1 files changed, 91 insertions, 0 deletions
diff --git a/liblzma/common/stream_buffer_decoder.c b/liblzma/common/stream_buffer_decoder.c
new file mode 100644
index 0000000..ae75315
--- /dev/null
+++ b/liblzma/common/stream_buffer_decoder.c
@@ -0,0 +1,91 @@
+///////////////////////////////////////////////////////////////////////////////
+//
+/// \file       stream_buffer_decoder.c
+/// \brief      Single-call .xz Stream decoder
+//
+//  Author:     Lasse Collin
+//
+//  This file has been put into the public domain.
+//  You can do whatever you want with this file.
+//
+///////////////////////////////////////////////////////////////////////////////
+
+#include "stream_decoder.h"
+
+
+extern LZMA_API(lzma_ret)
+lzma_stream_buffer_decode(uint64_t *memlimit, uint32_t flags,
+		lzma_allocator *allocator,
+		const uint8_t *in, size_t *in_pos, size_t in_size,
+		uint8_t *out, size_t *out_pos, size_t out_size)
+{
+	// Sanity checks
+	if (in_pos == NULL || (in == NULL && *in_pos != in_size)
+			|| *in_pos > in_size || out_pos == NULL
+			|| (out == NULL && *out_pos != out_size)
+			|| *out_pos > out_size)
+		return LZMA_PROG_ERROR;
+
+	// Catch flags that are not allowed in buffer-to-buffer decoding.
+	if (flags & LZMA_TELL_ANY_CHECK)
+		return LZMA_PROG_ERROR;
+
+	// Initialize the Stream decoder.
+	// TODO: We need something to tell the decoder that it can use the
+	// output buffer as workspace, and thus save significant amount of RAM.
+	lzma_next_coder stream_decoder = LZMA_NEXT_CODER_INIT;
+	lzma_ret ret = lzma_stream_decoder_init(
+			&stream_decoder, allocator, *memlimit, flags);
+
+	if (ret == LZMA_OK) {
+		// Save the positions so that we can restore them in case
+		// an error occurs.
+		const size_t in_start = *in_pos;
+		const size_t out_start = *out_pos;
+
+		// Do the actual decoding.
+		ret = stream_decoder.code(stream_decoder.coder, allocator,
+				in, in_pos, in_size, out, out_pos, out_size,
+				LZMA_FINISH);
+
+		if (ret == LZMA_STREAM_END) {
+			ret = LZMA_OK;
+		} else {
+			// Something went wrong, restore the positions.
+			*in_pos = in_start;
+			*out_pos = out_start;
+
+			if (ret == LZMA_OK) {
+				// Either the input was truncated or the
+				// output buffer was too small.
+				assert(*in_pos == in_size
+						|| *out_pos == out_size);
+
+				// If all the input was consumed, then the
+				// input is truncated, even if the output
+				// buffer is also full. This is because
+				// processing the last byte of the Stream
+				// never produces output.
+				if (*in_pos == in_size)
+					ret = LZMA_DATA_ERROR;
+				else
+					ret = LZMA_BUF_ERROR;
+
+			} else if (ret == LZMA_MEMLIMIT_ERROR) {
+				// Let the caller know how much memory would
+				// have been needed.
+				uint64_t memusage;
+				(void)stream_decoder.memconfig(
+						stream_decoder.coder,
+						memlimit, &memusage, 0);
+			}
+		}
+	}
+
+	// Free the decoder memory. This needs to be done even if
+	// initialization fails, because the internal API doesn't
+	// require the initialization function to free its memory on error.
+	lzma_next_end(&stream_decoder, allocator);
+
+	return ret;
+}