mirror of https://github.com/madler/zlib.git
Mark Adler
13 years ago
parent
913afb9174
commit
4ca984fb44
21 changed files with 186 additions and 353 deletions
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/* inflate.c -- zlib interface to inflate modules
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* Copyright (C) 1995 Mark Adler |
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* For conditions of distribution and use, see copyright notice in zlib.h
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*/ |
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#include "zutil.h" |
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#include "infblock.h" |
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struct inflate_blocks_state {int dummy;}; /* for buggy compilers */ |
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/* inflate private state */ |
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struct internal_state { |
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/* mode */ |
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enum { |
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METHOD, /* waiting for method byte */ |
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FLAG, /* waiting for flag byte */ |
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START, /* make new blocks state */ |
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BLOCKS, /* decompressing blocks */ |
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CHECK4, /* four check bytes to go */ |
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CHECK3, /* three check bytes to go */ |
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CHECK2, /* two check bytes to go */ |
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CHECK1, /* one check byte to go */ |
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DONE, /* finished check, done */ |
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ERROR} /* got an error--stay here */ |
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mode; /* current inflate mode */ |
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/* mode dependent information */ |
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union { |
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uInt method; /* if FLAGS, method byte */ |
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struct inflate_blocks_state |
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*blocks; /* if BLOCKS, current state */ |
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struct { |
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uLong was; /* computed check value */ |
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uLong need; /* stream check value */ |
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} check; /* if CHECK, check values to compare */ |
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} sub; /* submode */ |
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/* mode independent information */ |
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int nowrap; /* flag for no wrapper */ |
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uInt wbits; /* log2(window size) (8..15, defaults to 15) */ |
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}; |
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int inflateInit(z) |
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z_stream *z; |
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{ |
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return inflateInit2(z, WBITS); |
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} |
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int inflateInit2(z, w) |
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z_stream *z; |
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int w; |
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{ |
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/* initialize state */ |
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if (z == Z_NULL) |
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return Z_STREAM_ERROR; |
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if (z->zalloc == Z_NULL) z->zalloc = zcalloc; |
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if (z->zfree == Z_NULL) z->zfree = zcfree; |
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z->total_in = z->total_out = 0; |
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z->msg = Z_NULL; |
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if ((z->state = (struct internal_state *) |
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ZALLOC(z,1,sizeof(struct internal_state))) == Z_NULL) |
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return Z_MEM_ERROR; |
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z->state->mode = METHOD; |
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/* handle undocumented nowrap option (no zlib header or check) */ |
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z->state->nowrap = 0; |
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if (w < 0) |
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{ |
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w = - w; |
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z->state->nowrap = 1; |
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z->state->mode = START; |
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} |
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/* set window size */ |
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if (w < 8 || w > 15) |
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{ |
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inflateEnd(z); |
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return Z_STREAM_ERROR; |
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} |
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z->state->wbits = w; |
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return Z_OK; |
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} |
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#define NEXTBYTE (z->avail_in--,z->total_in++,*z->next_in++) |
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int inflate(z, f) |
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z_stream *z; |
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int f; |
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{ |
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int r; |
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uInt b; |
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uLong c; |
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if (z == Z_NULL || z->next_in == Z_NULL) |
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return Z_STREAM_ERROR; |
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r = Z_BUF_ERROR; |
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while (1) switch (z->state->mode) |
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{ |
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case METHOD: |
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if (z->avail_in == 0) return r; r = Z_OK; |
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if (((z->state->sub.method = NEXTBYTE) & 0xf != DEFLATED)) |
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{ |
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z->state->mode = ERROR; |
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z->msg = "unknown compression method"; |
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return Z_DATA_ERROR; |
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} |
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if ((z->state->sub.method >> 4) > z->state->wbits) |
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{ |
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z->state->mode = ERROR; |
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z->msg = "invalid window size"; |
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return Z_DATA_ERROR; |
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} |
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z->state->mode = FLAG; |
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case FLAG: |
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if (z->avail_in == 0) return r; r = Z_OK; |
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if ((b = NEXTBYTE) & 0x20) |
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{ |
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z->state->mode = ERROR; |
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z->msg = "invalid reserved bit"; |
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return Z_DATA_ERROR; |
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} |
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if (((z->state->sub.method << 8) + b) % 31) |
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{ |
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z->state->mode = ERROR; |
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z->msg = "incorrect header check"; |
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return Z_DATA_ERROR; |
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} |
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z->state->mode = START; |
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case START: |
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if ((z->state->sub.blocks = |
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inflate_blocks_new(z,1<< z->state->wbits)) == Z_NULL) |
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return Z_MEM_ERROR; |
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z->state->mode = BLOCKS; |
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case BLOCKS: |
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if ((r = inflate_blocks(z->state->sub.blocks, z, r)) != Z_STREAM_END) |
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return r; |
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inflate_blocks_free(z->state->sub.blocks, z, &c, &r); |
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if (z->state->nowrap) |
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{ |
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if (r != -1) |
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z->msg = "inflate bug--took one too many bytes"; |
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z->state->mode = r == -1 ? DONE : ERROR; |
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break; |
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} |
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z->state->sub.check.was = c; |
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if (r != -1) |
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{ |
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z->state->sub.check.need = (uLong)r << 24; |
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z->state->mode = CHECK3; |
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r = Z_OK; |
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break; |
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} |
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r = Z_OK; |
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z->state->mode = CHECK4; |
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case CHECK4: |
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if (z->avail_in == 0) return r; r = Z_OK; |
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z->state->sub.check.need = (uLong)NEXTBYTE << 24; |
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z->state->mode = CHECK3; |
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case CHECK3: |
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if (z->avail_in == 0) return r; r = Z_OK; |
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z->state->sub.check.need += (uLong)NEXTBYTE << 16; |
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z->state->mode = CHECK2; |
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case CHECK2: |
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if (z->avail_in == 0) return r; r = Z_OK; |
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z->state->sub.check.need += (uLong)NEXTBYTE << 8; |
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z->state->mode = CHECK1; |
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case CHECK1: |
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if (z->avail_in == 0) return r; r = Z_OK; |
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z->state->sub.check.need += (uLong)NEXTBYTE; |
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if (z->state->sub.check.was != z->state->sub.check.need) |
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{ |
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z->state->mode = ERROR; |
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z->msg = "incorrect data check"; |
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return Z_DATA_ERROR; |
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} |
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z->state->mode = DONE; |
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case DONE: |
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return Z_STREAM_END; |
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case ERROR: |
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return Z_DATA_ERROR; |
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default: |
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return Z_STREAM_ERROR; |
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} |
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} |
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int inflateEnd(z) |
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z_stream *z; |
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{ |
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uLong c; |
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int e; |
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if (z == Z_NULL || z->state == Z_NULL || z->zfree == Z_NULL) |
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return Z_STREAM_ERROR; |
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if (z->state->mode == BLOCKS) |
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inflate_blocks_free(z->state->sub.blocks, z, &c, &e); |
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ZFREE(z, z->state); |
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z->state = Z_NULL; |
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return Z_OK; |
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} |
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/* inflateSync not implemented yet--this just consumes input */ |
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int inflateSync(z) |
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z_stream *z; |
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{ |
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if (z == Z_NULL) return Z_STREAM_ERROR; |
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if (z->avail_in == 0) return Z_BUF_ERROR; |
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do { |
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z->total_in++; |
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} while (--z->avail_in); |
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return Z_DATA_ERROR; |
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} |
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/* inflateReset not fully implemented yet--this frees and reallocates */ |
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int inflateReset(z) |
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z_stream *z; |
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{ |
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int r; |
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if ((r = inflateEnd(z)) != Z_OK) |
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return r; |
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return inflateInit(z); |
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} |
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