stream_buffer_decoder.c revision 292588 
1///////////////////////////////////////////////////////////////////////////////
2//
3/// \file       stream_buffer_decoder.c
4/// \brief      Single-call .xz Stream decoder
5//
6//  Author:     Lasse Collin
7//
8//  This file has been put into the public domain.
9//  You can do whatever you want with this file.
10//
11///////////////////////////////////////////////////////////////////////////////
12
13#include "stream_decoder.h"
14
15
16extern LZMA_API(lzma_ret)
17lzma_stream_buffer_decode(uint64_t *memlimit, uint32_t flags,
18		const lzma_allocator *allocator,
19		const uint8_t *in, size_t *in_pos, size_t in_size,
20		uint8_t *out, size_t *out_pos, size_t out_size)
21{
22	// Sanity checks
23	if (in_pos == NULL || (in == NULL && *in_pos != in_size)
24			|| *in_pos > in_size || out_pos == NULL
25			|| (out == NULL && *out_pos != out_size)
26			|| *out_pos > out_size)
27		return LZMA_PROG_ERROR;
28
29	// Catch flags that are not allowed in buffer-to-buffer decoding.
30	if (flags & LZMA_TELL_ANY_CHECK)
31		return LZMA_PROG_ERROR;
32
33	// Initialize the Stream decoder.
34	// TODO: We need something to tell the decoder that it can use the
35	// output buffer as workspace, and thus save significant amount of RAM.
36	lzma_next_coder stream_decoder = LZMA_NEXT_CODER_INIT;
37	lzma_ret ret = lzma_stream_decoder_init(
38			&stream_decoder, allocator, *memlimit, flags);
39
40	if (ret == LZMA_OK) {
41		// Save the positions so that we can restore them in case
42		// an error occurs.
43		const size_t in_start = *in_pos;
44		const size_t out_start = *out_pos;
45
46		// Do the actual decoding.
47		ret = stream_decoder.code(stream_decoder.coder, allocator,
48				in, in_pos, in_size, out, out_pos, out_size,
49				LZMA_FINISH);
50
51		if (ret == LZMA_STREAM_END) {
52			ret = LZMA_OK;
53		} else {
54			// Something went wrong, restore the positions.
55			*in_pos = in_start;
56			*out_pos = out_start;
57
58			if (ret == LZMA_OK) {
59				// Either the input was truncated or the
60				// output buffer was too small.
61				assert(*in_pos == in_size
62						|| *out_pos == out_size);
63
64				// If all the input was consumed, then the
65				// input is truncated, even if the output
66				// buffer is also full. This is because
67				// processing the last byte of the Stream
68				// never produces output.
69				if (*in_pos == in_size)
70					ret = LZMA_DATA_ERROR;
71				else
72					ret = LZMA_BUF_ERROR;
73
74			} else if (ret == LZMA_MEMLIMIT_ERROR) {
75				// Let the caller know how much memory would
76				// have been needed.
77				uint64_t memusage;
78				(void)stream_decoder.memconfig(
79						stream_decoder.coder,
80						memlimit, &memusage, 0);
81			}
82		}
83	}
84
85	// Free the decoder memory. This needs to be done even if
86	// initialization fails, because the internal API doesn't
87	// require the initialization function to free its memory on error.
88	lzma_next_end(&stream_decoder, allocator);
89
90	return ret;
91}
92