1 files changed, 161 insertions, 147 deletions

diff --git a/src/liblzma/lz/lz_decoder.h b/src/liblzma/lz/lz_decoder.h
index 1acf9831..d2a77ba4 100644
--- a/src/liblzma/lz/lz_decoder.h
+++ b/src/liblzma/lz/lz_decoder.h
@@ -18,201 +18,215 @@
 //
 ///////////////////////////////////////////////////////////////////////////////
 
-#ifndef LZMA_LZ_OUT_H
-#define LZMA_LZ_OUT_H
+#ifndef LZMA_LZ_DECODER_H
+#define LZMA_LZ_DECODER_H
 
 #include "common.h"
 
 
-/// Get a byte from the history buffer.
-#define lz_get_byte(lz, distance) \
-	((distance) < (lz).pos \
-		? (lz).dict[(lz).pos - (distance) - 1] \
-		: (lz).dict[(lz).pos - (distance) - 1 + (lz).end])
-
-
-/// Test if dictionary is empty.
-#define lz_is_empty(lz) \
-	((lz).pos == 0 && !(lz).is_full)
-
-
-#define LZMA_LZ_DECODER_INIT \
-	(lzma_lz_decoder){ .dict = NULL, .size = 0, .match_max_len = 0 }
-
-
 typedef struct {
-	/// Function to do the actual decoding (LZMA or Inflate)
-	bool (*process)(lzma_coder *restrict coder, const uint8_t *restrict in,
-			size_t *restrict in_pos, size_t size_in,
-			bool has_safe_buffer);
+	/// Pointer to the dictionary buffer. It can be an allocated buffer
+	/// internal to liblzma, or it can a be a buffer given by the
+	/// application when in single-call mode (not implemented yet).
+	uint8_t *buf;
 
-	/// Pointer to dictionary (history) buffer.
-	/// \note Not 'restrict' because can alias next_out.
-	uint8_t *dict;
-
-	/// Next write goes to dict[pos].
+	/// Write position in dictionary. The next byte will be written to
+	/// buf[pos].
 	size_t pos;
 
-	/// Next byte to flush is buffer[start].
-	size_t start;
-
-	/// First byte to not flush is buffer[end].
-	size_t end;
+	/// Indicates how full the dictionary is. This is used by
+	/// dict_is_distance_valid() to detect corrupt files that would
+	/// read beyond the beginning of the dictionary.
+	size_t full;
 
-	/// First position to which data must not be written.
+	/// Write limit
 	size_t limit;
 
-	/// True if dictionary has needed wrapping.
-	bool is_full;
-
-	/// True if process() has detected End of Payload Marker.
-	bool eopm_detected;
+	/// Size of the dictionary
+	size_t size;
 
-	/// True if the next coder in the chain has returned LZMA_STREAM_END.
-	bool next_finished;
+} lzma_dict;
 
-	/// True if the LZ decoder (e.g. LZMA) has detected End of Payload
-	/// Marker. This may become true before next_finished becomes true.
-	bool this_finished;
 
-	/// When pos >= must_flush_pos, we must not call process().
-	size_t must_flush_pos;
+typedef struct {
+	/// Data specific to the LZ-based decoder
+	lzma_coder *coder;
 
-	/// Maximum number of bytes that a single decoding loop inside
-	/// process() can produce data into dict. This amount is kept
-	/// always available at dict + pos i.e. it is safe to write a byte
-	/// to dict[pos + match_max_len - 1].
-	size_t match_max_len;
+	/// Function to decode from in[] to *dict
+	lzma_ret (*code)(lzma_coder *restrict coder,
+			lzma_dict *restrict dict, const uint8_t *restrict in,
+			size_t *restrict in_pos, size_t in_size);
 
-	/// Number of bytes allocated to dict.
-	size_t size;
+	void (*reset)(lzma_coder *coder, const void *options);
 
-	/// Requested size of the dictionary. This is needed because we avoid
-	/// using extremely tiny history buffers.
-	size_t requested_size;
+	/// Set the uncompressed size
+	void (*set_uncompressed)(lzma_coder *coder,
+			lzma_vli uncompressed_size);
 
-	/// Uncompressed Size or LZMA_VLI_VALUE_UNKNOWN if unknown.
-	lzma_vli uncompressed_size;
+	/// Free allocated resources
+	void (*end)(lzma_coder *coder, lzma_allocator *allocator);
 
-	/// Number of bytes currently in temp[].
-	size_t temp_size;
+} lzma_lz_decoder;
 
-	/// Temporary buffer needed when
-	/// 1) we cannot make the input buffer completely empty; or
-	/// 2) we are not the last filter in the chain.
-	uint8_t temp[LZMA_BUFFER_SIZE];
 
-} lzma_lz_decoder;
+#define LZMA_LZ_DECODER_INIT \
+	(lzma_lz_decoder){ \
+		.coder = NULL, \
+		.code = NULL, \
+		.reset = NULL, \
+		.set_uncompressed = NULL, \
+		.end = NULL, \
+	}
 
 
-/////////////////////////
-// Function prototypes //
-/////////////////////////
+extern lzma_ret lzma_lz_decoder_init(lzma_next_coder *next,
+		lzma_allocator *allocator, const lzma_filter_info *filters,
+		lzma_ret (*lz_init)(lzma_lz_decoder *lz,
+			lzma_allocator *allocator, const void *options,
+			size_t *dict_size));
 
-extern lzma_ret lzma_lz_decoder_reset(lzma_lz_decoder *lz,
-		lzma_allocator *allocator, bool (*process)(
-			lzma_coder *restrict coder, const uint8_t *restrict in,
-			size_t *restrict in_pos, size_t in_size,
-			bool has_safe_buffer),
-		size_t history_size, size_t match_max_len);
+extern uint64_t lzma_lz_decoder_memusage(size_t dictionary_size);
 
-extern lzma_ret lzma_lz_decode(lzma_coder *coder, lzma_allocator *allocator,
-		const uint8_t *restrict in, size_t *restrict in_pos,
-		size_t in_size, uint8_t *restrict out,
-		size_t *restrict out_pos, size_t out_size,
-		lzma_action action);
+extern void lzma_lz_decoder_uncompressed(
+		lzma_coder *coder, lzma_vli uncompressed_size);
 
-/// Deallocates the history buffer if one exists.
-extern void lzma_lz_decoder_end(
-		lzma_lz_decoder *lz, lzma_allocator *allocator);
 
 //////////////////////
 // Inline functions //
 //////////////////////
 
-// Repeat a block of data from the history. Because memcpy() is faster
-// than copying byte by byte in a loop, the copying process gets split
-// into three cases:
-// 1. distance < length
-//    Source and target areas overlap, thus we can't use memcpy()
-//    (nor memmove()) safely.
-//    TODO: If this is common enough, it might be worth optimizing this
-//    more e.g. by checking if distance > sizeof(uint8_t*) and using
-//    memcpy in small chunks.
-// 2. distance < pos
-//    This is the easiest and the fastest case. The block being copied
-//    is a contiguous piece in the history buffer. The buffer offset
-//    doesn't need wrapping.
-// 3. distance >= pos
-//    We need to wrap the position, because otherwise we would try copying
-//    behind the first byte of the allocated buffer. It is possible that
-//    the block is fragmeneted into two pieces, thus we might need to call
-//    memcpy() twice.
-// NOTE: The function using this macro must ensure that length is positive
-// and that distance is FIXME
+/// Get a byte from the history buffer.
+static inline uint8_t
+dict_get(const lzma_dict *const dict, const uint32_t distance)
+{
+	return dict->buf[dict->pos - distance - 1
+			+ (distance < dict->pos ? 0 : dict->size)];
+}
+
+
+/// Test if dictionary is empty.
+static inline bool
+dict_is_empty(const lzma_dict *const dict)
+{
+	return dict->full == 0;
+}
+
+
+/// Validate the match distance
+static inline bool
+dict_is_distance_valid(const lzma_dict *const dict, const size_t distance)
+{
+	return dict->full >= distance;
+}
+
+
+/// Repeat *len bytes at distance.
 static inline bool
-lzma_lz_out_repeat(lzma_lz_decoder *lz, size_t distance, size_t length)
+dict_repeat(lzma_dict *dict, uint32_t distance, uint32_t *len)
 {
-	// Validate offset of the block to be repeated. It doesn't
-	// make sense to copy data behind the beginning of the stream.
-	// Leaving this check away would lead to a security problem,
-	// in which e.g. the data of the previously decoded file(s)
-	// would be leaked (or whatever happens to be in unused
-	// part of the dictionary buffer).
-	if (unlikely(distance >= lz->pos && !lz->is_full))
-		return false;
-
-	// It also doesn't make sense to copy data farer than
-	// the dictionary size.
-	if (unlikely(distance >= lz->requested_size))
-		return false;
-
-	// The caller must have checked these!
-	assert(distance <= lz->size);
-	assert(length > 0);
-	assert(length <= lz->match_max_len);
-
-	// Copy the amount of data requested by the decoder.
-	if (distance < length) {
+	// Don't write past the end of the dictionary.
+	const size_t dict_avail = dict->limit - dict->pos;
+	uint32_t left = MIN(dict_avail, *len);
+	*len -= left;
+
+	// Repeat a block of data from the history. Because memcpy() is faster
+	// than copying byte by byte in a loop, the copying process gets split
+	// into three cases.
+	if (distance < left) {
 		// Source and target areas overlap, thus we can't use
-		// memcpy() nor even memmove() safely. :-(
-		// TODO: Copying byte by byte is slow. It might be
-		// worth optimizing this more if this case is common.
+		// memcpy() nor even memmove() safely.
 		do {
-			lz->dict[lz->pos] = lz_get_byte(*lz, distance);
-			++lz->pos;
-		} while (--length > 0);
+			dict->buf[dict->pos] = dict_get(dict, distance);
+			++dict->pos;
+		} while (--left > 0);
 
-	} else if (distance < lz->pos) {
+	} else if (distance < dict->pos) {
 		// The easiest and fastest case
-		memcpy(lz->dict + lz->pos,
-				lz->dict + lz->pos - distance - 1,
-				length);
-		lz->pos += length;
+		memcpy(dict->buf + dict->pos,
+				dict->buf + dict->pos - distance - 1,
+				left);
+		dict->pos += left;
 
 	} else {
 		// The bigger the dictionary, the more rare this
 		// case occurs. We need to "wrap" the dict, thus
 		// we might need two memcpy() to copy all the data.
-		assert(lz->is_full);
-		const uint32_t copy_pos = lz->pos - distance - 1 + lz->end;
-		uint32_t copy_size = lz->end - copy_pos;
+		assert(dict->full == dict->size);
+		const uint32_t copy_pos
+				= dict->pos - distance - 1 + dict->size;
+		uint32_t copy_size = dict->size - copy_pos;
 
-		if (copy_size < length) {
-			memcpy(lz->dict + lz->pos, lz->dict + copy_pos,
+		if (copy_size < left) {
+			memcpy(dict->buf + dict->pos, dict->buf + copy_pos,
 					copy_size);
-			lz->pos += copy_size;
-			copy_size = length - copy_size;
-			memcpy(lz->dict + lz->pos, lz->dict, copy_size);
-			lz->pos += copy_size;
+			dict->pos += copy_size;
+			copy_size = left - copy_size;
+			memcpy(dict->buf + dict->pos, dict->buf, copy_size);
+			dict->pos += copy_size;
 		} else {
-			memcpy(lz->dict + lz->pos, lz->dict + copy_pos,
-					length);
-			lz->pos += length;
+			memcpy(dict->buf + dict->pos, dict->buf + copy_pos,
+					left);
+			dict->pos += left;
 		}
 	}
 
-	return true;
+	// Update how full the dictionary is.
+	if (dict->full < dict->pos)
+		dict->full = dict->pos;
+
+	return unlikely(*len != 0);
+}
+
+
+/// Puts one byte into the dictionary. Returns true if the dictionary was
+/// already full and the byte couldn't be added.
+static inline bool
+dict_put(lzma_dict *dict, uint8_t byte)
+{
+	if (unlikely(dict->pos == dict->limit))
+		return true;
+
+	dict->buf[dict->pos++] = byte;
+
+	if (dict->pos > dict->full)
+		dict->full = dict->pos;
+
+	return false;
+}
+
+
+/// Copies arbitrary amount of data into the dictionary.
+static inline void
+dict_write(lzma_dict *restrict dict, const uint8_t *restrict in,
+		size_t *restrict in_pos, size_t in_size,
+		size_t *restrict left)
+{
+	// NOTE: If we are being given more data than the size of the
+	// dictionary, it could be possible to optimize the LZ decoder
+	// so that not everything needs to go through the dictionary.
+	// This shouldn't be very common thing in practice though, and
+	// the slowdown of one extra memcpy() isn't bad compared to how
+	// much time it would have taken if the data were compressed.
+
+	if (in_size - *in_pos > *left)
+		in_size = *in_pos + *left;
+
+	*left -= lzma_bufcpy(in, in_pos, in_size,
+			dict->buf, &dict->pos, dict->limit);
+
+	if (dict->pos > dict->full)
+		dict->full = dict->pos;
+
+	return;
+}
+
+
+static inline void
+dict_reset(lzma_dict *dict)
+{
+	dict->pos = 0;
+	dict->full = 0;
+	dict->buf[dict->size - 1] = '\0';
 }
 
 #endif