liblzma: Fix handling of memlimit == 0 in lzma_index_decoder().
It returned LZMA_PROG_ERROR, which was done to avoid zero as
the limit (because it's a special value elsewhere), but using
LZMA_PROG_ERROR is simply inconvenient and can cause bugs.
The fix/workaround is to treat 0 as if it were 1 byte. It's
effectively the same thing. The only weird consequence is
that then lzma_memlimit_get() will return 1 even when 0 was
specified as the limit.
This fixes a very rare corner case in xz --list where a specific
memory usage limit and a multi-stream file could print the
error message "Internal error (bug)" instead of saying that
the memory usage limit is too low.
diff --git a/src/liblzma/api/lzma/index.h b/src/liblzma/api/lzma/index.h
index dda60ec..3dac6fb 100644
--- a/src/liblzma/api/lzma/index.h
+++ b/src/liblzma/api/lzma/index.h
@@ -586,8 +586,7 @@
* \param i Pointer to lzma_index which should be encoded.
*
* The valid `action' values for lzma_code() are LZMA_RUN and LZMA_FINISH.
- * It is enough to use only one of them (you can choose freely; use LZMA_RUN
- * to support liblzma versions older than 5.0.0).
+ * It is enough to use only one of them (you can choose freely).
*
* \return - LZMA_OK: Initialization succeeded, continue with lzma_code().
* - LZMA_MEM_ERROR
@@ -610,16 +609,21 @@
* to a new lzma_index, which the application
* has to later free with lzma_index_end().
* \param memlimit How much memory the resulting lzma_index is
- * allowed to require.
+ * allowed to require. liblzma 5.2.3 and earlier
+ * don't allow 0 here and return LZMA_PROG_ERROR;
+ * later versions treat 0 as if 1 had been specified.
*
- * The valid `action' values for lzma_code() are LZMA_RUN and LZMA_FINISH.
- * It is enough to use only one of them (you can choose freely; use LZMA_RUN
- * to support liblzma versions older than 5.0.0).
+ * Valid `action' arguments to lzma_code() are LZMA_RUN and LZMA_FINISH.
+ * There is no need to use LZMA_FINISH, but it's allowed because it may
+ * simplify certain types of applications.
*
* \return - LZMA_OK: Initialization succeeded, continue with lzma_code().
* - LZMA_MEM_ERROR
- * - LZMA_MEMLIMIT_ERROR
* - LZMA_PROG_ERROR
+ *
+ * liblzma 5.2.3 and older list also LZMA_MEMLIMIT_ERROR here
+ * but that error code has never been possible from this
+ * initialization function.
*/
extern LZMA_API(lzma_ret) lzma_index_decoder(
lzma_stream *strm, lzma_index **i, uint64_t memlimit)
diff --git a/src/liblzma/common/index_decoder.c b/src/liblzma/common/index_decoder.c
index 1e33f0b..cc07a1b 100644
--- a/src/liblzma/common/index_decoder.c
+++ b/src/liblzma/common/index_decoder.c
@@ -256,7 +256,7 @@
// Initialize the rest.
coder->sequence = SEQ_INDICATOR;
- coder->memlimit = memlimit;
+ coder->memlimit = my_max(1, memlimit);
coder->count = 0; // Needs to be initialized due to _memconfig().
coder->pos = 0;
coder->crc32 = 0;
@@ -271,7 +271,7 @@
{
lzma_next_coder_init(&index_decoder_init, next, allocator);
- if (i == NULL || memlimit == 0)
+ if (i == NULL)
return LZMA_PROG_ERROR;
lzma_index_coder *coder = next->coder;
