Updated auto decoder to handle LZMA_CONCATENATED when decoding

LZMA_Alone files. Decoding of concatenated LZMA_Alone files is
intentionally not supported, so it is better to put this in
auto decoder than LZMA_Alone decoder.

diff --git a/src/liblzma/common/auto_decoder.c b/src/liblzma/common/auto_decoder.c
index 5fcdf16..469245d 100644 (file)
--- a/src/liblzma/common/auto_decoder.c
+++ b/src/liblzma/common/auto_decoder.c
@@ -22,10 +22,17 @@
 
 
 struct lzma_coder_s {
+       /// Stream decoder or LZMA_Alone decoder
        lzma_next_coder next;
+
        uint64_t memlimit;
        uint32_t flags;
-       bool initialized;
+
+       enum {
+               SEQ_INIT,
+               SEQ_CODE,
+               SEQ_FINISH,
+       } sequence;
 };
 
 
@@ -35,28 +42,67 @@ auto_decode(lzma_coder *coder, lzma_allocator *allocator,
                size_t in_size, uint8_t *restrict out,
                size_t *restrict out_pos, size_t out_size, lzma_action action)
 {
-       if (!coder->initialized) {
+       switch (coder->sequence) {
+       case SEQ_INIT:
                if (*in_pos >= in_size)
                        return LZMA_OK;
 
-               lzma_ret ret;
+               // Update the sequence now, because we want to continue from
+               // SEQ_CODE even if we return some LZMA_*_CHECK.
+               coder->sequence = SEQ_CODE;
 
-               if (in[*in_pos] == 0xFF)
-                       ret = lzma_stream_decoder_init(
+               // Detect the file format. For now this is simple, since if
+               // it doesn't start with 0xFF (the first magic byte of the
+               // new format), it has to be LZMA_Alone, or something that
+               // we don't support at all.
+               if (in[*in_pos] == 0xFF) {
+                       return_if_error(lzma_stream_decoder_init(
                                        &coder->next, allocator,
-                                       coder->memlimit, coder->flags);
-               else
-                       ret = lzma_alone_decoder_init(&coder->next,
-                                       allocator, coder->memlimit);
-
-               if (ret != LZMA_OK)
+                                       coder->memlimit, coder->flags));
+               } else {
+                       return_if_error(lzma_alone_decoder_init(&coder->next,
+                                       allocator, coder->memlimit));
+
+                       // If the application wants a warning about missing
+                       // integrity check or about the check in general, we
+                       // need to handle it here, because LZMA_Alone decoder
+                       // doesn't accept any flags.
+                       if (coder->flags & LZMA_WARN_NO_CHECK)
+                               return LZMA_NO_CHECK;
+
+                       if (coder->flags & LZMA_TELL_CHECK)
+                               return LZMA_SEE_CHECK;
+               }
+
+       // Fall through
+
+       case SEQ_CODE: {
+               const lzma_ret ret = coder->next.code(
+                               coder->next.coder, allocator,
+                               in, in_pos, in_size,
+                               out, out_pos, out_size, action);
+               if (ret != LZMA_STREAM_END
+                               || (coder->flags & LZMA_CONCATENATED) == 0)
                        return ret;
 
-               coder->initialized = true;
+               coder->sequence = SEQ_FINISH;
+
+       // Fall through
+
+       case SEQ_FINISH:
+               // When LZMA_DECODE_CONCATENATED was used and we were decoding
+               // LZMA_Alone file, we need to check check that there is no
+               // trailing garbage and wait for LZMA_FINISH.
+               if (*in_pos < in_size)
+                       return LZMA_DATA_ERROR;
+
+               return action == LZMA_FINISH ? LZMA_STREAM_END : LZMA_OK;
        }
 
-       return coder->next.code(coder->next.coder, allocator,
-                       in, in_pos, in_size, out, out_pos, out_size, action);
+       default:
+               assert(0);
+               return LZMA_PROG_ERROR;
+       }
 }
 
 
@@ -69,6 +115,15 @@ auto_decoder_end(lzma_coder *coder, lzma_allocator *allocator)
 }
 
 
+static lzma_check
+auto_decoder_see_check(const lzma_coder *coder)
+{
+       // It is LZMA_Alone if see_check is NULL.
+       return coder->next.see_check == NULL ? LZMA_CHECK_NONE
+                       : coder->next.see_check(coder->next.coder);
+}
+
+
 static lzma_ret
 auto_decoder_init(lzma_next_coder *next, lzma_allocator *allocator,
                uint64_t memlimit, uint32_t flags)
@@ -85,12 +140,13 @@ auto_decoder_init(lzma_next_coder *next, lzma_allocator *allocator,
 
                next->code = &auto_decode;
                next->end = &auto_decoder_end;
+               next->see_check = &auto_decoder_see_check;
                next->coder->next = LZMA_NEXT_CODER_INIT;
        }
 
        next->coder->memlimit = memlimit;
        next->coder->flags = flags;
-       next->coder->initialized = false;
+       next->coder->sequence = SEQ_INIT;
 
        return LZMA_OK;
 }
@@ -102,7 +158,6 @@ lzma_auto_decoder(lzma_stream *strm, uint64_t memlimit, uint32_t flags)
        lzma_next_strm_init(auto_decoder_init, strm, memlimit, flags);
 
        strm->internal->supported_actions[LZMA_RUN] = true;
-//     strm->internal->supported_actions[LZMA_SYNC_FLUSH] = true; FIXME
        strm->internal->supported_actions[LZMA_FINISH] = true;
 
        return LZMA_OK;