liblzma: Add rough support for output-size-limited encoding in LZMA1.

With this it is possible to encode LZMA1 data without EOPM so that
the encoder will encode as much input as it can without exceeding
the specified output size limit. The resulting LZMA1 stream will
be a normal LZMA1 stream without EOPM. The actual uncompressed size
will be available to the caller via the uncomp_size pointer.

One missing thing is that the LZMA layer doesn't inform the LZ layer
when the encoding is finished and thus the LZ may read more input
when it won't be used. However, this doesn't matter if encoding is
done with a single call (which is the planned use case for now).
For proper multi-call encoding this should be improved.

This commit only adds the functionality for internal use.
Nothing uses it yet.

1 files changed, 12 insertions, 0 deletions

diff --git a/src/liblzma/lzma/lzma_encoder_private.h b/src/liblzma/lzma/lzma_encoder_private.h
index 2e34aace..8960c52c 100644
--- a/src/liblzma/lzma/lzma_encoder_private.h
+++ b/src/liblzma/lzma/lzma_encoder_private.h
@@ -72,6 +72,18 @@ struct lzma_lzma1_encoder_s {
 	/// Range encoder
 	lzma_range_encoder rc;
 
+	/// Uncompressed size (doesn't include possible preset dictionary)
+	uint64_t uncomp_size;
+
+	/// If non-zero, produce at most this much output.
+	/// Some input may then be missing from the output.
+	uint64_t out_limit;
+
+	/// If the above out_limit is non-zero, *uncomp_size_ptr is set to
+	/// the amount of uncompressed data that we were able to fit
+	/// in the output buffer.
+	uint64_t *uncomp_size_ptr;
+
 	/// State
 	lzma_lzma_state state;