1 files changed, 263 insertions, 0 deletions
diff --git a/src/liblzma/common/index_encoder.c b/src/liblzma/common/index_encoder.c
new file mode 100644
index 0000000..204490c
--- /dev/null
+++ b/src/liblzma/common/index_encoder.c
@@ -0,0 +1,263 @@
+///////////////////////////////////////////////////////////////////////////////
+//
+/// \file       index_encoder.c
+/// \brief      Encodes the Index field
+//
+//  Author:     Lasse Collin
+//
+//  This file has been put into the public domain.
+//  You can do whatever you want with this file.
+//
+///////////////////////////////////////////////////////////////////////////////
+
+#include "index_encoder.h"
+#include "index.h"
+#include "check.h"
+
+
+typedef struct {
+	enum {
+		SEQ_INDICATOR,
+		SEQ_COUNT,
+		SEQ_UNPADDED,
+		SEQ_UNCOMPRESSED,
+		SEQ_NEXT,
+		SEQ_PADDING,
+		SEQ_CRC32,
+	} sequence;
+
+	/// Index being encoded
+	const lzma_index *index;
+
+	/// Iterator for the Index being encoded
+	lzma_index_iter iter;
+
+	/// Position in integers
+	size_t pos;
+
+	/// CRC32 of the List of Records field
+	uint32_t crc32;
+} lzma_index_coder;
+
+
+static lzma_ret
+index_encode(void *coder_ptr,
+		const lzma_allocator *allocator lzma_attribute((__unused__)),
+		const uint8_t *restrict in lzma_attribute((__unused__)),
+		size_t *restrict in_pos lzma_attribute((__unused__)),
+		size_t in_size lzma_attribute((__unused__)),
+		uint8_t *restrict out, size_t *restrict out_pos,
+		size_t out_size,
+		lzma_action action lzma_attribute((__unused__)))
+{
+	lzma_index_coder *coder = coder_ptr;
+
+	// Position where to start calculating CRC32. The idea is that we
+	// need to call lzma_crc32() only once per call to index_encode().
+	const size_t out_start = *out_pos;
+
+	// Return value to use if we return at the end of this function.
+	// We use "goto out" to jump out of the while-switch construct
+	// instead of returning directly, because that way we don't need
+	// to copypaste the lzma_crc32() call to many places.
+	lzma_ret ret = LZMA_OK;
+
+	while (*out_pos < out_size)
+	switch (coder->sequence) {
+	case SEQ_INDICATOR:
+		out[*out_pos] = INDEX_INDICATOR;
+		++*out_pos;
+		coder->sequence = SEQ_COUNT;
+		break;
+
+	case SEQ_COUNT: {
+		const lzma_vli count = lzma_index_block_count(coder->index);
+		ret = lzma_vli_encode(count, &coder->pos,
+				out, out_pos, out_size);
+		if (ret != LZMA_STREAM_END)
+			goto out;
+
+		ret = LZMA_OK;
+		coder->pos = 0;
+		coder->sequence = SEQ_NEXT;
+		break;
+	}
+
+	case SEQ_NEXT:
+		if (lzma_index_iter_next(
+				&coder->iter, LZMA_INDEX_ITER_BLOCK)) {
+			// Get the size of the Index Padding field.
+			coder->pos = lzma_index_padding_size(coder->index);
+			assert(coder->pos <= 3);
+			coder->sequence = SEQ_PADDING;
+			break;
+		}
+
+		coder->sequence = SEQ_UNPADDED;
+
+	// Fall through
+
+	case SEQ_UNPADDED:
+	case SEQ_UNCOMPRESSED: {
+		const lzma_vli size = coder->sequence == SEQ_UNPADDED
+				? coder->iter.block.unpadded_size
+				: coder->iter.block.uncompressed_size;
+
+		ret = lzma_vli_encode(size, &coder->pos,
+				out, out_pos, out_size);
+		if (ret != LZMA_STREAM_END)
+			goto out;
+
+		ret = LZMA_OK;
+		coder->pos = 0;
+
+		// Advance to SEQ_UNCOMPRESSED or SEQ_NEXT.
+		++coder->sequence;
+		break;
+	}
+
+	case SEQ_PADDING:
+		if (coder->pos > 0) {
+			--coder->pos;
+			out[(*out_pos)++] = 0x00;
+			break;
+		}
+
+		// Finish the CRC32 calculation.
+		coder->crc32 = lzma_crc32(out + out_start,
+				*out_pos - out_start, coder->crc32);
+
+		coder->sequence = SEQ_CRC32;
+
+	// Fall through
+
+	case SEQ_CRC32:
+		// We don't use the main loop, because we don't want
+		// coder->crc32 to be touched anymore.
+		do {
+			if (*out_pos == out_size)
+				return LZMA_OK;
+
+			out[*out_pos] = (coder->crc32 >> (coder->pos * 8))
+					& 0xFF;
+			++*out_pos;
+
+		} while (++coder->pos < 4);
+
+		return LZMA_STREAM_END;
+
+	default:
+		assert(0);
+		return LZMA_PROG_ERROR;
+	}
+
+out:
+	// Update the CRC32.
+	//
+	// Avoid null pointer + 0 (undefined behavior) in "out + out_start".
+	// In such a case we had no input and thus out_used == 0.
+	{
+		const size_t out_used = *out_pos - out_start;
+		if (out_used > 0)
+			coder->crc32 = lzma_crc32(out + out_start,
+					out_used, coder->crc32);
+	}
+
+	return ret;
+}
+
+
+static void
+index_encoder_end(void *coder, const lzma_allocator *allocator)
+{
+	lzma_free(coder, allocator);
+	return;
+}
+
+
+static void
+index_encoder_reset(lzma_index_coder *coder, const lzma_index *i)
+{
+	lzma_index_iter_init(&coder->iter, i);
+
+	coder->sequence = SEQ_INDICATOR;
+	coder->index = i;
+	coder->pos = 0;
+	coder->crc32 = 0;
+
+	return;
+}
+
+
+extern lzma_ret
+lzma_index_encoder_init(lzma_next_coder *next, const lzma_allocator *allocator,
+		const lzma_index *i)
+{
+	lzma_next_coder_init(&lzma_index_encoder_init, next, allocator);
+
+	if (i == NULL)
+		return LZMA_PROG_ERROR;
+
+	if (next->coder == NULL) {
+		next->coder = lzma_alloc(sizeof(lzma_index_coder), allocator);
+		if (next->coder == NULL)
+			return LZMA_MEM_ERROR;
+
+		next->code = &index_encode;
+		next->end = &index_encoder_end;
+	}
+
+	index_encoder_reset(next->coder, i);
+
+	return LZMA_OK;
+}
+
+
+extern LZMA_API(lzma_ret)
+lzma_index_encoder(lzma_stream *strm, const lzma_index *i)
+{
+	lzma_next_strm_init(lzma_index_encoder_init, strm, i);
+
+	strm->internal->supported_actions[LZMA_RUN] = true;
+	strm->internal->supported_actions[LZMA_FINISH] = true;
+
+	return LZMA_OK;
+}
+
+
+extern LZMA_API(lzma_ret)
+lzma_index_buffer_encode(const lzma_index *i,
+		uint8_t *out, size_t *out_pos, size_t out_size)
+{
+	// Validate the arguments.
+	if (i == NULL || out == NULL || out_pos == NULL || *out_pos > out_size)
+		return LZMA_PROG_ERROR;
+
+	// Don't try to encode if there's not enough output space.
+	if (out_size - *out_pos < lzma_index_size(i))
+		return LZMA_BUF_ERROR;
+
+	// The Index encoder needs just one small data structure so we can
+	// allocate it on stack.
+	lzma_index_coder coder;
+	index_encoder_reset(&coder, i);
+
+	// Do the actual encoding. This should never fail, but store
+	// the original *out_pos just in case.
+	const size_t out_start = *out_pos;
+	lzma_ret ret = index_encode(&coder, NULL, NULL, NULL, 0,
+			out, out_pos, out_size, LZMA_RUN);
+
+	if (ret == LZMA_STREAM_END) {
+		ret = LZMA_OK;
+	} else {
+		// We should never get here, but just in case, restore the
+		// output position and set the error accordingly if something
+		// goes wrong and debugging isn't enabled.
+		assert(0);
+		*out_pos = out_start;
+		ret = LZMA_PROG_ERROR;
+	}
+
+	return ret;
+}