1 // SPDX-License-Identifier: 0BSD 2 3 /////////////////////////////////////////////////////////////////////////////// 4 // 5 /// \file stream_buffer_encoder.c 6 /// \brief Single-call .xz Stream encoder 7 // 8 // Author: Lasse Collin 9 // 10 /////////////////////////////////////////////////////////////////////////////// 11 12 #include "common.h" 13 #include "index.h" 14 15 16 /// Maximum size of Index that has exactly one Record. 17 /// Index Indicator + Number of Records + Record + CRC32 rounded up to 18 /// the next multiple of four. 19 #define INDEX_BOUND ((1 + 1 + 2 * LZMA_VLI_BYTES_MAX + 4 + 3) & ~3) 20 21 /// Stream Header, Stream Footer, and Index 22 #define HEADERS_BOUND (2 * LZMA_STREAM_HEADER_SIZE + INDEX_BOUND) 23 24 25 extern LZMA_API(size_t) 26 lzma_stream_buffer_bound(size_t uncompressed_size) 27 { 28 // Get the maximum possible size of a Block. 29 const size_t block_bound = lzma_block_buffer_bound(uncompressed_size); 30 if (block_bound == 0) 31 return 0; 32 33 // Catch the possible integer overflow and also prevent the size of 34 // the Stream exceeding LZMA_VLI_MAX (theoretically possible on 35 // 64-bit systems). 36 if (my_min(SIZE_MAX, LZMA_VLI_MAX) - block_bound < HEADERS_BOUND) 37 return 0; 38 39 return block_bound + HEADERS_BOUND; 40 } 41 42 43 extern LZMA_API(lzma_ret) 44 lzma_stream_buffer_encode(lzma_filter *filters, lzma_check check, 45 const lzma_allocator *allocator, 46 const uint8_t *in, size_t in_size, 47 uint8_t *out, size_t *out_pos_ptr, size_t out_size) 48 { 49 // Sanity checks 50 if (filters == NULL || (unsigned int)(check) > LZMA_CHECK_ID_MAX 51 || (in == NULL && in_size != 0) || out == NULL 52 || out_pos_ptr == NULL || *out_pos_ptr > out_size) 53 return LZMA_PROG_ERROR; 54 55 if (!lzma_check_is_supported(check)) 56 return LZMA_UNSUPPORTED_CHECK; 57 58 // Note for the paranoids: Index encoder prevents the Stream from 59 // getting too big and still being accepted with LZMA_OK, and Block 60 // encoder catches if the input is too big. So we don't need to 61 // separately check if the buffers are too big. 62 63 // Use a local copy. We update *out_pos_ptr only if everything 64 // succeeds. 65 size_t out_pos = *out_pos_ptr; 66 67 // Check that there's enough space for both Stream Header and 68 // Stream Footer. 69 if (out_size - out_pos <= 2 * LZMA_STREAM_HEADER_SIZE) 70 return LZMA_BUF_ERROR; 71 72 // Reserve space for Stream Footer so we don't need to check for 73 // available space again before encoding Stream Footer. 74 out_size -= LZMA_STREAM_HEADER_SIZE; 75 76 // Encode the Stream Header. 77 lzma_stream_flags stream_flags = { 78 .version = 0, 79 .check = check, 80 }; 81 82 if (lzma_stream_header_encode(&stream_flags, out + out_pos) 83 != LZMA_OK) 84 return LZMA_PROG_ERROR; 85 86 out_pos += LZMA_STREAM_HEADER_SIZE; 87 88 // Encode a Block but only if there is at least one byte of input. 89 lzma_block block = { 90 .version = 0, 91 .check = check, 92 .filters = filters, 93 }; 94 95 if (in_size > 0) 96 return_if_error(lzma_block_buffer_encode(&block, allocator, 97 in, in_size, out, &out_pos, out_size)); 98 99 // Index 100 { 101 // Create an Index. It will have one Record if there was 102 // at least one byte of input to encode. Otherwise the 103 // Index will be empty. 104 lzma_index *i = lzma_index_init(allocator); 105 if (i == NULL) 106 return LZMA_MEM_ERROR; 107 108 lzma_ret ret = LZMA_OK; 109 110 if (in_size > 0) 111 ret = lzma_index_append(i, allocator, 112 lzma_block_unpadded_size(&block), 113 block.uncompressed_size); 114 115 // If adding the Record was successful, encode the Index 116 // and get its size which will be stored into Stream Footer. 117 if (ret == LZMA_OK) { 118 ret = lzma_index_buffer_encode( 119 i, out, &out_pos, out_size); 120 121 stream_flags.backward_size = lzma_index_size(i); 122 } 123 124 lzma_index_end(i, allocator); 125 126 if (ret != LZMA_OK) 127 return ret; 128 } 129 130 // Stream Footer. We have already reserved space for this. 131 if (lzma_stream_footer_encode(&stream_flags, out + out_pos) 132 != LZMA_OK) 133 return LZMA_PROG_ERROR; 134 135 out_pos += LZMA_STREAM_HEADER_SIZE; 136 137 // Everything went fine, make the new output position available 138 // to the application. 139 *out_pos_ptr = out_pos; 140 return LZMA_OK; 141 } 142