xref: /freebsd/contrib/xz/src/liblzma/common/stream_buffer_decoder.c (revision 8a802df1de2d77fd0a62996bd785ca3f1326887f)
1 // SPDX-License-Identifier: 0BSD
2 
3 ///////////////////////////////////////////////////////////////////////////////
4 //
5 /// \file       stream_buffer_decoder.c
6 /// \brief      Single-call .xz Stream decoder
7 //
8 //  Author:     Lasse Collin
9 //
10 ///////////////////////////////////////////////////////////////////////////////
11 
12 #include "stream_decoder.h"
13 
14 
15 extern LZMA_API(lzma_ret)
16 lzma_stream_buffer_decode(uint64_t *memlimit, uint32_t flags,
17 		const lzma_allocator *allocator,
18 		const uint8_t *in, size_t *in_pos, size_t in_size,
19 		uint8_t *out, size_t *out_pos, size_t out_size)
20 {
21 	// Sanity checks
22 	if (in_pos == NULL || (in == NULL && *in_pos != in_size)
23 			|| *in_pos > in_size || out_pos == NULL
24 			|| (out == NULL && *out_pos != out_size)
25 			|| *out_pos > out_size)
26 		return LZMA_PROG_ERROR;
27 
28 	// Catch flags that are not allowed in buffer-to-buffer decoding.
29 	if (flags & LZMA_TELL_ANY_CHECK)
30 		return LZMA_PROG_ERROR;
31 
32 	// Initialize the Stream decoder.
33 	// TODO: We need something to tell the decoder that it can use the
34 	// output buffer as workspace, and thus save significant amount of RAM.
35 	lzma_next_coder stream_decoder = LZMA_NEXT_CODER_INIT;
36 	lzma_ret ret = lzma_stream_decoder_init(
37 			&stream_decoder, allocator, *memlimit, flags);
38 
39 	if (ret == LZMA_OK) {
40 		// Save the positions so that we can restore them in case
41 		// an error occurs.
42 		const size_t in_start = *in_pos;
43 		const size_t out_start = *out_pos;
44 
45 		// Do the actual decoding.
46 		ret = stream_decoder.code(stream_decoder.coder, allocator,
47 				in, in_pos, in_size, out, out_pos, out_size,
48 				LZMA_FINISH);
49 
50 		if (ret == LZMA_STREAM_END) {
51 			ret = LZMA_OK;
52 		} else {
53 			// Something went wrong, restore the positions.
54 			*in_pos = in_start;
55 			*out_pos = out_start;
56 
57 			if (ret == LZMA_OK) {
58 				// Either the input was truncated or the
59 				// output buffer was too small.
60 				assert(*in_pos == in_size
61 						|| *out_pos == out_size);
62 
63 				// If all the input was consumed, then the
64 				// input is truncated, even if the output
65 				// buffer is also full. This is because
66 				// processing the last byte of the Stream
67 				// never produces output.
68 				if (*in_pos == in_size)
69 					ret = LZMA_DATA_ERROR;
70 				else
71 					ret = LZMA_BUF_ERROR;
72 
73 			} else if (ret == LZMA_MEMLIMIT_ERROR) {
74 				// Let the caller know how much memory would
75 				// have been needed.
76 				uint64_t memusage;
77 				(void)stream_decoder.memconfig(
78 						stream_decoder.coder,
79 						memlimit, &memusage, 0);
80 			}
81 		}
82 	}
83 
84 	// Free the decoder memory. This needs to be done even if
85 	// initialization fails, because the internal API doesn't
86 	// require the initialization function to free its memory on error.
87 	lzma_next_end(&stream_decoder, allocator);
88 
89 	return ret;
90 }
91