Added lzma_stream_buffer_decode() and made minor cleanups.

src/liblzma/api/lzma/block.h

@@ -471,4 +471,5 @@ extern size_t lzma_block_buffer_bound(size_t uncompressed_size);
 extern lzma_ret lzma_block_buffer_encode(
 		lzma_block *block, lzma_allocator *allocator,
 		const uint8_t *in, size_t in_size,
-		uint8_t *out, size_t *out_pos, size_t out_size);
+		uint8_t *out, size_t *out_pos, size_t out_size)
+		lzma_attr_warn_unused_result;

src/liblzma/api/lzma/container.h

@@ -222,7 +222,8 @@ extern size_t lzma_stream_buffer_bound(size_t uncompressed_size);
 extern lzma_ret lzma_stream_buffer_encode(
 		lzma_filter *filters, lzma_check check,
 		lzma_allocator *allocator, const uint8_t *in, size_t in_size,
-		uint8_t *out, size_t *out_pos, size_t out_size);
+		uint8_t *out, size_t *out_pos, size_t out_size)
+		lzma_attr_warn_unused_result;
 
 
 /************
@@ -277,6 +278,9 @@ extern lzma_ret lzma_stream_buffer_encode(
  *
  * \param       strm        Pointer to properly prepared lzma_stream
  * \param       memlimit    Rough memory usage limit as bytes
+ * \param       flags       Bitwise-or of zero or more of the decoder flags:
+ *                          LZMA_TELL_NO_CHECK, LZMA_TELL_UNSUPPORTED_CHECK,
+ *                          LZMA_TELL_ANY_CHECK, LZMA_CONCATENATED
  *
  * \return      - LZMA_OK: Initialization was successful.
  *              - LZMA_MEM_ERROR: Cannot allocate memory.
@@ -319,3 +323,48 @@ extern lzma_ret lzma_auto_decoder(
  */
 extern lzma_ret lzma_alone_decoder(lzma_stream *strm, uint64_t memlimit)
 		lzma_attr_warn_unused_result;
+
+
+/**
+ * \brief       Single-call .xz Stream decoder
+ *
+ * \param       memlimit    Pointer to how much memory the decoder is allowed
+ *                          to allocate. The value pointed by this pointer is
+ *                          modified if and only if LZMA_MEMLIMIT_ERROR is
+ *                          returned.
+ * \param       flags       Bitwise-or of zero or more of the decoder flags:
+ *                          LZMA_TELL_NO_CHECK, LZMA_TELL_UNSUPPORTED_CHECK,
+ *                          LZMA_CONCATENATED. Note that LZMA_TELL_ANY_CHECK
+ *                          is not allowed and will return LZMA_PROG_ERROR.
+ * \param       allocator   lzma_allocator for custom allocator functions.
+ *                          Set to NULL to use malloc() and free().
+ * \param       in          Beginning of the input buffer
+ * \param       in_pos      The next byte will be read from in[*in_pos].
+ *                          *in_pos is updated only if decoding succeeds.
+ * \param       in_size     Size of the input buffer; the first byte that
+ *                          won't be read is in[in_size].
+ * \param       out         Beginning of the output buffer
+ * \param       out_pos     The next byte will be written to out[*out_pos].
+ *                          *out_pos is updated only if encoding succeeds.
+ * \param       out_size    Size of the out buffer; the first byte into
+ *                          which no data is written to is out[out_size].
+ *
+ * \return      - LZMA_OK: Decoding was successful.
+ *              - LZMA_FORMAT_ERROR
+ *              - LZMA_OPTIONS_ERROR
+ *              - LZMA_DATA_ERROR
+ *              - LZMA_NO_CHECK: This can be returned only if using
+ *                the LZMA_TELL_NO_CHECK flag.
+ *              - LZMA_UNSUPPORTED_CHECK: This can be returned only if using
+ *                the LZMA_TELL_UNSUPPORTED_CHECK flag.
+ *              - LZMA_MEM_ERROR
+ *              - LZMA_MEMLIMIT_ERROR: Memory usage limit was reached.
+ *                The minimum required memlimit value was stored to *memlimit.
+ *              - LZMA_BUF_ERROR: Output buffer was too small.
+ *              - LZMA_PROG_ERROR
+ */
+extern 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)
+		lzma_attr_warn_unused_result;

src/liblzma/common/Makefile.am

@@ -69,6 +69,7 @@ libcommon_la_SOURCES += \
 	filter_flags_decoder.c \
 	index_decoder.c \
 	index_hash.c \
+	stream_buffer_decoder.c \
 	stream_decoder.c \
 	stream_decoder.h \
 	stream_flags_decoder.c \

src/liblzma/common/stream_buffer_decoder.c

@@ -0,0 +1,91 @@
+///////////////////////////////////////////////////////////////////////////////
+//
+/// \file       stream_buffer_decoder.c
+/// \brief      Single-call .xz Stream decoder
+//
+//  Copyright (C) 2009 Lasse Collin
+//
+//  This library is free software; you can redistribute it and/or
+//  modify it under the terms of the GNU Lesser General Public
+//  License as published by the Free Software Foundation; either
+//  version 2.1 of the License, or (at your option) any later version.
+//
+//  This library is distributed in the hope that it will be useful,
+//  but WITHOUT ANY WARRANTY; without even the implied warranty of
+//  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+//  Lesser General Public License for more details.
+//
+///////////////////////////////////////////////////////////////////////////////
+
+#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)
+{
+	// 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;
+}