patch-2.4.14 linux/fs/inflate_fs/infblock.c

• Lines: 356
• Date: Thu Oct 25 13:53:53 2001
• Orig file: v2.4.13/linux/fs/inflate_fs/infblock.c
• Orig date: Wed Dec 31 16:00:00 1969

diff -u --recursive --new-file v2.4.13/linux/fs/inflate_fs/infblock.c linux/fs/inflate_fs/infblock.c
@@ -0,0 +1,355 @@
+/* infblock.c -- interpret and process block types to last block
+ * Copyright (C) 1995-1998 Mark Adler
+ * For conditions of distribution and use, see copyright notice in zlib.h 
+ */
+
+#include "zutil.h"
+#include "infblock.h"
+#include "inftrees.h"
+#include "infcodes.h"
+#include "infutil.h"
+
+struct inflate_codes_state;
+
+/* simplify the use of the inflate_huft type with some defines */
+#define exop word.what.Exop
+#define bits word.what.Bits
+
+/* Table for deflate from PKZIP's appnote.txt. */
+local const uInt 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};
+
+/*
+   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.  Similarily, 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.
+ */
+
+
+void zlib_fs_inflate_blocks_reset(s, z, c)
+inflate_blocks_statef *s;
+z_streamp z;
+uLongf *c;
+{
+  if (c != Z_NULL)
+    *c = s->check;
+  if (s->mode == CODES)
+    zlib_fs_inflate_codes_free(s->sub.decode.codes, z);
+  s->mode = TYPE;
+  s->bitk = 0;
+  s->bitb = 0;
+  s->read = s->write = s->window;
+  if (s->checkfn != Z_NULL)
+    z->adler = s->check = (*s->checkfn)(0L, (const Bytef *)Z_NULL, 0);
+}
+
+inflate_blocks_statef *zlib_fs_inflate_blocks_new(z, c, w)
+z_streamp z;
+check_func c;
+uInt w;
+{
+  inflate_blocks_statef *s;
+
+  s = &WS(z)->working_blocks_state;
+  s->hufts = WS(z)->working_hufts;
+  s->window = WS(z)->working_window;
+  s->end = s->window + w;
+  s->checkfn = c;
+  s->mode = TYPE;
+  zlib_fs_inflate_blocks_reset(s, z, Z_NULL);
+  return s;
+}
+
+
+int zlib_fs_inflate_blocks(s, z, r)
+inflate_blocks_statef *s;
+z_streamp z;
+int r;
+{
+  uInt t;               /* temporary storage */
+  uLong b;              /* bit buffer */
+  uInt k;               /* bits in bit buffer */
+  Bytef *p;             /* input data pointer */
+  uInt n;               /* bytes available there */
+  Bytef *q;             /* output window write pointer */
+  uInt m;               /* bytes to end of window or read pointer */
+
+  /* copy input/output information to locals (UPDATE macro restores) */
+  LOAD
+
+  /* process input based on current state */
+  while (1) switch (s->mode)
+  {
+    case TYPE:
+      NEEDBITS(3)
+      t = (uInt)b & 7;
+      s->last = t & 1;
+      switch (t >> 1)
+      {
+        case 0:                         /* stored */
+          DUMPBITS(3)
+          t = k & 7;                    /* go to byte boundary */
+          DUMPBITS(t)
+          s->mode = LENS;               /* get length of stored block */
+          break;
+        case 1:                         /* fixed */
+          {
+            uInt bl, bd;
+            inflate_huft *tl, *td;
+
+            zlib_fs_inflate_trees_fixed(&bl, &bd, &tl, &td, z);
+            s->sub.decode.codes = zlib_fs_inflate_codes_new(bl, bd, tl, td, z);
+            if (s->sub.decode.codes == Z_NULL)
+            {
+              r = Z_MEM_ERROR;
+              LEAVE
+            }
+          }
+          DUMPBITS(3)
+          s->mode = CODES;
+          break;
+        case 2:                         /* dynamic */
+          DUMPBITS(3)
+          s->mode = TABLE;
+          break;
+        case 3:                         /* illegal */
+          DUMPBITS(3)
+          s->mode = B_BAD;
+          z->msg = (char*)"invalid block type";
+          r = Z_DATA_ERROR;
+          LEAVE
+      }
+      break;
+    case LENS:
+      NEEDBITS(32)
+      if ((((~b) >> 16) & 0xffff) != (b & 0xffff))
+      {
+        s->mode = B_BAD;
+        z->msg = (char*)"invalid stored block lengths";
+        r = Z_DATA_ERROR;
+        LEAVE
+      }
+      s->sub.left = (uInt)b & 0xffff;
+      b = k = 0;                      /* dump bits */
+      s->mode = s->sub.left ? STORED : (s->last ? DRY : TYPE);
+      break;
+    case STORED:
+      if (n == 0)
+        LEAVE
+      NEEDOUT
+      t = s->sub.left;
+      if (t > n) t = n;
+      if (t > m) t = m;
+      memcpy(q, p, t);
+      p += t;  n -= t;
+      q += t;  m -= t;
+      if ((s->sub.left -= t) != 0)
+        break;
+      s->mode = s->last ? DRY : TYPE;
+      break;
+    case TABLE:
+      NEEDBITS(14)
+      s->sub.trees.table = t = (uInt)b & 0x3fff;
+#ifndef PKZIP_BUG_WORKAROUND
+      if ((t & 0x1f) > 29 || ((t >> 5) & 0x1f) > 29)
+      {
+        s->mode = B_BAD;
+        z->msg = (char*)"too many length or distance symbols";
+        r = Z_DATA_ERROR;
+        LEAVE
+      }
+#endif
+      {
+      	s->sub.trees.blens = WS(z)->working_blens;
+      }
+      DUMPBITS(14)
+      s->sub.trees.index = 0;
+      s->mode = BTREE;
+    case BTREE:
+      while (s->sub.trees.index < 4 + (s->sub.trees.table >> 10))
+      {
+        NEEDBITS(3)
+        s->sub.trees.blens[border[s->sub.trees.index++]] = (uInt)b & 7;
+        DUMPBITS(3)
+      }
+      while (s->sub.trees.index < 19)
+        s->sub.trees.blens[border[s->sub.trees.index++]] = 0;
+      s->sub.trees.bb = 7;
+      t = zlib_fs_inflate_trees_bits(s->sub.trees.blens, &s->sub.trees.bb,
+                             &s->sub.trees.tb, s->hufts, z);
+      if (t != Z_OK)
+      {
+        r = t;
+        if (r == Z_DATA_ERROR)
+          s->mode = B_BAD;
+        LEAVE
+      }
+      s->sub.trees.index = 0;
+      s->mode = DTREE;
+    case DTREE:
+      while (t = s->sub.trees.table,
+             s->sub.trees.index < 258 + (t & 0x1f) + ((t >> 5) & 0x1f))
+      {
+        inflate_huft *h;
+        uInt i, j, c;
+
+        t = s->sub.trees.bb;
+        NEEDBITS(t)
+        h = s->sub.trees.tb + ((uInt)b & zlib_fs_inflate_mask[t]);
+        t = h->bits;
+        c = h->base;
+        if (c < 16)
+        {
+          DUMPBITS(t)
+          s->sub.trees.blens[s->sub.trees.index++] = c;
+        }
+        else /* c == 16..18 */
+        {
+          i = c == 18 ? 7 : c - 14;
+          j = c == 18 ? 11 : 3;
+          NEEDBITS(t + i)
+          DUMPBITS(t)
+          j += (uInt)b & zlib_fs_inflate_mask[i];
+          DUMPBITS(i)
+          i = s->sub.trees.index;
+          t = s->sub.trees.table;
+          if (i + j > 258 + (t & 0x1f) + ((t >> 5) & 0x1f) ||
+              (c == 16 && i < 1))
+          {
+            s->mode = B_BAD;
+            z->msg = (char*)"invalid bit length repeat";
+            r = Z_DATA_ERROR;
+            LEAVE
+          }
+          c = c == 16 ? s->sub.trees.blens[i - 1] : 0;
+          do {
+            s->sub.trees.blens[i++] = c;
+          } while (--j);
+          s->sub.trees.index = i;
+        }
+      }
+      s->sub.trees.tb = Z_NULL;
+      {
+        uInt bl, bd;
+        inflate_huft *tl, *td;
+        inflate_codes_statef *c;
+
+        bl = 9;         /* must be <= 9 for lookahead assumptions */
+        bd = 6;         /* must be <= 9 for lookahead assumptions */
+        t = s->sub.trees.table;
+        t = zlib_fs_inflate_trees_dynamic(257 + (t & 0x1f), 1 + ((t >> 5) & 0x1f),
+                                  s->sub.trees.blens, &bl, &bd, &tl, &td,
+                                  s->hufts, z);
+        if (t != Z_OK)
+        {
+          if (t == (uInt)Z_DATA_ERROR)
+            s->mode = B_BAD;
+          r = t;
+          LEAVE
+        }
+        if ((c = zlib_fs_inflate_codes_new(bl, bd, tl, td, z)) == Z_NULL)
+        {
+          r = Z_MEM_ERROR;
+          LEAVE
+        }
+        s->sub.decode.codes = c;
+      }
+      s->mode = CODES;
+    case CODES:
+      UPDATE
+      if ((r = zlib_fs_inflate_codes(s, z, r)) != Z_STREAM_END)
+        return zlib_fs_inflate_flush(s, z, r);
+      r = Z_OK;
+      zlib_fs_inflate_codes_free(s->sub.decode.codes, z);
+      LOAD
+      if (!s->last)
+      {
+        s->mode = TYPE;
+        break;
+      }
+      s->mode = DRY;
+    case DRY:
+      FLUSH
+      if (s->read != s->write)
+        LEAVE
+      s->mode = B_DONE;
+    case B_DONE:
+      r = Z_STREAM_END;
+      LEAVE
+    case B_BAD:
+      r = Z_DATA_ERROR;
+      LEAVE
+    default:
+      r = Z_STREAM_ERROR;
+      LEAVE
+  }
+}
+
+
+int zlib_fs_inflate_blocks_free(s, z)
+inflate_blocks_statef *s;
+z_streamp z;
+{
+  zlib_fs_inflate_blocks_reset(s, z, Z_NULL);
+  return Z_OK;
+}
+
+
+void zlib_fs_inflate_set_dictionary(s, d, n)
+inflate_blocks_statef *s;
+const Bytef *d;
+uInt  n;
+{
+  memcpy(s->window, d, n);
+  s->read = s->write = s->window + n;
+}
+
+
+/* Returns true if inflate is currently at the end of a block generated
+ * by Z_SYNC_FLUSH or Z_FULL_FLUSH. 
+ * IN assertion: s != Z_NULL
+ */
+int zlib_fs_inflate_blocks_sync_point(s)
+inflate_blocks_statef *s;
+{
+  return s->mode == LENS;
+}