3
* Copyright (C) 2002-2010 Mark Adler
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* For conditions of distribution and use, see copyright notice in puff.h
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* version 2.1, 4 Apr 2010
7
* puff.c is a simple inflate written to be an unambiguous way to specify the
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* deflate format. It is not written for speed but rather simplicity. As a
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* side benefit, this code might actually be useful when small code is more
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* important than speed, such as bootstrap applications. For typical deflate
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* data, zlib's inflate() is about four times as fast as puff(). zlib's
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* inflate compiles to around 20K on my machine, whereas puff.c compiles to
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* around 4K on my machine (a PowerPC using GNU cc). If the faster decode()
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* function here is used, then puff() is only twice as slow as zlib's
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* All dynamically allocated memory comes from the stack. The stack required
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* is less than 2K bytes. This code is compatible with 16-bit int's and
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* assumes that long's are at least 32 bits. puff.c uses the short data type,
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* assumed to be 16 bits, for arrays in order to to conserve memory. The code
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* works whether integers are stored big endian or little endian.
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* In the comments below are "Format notes" that describe the inflate process
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* and document some of the less obvious aspects of the format. This source
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* code is meant to supplement RFC 1951, which formally describes the deflate
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* http://www.zlib.org/rfc-deflate.html
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* 1.0 10 Feb 2002 - First version
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* 1.1 17 Feb 2002 - Clarifications of some comments and notes
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* - Update puff() dest and source pointers on negative
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* errors to facilitate debugging deflators
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* - Remove longest from struct huffman -- not needed
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* - Simplify offs[] index in construct()
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* - Add input size and checking, using longjmp() to
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* maintain easy readability
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* - Use short data type for large arrays
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* - Use pointers instead of long to specify source and
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* destination sizes to avoid arbitrary 4 GB limits
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* 1.2 17 Mar 2002 - Add faster version of decode(), doubles speed (!),
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* but leave simple version for readabilty
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* - Make sure invalid distances detected if pointers
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* - Fix fixed codes table error
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* - Provide a scanning mode for determining size of
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* 1.3 20 Mar 2002 - Go back to lengths for puff() parameters [Jean-loup]
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* - Add a puff.h file for the interface
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* - Add braces in puff() for else do [Jean-loup]
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* - Use indexes instead of pointers for readability
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* 1.4 31 Mar 2002 - Simplify construct() code set check
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* - Add FIXLCODES #define
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* 1.5 6 Apr 2002 - Minor comment fixes
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* 1.6 7 Aug 2002 - Minor format changes
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* 1.7 3 Mar 2003 - Added test code for distribution
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* - Added zlib-like license
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* 1.8 9 Jan 2004 - Added some comments on no distance codes case
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* 1.9 21 Feb 2008 - Fix bug on 16-bit integer architectures [Pohland]
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* - Catch missing end-of-block symbol error
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* 2.0 25 Jul 2008 - Add #define to permit distance too far back
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* - Add option in TEST code for puff to write the data
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* - Add option in TEST code to skip input bytes
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* - Allow TEST code to read from piped stdin
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* 2.1 4 Apr 2010 - Avoid variable initialization for happier compilers
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* - Avoid unsigned comparisons for even happier compilers
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#include <setjmp.h> /* for setjmp(), longjmp(), and jmp_buf */
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#include "puff.h" /* prototype for puff() */
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#define local static /* for local function definitions */
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#define NIL ((unsigned char *)0) /* for no output option */
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* Maximums for allocations and loops. It is not useful to change these --
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* they are fixed by the deflate format.
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#define MAXBITS 15 /* maximum bits in a code */
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#define MAXLCODES 286 /* maximum number of literal/length codes */
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#define MAXDCODES 30 /* maximum number of distance codes */
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#define MAXCODES (MAXLCODES+MAXDCODES) /* maximum codes lengths to read */
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#define FIXLCODES 288 /* number of fixed literal/length codes */
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/* input and output state */
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unsigned char *out; /* output buffer */
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unsigned long outlen; /* available space at out */
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unsigned long outcnt; /* bytes written to out so far */
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unsigned char *in; /* input buffer */
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unsigned long inlen; /* available input at in */
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unsigned long incnt; /* bytes read so far */
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int bitbuf; /* bit buffer */
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int bitcnt; /* number of bits in bit buffer */
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/* input limit error return state for bits() and decode() */
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* Return need bits from the input stream. This always leaves less than
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* eight bits in the buffer. bits() works properly for need == 0.
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* - Bits are stored in bytes from the least significant bit to the most
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* significant bit. Therefore bits are dropped from the bottom of the bit
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* buffer, using shift right, and new bytes are appended to the top of the
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* bit buffer, using shift left.
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local int bits(struct state *s, int need)
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long val; /* bit accumulator (can use up to 20 bits) */
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/* load at least need bits into val */
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while (s->bitcnt < need) {
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if (s->incnt == s->inlen) longjmp(s->env, 1); /* out of input */
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val |= (long)(s->in[s->incnt++]) << s->bitcnt; /* load eight bits */
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/* drop need bits and update buffer, always zero to seven bits left */
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s->bitbuf = (int)(val >> need);
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/* return need bits, zeroing the bits above that */
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return (int)(val & ((1L << need) - 1));
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* Process a stored block.
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* - After the two-bit stored block type (00), the stored block length and
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* stored bytes are byte-aligned for fast copying. Therefore any leftover
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* bits in the byte that has the last bit of the type, as many as seven, are
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* discarded. The value of the discarded bits are not defined and should not
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* be checked against any expectation.
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* - The second inverted copy of the stored block length does not have to be
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* checked, but it's probably a good idea to do so anyway.
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* - A stored block can have zero length. This is sometimes used to byte-align
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* subsets of the compressed data for random access or partial recovery.
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local int stored(struct state *s)
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unsigned len; /* length of stored block */
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/* discard leftover bits from current byte (assumes s->bitcnt < 8) */
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/* get length and check against its one's complement */
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if (s->incnt + 4 > s->inlen) return 2; /* not enough input */
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len = s->in[s->incnt++];
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len |= s->in[s->incnt++] << 8;
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if (s->in[s->incnt++] != (~len & 0xff) ||
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s->in[s->incnt++] != ((~len >> 8) & 0xff))
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return -2; /* didn't match complement! */
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/* copy len bytes from in to out */
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if (s->incnt + len > s->inlen) return 2; /* not enough input */
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if (s->outcnt + len > s->outlen)
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return 1; /* not enough output space */
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s->out[s->outcnt++] = s->in[s->incnt++];
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else { /* just scanning */
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/* done with a valid stored block */
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* Huffman code decoding tables. count[1..MAXBITS] is the number of symbols of
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* each length, which for a canonical code are stepped through in order.
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* symbol[] are the symbol values in canonical order, where the number of
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* entries is the sum of the counts in count[]. The decoding process can be
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* seen in the function decode() below.
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short *count; /* number of symbols of each length */
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short *symbol; /* canonically ordered symbols */
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* Decode a code from the stream s using huffman table h. Return the symbol or
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* a negative value if there is an error. If all of the lengths are zero, i.e.
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* an empty code, or if the code is incomplete and an invalid code is received,
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* then -10 is returned after reading MAXBITS bits.
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* - The codes as stored in the compressed data are bit-reversed relative to
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* a simple integer ordering of codes of the same lengths. Hence below the
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* bits are pulled from the compressed data one at a time and used to
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* build the code value reversed from what is in the stream in order to
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* permit simple integer comparisons for decoding. A table-based decoding
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* scheme (as used in zlib) does not need to do this reversal.
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* - The first code for the shortest length is all zeros. Subsequent codes of
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* the same length are simply integer increments of the previous code. When
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* moving up a length, a zero bit is appended to the code. For a complete
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* code, the last code of the longest length will be all ones.
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* - Incomplete codes are handled by this decoder, since they are permitted
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* in the deflate format. See the format notes for fixed() and dynamic().
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local int decode(struct state *s, struct huffman *h)
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int len; /* current number of bits in code */
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int code; /* len bits being decoded */
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int first; /* first code of length len */
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int count; /* number of codes of length len */
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int index; /* index of first code of length len in symbol table */
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code = first = index = 0;
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for (len = 1; len <= MAXBITS; len++) {
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code |= bits(s, 1); /* get next bit */
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count = h->count[len];
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if (code - count < first) /* if length len, return symbol */
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return h->symbol[index + (code - first)];
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index += count; /* else update for next length */
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return -10; /* ran out of codes */
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* A faster version of decode() for real applications of this code. It's not
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* as readable, but it makes puff() twice as fast. And it only makes the code
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* a few percent larger.
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local int decode(struct state *s, struct huffman *h)
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int len; /* current number of bits in code */
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int code; /* len bits being decoded */
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int first; /* first code of length len */
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int count; /* number of codes of length len */
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int index; /* index of first code of length len in symbol table */
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int bitbuf; /* bits from stream */
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int left; /* bits left in next or left to process */
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short *next; /* next number of codes */
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code = first = index = 0;
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if (code - count < first) { /* if length len, return symbol */
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s->bitcnt = (s->bitcnt - len) & 7;
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return h->symbol[index + (code - first)];
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index += count; /* else update for next length */
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left = (MAXBITS+1) - len;
286
if (left == 0) break;
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if (s->incnt == s->inlen) longjmp(s->env, 1); /* out of input */
288
bitbuf = s->in[s->incnt++];
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if (left > 8) left = 8;
291
return -10; /* ran out of codes */
296
* Given the list of code lengths length[0..n-1] representing a canonical
297
* Huffman code for n symbols, construct the tables required to decode those
298
* codes. Those tables are the number of codes of each length, and the symbols
299
* sorted by length, retaining their original order within each length. The
300
* return value is zero for a complete code set, negative for an over-
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* subscribed code set, and positive for an incomplete code set. The tables
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* can be used if the return value is zero or positive, but they cannot be used
303
* if the return value is negative. If the return value is zero, it is not
304
* possible for decode() using that table to return an error--any stream of
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* enough bits will resolve to a symbol. If the return value is positive, then
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* it is possible for decode() using that table to return an error for received
307
* codes past the end of the incomplete lengths.
309
* Not used by decode(), but used for error checking, h->count[0] is the number
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* of the n symbols not in the code. So n - h->count[0] is the number of
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* codes. This is useful for checking for incomplete codes that have more than
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* one symbol, which is an error in a dynamic block.
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* Assumption: for all i in 0..n-1, 0 <= length[i] <= MAXBITS
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* This is assured by the construction of the length arrays in dynamic() and
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* fixed() and is not verified by construct().
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* - Permitted and expected examples of incomplete codes are one of the fixed
321
* codes and any code with a single symbol which in deflate is coded as one
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* bit instead of zero bits. See the format notes for fixed() and dynamic().
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* - Within a given code length, the symbols are kept in ascending order for
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* the code bits definition.
327
local int construct(struct huffman *h, short *length, int n)
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int symbol; /* current symbol when stepping through length[] */
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int len; /* current length when stepping through h->count[] */
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int left; /* number of possible codes left of current length */
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short offs[MAXBITS+1]; /* offsets in symbol table for each length */
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/* count number of codes of each length */
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for (len = 0; len <= MAXBITS; len++)
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for (symbol = 0; symbol < n; symbol++)
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(h->count[length[symbol]])++; /* assumes lengths are within bounds */
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if (h->count[0] == n) /* no codes! */
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return 0; /* complete, but decode() will fail */
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/* check for an over-subscribed or incomplete set of lengths */
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left = 1; /* one possible code of zero length */
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for (len = 1; len <= MAXBITS; len++) {
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left <<= 1; /* one more bit, double codes left */
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left -= h->count[len]; /* deduct count from possible codes */
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if (left < 0) return left; /* over-subscribed--return negative */
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} /* left > 0 means incomplete */
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/* generate offsets into symbol table for each length for sorting */
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for (len = 1; len < MAXBITS; len++)
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offs[len + 1] = offs[len] + h->count[len];
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* put symbols in table sorted by length, by symbol order within each
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for (symbol = 0; symbol < n; symbol++)
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if (length[symbol] != 0)
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h->symbol[offs[length[symbol]]++] = symbol;
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/* return zero for complete set, positive for incomplete set */
368
* Decode literal/length and distance codes until an end-of-block code.
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* - Compressed data that is after the block type if fixed or after the code
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* description if dynamic is a combination of literals and length/distance
374
* pairs terminated by and end-of-block code. Literals are simply Huffman
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* coded bytes. A length/distance pair is a coded length followed by a
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* coded distance to represent a string that occurs earlier in the
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* uncompressed data that occurs again at the current location.
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* - Literals, lengths, and the end-of-block code are combined into a single
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* code of up to 286 symbols. They are 256 literals (0..255), 29 length
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* symbols (257..285), and the end-of-block symbol (256).
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* - There are 256 possible lengths (3..258), and so 29 symbols are not enough
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* to represent all of those. Lengths 3..10 and 258 are in fact represented
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* by just a length symbol. Lengths 11..257 are represented as a symbol and
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* some number of extra bits that are added as an integer to the base length
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* of the length symbol. The number of extra bits is determined by the base
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* length symbol. These are in the static arrays below, lens[] for the base
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* lengths and lext[] for the corresponding number of extra bits.
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* - The reason that 258 gets its own symbol is that the longest length is used
392
* often in highly redundant files. Note that 258 can also be coded as the
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* base value 227 plus the maximum extra value of 31. While a good deflate
394
* should never do this, it is not an error, and should be decoded properly.
396
* - If a length is decoded, including its extra bits if any, then it is
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* followed a distance code. There are up to 30 distance symbols. Again
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* there are many more possible distances (1..32768), so extra bits are added
399
* to a base value represented by the symbol. The distances 1..4 get their
400
* own symbol, but the rest require extra bits. The base distances and
401
* corresponding number of extra bits are below in the static arrays dist[]
404
* - Literal bytes are simply written to the output. A length/distance pair is
405
* an instruction to copy previously uncompressed bytes to the output. The
406
* copy is from distance bytes back in the output stream, copying for length
409
* - Distances pointing before the beginning of the output data are not
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* - Overlapped copies, where the length is greater than the distance, are
413
* allowed and common. For example, a distance of one and a length of 258
414
* simply copies the last byte 258 times. A distance of four and a length of
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* twelve copies the last four bytes three times. A simple forward copy
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* ignoring whether the length is greater than the distance or not implements
417
* this correctly. You should not use memcpy() since its behavior is not
418
* defined for overlapped arrays. You should not use memmove() or bcopy()
419
* since though their behavior -is- defined for overlapping arrays, it is
420
* defined to do the wrong thing in this case.
422
local int codes(struct state *s,
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struct huffman *lencode,
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struct huffman *distcode)
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int symbol; /* decoded symbol */
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int len; /* length for copy */
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unsigned dist; /* distance for copy */
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static const short lens[29] = { /* Size base for length codes 257..285 */
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3, 4, 5, 6, 7, 8, 9, 10, 11, 13, 15, 17, 19, 23, 27, 31,
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35, 43, 51, 59, 67, 83, 99, 115, 131, 163, 195, 227, 258};
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static const short lext[29] = { /* Extra bits for length codes 257..285 */
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0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 2, 2, 2, 2,
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3, 3, 3, 3, 4, 4, 4, 4, 5, 5, 5, 5, 0};
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static const short dists[30] = { /* Offset base for distance codes 0..29 */
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1, 2, 3, 4, 5, 7, 9, 13, 17, 25, 33, 49, 65, 97, 129, 193,
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257, 385, 513, 769, 1025, 1537, 2049, 3073, 4097, 6145,
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8193, 12289, 16385, 24577};
439
static const short dext[30] = { /* Extra bits for distance codes 0..29 */
440
0, 0, 0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6,
441
7, 7, 8, 8, 9, 9, 10, 10, 11, 11,
444
/* decode literals and length/distance pairs */
446
symbol = decode(s, lencode);
447
if (symbol < 0) return symbol; /* invalid symbol */
448
if (symbol < 256) { /* literal: symbol is the byte */
449
/* write out the literal */
451
if (s->outcnt == s->outlen) return 1;
452
s->out[s->outcnt] = symbol;
456
else if (symbol > 256) { /* length */
457
/* get and compute length */
459
if (symbol >= 29) return -10; /* invalid fixed code */
460
len = lens[symbol] + bits(s, lext[symbol]);
462
/* get and check distance */
463
symbol = decode(s, distcode);
464
if (symbol < 0) return symbol; /* invalid symbol */
465
dist = dists[symbol] + bits(s, dext[symbol]);
466
#ifndef INFLATE_ALLOW_INVALID_DISTANCE_TOOFAR_ARRR
467
if (dist > s->outcnt)
468
return -11; /* distance too far back */
471
/* copy length bytes from distance bytes back */
473
if (s->outcnt + len > s->outlen) return 1;
476
#ifdef INFLATE_ALLOW_INVALID_DISTANCE_TOOFAR_ARRR
477
dist > s->outcnt ? 0 :
479
s->out[s->outcnt - dist];
486
} while (symbol != 256); /* end of block symbol */
488
/* done with a valid fixed or dynamic block */
493
* Process a fixed codes block.
497
* - This block type can be useful for compressing small amounts of data for
498
* which the size of the code descriptions in a dynamic block exceeds the
499
* benefit of custom codes for that block. For fixed codes, no bits are
500
* spent on code descriptions. Instead the code lengths for literal/length
501
* codes and distance codes are fixed. The specific lengths for each symbol
502
* can be seen in the "for" loops below.
504
* - The literal/length code is complete, but has two symbols that are invalid
505
* and should result in an error if received. This cannot be implemented
506
* simply as an incomplete code since those two symbols are in the "middle"
507
* of the code. They are eight bits long and the longest literal/length\
508
* code is nine bits. Therefore the code must be constructed with those
509
* symbols, and the invalid symbols must be detected after decoding.
511
* - The fixed distance codes also have two invalid symbols that should result
512
* in an error if received. Since all of the distance codes are the same
513
* length, this can be implemented as an incomplete code. Then the invalid
514
* codes are detected while decoding.
516
local int fixed(struct state *s)
518
static int virgin = 1;
519
static short lencnt[MAXBITS+1], lensym[FIXLCODES];
520
static short distcnt[MAXBITS+1], distsym[MAXDCODES];
521
static struct huffman lencode, distcode;
523
/* build fixed huffman tables if first call (may not be thread safe) */
526
short lengths[FIXLCODES];
528
/* literal/length table */
529
for (symbol = 0; symbol < 144; symbol++)
531
for (; symbol < 256; symbol++)
533
for (; symbol < 280; symbol++)
535
for (; symbol < FIXLCODES; symbol++)
537
construct(&lencode, lengths, FIXLCODES);
540
for (symbol = 0; symbol < MAXDCODES; symbol++)
542
construct(&distcode, lengths, MAXDCODES);
544
/* construct lencode and distcode */
545
lencode.count = lencnt;
546
lencode.symbol = lensym;
547
distcode.count = distcnt;
548
distcode.symbol = distsym;
550
/* do this just once */
554
/* decode data until end-of-block code */
555
return codes(s, &lencode, &distcode);
559
* Process a dynamic codes block.
563
* - A dynamic block starts with a description of the literal/length and
564
* distance codes for that block. New dynamic blocks allow the compressor to
565
* rapidly adapt to changing data with new codes optimized for that data.
567
* - The codes used by the deflate format are "canonical", which means that
568
* the actual bits of the codes are generated in an unambiguous way simply
569
* from the number of bits in each code. Therefore the code descriptions
570
* are simply a list of code lengths for each symbol.
572
* - The code lengths are stored in order for the symbols, so lengths are
573
* provided for each of the literal/length symbols, and for each of the
576
* - If a symbol is not used in the block, this is represented by a zero as
577
* as the code length. This does not mean a zero-length code, but rather
578
* that no code should be created for this symbol. There is no way in the
579
* deflate format to represent a zero-length code.
581
* - The maximum number of bits in a code is 15, so the possible lengths for
582
* any code are 1..15.
584
* - The fact that a length of zero is not permitted for a code has an
585
* interesting consequence. Normally if only one symbol is used for a given
586
* code, then in fact that code could be represented with zero bits. However
587
* in deflate, that code has to be at least one bit. So for example, if
588
* only a single distance base symbol appears in a block, then it will be
589
* represented by a single code of length one, in particular one 0 bit. This
590
* is an incomplete code, since if a 1 bit is received, it has no meaning,
591
* and should result in an error. So incomplete distance codes of one symbol
592
* should be permitted, and the receipt of invalid codes should be handled.
594
* - It is also possible to have a single literal/length code, but that code
595
* must be the end-of-block code, since every dynamic block has one. This
596
* is not the most efficient way to create an empty block (an empty fixed
597
* block is fewer bits), but it is allowed by the format. So incomplete
598
* literal/length codes of one symbol should also be permitted.
600
* - If there are only literal codes and no lengths, then there are no distance
601
* codes. This is represented by one distance code with zero bits.
603
* - The list of up to 286 length/literal lengths and up to 30 distance lengths
604
* are themselves compressed using Huffman codes and run-length encoding. In
605
* the list of code lengths, a 0 symbol means no code, a 1..15 symbol means
606
* that length, and the symbols 16, 17, and 18 are run-length instructions.
607
* Each of 16, 17, and 18 are follwed by extra bits to define the length of
608
* the run. 16 copies the last length 3 to 6 times. 17 represents 3 to 10
609
* zero lengths, and 18 represents 11 to 138 zero lengths. Unused symbols
610
* are common, hence the special coding for zero lengths.
612
* - The symbols for 0..18 are Huffman coded, and so that code must be
613
* described first. This is simply a sequence of up to 19 three-bit values
614
* representing no code (0) or the code length for that symbol (1..7).
616
* - A dynamic block starts with three fixed-size counts from which is computed
617
* the number of literal/length code lengths, the number of distance code
618
* lengths, and the number of code length code lengths (ok, you come up with
619
* a better name!) in the code descriptions. For the literal/length and
620
* distance codes, lengths after those provided are considered zero, i.e. no
621
* code. The code length code lengths are received in a permuted order (see
622
* the order[] array below) to make a short code length code length list more
623
* likely. As it turns out, very short and very long codes are less likely
624
* to be seen in a dynamic code description, hence what may appear initially
625
* to be a peculiar ordering.
627
* - Given the number of literal/length code lengths (nlen) and distance code
628
* lengths (ndist), then they are treated as one long list of nlen + ndist
629
* code lengths. Therefore run-length coding can and often does cross the
630
* boundary between the two sets of lengths.
632
* - So to summarize, the code description at the start of a dynamic block is
633
* three counts for the number of code lengths for the literal/length codes,
634
* the distance codes, and the code length codes. This is followed by the
635
* code length code lengths, three bits each. This is used to construct the
636
* code length code which is used to read the remainder of the lengths. Then
637
* the literal/length code lengths and distance lengths are read as a single
638
* set of lengths using the code length codes. Codes are constructed from
639
* the resulting two sets of lengths, and then finally you can start
640
* decoding actual compressed data in the block.
642
* - For reference, a "typical" size for the code description in a dynamic
643
* block is around 80 bytes.
645
local int dynamic(struct state *s)
647
int nlen, ndist, ncode; /* number of lengths in descriptor */
648
int index; /* index of lengths[] */
649
int err; /* construct() return value */
650
short lengths[MAXCODES]; /* descriptor code lengths */
651
short lencnt[MAXBITS+1], lensym[MAXLCODES]; /* lencode memory */
652
short distcnt[MAXBITS+1], distsym[MAXDCODES]; /* distcode memory */
653
struct huffman lencode, distcode; /* length and distance codes */
654
static const short order[19] = /* permutation of code length codes */
655
{16, 17, 18, 0, 8, 7, 9, 6, 10, 5, 11, 4, 12, 3, 13, 2, 14, 1, 15};
657
/* construct lencode and distcode */
658
lencode.count = lencnt;
659
lencode.symbol = lensym;
660
distcode.count = distcnt;
661
distcode.symbol = distsym;
663
/* get number of lengths in each table, check lengths */
664
nlen = bits(s, 5) + 257;
665
ndist = bits(s, 5) + 1;
666
ncode = bits(s, 4) + 4;
667
if (nlen > MAXLCODES || ndist > MAXDCODES)
668
return -3; /* bad counts */
670
/* read code length code lengths (really), missing lengths are zero */
671
for (index = 0; index < ncode; index++)
672
lengths[order[index]] = bits(s, 3);
673
for (; index < 19; index++)
674
lengths[order[index]] = 0;
676
/* build huffman table for code lengths codes (use lencode temporarily) */
677
err = construct(&lencode, lengths, 19);
678
if (err != 0) return -4; /* require complete code set here */
680
/* read length/literal and distance code length tables */
682
while (index < nlen + ndist) {
683
int symbol; /* decoded value */
684
int len; /* last length to repeat */
686
symbol = decode(s, &lencode);
687
if (symbol < 16) /* length in 0..15 */
688
lengths[index++] = symbol;
689
else { /* repeat instruction */
690
len = 0; /* assume repeating zeros */
691
if (symbol == 16) { /* repeat last length 3..6 times */
692
if (index == 0) return -5; /* no last length! */
693
len = lengths[index - 1]; /* last length */
694
symbol = 3 + bits(s, 2);
696
else if (symbol == 17) /* repeat zero 3..10 times */
697
symbol = 3 + bits(s, 3);
698
else /* == 18, repeat zero 11..138 times */
699
symbol = 11 + bits(s, 7);
700
if (index + symbol > nlen + ndist)
701
return -6; /* too many lengths! */
702
while (symbol--) /* repeat last or zero symbol times */
703
lengths[index++] = len;
707
/* check for end-of-block code -- there better be one! */
708
if (lengths[256] == 0)
711
/* build huffman table for literal/length codes */
712
err = construct(&lencode, lengths, nlen);
713
if (err < 0 || (err > 0 && nlen - lencode.count[0] != 1))
714
return -7; /* only allow incomplete codes if just one code */
716
/* build huffman table for distance codes */
717
err = construct(&distcode, lengths + nlen, ndist);
718
if (err < 0 || (err > 0 && ndist - distcode.count[0] != 1))
719
return -8; /* only allow incomplete codes if just one code */
721
/* decode data until end-of-block code */
722
return codes(s, &lencode, &distcode);
726
* Inflate source to dest. On return, destlen and sourcelen are updated to the
727
* size of the uncompressed data and the size of the deflate data respectively.
728
* On success, the return value of puff() is zero. If there is an error in the
729
* source data, i.e. it is not in the deflate format, then a negative value is
730
* returned. If there is not enough input available or there is not enough
731
* output space, then a positive error is returned. In that case, destlen and
732
* sourcelen are not updated to facilitate retrying from the beginning with the
733
* provision of more input data or more output space. In the case of invalid
734
* inflate data (a negative error), the dest and source pointers are updated to
735
* facilitate the debugging of deflators.
737
* puff() also has a mode to determine the size of the uncompressed output with
738
* no output written. For this dest must be (unsigned char *)0. In this case,
739
* the input value of *destlen is ignored, and on return *destlen is set to the
740
* size of the uncompressed output.
742
* The return codes are:
744
* 2: available inflate data did not terminate
745
* 1: output space exhausted before completing inflate
746
* 0: successful inflate
747
* -1: invalid block type (type == 3)
748
* -2: stored block length did not match one's complement
749
* -3: dynamic block code description: too many length or distance codes
750
* -4: dynamic block code description: code lengths codes incomplete
751
* -5: dynamic block code description: repeat lengths with no first length
752
* -6: dynamic block code description: repeat more than specified lengths
753
* -7: dynamic block code description: invalid literal/length code lengths
754
* -8: dynamic block code description: invalid distance code lengths
755
* -9: dynamic block code description: missing end-of-block code
756
* -10: invalid literal/length or distance code in fixed or dynamic block
757
* -11: distance is too far back in fixed or dynamic block
761
* - Three bits are read for each block to determine the kind of block and
762
* whether or not it is the last block. Then the block is decoded and the
763
* process repeated if it was not the last block.
765
* - The leftover bits in the last byte of the deflate data after the last
766
* block (if it was a fixed or dynamic block) are undefined and have no
767
* expected values to check.
769
int puff(unsigned char *dest, /* pointer to destination pointer */
770
unsigned long *destlen, /* amount of output space */
771
unsigned char *source, /* pointer to source data pointer */
772
unsigned long *sourcelen) /* amount of input available */
774
struct state s; /* input/output state */
775
int last, type; /* block information */
776
int err; /* return value */
778
/* initialize output state */
780
s.outlen = *destlen; /* ignored if dest is NIL */
783
/* initialize input state */
785
s.inlen = *sourcelen;
790
/* return if bits() or decode() tries to read past available input */
791
if (setjmp(s.env) != 0) /* if came back here via longjmp() */
792
err = 2; /* then skip do-loop, return error */
794
/* process blocks until last block or error */
796
last = bits(&s, 1); /* one if last block */
797
type = bits(&s, 2); /* block type 0..3 */
798
err = type == 0 ? stored(&s) :
799
(type == 1 ? fixed(&s) :
800
(type == 2 ? dynamic(&s) :
801
-1)); /* type == 3, invalid */
802
if (err != 0) break; /* return with error */
806
/* update the lengths and return */
809
*sourcelen = s.incnt;
815
/* Examples of how to use puff().
817
Usage: puff [-w] [-nnn] file
818
... | puff [-w] [-nnn]
820
where file is the input file with deflate data, nnn is the number of bytes
821
of input to skip before inflating (e.g. to skip a zlib or gzip header), and
822
-w is used to write the decompressed data to stdout */
827
/* Return size times approximately the cube root of 2, keeping the result as 1,
828
3, or 5 times a power of 2 -- the result is always > size, until the result
829
is the maximum value of an unsigned long, where it remains. This is useful
830
to keep reallocations less than ~33% over the actual data. */
831
local size_t bythirds(size_t size)
845
return m > size ? m : (size_t)(-1);
848
/* Read the input file *name, or stdin if name is NULL, into allocated memory.
849
Reallocate to larger buffers until the entire file is read in. Return a
850
pointer to the allocated data, or NULL if there was a memory allocation
851
failure. *len is the number of bytes of data read from the input file (even
852
if load() returns NULL). If the input file was empty or could not be opened
853
or read, *len is zero. */
854
local void *load(char *name, size_t *len)
861
buf = malloc(size = 4096);
864
in = name == NULL ? stdin : fopen(name, "rb");
867
*len += fread((char *)buf + *len, 1, size - *len, in);
868
if (*len < size) break;
869
size = bythirds(size);
870
if (size == *len || (swap = realloc(buf, size)) == NULL) {
882
int main(int argc, char **argv)
886
char *arg, *name = NULL;
887
unsigned char *source = NULL, *dest;
889
unsigned long sourcelen, destlen;
891
/* process arguments */
892
while (arg = *++argv, --argc)
894
if (arg[1] == 'w' && arg[2] == 0)
896
else if (arg[1] >= '0' && arg[1] <= '9')
897
skip = (unsigned)atoi(arg + 1);
899
fprintf(stderr, "invalid option %s\n", arg);
903
else if (name != NULL) {
904
fprintf(stderr, "only one file name allowed\n");
909
source = load(name, &len);
910
if (source == NULL) {
911
fprintf(stderr, "memory allocation failure\n");
915
fprintf(stderr, "could not read %s, or it was empty\n",
916
name == NULL ? "<stdin>" : name);
921
fprintf(stderr, "skip request of %d leaves no input\n", skip);
926
/* test inflate data with offset skip */
928
sourcelen = (unsigned long)len;
929
ret = puff(NIL, &destlen, source + skip, &sourcelen);
931
fprintf(stderr, "puff() failed with return code %d\n", ret);
933
fprintf(stderr, "puff() succeeded uncompressing %lu bytes\n", destlen);
934
if (sourcelen < len) fprintf(stderr, "%lu compressed bytes unused\n",
938
/* if requested, inflate again and write decompressd data to stdout */
940
dest = malloc(destlen);
942
fprintf(stderr, "memory allocation failure\n");
946
puff(dest, &destlen, source + skip, &sourcelen);
947
fwrite(dest, 1, destlen, stdout);
added
removed
win32/3rdparty/zlib/contrib/puff/puff.c
