xz: Use lzma_file_info_decoder() for --list.

1 files changed, 44 insertions, 210 deletions

diff --git a/src/xz/list.c b/src/xz/list.c
index 449c2bc4..c297d2e3 100644
--- a/src/xz/list.c
+++ b/src/xz/list.c
@@ -143,9 +143,6 @@ xz_ver_to_str(uint32_t ver)
 ///
 /// \return     On success, false is returned. On error, true is returned.
 ///
-// TODO: This function is pretty big. liblzma should have a function that
-// takes a callback function to parse the Index(es) from a .xz file to make
-// it easy for applications.
 static bool
 parse_indexes(xz_file_info *xfi, file_pair *pair)
 {
@@ -161,238 +158,75 @@ parse_indexes(xz_file_info *xfi, file_pair *pair)
 	}
 
 	io_buf buf;
-	lzma_stream_flags header_flags;
-	lzma_stream_flags footer_flags;
-	lzma_ret ret;
-
-	// lzma_stream for the Index decoder
 	lzma_stream strm = LZMA_STREAM_INIT;
+	lzma_index *idx = NULL;
 
-	// All Indexes decoded so far
-	lzma_index *combined_index = NULL;
-
-	// The Index currently being decoded
-	lzma_index *this_index = NULL;
-
-	// Current position in the file. We parse the file backwards so
-	// initialize it to point to the end of the file.
-	off_t pos = pair->src_st.st_size;
-
-	// Each loop iteration decodes one Index.
-	do {
-		// Check that there is enough data left to contain at least
-		// the Stream Header and Stream Footer. This check cannot
-		// fail in the first pass of this loop.
-		if (pos < 2 * LZMA_STREAM_HEADER_SIZE) {
-			message_error("%s: %s", pair->src_name,
-					message_strm(LZMA_DATA_ERROR));
-			goto error;
-		}
-
-		pos -= LZMA_STREAM_HEADER_SIZE;
-		lzma_vli stream_padding = 0;
-
-		// Locate the Stream Footer. There may be Stream Padding which
-		// we must skip when reading backwards.
-		while (true) {
-			if (pos < LZMA_STREAM_HEADER_SIZE) {
-				message_error("%s: %s", pair->src_name,
-						message_strm(
-							LZMA_DATA_ERROR));
-				goto error;
-			}
+	lzma_ret ret = lzma_file_info_decoder(&strm, &idx,
+			hardware_memlimit_get(MODE_LIST),
+			(uint64_t)(pair->src_st.st_size));
+	if (ret != LZMA_OK) {
+		message_error("%s: %s", pair->src_name, message_strm(ret));
+		return true;
+	}
 
-			if (io_pread(pair, &buf,
-					LZMA_STREAM_HEADER_SIZE, pos))
+	while (true) {
+		if (strm.avail_in == 0) {
+			strm.next_in = buf.u8;
+			strm.avail_in = io_read(pair, &buf, IO_BUFFER_SIZE);
+			if (strm.avail_in == SIZE_MAX)
 				goto error;
-
-			// Stream Padding is always a multiple of four bytes.
-			int i = 2;
-			if (buf.u32[i] != 0)
-				break;
-
-			// To avoid calling io_pread() for every four bytes
-			// of Stream Padding, take advantage that we read
-			// 12 bytes (LZMA_STREAM_HEADER_SIZE) already and
-			// check them too before calling io_pread() again.
-			do {
-				stream_padding += 4;
-				pos -= 4;
-				--i;
-			} while (i >= 0 && buf.u32[i] == 0);
 		}
 
-		// Decode the Stream Footer.
-		ret = lzma_stream_footer_decode(&footer_flags, buf.u8);
-		if (ret != LZMA_OK) {
-			message_error("%s: %s", pair->src_name,
-					message_strm(ret));
-			goto error;
-		}
+		ret = lzma_code(&strm, LZMA_RUN);
 
-		// Check that the Stream Footer doesn't specify something
-		// that we don't support. This can only happen if the xz
-		// version is older than liblzma and liblzma supports
-		// something new.
-		//
-		// It is enough to check Stream Footer. Stream Header must
-		// match when it is compared against Stream Footer with
-		// lzma_stream_flags_compare().
-		if (footer_flags.version != 0) {
-			message_error("%s: %s", pair->src_name,
-					message_strm(LZMA_OPTIONS_ERROR));
-			goto error;
-		}
+		switch (ret) {
+		case LZMA_OK:
+			break;
 
-		// Check that the size of the Index field looks sane.
-		lzma_vli index_size = footer_flags.backward_size;
-		if ((lzma_vli)(pos) < index_size + LZMA_STREAM_HEADER_SIZE) {
-			message_error("%s: %s", pair->src_name,
-					message_strm(LZMA_DATA_ERROR));
-			goto error;
-		}
+		case LZMA_SEEK_NEEDED:
+			// The cast is safe because liblzma won't ask us to
+			// seek past the known size of the input file which
+			// did fit into off_t.
+			assert(strm.seek_pos
+					<= (uint64_t)(pair->src_st.st_size));
+			if (io_seek_src(pair, (off_t)(strm.seek_pos)))
+				goto error;
 
-		// Set pos to the beginning of the Index.
-		pos -= index_size;
+			// avail_in must be zero so that we will read new
+			// input.
+			strm.avail_in = 0;
+			break;
 
-		// See how much memory we can use for decoding this Index.
-		uint64_t memlimit = hardware_memlimit_get(MODE_LIST);
-		uint64_t memused = 0;
-		if (combined_index != NULL) {
-			memused = lzma_index_memused(combined_index);
-			if (memused > memlimit)
-				message_bug();
+		case LZMA_STREAM_END: {
+			lzma_end(&strm);
+			xfi->idx = idx;
 
-			memlimit -= memused;
-		}
+			// Calculate xfi->stream_padding.
+			lzma_index_iter iter;
+			lzma_index_iter_init(&iter, xfi->idx);
+			while (!lzma_index_iter_next(&iter,
+					LZMA_INDEX_ITER_STREAM))
+				xfi->stream_padding += iter.stream.padding;
 
-		// Decode the Index.
-		ret = lzma_index_decoder(&strm, &this_index, memlimit);
-		if (ret != LZMA_OK) {
-			message_error("%s: %s", pair->src_name,
-					message_strm(ret));
-			goto error;
+			return false;
 		}
 
-		do {
-			// Don't give the decoder more input than the
-			// Index size.
-			strm.avail_in = my_min(IO_BUFFER_SIZE, index_size);
-			if (io_pread(pair, &buf, strm.avail_in, pos))
-				goto error;
-
-			pos += strm.avail_in;
-			index_size -= strm.avail_in;
-
-			strm.next_in = buf.u8;
-			ret = lzma_code(&strm, LZMA_RUN);
-
-		} while (ret == LZMA_OK);
-
-		// If the decoding seems to be successful, check also that
-		// the Index decoder consumed as much input as indicated
-		// by the Backward Size field.
-		if (ret == LZMA_STREAM_END)
-			if (index_size != 0 || strm.avail_in != 0)
-				ret = LZMA_DATA_ERROR;
-
-		if (ret != LZMA_STREAM_END) {
-			// LZMA_BUFFER_ERROR means that the Index decoder
-			// would have liked more input than what the Index
-			// size should be according to Stream Footer.
-			// The message for LZMA_DATA_ERROR makes more
-			// sense in that case.
-			if (ret == LZMA_BUF_ERROR)
-				ret = LZMA_DATA_ERROR;
-
+		default:
 			message_error("%s: %s", pair->src_name,
 					message_strm(ret));
 
 			// If the error was too low memory usage limit,
 			// show also how much memory would have been needed.
-			if (ret == LZMA_MEMLIMIT_ERROR) {
-				uint64_t needed = lzma_memusage(&strm);
-				if (UINT64_MAX - needed < memused)
-					needed = UINT64_MAX;
-				else
-					needed += memused;
-
-				message_mem_needed(V_ERROR, needed);
-			}
+			if (ret == LZMA_MEMLIMIT_ERROR)
+				message_mem_needed(V_ERROR,
+						lzma_memusage(&strm));
 
 			goto error;
 		}
-
-		// Decode the Stream Header and check that its Stream Flags
-		// match the Stream Footer.
-		pos -= footer_flags.backward_size + LZMA_STREAM_HEADER_SIZE;
-		if ((lzma_vli)(pos) < lzma_index_total_size(this_index)) {
-			message_error("%s: %s", pair->src_name,
-					message_strm(LZMA_DATA_ERROR));
-			goto error;
-		}
-
-		pos -= lzma_index_total_size(this_index);
-		if (io_pread(pair, &buf, LZMA_STREAM_HEADER_SIZE, pos))
-			goto error;
-
-		ret = lzma_stream_header_decode(&header_flags, buf.u8);
-		if (ret != LZMA_OK) {
-			message_error("%s: %s", pair->src_name,
-					message_strm(ret));
-			goto error;
-		}
-
-		ret = lzma_stream_flags_compare(&header_flags, &footer_flags);
-		if (ret != LZMA_OK) {
-			message_error("%s: %s", pair->src_name,
-					message_strm(ret));
-			goto error;
-		}
-
-		// Store the decoded Stream Flags into this_index. This is
-		// needed so that we can print which Check is used in each
-		// Stream.
-		ret = lzma_index_stream_flags(this_index, &footer_flags);
-		if (ret != LZMA_OK)
-			message_bug();
-
-		// Store also the size of the Stream Padding field. It is
-		// needed to show the offsets of the Streams correctly.
-		ret = lzma_index_stream_padding(this_index, stream_padding);
-		if (ret != LZMA_OK)
-			message_bug();
-
-		if (combined_index != NULL) {
-			// Append the earlier decoded Indexes
-			// after this_index.
-			ret = lzma_index_cat(
-					this_index, combined_index, NULL);
-			if (ret != LZMA_OK) {
-				message_error("%s: %s", pair->src_name,
-						message_strm(ret));
-				goto error;
-			}
-		}
-
-		combined_index = this_index;
-		this_index = NULL;
-
-		xfi->stream_padding += stream_padding;
-
-	} while (pos > 0);
-
-	lzma_end(&strm);
-
-	// All OK. Make combined_index available to the caller.
-	xfi->idx = combined_index;
-	return false;
+	}
 
 error:
-	// Something went wrong, free the allocated memory.
 	lzma_end(&strm);
-	lzma_index_end(combined_index, NULL);
-	lzma_index_end(this_index, NULL);
 	return true;
 }