Fix LZMA_SYNC_FLUSH handling in LZ and LZMA encoders.

That code is now almost completely in LZ coder, where
it can be shared with other LZ77-based algorithms in
future.

diff --git a/src/liblzma/lz/lz_encoder.c b/src/liblzma/lz/lz_encoder.c
index 8d2277e..43e6d3b 100644 (file)
--- a/src/liblzma/lz/lz_encoder.c
+++ b/src/liblzma/lz/lz_encoder.c
@@ -141,7 +141,7 @@ lzma_lz_encoder_reset(lzma_lz_encoder *lz, lzma_allocator *allocator,
                const uint8_t *preset_dictionary,
                size_t preset_dictionary_size)
 {
-       lz->sequence = SEQ_RUN;
+       lz->sequence = SEQ_START;
        lz->uncompressed_size = uncompressed_size;
        lz->temp_size = 0;
 
@@ -477,24 +477,42 @@ lzma_lz_encode(lzma_coder *coder, lzma_allocator *allocator,
                coder->lz.temp_size = 0;
        }
 
-       if (coder->lz.sequence == SEQ_FLUSH_END) {
+       switch (coder->lz.sequence) {
+       case SEQ_START:
+               assert(coder->lz.read_pos == coder->lz.write_pos);
+
+               // If there is no new input data and LZMA_SYNC_FLUSH is used
+               // immediatelly after previous LZMA_SYNC_FLUSH finished or
+               // at the very beginning of the input stream, we return
+               // LZMA_STREAM_END immediatelly. Writing a flush marker
+               // to the very beginning of the stream or right after previous
+               // flush marker is not allowed by the LZMA stream format.
+               if (*in_pos == in_size && action == LZMA_SYNC_FLUSH)
+                       return LZMA_STREAM_END;
+
+               coder->lz.sequence = SEQ_RUN;
+               break;
+
+       case SEQ_FLUSH_END:
                // During an earlier call to this function, flushing was
                // otherwise finished except some data was left pending
                // in coder->lz.buffer. Now we have copied all that data
                // to the output buffer and can return LZMA_STREAM_END.
-               coder->lz.sequence = SEQ_RUN;
+               coder->lz.sequence = SEQ_START;
                assert(action == LZMA_SYNC_FLUSH);
                return LZMA_STREAM_END;
-       }
 
-       if (coder->lz.sequence == SEQ_END) {
+       case SEQ_END:
                // This is like the above flushing case, but for finishing
                // the encoding.
                //
                // NOTE: action is not necesarily LZMA_FINISH; it can
-               // be LZMA_SYNC_FLUSH too in case it is used at the
-               // end of the stream with known Uncompressed Size.
+               // be LZMA_RUN or LZMA_SYNC_FLUSH too in case it is used
+               // at the end of the stream with known Uncompressed Size.
                return action != LZMA_RUN ? LZMA_STREAM_END : LZMA_OK;
+
+       default:
+               break;
        }
 
        while (*out_pos < out_size
@@ -511,7 +529,7 @@ lzma_lz_encode(lzma_coder *coder, lzma_allocator *allocator,
                                assert(action == LZMA_SYNC_FLUSH);
                                if (coder->lz.temp_size == 0) {
                                        // Flushing was finished successfully.
-                                       coder->lz.sequence = SEQ_RUN;
+                                       coder->lz.sequence = SEQ_START;
                                } else {
                                        // Flushing was otherwise finished,
                                        // except that some data was left

diff --git a/src/liblzma/lz/lz_encoder.h b/src/liblzma/lz/lz_encoder.h
index 11d1272..78ac4a3 100644 (file)
--- a/src/liblzma/lz/lz_encoder.h
+++ b/src/liblzma/lz/lz_encoder.h
@@ -30,6 +30,7 @@
 typedef struct lzma_lz_encoder_s lzma_lz_encoder;
 struct lzma_lz_encoder_s {
        enum {
+               SEQ_START,
                SEQ_RUN,
                SEQ_FLUSH,
                SEQ_FLUSH_END,

diff --git a/src/liblzma/lzma/lzma_encoder.c b/src/liblzma/lzma/lzma_encoder.c
index 8a5b014..0fcb755 100644 (file)
--- a/src/liblzma/lzma/lzma_encoder.c
+++ b/src/liblzma/lzma/lzma_encoder.c
@@ -157,31 +157,8 @@ lzma_lzma_encode(lzma_coder *coder, uint8_t *restrict out,
        // Initialize the stream if no data has been encoded yet.
        if (!coder->is_initialized) {
                if (coder->lz.read_pos == coder->lz.read_limit) {
-                       switch (coder->lz.sequence) {
-                       case SEQ_RUN:
-                               // Cannot initialize, because there is
-                               // no input data.
-                               return false;
-
-                       case SEQ_FLUSH:
-                               // Nothing to flush. There cannot be a flush
-                               // marker when no data has been processed
-                               // yet (file format doesn't allow it, and
-                               // it would be just waste of space).
-                               return true;
-
-                       case SEQ_FINISH:
-                               // We are encoding an empty file. No need
-                               // to initialize the encoder.
-                               assert(coder->lz.write_pos == coder->lz.read_pos);
-                               break;
-
-                       default:
-                               // We never get here.
-                               assert(0);
-                               return true;
-                       }
-
+                       assert(coder->lz.write_pos == coder->lz.read_pos);
+                       assert(coder->lz.sequence == SEQ_FINISH);
                } else {
                        // Do the actual initialization.
                        uint32_t len;