exec: remove support for transparently ungziping executables

Remove support for transparently ungziping executables from the exec
server. The code in question makes the exec server unnecessarily
complex and since the exec server is an essential process, crashing it
makes /hurd/init crash the whole system.

Since the gzip code is not thread-safe, all access to it is
serialized, so there is a trivial way for one user to delay another
users gzipped executables for some unspecified time.

This can be accomplished by padding any program with easily compressed
data, zipping it and executing it. Using such a program as an passive
translator and then triggering its execution by the filesystem
translator also stalls any requests to that filesystem (observed using
the libdiskfs-based ext2fs).

Since compressed executables cannot be mapped into the memory, they
have to be uncompressed into allocated memory first. This is slower
and any user with access to the exec server can make it allocate
arbitrary amounts of memory. If the Hurd had proper memory accounting,
this would probably be a way around it.

So the compression support in exec seemingly creates various issues
for little value, at least with the abundance of nonvolatile memory
available today.

* exec/Makefile: Remove gzip related files.
* exec/exec.c: Remove anything #ifdef GZIPped.
* exec/unzip.c: Move to libstore.
* exec/crypt.h: Likewise.
* exec/gzip.h: Likewise.
* exec/inflate.c: Likewise.
* exec/tailor.h: Likewise.
* exec/util.c: Likewise.
* libstore/Makefile: Remove the vpath magic for looking up the zip
  stuff.

7 files changed, 1766 insertions, 4 deletions

diff --git a/libstore/Makefile b/libstore/Makefile
index eafdd0a7..607940b7 100644
--- a/libstore/Makefile
+++ b/libstore/Makefile
@@ -60,10 +60,6 @@ OBJS = $(SRCS:.c=.o) $(GUNZIP_OBJS) $(BUNZIP2_OBJS)
 
 include ../Makeconf
 
-# Look for zip stuff
-vpath %.c $(srcdir)/../exec
-CPPFLAGS += -I$(srcdir)/../exec
-
 module-CPPFLAGS = -D'STORE_SONAME_SUFFIX=".so.$(hurd-version)"'
 module-DEPS = $(..)config.make
 
diff --git a/libstore/crypt.h b/libstore/crypt.h
new file mode 100644
index 00000000..2a4c203c
--- /dev/null
+++ b/libstore/crypt.h
@@ -0,0 +1,12 @@
+/* crypt.h (dummy version) -- do not perform encryption
+ * Hardly worth copyrighting :-)
+ */
+
+#ifdef CRYPT
+#  undef CRYPT      /* dummy version */
+#endif
+
+#define RAND_HEAD_LEN  12  /* length of encryption random header */
+
+#define zencode
+#define zdecode
diff --git a/libstore/gzip.h b/libstore/gzip.h
new file mode 100644
index 00000000..aedc257d
--- /dev/null
+++ b/libstore/gzip.h
@@ -0,0 +1,315 @@
+/* gzip.h -- common declarations for all gzip modules
+ * Copyright (C) 1992-1993, 1996 Jean-loup Gailly.
+ * This is free software; you can redistribute it and/or modify it under the
+ * terms of the GNU General Public License, see the file COPYING.
+ */
+
+#if defined(__STDC__) || defined(PROTO)
+#  define OF(args)  args
+#else
+#  define OF(args)  ()
+#endif
+
+#ifdef __STDC__
+   typedef void *voidp;
+#else
+   typedef char *voidp;
+#endif
+
+/* I don't like nested includes, but the string and io functions are used
+ * too often
+ */
+#include <stdio.h>
+#if !defined(NO_STRING_H) || defined(STDC_HEADERS)
+#  include <string.h>
+#  if !defined(STDC_HEADERS) && !defined(NO_MEMORY_H) && !defined(__GNUC__)
+#    include <memory.h>
+#  endif
+#  define memzero(s, n)     memset ((voidp)(s), 0, (n))
+#else
+#  include <strings.h>
+#  define strchr            index 
+#  define strrchr           rindex
+#  define memcpy(d, s, n)   bcopy((s), (d), (n)) 
+#  define memcmp(s1, s2, n) bcmp((s1), (s2), (n)) 
+#  define memzero(s, n)     bzero((s), (n))
+#endif
+
+#ifndef RETSIGTYPE
+#  define RETSIGTYPE void
+#endif
+
+#define local static
+
+typedef unsigned char  uch;
+typedef unsigned short ush;
+typedef unsigned long  ulg;
+
+/* Return codes from gzip */
+#define OK      0
+#define ERROR   1
+#define WARNING 2
+
+/* Compression methods (see algorithm.doc) */
+#define STORED      0
+#define COMPRESSED  1
+#define PACKED      2
+#define LZHED       3
+/* methods 4 to 7 reserved */
+#define DEFLATED    8
+#define MAX_METHODS 9
+extern int method;         /* compression method */
+
+/* To save memory for 16 bit systems, some arrays are overlaid between
+ * the various modules:
+ * deflate:  prev+head   window      d_buf  l_buf  outbuf
+ * unlzw:    tab_prefix  tab_suffix  stack  inbuf  outbuf
+ * inflate:              window             inbuf
+ * unpack:               window             inbuf  prefix_len
+ * unlzh:    left+right  window      c_table inbuf c_len
+ * For compression, input is done in window[]. For decompression, output
+ * is done in window except for unlzw.
+ */
+
+#ifndef	INBUFSIZ
+#  ifdef SMALL_MEM
+#    define INBUFSIZ  0x2000  /* input buffer size */
+#  else
+#    define INBUFSIZ  0x8000  /* input buffer size */
+#  endif
+#endif
+#define INBUF_EXTRA  64     /* required by unlzw() */
+
+#ifndef	OUTBUFSIZ
+#  ifdef SMALL_MEM
+#    define OUTBUFSIZ   8192  /* output buffer size */
+#  else
+#    define OUTBUFSIZ  16384  /* output buffer size */
+#  endif
+#endif
+#define OUTBUF_EXTRA 2048   /* required by unlzw() */
+
+#ifndef DIST_BUFSIZE
+#  ifdef SMALL_MEM
+#    define DIST_BUFSIZE 0x2000 /* buffer for distances, see trees.c */
+#  else
+#    define DIST_BUFSIZE 0x8000 /* buffer for distances, see trees.c */
+#  endif
+#endif
+
+#ifdef DYN_ALLOC
+#  define EXTERN(type, array)  extern type * near array
+#  define DECLARE(type, array, size)  type * near array
+#  define ALLOC(type, array, size) { \
+      array = (type*)fcalloc((size_t)(((size)+1L)/2), 2*sizeof(type)); \
+      if (array == NULL) error("insufficient memory"); \
+   }
+#  define FREE(array) {if (array != NULL) fcfree(array), array=NULL;}
+#else
+#  define EXTERN(type, array)  extern type array[]
+#  define DECLARE(type, array, size)  type array[size]
+#  define ALLOC(type, array, size)
+#  define FREE(array)
+#endif
+
+EXTERN(uch, inbuf);          /* input buffer */
+EXTERN(uch, outbuf);         /* output buffer */
+EXTERN(ush, d_buf);          /* buffer for distances, see trees.c */
+EXTERN(uch, window);         /* Sliding window and suffix table (unlzw) */
+#define tab_suffix window
+#ifndef MAXSEG_64K
+#  define tab_prefix prev    /* hash link (see deflate.c) */
+#  define head (prev+WSIZE)  /* hash head (see deflate.c) */
+   EXTERN(ush, tab_prefix);  /* prefix code (see unlzw.c) */
+#else
+#  define tab_prefix0 prev
+#  define head tab_prefix1
+   EXTERN(ush, tab_prefix0); /* prefix for even codes */
+   EXTERN(ush, tab_prefix1); /* prefix for odd  codes */
+#endif
+
+extern unsigned insize; /* valid bytes in inbuf */
+extern unsigned inptr;  /* index of next byte to be processed in inbuf */
+extern unsigned outcnt; /* bytes in output buffer */
+
+extern long bytes_in;   /* number of input bytes */
+extern long bytes_out;  /* number of output bytes */
+extern long header_bytes;/* number of bytes in gzip header */
+
+#define isize bytes_in
+/* for compatibility with old zip sources (to be cleaned) */
+
+extern int  ifd;        /* input file descriptor */
+extern int  ofd;        /* output file descriptor */
+extern char ifname[];   /* input file name or "stdin" */
+extern char ofname[];   /* output file name or "stdout" */
+extern char *progname;  /* program name */
+
+extern long time_stamp; /* original time stamp (modification time) */
+extern long ifile_size; /* input file size, -1 for devices (debug only) */
+
+typedef int file_t;     /* Do not use stdio */
+#define NO_FILE  (-1)   /* in memory compression */
+
+
+#define	PACK_MAGIC     "\037\036" /* Magic header for packed files */
+#define	GZIP_MAGIC     "\037\213" /* Magic header for gzip files, 1F 8B */
+#define	OLD_GZIP_MAGIC "\037\236" /* Magic header for gzip 0.5 = freeze 1.x */
+#define	LZH_MAGIC      "\037\240" /* Magic header for SCO LZH Compress files*/
+#define PKZIP_MAGIC    "\120\113\003\004" /* Magic header for pkzip files */
+
+/* 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 */
+
+/* internal file attribute */
+#define UNKNOWN 0xffff
+#define BINARY  0
+#define ASCII   1
+
+#ifndef WSIZE
+#  define WSIZE 0x8000     /* window size--must be a power of two, and */
+#endif                     /*  at least 32K for zip's deflate method */
+
+#define MIN_MATCH  3
+#define MAX_MATCH  258
+/* The minimum and maximum match lengths */
+
+#define MIN_LOOKAHEAD (MAX_MATCH+MIN_MATCH+1)
+/* Minimum amount of lookahead, except at the end of the input file.
+ * See deflate.c for comments about the MIN_MATCH+1.
+ */
+
+#define MAX_DIST  (WSIZE-MIN_LOOKAHEAD)
+/* In order to simplify the code, particularly on 16 bit machines, match
+ * distances are limited to MAX_DIST instead of WSIZE.
+ */
+
+extern int decrypt;        /* flag to turn on decryption */
+extern int exit_code;      /* program exit code */
+extern int verbose;        /* be verbose (-v) */
+extern int quiet;          /* be quiet (-q) */
+extern int level;          /* compression level */
+extern int test;           /* check .z file integrity */
+extern int to_stdout;      /* output to stdout (-c) */
+extern int save_orig_name; /* set if original name must be saved */
+
+#define get_byte()  (inptr < insize ? inbuf[inptr++] : fill_inbuf(0))
+#define try_byte()  (inptr < insize ? inbuf[inptr++] : fill_inbuf(1))
+
+/* put_byte is used for the compressed output, put_ubyte for the
+ * uncompressed output. However unlzw() uses window for its
+ * suffix table instead of its output buffer, so it does not use put_ubyte
+ * (to be cleaned up).
+ */
+#define put_byte(c) {outbuf[outcnt++]=(uch)(c); if (outcnt==OUTBUFSIZ)\
+   flush_outbuf();}
+#define put_ubyte(c) {window[outcnt++]=(uch)(c); if (outcnt==WSIZE)\
+   flush_window();}
+
+/* Output a 16 bit value, lsb first */
+#define put_short(w) \
+{ if (outcnt < OUTBUFSIZ-2) { \
+    outbuf[outcnt++] = (uch) ((w) & 0xff); \
+    outbuf[outcnt++] = (uch) ((ush)(w) >> 8); \
+  } else { \
+    put_byte((uch)((w) & 0xff)); \
+    put_byte((uch)((ush)(w) >> 8)); \
+  } \
+}
+
+/* Output a 32 bit value to the bit stream, lsb first */
+#define put_long(n) { \
+    put_short((n) & 0xffff); \
+    put_short(((ulg)(n)) >> 16); \
+}
+
+#define seekable()    0  /* force sequential output */
+#define translate_eol 0  /* no option -a yet */
+
+#define tolow(c)  (isupper(c) ? (c)-'A'+'a' : (c))    /* force to lower case */
+
+/* Macros for getting two-byte and four-byte header values */
+#define SH(p) ((ush)(uch)((p)[0]) | ((ush)(uch)((p)[1]) << 8))
+#define LG(p) ((ulg)(SH(p)) | ((ulg)(SH((p)+2)) << 16))
+
+/* Diagnostic functions */
+#ifdef DEBUG
+#  define Assert(cond,msg) {if(!(cond)) error(msg);}
+#  define Trace(x) fprintf x
+#  define Tracev(x) {if (verbose) fprintf x ;}
+#  define Tracevv(x) {if (verbose>1) fprintf x ;}
+#  define Tracec(c,x) {if (verbose && (c)) fprintf x ;}
+#  define Tracecv(c,x) {if (verbose>1 && (c)) fprintf x ;}
+#else
+#  define Assert(cond,msg)
+#  define Trace(x)
+#  define Tracev(x)
+#  define Tracevv(x)
+#  define Tracec(c,x)
+#  define Tracecv(c,x)
+#endif
+
+#define WARN(msg) {if (!quiet) fprintf msg ; \
+		   if (exit_code == OK) exit_code = WARNING;}
+
+	/* in zip.c: */
+extern int zip        OF((int in, int out));
+extern int file_read  OF((char *buf,  unsigned size));
+
+	/* in unzip.c */
+extern int unzip      OF((int in, int out));
+extern int check_zipfile OF((int in));
+
+	/* in unpack.c */
+extern int unpack     OF((int in, int out));
+
+	/* in unlzh.c */
+extern int unlzh      OF((int in, int out));
+
+	/* in gzip.c */
+RETSIGTYPE abort_gzip OF((void));
+
+        /* in deflate.c */
+void lm_init OF((int pack_level, ush *flags));
+ulg  deflate OF((void));
+
+        /* in trees.c */
+void ct_init     OF((ush *attr, int *method));
+int  ct_tally    OF((int dist, int lc));
+ulg  flush_block OF((char *buf, ulg stored_len, int eof));
+
+        /* in bits.c */
+void     bi_init    OF((file_t zipfile));
+void     send_bits  OF((int value, int length));
+unsigned bi_reverse OF((unsigned value, int length));
+void     bi_windup  OF((void));
+void     copy_block OF((char *buf, unsigned len, int header));
+extern   int (*read_buf) OF((char *buf, unsigned size));
+
+	/* in util.c: */
+extern int copy           OF((int in, int out));
+extern ulg  updcrc        OF((uch *s, unsigned n));
+extern void clear_bufs    OF((void));
+extern int  fill_inbuf    OF((int eof_ok));
+extern void flush_outbuf  OF((void));
+extern void flush_window  OF((void));
+extern void write_buf     OF((int fd, voidp buf, unsigned cnt));
+extern char *strlwr       OF((char *s));
+/* extern char *basename     OF((char *fname));*/
+extern void make_simple_name OF((char *name));
+extern char *add_envopt   OF((int *argcp, char ***argvp, char *env));
+extern void error         OF((char *m));
+extern void warn          OF((char *a, char *b));
+extern void read_error    OF((void));
+extern void write_error   OF((void));
+extern void display_ratio OF((long num, long den, FILE *file));
+extern voidp xmalloc      OF((unsigned int size));
+
+	/* in inflate.c */
+extern int inflate OF((void));
diff --git a/libstore/inflate.c b/libstore/inflate.c
new file mode 100644
index 00000000..c3be4381
--- /dev/null
+++ b/libstore/inflate.c
@@ -0,0 +1,954 @@
+/* inflate.c -- Not copyrighted 1992 by Mark Adler
+   version c10p1, 10 January 1993 */
+
+/* You can do whatever you like with this source file, though I would
+   prefer that if you modify it and redistribute it that you include
+   comments to that effect with your name and the date.  Thank you.
+   [The history has been moved to the file ChangeLog.]
+ */
+
+/*
+   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 1.1 1994/12/14 04:31:21 roland Exp $";
+#endif
+
+#include <sys/types.h>
+
+#include "tailor.h"
+
+#if defined(STDC_HEADERS) || !defined(NO_STDLIB_H)
+#  include <stdlib.h>
+#endif
+
+#include "gzip.h"
+#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 */
+int huft_build OF((unsigned *, unsigned, unsigned, ush *, ush *,
+                   struct huft **, int *));
+int huft_free OF((struct huft *));
+int inflate_codes OF((struct huft *, struct huft *, int, int));
+int inflate_stored OF((void));
+int inflate_fixed OF((void));
+int inflate_dynamic OF((void));
+int inflate_block OF((int *));
+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.
+ */
+
+ulg bb;                         /* bit buffer */
+unsigned bk;                    /* bits in bit buffer */
+
+ush mask_bits[] = {
+    0x0000,
+    0x0001, 0x0003, 0x0007, 0x000f, 0x001f, 0x003f, 0x007f, 0x00ff,
+    0x01ff, 0x03ff, 0x07ff, 0x0fff, 0x1fff, 0x3fff, 0x7fff, 0xffff
+};
+
+#ifdef CRYPT
+  uch cc;
+#  define NEXTBYTE() \
+     (decrypt ? (cc = get_byte(), zdecode(cc), cc) : get_byte())
+#else
+#  define NEXTBYTE()  (uch)get_byte()
+#endif
+#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.
+ */
+
+
+int lbits = 9;          /* bits in base literal/length lookup table */
+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 */
+
+
+unsigned hufts;         /* track memory usage */
+
+
+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 */
+
+
+  /* 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;
+  }
+
+
+  /* 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;
+
+
+  /* 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;
+
+
+  /* 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++);
+  }
+
+
+  /* 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);
+
+
+  /* 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 */
+
+  /* go through the bit lengths (k already is bits in shortest code) */
+  for (; k <= g; k++)
+  {
+    a = c[k];
+    while (a--)
+    {
+      /* here i is the Huffman code of length k bits for value *p */
+      /* make tables up to required level */
+      while (k > w + l)
+      {
+        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 */
+          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 */
+          }
+        }
+        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 */
+        }
+        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 */
+
+        /* 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 */
+        }
+      }
+
+      /* 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];
+      }
+
+      /* 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;
+      }
+    }
+  }
+
+
+  /* Return true (1) if we were given an incomplete table */
+  return y != 0 && g != 1;
+}
+
+
+
+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;
+}
+
+
+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;
+}
+
+
+
+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 */
+
+
+  /* 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;
+  return 0;
+}
+
+
+
+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 */
+
+
+  /* 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);
+    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;
+}
+
+
+
+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 */
+
+
+  /* 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 */
+
+
+  /* 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;
+
+
+  /* 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 */
+  }
+
+
+  /* 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;
+    }
+  }
+
+
+  /* free decoding table for trees */
+  huft_free(tl);
+
+
+  /* restore the global bit buffer */
+  bb = b;
+  bk = k;
+
+
+  /* build the decoding tables for literal/length and distance codes */
+  bl = lbits;
+  if ((i = huft_build(ll, nl, 257, cplens, cplext, &tl, &bl)) != 0)
+  {
+    if (i == 1) {
+      fprintf(stderr, " incomplete literal tree\n");
+      huft_free(tl);
+    }
+    return i;                   /* incomplete code set */
+  }
+  bd = dbits;
+  if ((i = huft_build(ll + nl, nd, 0, cpdist, cpdext, &td, &bd)) != 0)
+  {
+    if (i == 1) {
+      fprintf(stderr, " incomplete distance tree\n");
+#ifdef PKZIP_BUG_WORKAROUND
+      i = 0;
+    }
+#else
+      huft_free(td);
+    }
+    huft_free(tl);
+    return i;                   /* incomplete code set */
+#endif
+  }
+
+
+  /* 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;
+}
+
+
+
+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 */
+
+
+  /* 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();
+
+
+  /* bad block type */
+  return 2;
+}
+
+
+
+int inflate()
+/* decompress an inflated entry */
+{
+  int e;                /* last block flag */
+  int r;                /* result code */
+  unsigned h;           /* maximum struct huft's malloc'ed */
+
+
+  /* initialize window, bit buffer */
+  wp = 0;
+  bk = 0;
+  bb = 0;
+
+
+  /* decompress until the last block */
+  h = 0;
+  do {
+    hufts = 0;
+    if ((r = inflate_block(&e)) != 0)
+      return r;
+    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;
+}
diff --git a/libstore/tailor.h b/libstore/tailor.h
new file mode 100644
index 00000000..d207af55
--- /dev/null
+++ b/libstore/tailor.h
@@ -0,0 +1,14 @@
+
+#ifndef get_char
+#  define get_char() get_byte()
+#endif
+
+#ifndef put_char
+#  define put_char(c) put_byte(c)
+#endif
+
+#include <stdio.h>
+#define fprintf(stream, fmt...) /* ignore useless error msgs */ ((void)0)
+
+void (*unzip_error) (const char *msg);
+#define error(msg) (*unzip_error) (msg)
diff --git a/libstore/unzip.c b/libstore/unzip.c
new file mode 100644
index 00000000..d0f5bf11
--- /dev/null
+++ b/libstore/unzip.c
@@ -0,0 +1,199 @@
+/* unzip.c -- decompress files in gzip or pkzip format.
+ * Copyright (C) 1992-1993 Jean-loup Gailly
+ * This is free software; you can redistribute it and/or modify it under the
+ * terms of the GNU General Public License, see the file COPYING.
+ *
+ * The code in this file is derived from the file funzip.c written
+ * and put in the public domain by Mark Adler.
+ */
+
+/*
+   This version can extract files in gzip or pkzip format.
+   For the latter, only the first entry is extracted, and it has to be
+   either deflated or stored.
+ */
+
+#ifdef RCSID
+static char rcsid[] = "$Id: unzip.c,v 1.1 1994/12/14 04:30:25 roland Exp $";
+#endif
+
+#include "tailor.h"
+#include "gzip.h"
+#include "crypt.h"
+
+/* PKZIP header definitions */
+#define LOCSIG 0x04034b50L      /* four-byte lead-in (lsb first) */
+#define LOCFLG 6                /* offset of bit flag */
+#define  CRPFLG 1               /*  bit for encrypted entry */
+#define  EXTFLG 8               /*  bit for extended local header */
+#define LOCHOW 8                /* offset of compression method */
+#define LOCTIM 10               /* file mod time (for decryption) */
+#define LOCCRC 14               /* offset of crc */
+#define LOCSIZ 18               /* offset of compressed size */
+#define LOCLEN 22               /* offset of uncompressed length */
+#define LOCFIL 26               /* offset of file name field length */
+#define LOCEXT 28               /* offset of extra field length */
+#define LOCHDR 30               /* size of local header, including sig */
+#define EXTHDR 16               /* size of extended local header, inc sig */
+
+
+/* Globals */
+
+int decrypt;        /* flag to turn on decryption */
+char *key;          /* not used--needed to link crypt.c */
+int pkzip = 0;      /* set for a pkzip file */
+int ext_header = 0; /* set if extended local header */
+
+/* ===========================================================================
+ * Check zip file and advance inptr to the start of the compressed data.
+ * Get ofname from the local header if necessary.
+ */
+int check_zipfile(in)
+    int in;   /* input file descriptors */
+{
+    uch *h = inbuf + inptr; /* first local header */
+
+    ifd = in;
+
+    /* Check validity of local header, and skip name and extra fields */
+    inptr += LOCHDR + SH(h + LOCFIL) + SH(h + LOCEXT);
+
+    if (inptr > insize || LG(h) != LOCSIG) {
+	fprintf(stderr, "\n%s: %s: not a valid zip file\n",
+		progname, ifname);
+	exit_code = ERROR;
+	return ERROR;
+    }
+    method = h[LOCHOW];
+    if (method != STORED && method != DEFLATED) {
+	fprintf(stderr,
+		"\n%s: %s: first entry not deflated or stored -- use unzip\n",
+		progname, ifname);
+	exit_code = ERROR;
+	return ERROR;
+    }
+
+    /* If entry encrypted, decrypt and validate encryption header */
+    if ((decrypt = h[LOCFLG] & CRPFLG) != 0) {
+	fprintf(stderr, "\n%s: %s: encrypted file -- use unzip\n",
+		progname, ifname);
+	exit_code = ERROR;
+	return ERROR;
+    }
+
+    /* Save flags for unzip() */
+    ext_header = (h[LOCFLG] & EXTFLG) != 0;
+    pkzip = 1;
+
+    /* Get ofname and time stamp from local header (to be done) */
+    return OK;
+}
+
+/* ===========================================================================
+ * Unzip in to out.  This routine works on both gzip and pkzip files.
+ *
+ * IN assertions: the buffer inbuf contains already the beginning of
+ *   the compressed data, from offsets inptr to insize-1 included.
+ *   The magic header has already been checked. The output buffer is cleared.
+ */
+int unzip(in, out)
+    int in, out;   /* input and output file descriptors */
+{
+    ulg orig_crc = 0;       /* original crc */
+    ulg orig_len = 0;       /* original uncompressed length */
+    int n;
+    uch buf[EXTHDR];        /* extended local header */
+
+    ifd = in;
+    ofd = out;
+
+    updcrc(NULL, 0);           /* initialize crc */
+
+    if (pkzip && !ext_header) {  /* crc and length at the end otherwise */
+	orig_crc = LG(inbuf + LOCCRC);
+	orig_len = LG(inbuf + LOCLEN);
+    }
+
+    /* Decompress */
+    if (method == DEFLATED)  {
+
+	int res = inflate();
+
+	if (res == 3) {
+	    error("out of memory");
+	} else if (res != 0) {
+	    error("invalid compressed data--format violated");
+	}
+
+    } else if (pkzip && method == STORED) {
+
+	register ulg n = LG(inbuf + LOCLEN);
+
+	if (n != LG(inbuf + LOCSIZ) - (decrypt ? RAND_HEAD_LEN : 0)) {
+
+	    fprintf(stderr, "len %ld, siz %ld\n", n, LG(inbuf + LOCSIZ));
+	    error("invalid compressed data--length mismatch");
+	}
+	while (n--) {
+	    uch c = (uch)get_byte();
+#ifdef CRYPT
+	    if (decrypt) zdecode(c);
+#endif
+	    put_ubyte(c);
+	}
+	flush_window();
+    } else {
+	error("internal error, invalid method");
+    }
+
+    /* Get the crc and original length */
+    if (!pkzip) {
+        /* crc32  (see algorithm.doc)
+	 * uncompressed input size modulo 2^32
+         */
+	for (n = 0; n < 8; n++) {
+	    buf[n] = (uch)get_byte(); /* may cause an error if EOF */
+	}
+	orig_crc = LG(buf);
+	orig_len = LG(buf+4);
+
+    } else if (ext_header) {  /* If extended header, check it */
+	/* signature - 4bytes: 0x50 0x4b 0x07 0x08
+	 * CRC-32 value
+         * compressed size 4-bytes
+         * uncompressed size 4-bytes
+	 */
+	for (n = 0; n < EXTHDR; n++) {
+	    buf[n] = (uch)get_byte(); /* may cause an error if EOF */
+	}
+	orig_crc = LG(buf+4);
+	orig_len = LG(buf+12);
+    }
+
+    /* Validate decompression */
+    if (orig_crc != updcrc(outbuf, 0)) {
+	error("invalid compressed data--crc error");
+    }
+    if (orig_len != (ulg)bytes_out) {
+	error("invalid compressed data--length error");
+    }
+
+    /* Check if there are more entries in a pkzip file */
+    if (pkzip && inptr + 4 < insize && LG(inbuf+inptr) == LOCSIG) {
+	if (to_stdout) {
+	    WARN((stderr,
+		  "%s: %s has more than one entry--rest ignored\n",
+		  progname, ifname));
+	} else {
+	    /* Don't destroy the input zip file */
+	    fprintf(stderr,
+		    "%s: %s has more than one entry -- unchanged\n",
+		    progname, ifname);
+	    exit_code = ERROR;
+	    ext_header = pkzip = 0;
+	    return ERROR;
+	}
+    }
+    ext_header = pkzip = 0; /* for next file */
+    return OK;
+}
diff --git a/libstore/util.c b/libstore/util.c
new file mode 100644
index 00000000..598586f5
--- /dev/null
+++ b/libstore/util.c
@@ -0,0 +1,272 @@
+/* Hacked and slashed by roland@gnu.ai.mit.edu for use in Hurd exec server.  */
+
+/* util.c -- utility functions for gzip support
+ * Copyright (C) 1992-1993 Jean-loup Gailly
+ * This is free software; you can redistribute it and/or modify it under the
+ * terms of the GNU General Public License, see the file COPYING.
+ */
+
+#ifdef RCSID
+static char rcsid[] = "$Id: util.c,v 1.1 1994/12/14 04:29:37 roland Exp $";
+#endif
+
+#include <ctype.h>
+#include <errno.h>
+#include <sys/types.h>
+
+#include "tailor.h"
+
+#ifdef HAVE_UNISTD_H
+#  include <unistd.h>
+#endif
+#ifndef NO_FCNTL_H
+#  include <fcntl.h>
+#endif
+
+#if defined(STDC_HEADERS) || !defined(NO_STDLIB_H)
+#  include <stdlib.h>
+#else
+   extern int errno;
+#endif
+
+#include "gzip.h"
+#include "crypt.h"
+
+/* cruft */
+int ifd, ofd;
+int to_stdout=1,quiet=1;
+
+/* I/O interface */
+int (*unzip_read) (char *buf, size_t maxread);
+void (*unzip_write) (const char *buf, size_t nwrite);
+#define read_error() (*unzip_read_error) ()
+void (*unzip_read_error) (void);
+
+
+extern ulg crc_32_tab[];   /* crc table, defined below */
+
+int exit_code = OK;   /* program exit code */
+int method = DEFLATED;/* compression method */
+unsigned insize;           /* valid bytes in inbuf */
+unsigned inptr;            /* index of next byte to be processed in inbuf */
+unsigned outcnt;           /* bytes in output buffer */
+DECLARE(uch, inbuf,  INBUFSIZ +INBUF_EXTRA);
+DECLARE(uch, outbuf, OUTBUFSIZ+OUTBUF_EXTRA);
+DECLARE(uch, window, 2L*WSIZE);
+
+
+/* This function stolen from gzip.c. */
+/* ========================================================================
+ * Check the magic number of the input file and update ofname if an
+ * original name was given and to_stdout is not set.
+ * Return the compression method, -1 for error, -2 for warning.
+ * Set inptr to the offset of the next byte to be processed.
+ * Updates time_stamp if there is one and --no-time is not used.
+ * This function may be called repeatedly for an input file consisting
+ * of several contiguous gzip'ed members.
+ * IN assertions: there is at least one remaining compressed member.
+ *   If the member is a zip file, it must be the only one.
+ */
+int get_method(in)
+    int in;        /* input file descriptor */
+{
+    uch flags;     /* compression flags */
+    char magic[2]; /* magic header */
+    ulg stamp;     /* time stamp */
+
+    /* Prime the input buffer.  */
+    fill_inbuf(0);
+    inptr = 0;
+
+    magic[0] = (char)get_byte();
+    magic[1] = (char)get_byte();
+
+    method = -1;                 /* unknown yet */
+
+    if (memcmp(magic, GZIP_MAGIC, 2) == 0
+        || memcmp(magic, OLD_GZIP_MAGIC, 2) == 0) {
+
+	method = (int)get_byte();
+	if (method != DEFLATED)
+	  return -1;
+
+	flags  = (uch)get_byte();
+	if ((flags & ENCRYPTED) != 0) return -1;
+	if ((flags & CONTINUATION) != 0) return -1;
+	if ((flags & RESERVED) != 0) return -1;
+
+	stamp  = (ulg)get_byte();
+	stamp |= ((ulg)get_byte()) << 8;
+	stamp |= ((ulg)get_byte()) << 16;
+	stamp |= ((ulg)get_byte()) << 24;
+
+	(void)get_byte();  /* Ignore extra flags for the moment */
+	(void)get_byte();  /* Ignore OS type for the moment */
+
+	if ((flags & CONTINUATION) != 0) {
+	    unsigned part = (unsigned)get_byte();
+	    part |= ((unsigned)get_byte())<<8;
+	}
+	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 */
+	  char c; /* dummy used for NeXTstep 3.0 cc optimizer bug */
+	  do {c=get_byte();} while (c != 0);
+	} 
+
+	/* Discard file comment if any */
+	if ((flags & COMMENT) != 0) {
+	    while (get_char() != 0) /* null */ ;
+	}
+    } else if (memcmp(magic, PKZIP_MAGIC, 2) == 0 && inptr == 2
+	    && memcmp((char*)inbuf, PKZIP_MAGIC, 4) == 0) {
+      /* To simplify the code, we support a zip file when alone only.
+       * We are thus guaranteed that the entire local header fits in inbuf.
+       */
+      inptr = 0;
+      if (check_zipfile(in) == OK) return 0;
+    }
+
+    return method != DEFLATED;
+}
+
+
+/* ===========================================================================
+ * Run a set of bytes through the crc shift register.  If s is a NULL
+ * pointer, then initialize the crc shift register contents instead.
+ * Return the current crc in either case.
+ */
+ulg updcrc(s, n)
+    uch *s;                 /* pointer to bytes to pump through */
+    unsigned n;             /* number of bytes in s[] */
+{
+    register ulg c;         /* temporary variable */
+
+    static ulg crc = (ulg)0xffffffffL; /* shift register contents */
+
+    if (s == NULL) {
+	c = 0xffffffffL;
+    } else {
+	c = crc;
+        if (n) do {
+            c = crc_32_tab[((int)c ^ (*s++)) & 0xff] ^ (c >> 8);
+        } while (--n);
+    }
+    crc = c;
+    return c ^ 0xffffffffL;       /* (instead of ~c for 64-bit machines) */
+}
+
+/* ===========================================================================
+ * Clear input and output buffers
+ */
+void clear_bufs()
+{
+    outcnt = 0;
+    insize = inptr = 0;
+}
+
+/* ===========================================================================
+ * Fill the input buffer. This is called only when the buffer is empty.
+ */
+int fill_inbuf(eof_ok)
+    int eof_ok;          /* set if EOF acceptable as a result */
+{
+    int len;
+
+    /* Read as much as possible */
+    insize = 0;
+    do {
+	len = (*unzip_read)((char*)inbuf+insize, INBUFSIZ-insize);
+        if (len == 0 || len == EOF) break;
+	insize += len;
+    } while (insize < INBUFSIZ);
+
+    if (insize == 0) {
+	if (eof_ok) return EOF;
+	read_error();
+    }
+
+    inptr = 1;
+    return inbuf[0];
+}
+
+long int bytes_out;
+
+/* ===========================================================================
+ * Write the output window window[0..outcnt-1] and update crc and bytes_out.
+ * (Used for the decompressed data only.)
+ */
+void flush_window()
+{
+    if (outcnt == 0) return;
+    updcrc(window, outcnt);
+
+    (*unzip_write) ((char *) window, outcnt);
+    bytes_out += outcnt;
+
+    outcnt = 0;
+}
+
+/* ========================================================================
+ * Table of CRC-32's of all single-byte values (made by makecrc.c)
+ */
+ulg crc_32_tab[] = {
+  0x00000000L, 0x77073096L, 0xee0e612cL, 0x990951baL, 0x076dc419L,
+  0x706af48fL, 0xe963a535L, 0x9e6495a3L, 0x0edb8832L, 0x79dcb8a4L,
+  0xe0d5e91eL, 0x97d2d988L, 0x09b64c2bL, 0x7eb17cbdL, 0xe7b82d07L,
+  0x90bf1d91L, 0x1db71064L, 0x6ab020f2L, 0xf3b97148L, 0x84be41deL,
+  0x1adad47dL, 0x6ddde4ebL, 0xf4d4b551L, 0x83d385c7L, 0x136c9856L,
+  0x646ba8c0L, 0xfd62f97aL, 0x8a65c9ecL, 0x14015c4fL, 0x63066cd9L,
+  0xfa0f3d63L, 0x8d080df5L, 0x3b6e20c8L, 0x4c69105eL, 0xd56041e4L,
+  0xa2677172L, 0x3c03e4d1L, 0x4b04d447L, 0xd20d85fdL, 0xa50ab56bL,
+  0x35b5a8faL, 0x42b2986cL, 0xdbbbc9d6L, 0xacbcf940L, 0x32d86ce3L,
+  0x45df5c75L, 0xdcd60dcfL, 0xabd13d59L, 0x26d930acL, 0x51de003aL,
+  0xc8d75180L, 0xbfd06116L, 0x21b4f4b5L, 0x56b3c423L, 0xcfba9599L,
+  0xb8bda50fL, 0x2802b89eL, 0x5f058808L, 0xc60cd9b2L, 0xb10be924L,
+  0x2f6f7c87L, 0x58684c11L, 0xc1611dabL, 0xb6662d3dL, 0x76dc4190L,
+  0x01db7106L, 0x98d220bcL, 0xefd5102aL, 0x71b18589L, 0x06b6b51fL,
+  0x9fbfe4a5L, 0xe8b8d433L, 0x7807c9a2L, 0x0f00f934L, 0x9609a88eL,
+  0xe10e9818L, 0x7f6a0dbbL, 0x086d3d2dL, 0x91646c97L, 0xe6635c01L,
+  0x6b6b51f4L, 0x1c6c6162L, 0x856530d8L, 0xf262004eL, 0x6c0695edL,
+  0x1b01a57bL, 0x8208f4c1L, 0xf50fc457L, 0x65b0d9c6L, 0x12b7e950L,
+  0x8bbeb8eaL, 0xfcb9887cL, 0x62dd1ddfL, 0x15da2d49L, 0x8cd37cf3L,
+  0xfbd44c65L, 0x4db26158L, 0x3ab551ceL, 0xa3bc0074L, 0xd4bb30e2L,
+  0x4adfa541L, 0x3dd895d7L, 0xa4d1c46dL, 0xd3d6f4fbL, 0x4369e96aL,
+  0x346ed9fcL, 0xad678846L, 0xda60b8d0L, 0x44042d73L, 0x33031de5L,
+  0xaa0a4c5fL, 0xdd0d7cc9L, 0x5005713cL, 0x270241aaL, 0xbe0b1010L,
+  0xc90c2086L, 0x5768b525L, 0x206f85b3L, 0xb966d409L, 0xce61e49fL,
+  0x5edef90eL, 0x29d9c998L, 0xb0d09822L, 0xc7d7a8b4L, 0x59b33d17L,
+  0x2eb40d81L, 0xb7bd5c3bL, 0xc0ba6cadL, 0xedb88320L, 0x9abfb3b6L,
+  0x03b6e20cL, 0x74b1d29aL, 0xead54739L, 0x9dd277afL, 0x04db2615L,
+  0x73dc1683L, 0xe3630b12L, 0x94643b84L, 0x0d6d6a3eL, 0x7a6a5aa8L,
+  0xe40ecf0bL, 0x9309ff9dL, 0x0a00ae27L, 0x7d079eb1L, 0xf00f9344L,
+  0x8708a3d2L, 0x1e01f268L, 0x6906c2feL, 0xf762575dL, 0x806567cbL,
+  0x196c3671L, 0x6e6b06e7L, 0xfed41b76L, 0x89d32be0L, 0x10da7a5aL,
+  0x67dd4accL, 0xf9b9df6fL, 0x8ebeeff9L, 0x17b7be43L, 0x60b08ed5L,
+  0xd6d6a3e8L, 0xa1d1937eL, 0x38d8c2c4L, 0x4fdff252L, 0xd1bb67f1L,
+  0xa6bc5767L, 0x3fb506ddL, 0x48b2364bL, 0xd80d2bdaL, 0xaf0a1b4cL,
+  0x36034af6L, 0x41047a60L, 0xdf60efc3L, 0xa867df55L, 0x316e8eefL,
+  0x4669be79L, 0xcb61b38cL, 0xbc66831aL, 0x256fd2a0L, 0x5268e236L,
+  0xcc0c7795L, 0xbb0b4703L, 0x220216b9L, 0x5505262fL, 0xc5ba3bbeL,
+  0xb2bd0b28L, 0x2bb45a92L, 0x5cb36a04L, 0xc2d7ffa7L, 0xb5d0cf31L,
+  0x2cd99e8bL, 0x5bdeae1dL, 0x9b64c2b0L, 0xec63f226L, 0x756aa39cL,
+  0x026d930aL, 0x9c0906a9L, 0xeb0e363fL, 0x72076785L, 0x05005713L,
+  0x95bf4a82L, 0xe2b87a14L, 0x7bb12baeL, 0x0cb61b38L, 0x92d28e9bL,
+  0xe5d5be0dL, 0x7cdcefb7L, 0x0bdbdf21L, 0x86d3d2d4L, 0xf1d4e242L,
+  0x68ddb3f8L, 0x1fda836eL, 0x81be16cdL, 0xf6b9265bL, 0x6fb077e1L,
+  0x18b74777L, 0x88085ae6L, 0xff0f6a70L, 0x66063bcaL, 0x11010b5cL,
+  0x8f659effL, 0xf862ae69L, 0x616bffd3L, 0x166ccf45L, 0xa00ae278L,
+  0xd70dd2eeL, 0x4e048354L, 0x3903b3c2L, 0xa7672661L, 0xd06016f7L,
+  0x4969474dL, 0x3e6e77dbL, 0xaed16a4aL, 0xd9d65adcL, 0x40df0b66L,
+  0x37d83bf0L, 0xa9bcae53L, 0xdebb9ec5L, 0x47b2cf7fL, 0x30b5ffe9L,
+  0xbdbdf21cL, 0xcabac28aL, 0x53b39330L, 0x24b4a3a6L, 0xbad03605L,
+  0xcdd70693L, 0x54de5729L, 0x23d967bfL, 0xb3667a2eL, 0xc4614ab8L,
+  0x5d681b02L, 0x2a6f2b94L, 0xb40bbe37L, 0xc30c8ea1L, 0x5a05df1bL,
+  0x2d02ef8dL
+};