| 1 | /* compress.c -- compress a memory buffer |
| 2 | * Copyright (C) 1995-2005, 2014, 2016 Jean-loup Gailly, Mark Adler |
| 3 | * For conditions of distribution and use, see copyright notice in zlib.h |
| 4 | */ |
| 5 | |
| 6 | /* @(#) $Id$ */ |
| 7 | |
| 8 | #define ZLIB_INTERNAL |
| 9 | #include "zlib.h" |
| 10 | |
| 11 | /* =========================================================================== |
| 12 | Compresses the source buffer into the destination buffer. The level |
| 13 | parameter has the same meaning as in deflateInit. sourceLen is the byte |
| 14 | length of the source buffer. Upon entry, destLen is the total size of the |
| 15 | destination buffer, which must be at least 0.1% larger than sourceLen plus |
| 16 | 12 bytes. Upon exit, destLen is the actual size of the compressed buffer. |
| 17 | |
| 18 | compress2 returns Z_OK if success, Z_MEM_ERROR if there was not enough |
| 19 | memory, Z_BUF_ERROR if there was not enough room in the output buffer, |
| 20 | Z_STREAM_ERROR if the level parameter is invalid. |
| 21 | */ |
| 22 | int ZEXPORT compress2(Bytef *dest, uLongf *destLen, const Bytef *source, |
| 23 | uLong sourceLen, int level) { |
| 24 | z_stream stream; |
| 25 | int err; |
| 26 | const uInt max = (uInt)-1; |
| 27 | uLong left; |
| 28 | |
| 29 | left = *destLen; |
| 30 | *destLen = 0; |
| 31 | |
| 32 | stream.zalloc = (alloc_func)0; |
| 33 | stream.zfree = (free_func)0; |
| 34 | stream.opaque = (voidpf)0; |
| 35 | |
| 36 | err = deflateInit(&stream, level); |
| 37 | if (err != Z_OK) return err; |
| 38 | |
| 39 | stream.next_out = dest; |
| 40 | stream.avail_out = 0; |
| 41 | stream.next_in = (z_const Bytef *)source; |
| 42 | stream.avail_in = 0; |
| 43 | |
| 44 | do { |
| 45 | if (stream.avail_out == 0) { |
| 46 | stream.avail_out = left > (uLong)max ? max : (uInt)left; |
| 47 | left -= stream.avail_out; |
| 48 | } |
| 49 | if (stream.avail_in == 0) { |
| 50 | stream.avail_in = sourceLen > (uLong)max ? max : (uInt)sourceLen; |
| 51 | sourceLen -= stream.avail_in; |
| 52 | } |
| 53 | err = deflate(&stream, sourceLen ? Z_NO_FLUSH : Z_FINISH); |
| 54 | } while (err == Z_OK); |
| 55 | |
| 56 | *destLen = stream.total_out; |
| 57 | deflateEnd(&stream); |
| 58 | return err == Z_STREAM_END ? Z_OK : err; |
| 59 | } |
| 60 | |
| 61 | /* =========================================================================== |
| 62 | */ |
| 63 | int ZEXPORT compress(Bytef *dest, uLongf *destLen, const Bytef *source, |
| 64 | uLong sourceLen) { |
| 65 | return compress2(dest, destLen, source, sourceLen, Z_DEFAULT_COMPRESSION); |
| 66 | } |
| 67 | |
| 68 | /* =========================================================================== |
| 69 | If the default memLevel or windowBits for deflateInit() is changed, then |
| 70 | this function needs to be updated. |
| 71 | */ |
| 72 | uLong ZEXPORT compressBound(uLong sourceLen) { |
| 73 | return sourceLen + (sourceLen >> 12) + (sourceLen >> 14) + |
| 74 | (sourceLen >> 25) + 13; |
| 75 | } |