 
        next->coder->sequence = SEQ_FLAGS;
-       next->coder->todo_count = 0;
+       next->coder->todo_count = 1;
        next->coder->pos = 0;
        next->coder->tmp = 0;
        next->coder->metadata = metadata;