patch-1.3.48 linux/lib/inflate.c
Next file: linux/mm/filemap.c
Previous file: linux/kernel/ksyms.c
Back to the patch index
Back to the overall index
- Lines: 1168
- Date:
Thu Dec 14 08:16:52 1995
- Orig file:
v1.3.47/linux/lib/inflate.c
- Orig date:
Thu Jan 1 02:00:00 1970
diff -u --recursive --new-file v1.3.47/linux/lib/inflate.c linux/lib/inflate.c
@@ -0,0 +1,1167 @@
+#define DEBG(x)
+#define DEBG1(x)
+/* inflate.c -- Not copyrighted 1992 by Mark Adler
+ version c10p1, 10 January 1993 */
+
+/*
+ * Adapted for booting Linux by Hannu Savolainen 1993
+ * based on gzip-1.0.3
+ */
+
+/*
+ Inflate deflated (PKZIP's method 8 compressed) data. The compression
+ method searches for as much of the current string of bytes (up to a
+ length of 258) in the previous 32K bytes. If it doesn't find any
+ matches (of at least length 3), it codes the next byte. Otherwise, it
+ codes the length of the matched string and its distance backwards from
+ the current position. There is a single Huffman code that codes both
+ single bytes (called "literals") and match lengths. A second Huffman
+ code codes the distance information, which follows a length code. Each
+ length or distance code actually represents a base value and a number
+ of "extra" (sometimes zero) bits to get to add to the base value. At
+ the end of each deflated block is a special end-of-block (EOB) literal/
+ length code. The decoding process is basically: get a literal/length
+ code; if EOB then done; if a literal, emit the decoded byte; if a
+ length then get the distance and emit the referred-to bytes from the
+ sliding window of previously emitted data.
+
+ There are (currently) three kinds of inflate blocks: stored, fixed, and
+ dynamic. The compressor deals with some chunk of data at a time, and
+ decides which method to use on a chunk-by-chunk basis. A chunk might
+ typically be 32K or 64K. If the chunk is uncompressible, then the
+ "stored" method is used. In this case, the bytes are simply stored as
+ is, eight bits per byte, with none of the above coding. The bytes are
+ preceded by a count, since there is no longer an EOB code.
+
+ If the data is compressible, then either the fixed or dynamic methods
+ are used. In the dynamic method, the compressed data is preceded by
+ an encoding of the literal/length and distance Huffman codes that are
+ to be used to decode this block. The representation is itself Huffman
+ coded, and so is preceded by a description of that code. These code
+ descriptions take up a little space, and so for small blocks, there is
+ a predefined set of codes, called the fixed codes. The fixed method is
+ used if the block codes up smaller that way (usually for quite small
+ chunks), otherwise the dynamic method is used. In the latter case, the
+ codes are customized to the probabilities in the current block, and so
+ can code it much better than the pre-determined fixed codes.
+
+ The Huffman codes themselves are decoded using a mutli-level table
+ lookup, in order to maximize the speed of decoding plus the speed of
+ building the decoding tables. See the comments below that precede the
+ lbits and dbits tuning parameters.
+ */
+
+
+/*
+ Notes beyond the 1.93a appnote.txt:
+
+ 1. Distance pointers never point before the beginning of the output
+ stream.
+ 2. Distance pointers can point back across blocks, up to 32k away.
+ 3. There is an implied maximum of 7 bits for the bit length table and
+ 15 bits for the actual data.
+ 4. If only one code exists, then it is encoded using one bit. (Zero
+ would be more efficient, but perhaps a little confusing.) If two
+ codes exist, they are coded using one bit each (0 and 1).
+ 5. There is no way of sending zero distance codes--a dummy must be
+ sent if there are none. (History: a pre 2.0 version of PKZIP would
+ store blocks with no distance codes, but this was discovered to be
+ too harsh a criterion.) Valid only for 1.93a. 2.04c does allow
+ zero distance codes, which is sent as one code of zero bits in
+ length.
+ 6. There are up to 286 literal/length codes. Code 256 represents the
+ end-of-block. Note however that the static length tree defines
+ 288 codes just to fill out the Huffman codes. Codes 286 and 287
+ cannot be used though, since there is no length base or extra bits
+ defined for them. Similarly, there are up to 30 distance codes.
+ However, static trees define 32 codes (all 5 bits) to fill out the
+ Huffman codes, but the last two had better not show up in the data.
+ 7. Unzip can check dynamic Huffman blocks for complete code sets.
+ The exception is that a single code would not be complete (see #4).
+ 8. The five bits following the block type is really the number of
+ literal codes sent minus 257.
+ 9. Length codes 8,16,16 are interpreted as 13 length codes of 8 bits
+ (1+6+6). Therefore, to output three times the length, you output
+ three codes (1+1+1), whereas to output four times the same length,
+ you only need two codes (1+3). Hmm.
+ 10. In the tree reconstruction algorithm, Code = Code + Increment
+ only if BitLength(i) is not zero. (Pretty obvious.)
+ 11. Correction: 4 Bits: # of Bit Length codes - 4 (4 - 19)
+ 12. Note: length code 284 can represent 227-258, but length code 285
+ really is 258. The last length deserves its own, short code
+ since it gets used a lot in very redundant files. The length
+ 258 is special since 258 - 3 (the min match length) is 255.
+ 13. The literal/length and distance code bit lengths are read as a
+ single stream of lengths. It is possible (and advantageous) for
+ a repeat code (16, 17, or 18) to go across the boundary between
+ the two sets of lengths.
+ */
+
+#ifdef RCSID
+static char rcsid[] = "#Id: inflate.c,v 0.14 1993/06/10 13:27:04 jloup Exp #";
+#endif
+
+#ifndef STATIC
+
+#if defined(STDC_HEADERS) || defined(HAVE_STDLIB_H)
+# include <sys/types.h>
+# include <stdlib.h>
+#endif
+
+#include "gzip.h"
+#define STATIC
+#endif /* !STATIC */
+
+#define slide window
+
+/* Huffman code lookup table entry--this entry is four bytes for machines
+ that have 16-bit pointers (e.g. PC's in the small or medium model).
+ Valid extra bits are 0..13. e == 15 is EOB (end of block), e == 16
+ means that v is a literal, 16 < e < 32 means that v is a pointer to
+ the next table, which codes e - 16 bits, and lastly e == 99 indicates
+ an unused code. If a code with e == 99 is looked up, this implies an
+ error in the data. */
+struct huft {
+ uch e; /* number of extra bits or operation */
+ uch b; /* number of bits in this code or subcode */
+ union {
+ ush n; /* literal, length base, or distance base */
+ struct huft *t; /* pointer to next level of table */
+ } v;
+};
+
+
+/* Function prototypes */
+STATIC int huft_build OF((unsigned *, unsigned, unsigned, ush *, ush *,
+ struct huft **, int *));
+STATIC int huft_free OF((struct huft *));
+STATIC int inflate_codes OF((struct huft *, struct huft *, int, int));
+STATIC int inflate_stored OF((void));
+STATIC int inflate_fixed OF((void));
+STATIC int inflate_dynamic OF((void));
+STATIC int inflate_block OF((int *));
+STATIC int inflate OF((void));
+
+
+/* The inflate algorithm uses a sliding 32K byte window on the uncompressed
+ stream to find repeated byte strings. This is implemented here as a
+ circular buffer. The index is updated simply by incrementing and then
+ and'ing with 0x7fff (32K-1). */
+/* It is left to other modules to supply the 32K area. It is assumed
+ to be usable as if it were declared "uch slide[32768];" or as just
+ "uch *slide;" and then malloc'ed in the latter case. The definition
+ must be in unzip.h, included above. */
+/* unsigned wp; current position in slide */
+#define wp outcnt
+#define flush_output(w) (wp=(w),flush_window())
+
+/* Tables for deflate from PKZIP's appnote.txt. */
+static unsigned border[] = { /* Order of the bit length code lengths */
+ 16, 17, 18, 0, 8, 7, 9, 6, 10, 5, 11, 4, 12, 3, 13, 2, 14, 1, 15};
+static ush cplens[] = { /* Copy lengths for literal codes 257..285 */
+ 3, 4, 5, 6, 7, 8, 9, 10, 11, 13, 15, 17, 19, 23, 27, 31,
+ 35, 43, 51, 59, 67, 83, 99, 115, 131, 163, 195, 227, 258, 0, 0};
+ /* note: see note #13 above about the 258 in this list. */
+static ush cplext[] = { /* Extra bits for literal codes 257..285 */
+ 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 2, 2, 2, 2,
+ 3, 3, 3, 3, 4, 4, 4, 4, 5, 5, 5, 5, 0, 99, 99}; /* 99==invalid */
+static ush cpdist[] = { /* Copy offsets for distance codes 0..29 */
+ 1, 2, 3, 4, 5, 7, 9, 13, 17, 25, 33, 49, 65, 97, 129, 193,
+ 257, 385, 513, 769, 1025, 1537, 2049, 3073, 4097, 6145,
+ 8193, 12289, 16385, 24577};
+static ush cpdext[] = { /* Extra bits for distance codes */
+ 0, 0, 0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6,
+ 7, 7, 8, 8, 9, 9, 10, 10, 11, 11,
+ 12, 12, 13, 13};
+
+
+
+/* Macros for inflate() bit peeking and grabbing.
+ The usage is:
+
+ NEEDBITS(j)
+ x = b & mask_bits[j];
+ DUMPBITS(j)
+
+ where NEEDBITS makes sure that b has at least j bits in it, and
+ DUMPBITS removes the bits from b. The macros use the variable k
+ for the number of bits in b. Normally, b and k are register
+ variables for speed, and are initialized at the beginning of a
+ routine that uses these macros from a global bit buffer and count.
+
+ If we assume that EOB will be the longest code, then we will never
+ ask for bits with NEEDBITS that are beyond the end of the stream.
+ So, NEEDBITS should not read any more bytes than are needed to
+ meet the request. Then no bytes need to be "returned" to the buffer
+ at the end of the last block.
+
+ However, this assumption is not true for fixed blocks--the EOB code
+ is 7 bits, but the other literal/length codes can be 8 or 9 bits.
+ (The EOB code is shorter than other codes because fixed blocks are
+ generally short. So, while a block always has an EOB, many other
+ literal/length codes have a significantly lower probability of
+ showing up at all.) However, by making the first table have a
+ lookup of seven bits, the EOB code will be found in that first
+ lookup, and so will not require that too many bits be pulled from
+ the stream.
+ */
+
+STATIC ulg bb; /* bit buffer */
+STATIC unsigned bk; /* bits in bit buffer */
+
+STATIC ush mask_bits[] = {
+ 0x0000,
+ 0x0001, 0x0003, 0x0007, 0x000f, 0x001f, 0x003f, 0x007f, 0x00ff,
+ 0x01ff, 0x03ff, 0x07ff, 0x0fff, 0x1fff, 0x3fff, 0x7fff, 0xffff
+};
+
+#define NEXTBYTE() (uch)get_byte()
+#define NEEDBITS(n) {while(k<(n)){b|=((ulg)NEXTBYTE())<<k;k+=8;}}
+#define DUMPBITS(n) {b>>=(n);k-=(n);}
+
+
+/*
+ Huffman code decoding is performed using a multi-level table lookup.
+ The fastest way to decode is to simply build a lookup table whose
+ size is determined by the longest code. However, the time it takes
+ to build this table can also be a factor if the data being decoded
+ is not very long. The most common codes are necessarily the
+ shortest codes, so those codes dominate the decoding time, and hence
+ the speed. The idea is you can have a shorter table that decodes the
+ shorter, more probable codes, and then point to subsidiary tables for
+ the longer codes. The time it costs to decode the longer codes is
+ then traded against the time it takes to make longer tables.
+
+ This results of this trade are in the variables lbits and dbits
+ below. lbits is the number of bits the first level table for literal/
+ length codes can decode in one step, and dbits is the same thing for
+ the distance codes. Subsequent tables are also less than or equal to
+ those sizes. These values may be adjusted either when all of the
+ codes are shorter than that, in which case the longest code length in
+ bits is used, or when the shortest code is *longer* than the requested
+ table size, in which case the length of the shortest code in bits is
+ used.
+
+ There are two different values for the two tables, since they code a
+ different number of possibilities each. The literal/length table
+ codes 286 possible values, or in a flat code, a little over eight
+ bits. The distance table codes 30 possible values, or a little less
+ than five bits, flat. The optimum values for speed end up being
+ about one bit more than those, so lbits is 8+1 and dbits is 5+1.
+ The optimum values may differ though from machine to machine, and
+ possibly even between compilers. Your mileage may vary.
+ */
+
+
+STATIC int lbits = 9; /* bits in base literal/length lookup table */
+STATIC int dbits = 6; /* bits in base distance lookup table */
+
+
+/* If BMAX needs to be larger than 16, then h and x[] should be ulg. */
+#define BMAX 16 /* maximum bit length of any code (16 for explode) */
+#define N_MAX 288 /* maximum number of codes in any set */
+
+
+STATIC unsigned hufts; /* track memory usage */
+
+
+STATIC int huft_build(b, n, s, d, e, t, m)
+unsigned *b; /* code lengths in bits (all assumed <= BMAX) */
+unsigned n; /* number of codes (assumed <= N_MAX) */
+unsigned s; /* number of simple-valued codes (0..s-1) */
+ush *d; /* list of base values for non-simple codes */
+ush *e; /* list of extra bits for non-simple codes */
+struct huft **t; /* result: starting table */
+int *m; /* maximum lookup bits, returns actual */
+/* Given a list of code lengths and a maximum table size, make a set of
+ tables to decode that set of codes. Return zero on success, one if
+ the given code set is incomplete (the tables are still built in this
+ case), two if the input is invalid (all zero length codes or an
+ oversubscribed set of lengths), and three if not enough memory. */
+{
+ unsigned a; /* counter for codes of length k */
+ unsigned c[BMAX+1]; /* bit length count table */
+ unsigned f; /* i repeats in table every f entries */
+ int g; /* maximum code length */
+ int h; /* table level */
+ register unsigned i; /* counter, current code */
+ register unsigned j; /* counter */
+ register int k; /* number of bits in current code */
+ int l; /* bits per table (returned in m) */
+ register unsigned *p; /* pointer into c[], b[], or v[] */
+ register struct huft *q; /* points to current table */
+ struct huft r; /* table entry for structure assignment */
+ struct huft *u[BMAX]; /* table stack */
+ unsigned v[N_MAX]; /* values in order of bit length */
+ register int w; /* bits before this table == (l * h) */
+ unsigned x[BMAX+1]; /* bit offsets, then code stack */
+ unsigned *xp; /* pointer into x */
+ int y; /* number of dummy codes added */
+ unsigned z; /* number of entries in current table */
+
+DEBG("huft1 ");
+
+ /* Generate counts for each bit length */
+ memzero(c, sizeof(c));
+ p = b; i = n;
+ do {
+ Tracecv(*p, (stderr, (n-i >= ' ' && n-i <= '~' ? "%c %d\n" : "0x%x %d\n"),
+ n-i, *p));
+ c[*p]++; /* assume all entries <= BMAX */
+ p++; /* Can't combine with above line (Solaris bug) */
+ } while (--i);
+ if (c[0] == n) /* null input--all zero length codes */
+ {
+ *t = (struct huft *)NULL;
+ *m = 0;
+ return 0;
+ }
+
+DEBG("huft2 ");
+
+ /* Find minimum and maximum length, bound *m by those */
+ l = *m;
+ for (j = 1; j <= BMAX; j++)
+ if (c[j])
+ break;
+ k = j; /* minimum code length */
+ if ((unsigned)l < j)
+ l = j;
+ for (i = BMAX; i; i--)
+ if (c[i])
+ break;
+ g = i; /* maximum code length */
+ if ((unsigned)l > i)
+ l = i;
+ *m = l;
+
+DEBG("huft3 ");
+
+ /* Adjust last length count to fill out codes, if needed */
+ for (y = 1 << j; j < i; j++, y <<= 1)
+ if ((y -= c[j]) < 0)
+ return 2; /* bad input: more codes than bits */
+ if ((y -= c[i]) < 0)
+ return 2;
+ c[i] += y;
+
+DEBG("huft4 ");
+
+ /* Generate starting offsets into the value table for each length */
+ x[1] = j = 0;
+ p = c + 1; xp = x + 2;
+ while (--i) { /* note that i == g from above */
+ *xp++ = (j += *p++);
+ }
+
+DEBG("huft5 ");
+
+ /* Make a table of values in order of bit lengths */
+ p = b; i = 0;
+ do {
+ if ((j = *p++) != 0)
+ v[x[j]++] = i;
+ } while (++i < n);
+
+DEBG("h6 ");
+
+ /* Generate the Huffman codes and for each, make the table entries */
+ x[0] = i = 0; /* first Huffman code is zero */
+ p = v; /* grab values in bit order */
+ h = -1; /* no tables yet--level -1 */
+ w = -l; /* bits decoded == (l * h) */
+ u[0] = (struct huft *)NULL; /* just to keep compilers happy */
+ q = (struct huft *)NULL; /* ditto */
+ z = 0; /* ditto */
+DEBG("h6a ");
+
+ /* go through the bit lengths (k already is bits in shortest code) */
+ for (; k <= g; k++)
+ {
+DEBG("h6b ");
+ a = c[k];
+ while (a--)
+ {
+DEBG("h6b1 ");
+ /* here i is the Huffman code of length k bits for value *p */
+ /* make tables up to required level */
+ while (k > w + l)
+ {
+DEBG1("1 ");
+ h++;
+ w += l; /* previous table always l bits */
+
+ /* compute minimum size table less than or equal to l bits */
+ z = (z = g - w) > (unsigned)l ? l : z; /* upper limit on table size */
+ if ((f = 1 << (j = k - w)) > a + 1) /* try a k-w bit table */
+ { /* too few codes for k-w bit table */
+DEBG1("2 ");
+ f -= a + 1; /* deduct codes from patterns left */
+ xp = c + k;
+ while (++j < z) /* try smaller tables up to z bits */
+ {
+ if ((f <<= 1) <= *++xp)
+ break; /* enough codes to use up j bits */
+ f -= *xp; /* else deduct codes from patterns */
+ }
+ }
+DEBG1("3 ");
+ z = 1 << j; /* table entries for j-bit table */
+
+ /* allocate and link in new table */
+ if ((q = (struct huft *)malloc((z + 1)*sizeof(struct huft))) ==
+ (struct huft *)NULL)
+ {
+ if (h)
+ huft_free(u[0]);
+ return 3; /* not enough memory */
+ }
+DEBG1("4 ");
+ hufts += z + 1; /* track memory usage */
+ *t = q + 1; /* link to list for huft_free() */
+ *(t = &(q->v.t)) = (struct huft *)NULL;
+ u[h] = ++q; /* table starts after link */
+
+DEBG1("5 ");
+ /* connect to last table, if there is one */
+ if (h)
+ {
+ x[h] = i; /* save pattern for backing up */
+ r.b = (uch)l; /* bits to dump before this table */
+ r.e = (uch)(16 + j); /* bits in this table */
+ r.v.t = q; /* pointer to this table */
+ j = i >> (w - l); /* (get around Turbo C bug) */
+ u[h-1][j] = r; /* connect to last table */
+ }
+DEBG1("6 ");
+ }
+DEBG("h6c ");
+
+ /* set up table entry in r */
+ r.b = (uch)(k - w);
+ if (p >= v + n)
+ r.e = 99; /* out of values--invalid code */
+ else if (*p < s)
+ {
+ r.e = (uch)(*p < 256 ? 16 : 15); /* 256 is end-of-block code */
+ r.v.n = (ush)(*p); /* simple code is just the value */
+ p++; /* one compiler does not like *p++ */
+ }
+ else
+ {
+ r.e = (uch)e[*p - s]; /* non-simple--look up in lists */
+ r.v.n = d[*p++ - s];
+ }
+DEBG("h6d ");
+
+ /* fill code-like entries with r */
+ f = 1 << (k - w);
+ for (j = i >> w; j < z; j += f)
+ q[j] = r;
+
+ /* backwards increment the k-bit code i */
+ for (j = 1 << (k - 1); i & j; j >>= 1)
+ i ^= j;
+ i ^= j;
+
+ /* backup over finished tables */
+ while ((i & ((1 << w) - 1)) != x[h])
+ {
+ h--; /* don't need to update q */
+ w -= l;
+ }
+DEBG("h6e ");
+ }
+DEBG("h6f ");
+ }
+
+DEBG("huft7 ");
+
+ /* Return true (1) if we were given an incomplete table */
+ return y != 0 && g != 1;
+}
+
+
+
+STATIC int huft_free(t)
+struct huft *t; /* table to free */
+/* Free the malloc'ed tables built by huft_build(), which makes a linked
+ list of the tables it made, with the links in a dummy first entry of
+ each table. */
+{
+ register struct huft *p, *q;
+
+
+ /* Go through linked list, freeing from the malloced (t[-1]) address. */
+ p = t;
+ while (p != (struct huft *)NULL)
+ {
+ q = (--p)->v.t;
+ free((char*)p);
+ p = q;
+ }
+ return 0;
+}
+
+
+STATIC int inflate_codes(tl, td, bl, bd)
+struct huft *tl, *td; /* literal/length and distance decoder tables */
+int bl, bd; /* number of bits decoded by tl[] and td[] */
+/* inflate (decompress) the codes in a deflated (compressed) block.
+ Return an error code or zero if it all goes ok. */
+{
+ register unsigned e; /* table entry flag/number of extra bits */
+ unsigned n, d; /* length and index for copy */
+ unsigned w; /* current window position */
+ struct huft *t; /* pointer to table entry */
+ unsigned ml, md; /* masks for bl and bd bits */
+ register ulg b; /* bit buffer */
+ register unsigned k; /* number of bits in bit buffer */
+
+
+ /* make local copies of globals */
+ b = bb; /* initialize bit buffer */
+ k = bk;
+ w = wp; /* initialize window position */
+
+ /* inflate the coded data */
+ ml = mask_bits[bl]; /* precompute masks for speed */
+ md = mask_bits[bd];
+ for (;;) /* do until end of block */
+ {
+ NEEDBITS((unsigned)bl)
+ if ((e = (t = tl + ((unsigned)b & ml))->e) > 16)
+ do {
+ if (e == 99)
+ return 1;
+ DUMPBITS(t->b)
+ e -= 16;
+ NEEDBITS(e)
+ } while ((e = (t = t->v.t + ((unsigned)b & mask_bits[e]))->e) > 16);
+ DUMPBITS(t->b)
+ if (e == 16) /* then it's a literal */
+ {
+ slide[w++] = (uch)t->v.n;
+ Tracevv((stderr, "%c", slide[w-1]));
+ if (w == WSIZE)
+ {
+ flush_output(w);
+ w = 0;
+ }
+ }
+ else /* it's an EOB or a length */
+ {
+ /* exit if end of block */
+ if (e == 15)
+ break;
+
+ /* get length of block to copy */
+ NEEDBITS(e)
+ n = t->v.n + ((unsigned)b & mask_bits[e]);
+ DUMPBITS(e);
+
+ /* decode distance of block to copy */
+ NEEDBITS((unsigned)bd)
+ if ((e = (t = td + ((unsigned)b & md))->e) > 16)
+ do {
+ if (e == 99)
+ return 1;
+ DUMPBITS(t->b)
+ e -= 16;
+ NEEDBITS(e)
+ } while ((e = (t = t->v.t + ((unsigned)b & mask_bits[e]))->e) > 16);
+ DUMPBITS(t->b)
+ NEEDBITS(e)
+ d = w - t->v.n - ((unsigned)b & mask_bits[e]);
+ DUMPBITS(e)
+ Tracevv((stderr,"\\[%d,%d]", w-d, n));
+
+ /* do the copy */
+ do {
+ n -= (e = (e = WSIZE - ((d &= WSIZE-1) > w ? d : w)) > n ? n : e);
+#if !defined(NOMEMCPY) && !defined(DEBUG)
+ if (w - d >= e) /* (this test assumes unsigned comparison) */
+ {
+ memcpy(slide + w, slide + d, e);
+ w += e;
+ d += e;
+ }
+ else /* do it slow to avoid memcpy() overlap */
+#endif /* !NOMEMCPY */
+ do {
+ slide[w++] = slide[d++];
+ Tracevv((stderr, "%c", slide[w-1]));
+ } while (--e);
+ if (w == WSIZE)
+ {
+ flush_output(w);
+ w = 0;
+ }
+ } while (n);
+ }
+ }
+
+
+ /* restore the globals from the locals */
+ wp = w; /* restore global window pointer */
+ bb = b; /* restore global bit buffer */
+ bk = k;
+
+ /* done */
+ return 0;
+}
+
+
+
+STATIC int inflate_stored()
+/* "decompress" an inflated type 0 (stored) block. */
+{
+ unsigned n; /* number of bytes in block */
+ unsigned w; /* current window position */
+ register ulg b; /* bit buffer */
+ register unsigned k; /* number of bits in bit buffer */
+
+DEBG("<stor");
+
+ /* make local copies of globals */
+ b = bb; /* initialize bit buffer */
+ k = bk;
+ w = wp; /* initialize window position */
+
+
+ /* go to byte boundary */
+ n = k & 7;
+ DUMPBITS(n);
+
+
+ /* get the length and its complement */
+ NEEDBITS(16)
+ n = ((unsigned)b & 0xffff);
+ DUMPBITS(16)
+ NEEDBITS(16)
+ if (n != (unsigned)((~b) & 0xffff))
+ return 1; /* error in compressed data */
+ DUMPBITS(16)
+
+
+ /* read and output the compressed data */
+ while (n--)
+ {
+ NEEDBITS(8)
+ slide[w++] = (uch)b;
+ if (w == WSIZE)
+ {
+ flush_output(w);
+ w = 0;
+ }
+ DUMPBITS(8)
+ }
+
+
+ /* restore the globals from the locals */
+ wp = w; /* restore global window pointer */
+ bb = b; /* restore global bit buffer */
+ bk = k;
+
+ DEBG(">");
+ return 0;
+}
+
+
+
+STATIC int inflate_fixed()
+/* decompress an inflated type 1 (fixed Huffman codes) block. We should
+ either replace this with a custom decoder, or at least precompute the
+ Huffman tables. */
+{
+ int i; /* temporary variable */
+ struct huft *tl; /* literal/length code table */
+ struct huft *td; /* distance code table */
+ int bl; /* lookup bits for tl */
+ int bd; /* lookup bits for td */
+ unsigned l[288]; /* length list for huft_build */
+
+DEBG("<fix");
+
+ /* set up literal table */
+ for (i = 0; i < 144; i++)
+ l[i] = 8;
+ for (; i < 256; i++)
+ l[i] = 9;
+ for (; i < 280; i++)
+ l[i] = 7;
+ for (; i < 288; i++) /* make a complete, but wrong code set */
+ l[i] = 8;
+ bl = 7;
+ if ((i = huft_build(l, 288, 257, cplens, cplext, &tl, &bl)) != 0)
+ return i;
+
+
+ /* set up distance table */
+ for (i = 0; i < 30; i++) /* make an incomplete code set */
+ l[i] = 5;
+ bd = 5;
+ if ((i = huft_build(l, 30, 0, cpdist, cpdext, &td, &bd)) > 1)
+ {
+ huft_free(tl);
+
+ DEBG(">");
+ return i;
+ }
+
+
+ /* decompress until an end-of-block code */
+ if (inflate_codes(tl, td, bl, bd))
+ return 1;
+
+
+ /* free the decoding tables, return */
+ huft_free(tl);
+ huft_free(td);
+ return 0;
+}
+
+
+
+STATIC int inflate_dynamic()
+/* decompress an inflated type 2 (dynamic Huffman codes) block. */
+{
+ int i; /* temporary variables */
+ unsigned j;
+ unsigned l; /* last length */
+ unsigned m; /* mask for bit lengths table */
+ unsigned n; /* number of lengths to get */
+ struct huft *tl; /* literal/length code table */
+ struct huft *td; /* distance code table */
+ int bl; /* lookup bits for tl */
+ int bd; /* lookup bits for td */
+ unsigned nb; /* number of bit length codes */
+ unsigned nl; /* number of literal/length codes */
+ unsigned nd; /* number of distance codes */
+#ifdef PKZIP_BUG_WORKAROUND
+ unsigned ll[288+32]; /* literal/length and distance code lengths */
+#else
+ unsigned ll[286+30]; /* literal/length and distance code lengths */
+#endif
+ register ulg b; /* bit buffer */
+ register unsigned k; /* number of bits in bit buffer */
+
+DEBG("<dyn");
+
+ /* make local bit buffer */
+ b = bb;
+ k = bk;
+
+
+ /* read in table lengths */
+ NEEDBITS(5)
+ nl = 257 + ((unsigned)b & 0x1f); /* number of literal/length codes */
+ DUMPBITS(5)
+ NEEDBITS(5)
+ nd = 1 + ((unsigned)b & 0x1f); /* number of distance codes */
+ DUMPBITS(5)
+ NEEDBITS(4)
+ nb = 4 + ((unsigned)b & 0xf); /* number of bit length codes */
+ DUMPBITS(4)
+#ifdef PKZIP_BUG_WORKAROUND
+ if (nl > 288 || nd > 32)
+#else
+ if (nl > 286 || nd > 30)
+#endif
+ return 1; /* bad lengths */
+
+DEBG("dyn1 ");
+
+ /* read in bit-length-code lengths */
+ for (j = 0; j < nb; j++)
+ {
+ NEEDBITS(3)
+ ll[border[j]] = (unsigned)b & 7;
+ DUMPBITS(3)
+ }
+ for (; j < 19; j++)
+ ll[border[j]] = 0;
+
+DEBG("dyn2 ");
+
+ /* build decoding table for trees--single level, 7 bit lookup */
+ bl = 7;
+ if ((i = huft_build(ll, 19, 19, NULL, NULL, &tl, &bl)) != 0)
+ {
+ if (i == 1)
+ huft_free(tl);
+ return i; /* incomplete code set */
+ }
+
+DEBG("dyn3 ");
+
+ /* read in literal and distance code lengths */
+ n = nl + nd;
+ m = mask_bits[bl];
+ i = l = 0;
+ while ((unsigned)i < n)
+ {
+ NEEDBITS((unsigned)bl)
+ j = (td = tl + ((unsigned)b & m))->b;
+ DUMPBITS(j)
+ j = td->v.n;
+ if (j < 16) /* length of code in bits (0..15) */
+ ll[i++] = l = j; /* save last length in l */
+ else if (j == 16) /* repeat last length 3 to 6 times */
+ {
+ NEEDBITS(2)
+ j = 3 + ((unsigned)b & 3);
+ DUMPBITS(2)
+ if ((unsigned)i + j > n)
+ return 1;
+ while (j--)
+ ll[i++] = l;
+ }
+ else if (j == 17) /* 3 to 10 zero length codes */
+ {
+ NEEDBITS(3)
+ j = 3 + ((unsigned)b & 7);
+ DUMPBITS(3)
+ if ((unsigned)i + j > n)
+ return 1;
+ while (j--)
+ ll[i++] = 0;
+ l = 0;
+ }
+ else /* j == 18: 11 to 138 zero length codes */
+ {
+ NEEDBITS(7)
+ j = 11 + ((unsigned)b & 0x7f);
+ DUMPBITS(7)
+ if ((unsigned)i + j > n)
+ return 1;
+ while (j--)
+ ll[i++] = 0;
+ l = 0;
+ }
+ }
+
+DEBG("dyn4 ");
+
+ /* free decoding table for trees */
+ huft_free(tl);
+
+DEBG("dyn5 ");
+
+ /* restore the global bit buffer */
+ bb = b;
+ bk = k;
+
+DEBG("dyn5a ");
+
+ /* build the decoding tables for literal/length and distance codes */
+ bl = lbits;
+ if ((i = huft_build(ll, nl, 257, cplens, cplext, &tl, &bl)) != 0)
+ {
+DEBG("dyn5b ");
+ if (i == 1) {
+ error(" incomplete literal tree\n");
+ huft_free(tl);
+ }
+ return i; /* incomplete code set */
+ }
+DEBG("dyn5c ");
+ bd = dbits;
+ if ((i = huft_build(ll + nl, nd, 0, cpdist, cpdext, &td, &bd)) != 0)
+ {
+DEBG("dyn5d ");
+ if (i == 1) {
+ error(" incomplete distance tree\n");
+#ifdef PKZIP_BUG_WORKAROUND
+ i = 0;
+ }
+#else
+ huft_free(td);
+ }
+ huft_free(tl);
+ return i; /* incomplete code set */
+#endif
+ }
+
+DEBG("dyn6 ");
+
+ /* decompress until an end-of-block code */
+ if (inflate_codes(tl, td, bl, bd))
+ return 1;
+
+DEBG("dyn7 ");
+
+ /* free the decoding tables, return */
+ huft_free(tl);
+ huft_free(td);
+
+ DEBG(">");
+ return 0;
+}
+
+
+
+STATIC int inflate_block(e)
+int *e; /* last block flag */
+/* decompress an inflated block */
+{
+ unsigned t; /* block type */
+ register ulg b; /* bit buffer */
+ register unsigned k; /* number of bits in bit buffer */
+
+ DEBG("<blk");
+
+ /* make local bit buffer */
+ b = bb;
+ k = bk;
+
+
+ /* read in last block bit */
+ NEEDBITS(1)
+ *e = (int)b & 1;
+ DUMPBITS(1)
+
+
+ /* read in block type */
+ NEEDBITS(2)
+ t = (unsigned)b & 3;
+ DUMPBITS(2)
+
+
+ /* restore the global bit buffer */
+ bb = b;
+ bk = k;
+
+ /* inflate that block type */
+ if (t == 2)
+ return inflate_dynamic();
+ if (t == 0)
+ return inflate_stored();
+ if (t == 1)
+ return inflate_fixed();
+
+ DEBG(">");
+
+ /* bad block type */
+ return 2;
+}
+
+
+
+STATIC int inflate()
+/* decompress an inflated entry */
+{
+ int e; /* last block flag */
+ int r; /* result code */
+ unsigned h; /* maximum struct huft's malloc'ed */
+ void *ptr;
+
+ /* initialize window, bit buffer */
+ wp = 0;
+ bk = 0;
+ bb = 0;
+
+
+ /* decompress until the last block */
+ h = 0;
+ do {
+ hufts = 0;
+ gzip_mark(&ptr);
+ if ((r = inflate_block(&e)) != 0) {
+ gzip_release(&ptr);
+ return r;
+ }
+ gzip_release(&ptr);
+ if (hufts > h)
+ h = hufts;
+ } while (!e);
+
+ /* Undo too much lookahead. The next read will be byte aligned so we
+ * can discard unused bits in the last meaningful byte.
+ */
+ while (bk >= 8) {
+ bk -= 8;
+ inptr--;
+ }
+
+ /* flush out slide */
+ flush_output(wp);
+
+
+ /* return success */
+#ifdef DEBUG
+ fprintf(stderr, "<%u> ", h);
+#endif /* DEBUG */
+ return 0;
+}
+
+/**********************************************************************
+ *
+ * The following are support routines for inflate.c
+ *
+ **********************************************************************/
+
+static ulg crc_32_tab[256];
+static ulg crc = (ulg)0xffffffffL; /* shift register contents */
+#define CRC_VALUE (crc ^ 0xffffffffL)
+
+/*
+ * Code to compute the CRC-32 table. Borrowed from
+ * gzip-1.0.3/makecrc.c.
+ */
+
+static void
+makecrc(void)
+{
+/* Not copyrighted 1990 Mark Adler */
+
+ unsigned long c; /* crc shift register */
+ unsigned long e; /* polynomial exclusive-or pattern */
+ int i; /* counter for all possible eight bit values */
+ int k; /* byte being shifted into crc apparatus */
+
+ /* terms of polynomial defining this crc (except x^32): */
+ static int p[] = {0,1,2,4,5,7,8,10,11,12,16,22,23,26};
+
+ /* Make exclusive-or pattern from polynomial */
+ e = 0;
+ for (i = 0; i < sizeof(p)/sizeof(int); i++)
+ e |= 1L << (31 - p[i]);
+
+ crc_32_tab[0] = 0;
+
+ for (i = 1; i < 256; i++)
+ {
+ c = 0;
+ for (k = i | 256; k != 1; k >>= 1)
+ {
+ c = c & 1 ? (c >> 1) ^ e : c >> 1;
+ if (k & 1)
+ c ^= e;
+ }
+ crc_32_tab[i] = c;
+ }
+}
+
+/* gzip flag byte */
+#define ASCII_FLAG 0x01 /* bit 0 set: file probably ascii text */
+#define CONTINUATION 0x02 /* bit 1 set: continuation of multi-part gzip file */
+#define EXTRA_FIELD 0x04 /* bit 2 set: extra field present */
+#define ORIG_NAME 0x08 /* bit 3 set: original file name present */
+#define COMMENT 0x10 /* bit 4 set: file comment present */
+#define ENCRYPTED 0x20 /* bit 5 set: file is encrypted */
+#define RESERVED 0xC0 /* bit 6,7: reserved */
+
+/*
+ * Do the uncompression!
+ */
+static int gunzip(void)
+{
+ uch flags;
+ unsigned char magic[2]; /* magic header */
+ char method;
+ ulg orig_crc = 0; /* original crc */
+ ulg orig_len = 0; /* original uncompressed length */
+ int res;
+
+ magic[0] = (unsigned char)get_byte();
+ magic[1] = (unsigned char)get_byte();
+ method = (unsigned char)get_byte();
+
+ if (magic[0] != 037 ||
+ ((magic[1] != 0213) && (magic[1] != 0236))) {
+ error("bad gzip magic numbers");
+ return -1;
+ }
+
+ /* We only support method #8, DEFLATED */
+ if (method != 8) {
+ error("internal error, invalid method");
+ return -1;
+ }
+
+ flags = (uch)get_byte();
+ if ((flags & ENCRYPTED) != 0) {
+ error("Input is encrypted\n");
+ return -1;
+ }
+ if ((flags & CONTINUATION) != 0) {
+ error("Multi part input\n");
+ return -1;
+ }
+ if ((flags & RESERVED) != 0) {
+ error("Input has invalid flags\n");
+ return -1;
+ }
+ (ulg)get_byte(); /* Get timestamp */
+ ((ulg)get_byte()) << 8;
+ ((ulg)get_byte()) << 16;
+ ((ulg)get_byte()) << 24;
+
+ (void)get_byte(); /* Ignore extra flags for the moment */
+ (void)get_byte(); /* Ignore OS type for the moment */
+
+ if ((flags & EXTRA_FIELD) != 0) {
+ unsigned len = (unsigned)get_byte();
+ len |= ((unsigned)get_byte())<<8;
+ while (len--) (void)get_byte();
+ }
+
+ /* Get original file name if it was truncated */
+ if ((flags & ORIG_NAME) != 0) {
+ /* Discard the old name */
+ while (get_byte() != 0) /* null */ ;
+ }
+
+ /* Discard file comment if any */
+ if ((flags & COMMENT) != 0) {
+ while (get_byte() != 0) /* null */ ;
+ }
+
+ /* Decompress */
+ if ((res = inflate())) {
+ switch (res) {
+ case 0:
+ break;
+ case 1:
+ error("invalid compressed format (err=1)");
+ break;
+ case 2:
+ error("invalid compressed format (err=2)");
+ break;
+ case 3:
+ error("out of memory");
+ break;
+ default:
+ error("invalid compressed format (other)");
+ }
+ return -1;
+ }
+
+ /* Get the crc and original length */
+ /* crc32 (see algorithm.doc)
+ * uncompressed input size modulo 2^32
+ */
+ orig_crc = (ulg) get_byte();
+ orig_crc |= (ulg) get_byte() << 8;
+ orig_crc |= (ulg) get_byte() << 16;
+ orig_crc |= (ulg) get_byte() << 24;
+
+ orig_len = (ulg) get_byte();
+ orig_len |= (ulg) get_byte() << 8;
+ orig_len |= (ulg) get_byte() << 16;
+ orig_len |= (ulg) get_byte() << 24;
+
+ /* Validate decompression */
+ if (orig_crc != CRC_VALUE) {
+ error("crc error");
+ return -1;
+ }
+ if (orig_len != bytes_out) {
+ error("length error");
+ return -1;
+ }
+ return 0;
+}
+
+
FUNET's LINUX-ADM group, linux-adm@nic.funet.fi
TCL-scripts by Sam Shen, slshen@lbl.gov
with Sam's (original) version of this