ref: a81cf5aade126184e52ac6a2a9fd36b718b9038c
dir: /src/gzip/inflate.c/
/* inflate.c -- zlib interface to inflate modules * Copyright (C) 1995-2002 Mark Adler * For conditions of distribution and use, see copyright notice in zlib.h */ #include "zutil.h" #include "infblock.h" #define DONE INFLATE_DONE #define BAD INFLATE_BAD typedef enum { METHOD, /* waiting for method byte */ FLAG, /* waiting for flag byte */ DICT4, /* four dictionary check bytes to go */ DICT3, /* three dictionary check bytes to go */ DICT2, /* two dictionary check bytes to go */ DICT1, /* one dictionary check byte to go */ DICT0, /* waiting for inflateSetDictionary */ BLOCKS, /* decompressing blocks */ CHECK4, /* four check bytes to go */ CHECK3, /* three check bytes to go */ CHECK2, /* two check bytes to go */ CHECK1, /* one check byte to go */ DONE, /* finished check, done */ BAD} /* got an error--stay here */ inflate_mode; /* inflate private state */ struct internal_state { /* mode */ inflate_mode mode; /* current inflate mode */ /* mode dependent information */ union { uInt method; /* if FLAGS, method byte */ struct { uLong was; /* computed check value */ uLong need; /* stream check value */ } check; /* if CHECK, check values to compare */ uInt marker; /* if BAD, inflateSync's marker bytes count */ } sub; /* submode */ /* mode independent information */ int nowrap; /* flag for no wrapper */ uInt wbits; /* log2(window size) (8..15, defaults to 15) */ inflate_blocks_statef *blocks; /* current inflate_blocks state */ }; ZEXPORT(int) inflateReset( /* z) */ z_streamp z ) { if (z == Z_NULL || z->state == Z_NULL) return Z_STREAM_ERROR; z->total_in = z->total_out = 0; z->msg = Z_NULL; z->state->mode = z->state->nowrap ? BLOCKS : METHOD; inflate_blocks_reset(z->state->blocks, z, Z_NULL); Tracev((stderr, "inflate: reset\n")); return Z_OK; } ZEXPORT(int) inflateEnd( /* z) */ z_streamp z ) { if (z == Z_NULL || z->state == Z_NULL || z->zfree == Z_NULL) return Z_STREAM_ERROR; if (z->state->blocks != Z_NULL) inflate_blocks_free(z->state->blocks, z); ZFREE(z, z->state); z->state = Z_NULL; Tracev((stderr, "inflate: end\n")); return Z_OK; } ZEXPORT(int) inflateInit2_( /* z, w, version, stream_size) */ z_streamp z, int w, const char *version, int stream_size ) { if (version == Z_NULL || version[0] != ZLIB_VERSION[0] || stream_size != sizeof(z_stream)) return Z_VERSION_ERROR; /* initialize state */ if (z == Z_NULL) return Z_STREAM_ERROR; z->msg = Z_NULL; if (z->zalloc == Z_NULL) { z->zalloc = zcalloc; z->opaque = (voidpf)0; } if (z->zfree == Z_NULL) z->zfree = zcfree; if ((z->state = (struct internal_state FAR *) ZALLOC(z,1,sizeof(struct internal_state))) == Z_NULL) return Z_MEM_ERROR; z->state->blocks = Z_NULL; /* handle undocumented nowrap option (no zlib header or check) */ z->state->nowrap = 0; if (w < 0) { w = - w; z->state->nowrap = 1; } /* set window size */ if (w < 8 || w > 15) { inflateEnd(z); return Z_STREAM_ERROR; } z->state->wbits = (uInt)w; /* create inflate_blocks state */ if ((z->state->blocks = inflate_blocks_new(z, z->state->nowrap ? Z_NULL : adler32, (uInt)1 << w)) == Z_NULL) { inflateEnd(z); return Z_MEM_ERROR; } Tracev((stderr, "inflate: allocated\n")); /* reset state */ inflateReset(z); return Z_OK; } #undef NEEDBYTE #define NEEDBYTE {if(z->avail_in==0)return r;r=f;} #undef NEXTBYTE #define NEXTBYTE (z->avail_in--,z->total_in++,*z->next_in++) ZEXPORT(int) inflate( /* z, f) */ z_streamp z, int f ) { int r; uInt b; if (z == Z_NULL || z->state == Z_NULL || z->next_in == Z_NULL) return Z_STREAM_ERROR; f = f == Z_FINISH ? Z_BUF_ERROR : Z_OK; r = Z_BUF_ERROR; while (1) switch (z->state->mode) { case METHOD: NEEDBYTE if (((z->state->sub.method = NEXTBYTE) & 0xf) != Z_DEFLATED) { z->state->mode = BAD; z->msg = (char*)"unknown compression method"; z->state->sub.marker = 5; /* can't try inflateSync */ break; } if ((z->state->sub.method >> 4) + 8 > z->state->wbits) { z->state->mode = BAD; z->msg = (char*)"invalid window size"; z->state->sub.marker = 5; /* can't try inflateSync */ break; } z->state->mode = FLAG; /* fall through */ case FLAG: NEEDBYTE b = NEXTBYTE; if (((z->state->sub.method << 8) + b) % 31) { z->state->mode = BAD; z->msg = (char*)"incorrect header check"; z->state->sub.marker = 5; /* can't try inflateSync */ break; } Tracev((stderr, "inflate: zlib header ok\n")); if (!(b & PRESET_DICT)) { z->state->mode = BLOCKS; break; } z->state->mode = DICT4; /* fall through */ case DICT4: NEEDBYTE z->state->sub.check.need = (uLong)NEXTBYTE << 24; z->state->mode = DICT3; /* fall through */ case DICT3: NEEDBYTE z->state->sub.check.need += (uLong)NEXTBYTE << 16; z->state->mode = DICT2; /* fall through */ case DICT2: NEEDBYTE z->state->sub.check.need += (uLong)NEXTBYTE << 8; z->state->mode = DICT1; /* fall through */ case DICT1: NEEDBYTE z->state->sub.check.need += (uLong)NEXTBYTE; z->adler = z->state->sub.check.need; z->state->mode = DICT0; return Z_NEED_DICT; case DICT0: z->state->mode = BAD; z->msg = (char*)"need dictionary"; z->state->sub.marker = 0; /* can try inflateSync */ return Z_STREAM_ERROR; case BLOCKS: r = inflate_blocks(z->state->blocks, z, r); if (r == Z_DATA_ERROR) { z->state->mode = BAD; z->state->sub.marker = 0; /* can try inflateSync */ break; } if (r == Z_OK) r = f; if (r != Z_STREAM_END) return r; r = f; inflate_blocks_reset(z->state->blocks, z, &z->state->sub.check.was); if (z->state->nowrap) { z->state->mode = DONE; break; } z->state->mode = CHECK4; /* fall through */ case CHECK4: NEEDBYTE z->state->sub.check.need = (uLong)NEXTBYTE << 24; z->state->mode = CHECK3; /* fall through */ case CHECK3: NEEDBYTE z->state->sub.check.need += (uLong)NEXTBYTE << 16; z->state->mode = CHECK2; /* fall through */ case CHECK2: NEEDBYTE z->state->sub.check.need += (uLong)NEXTBYTE << 8; z->state->mode = CHECK1; /* fall through */ case CHECK1: NEEDBYTE z->state->sub.check.need += (uLong)NEXTBYTE; if (z->state->sub.check.was != z->state->sub.check.need) { z->state->mode = BAD; z->msg = (char*)"incorrect data check"; z->state->sub.marker = 5; /* can't try inflateSync */ break; } Tracev((stderr, "inflate: zlib check ok\n")); z->state->mode = DONE; /* fall through */ case DONE: return Z_STREAM_END; case BAD: return Z_DATA_ERROR; default: return Z_STREAM_ERROR; } #ifdef NEED_DUMMY_RETURN return Z_STREAM_ERROR; /* Some dumb compilers complain without this */ #endif }