unzip.c

   1 /* unzip.c -- decompress files in gzip or pkzip format.
   2  * Copyright (C) 1992-1993 Jean-loup Gailly
   3  * This is free software; you can redistribute it and/or modify it under the
   4  * terms of the GNU General Public License, see the file COPYING.
   5  *
   6  * The code in this file is derived from the file funzip.c written
   7  * and put in the public domain by Mark Adler.
   8  */
   9
  10 /*
  11    This version can extract files in gzip or pkzip format.
  12    For the latter, only the first entry is extracted, and it has to be
  13    either deflated or stored.
  14  */
  15
  16 #ifdef RCSID
  17 static char rcsid[] = "$Id$";
  18 #endif
  19
  20 #include <config.h>
  21 #include "tailor.h"
  22 #include "gzip.h"
  23 #include "crypt.h"
  24
  25 /* PKZIP header definitions */
  26 #define LOCSIG 0x04034b50L      /* four-byte lead-in (lsb first) */
  27 #define LOCFLG 6                /* offset of bit flag */
  28 #define  CRPFLG 1               /*  bit for encrypted entry */
  29 #define  EXTFLG 8               /*  bit for extended local header */
  30 #define LOCHOW 8                /* offset of compression method */
  31 #define LOCTIM 10               /* file mod time (for decryption) */
  32 #define LOCCRC 14               /* offset of crc */
  33 #define LOCSIZ 18               /* offset of compressed size */
  34 #define LOCLEN 22               /* offset of uncompressed length */
  35 #define LOCFIL 26               /* offset of file name field length */
  36 #define LOCEXT 28               /* offset of extra field length */
  37 #define LOCHDR 30               /* size of local header, including sig */
  38 #define EXTHDR 16               /* size of extended local header, inc sig */
  39 #define RAND_HEAD_LEN  12       /* length of encryption random header */
  40
  41
  42 /* Globals */
  43
  44 int decrypt;        /* flag to turn on decryption */
  45 char *key;          /* not used--needed to link crypt.c */
  46 int pkzip = 0;      /* set for a pkzip file */
  47 int ext_header = 0; /* set if extended local header */
  48
  49 /* ===========================================================================
  50  * Check zip file and advance inptr to the start of the compressed data.
  51  * Get ofname from the local header if necessary.
  52  */
  53 int check_zipfile(in)
  54     int in;   /* input file descriptors */
  55 {
  56     uch *h = inbuf + inptr; /* first local header */
  57
  58     ifd = in;
  59
  60     /* Check validity of local header, and skip name and extra fields */
  61     inptr += LOCHDR + SH(h + LOCFIL) + SH(h + LOCEXT);
  62
  63     if (inptr > insize || LG(h) != LOCSIG) {
  64         fprintf(stderr, "\n%s: %s: not a valid zip file\n",
  65                 progname, ifname);
  66         exit_code = ERROR;
  67         return ERROR;
  68     }
  69     method = h[LOCHOW];
  70     if (method != STORED && method != DEFLATED) {
  71         fprintf(stderr,
  72                 "\n%s: %s: first entry not deflated or stored -- use unzip\n",
  73                 progname, ifname);
  74         exit_code = ERROR;
  75         return ERROR;
  76     }
  77
  78     /* If entry encrypted, decrypt and validate encryption header */
  79     if ((decrypt = h[LOCFLG] & CRPFLG) != 0) {
  80         fprintf(stderr, "\n%s: %s: encrypted file -- use unzip\n",
  81                 progname, ifname);
  82         exit_code = ERROR;
  83         return ERROR;
  84     }
  85
  86     /* Save flags for unzip() */
  87     ext_header = (h[LOCFLG] & EXTFLG) != 0;
  88     pkzip = 1;
  89
  90     /* Get ofname and time stamp from local header (to be done) */
  91     return OK;
  92 }
  93
  94 /* ===========================================================================
  95  * Unzip in to out.  This routine works on both gzip and pkzip files.
  96  *
  97  * IN assertions: the buffer inbuf contains already the beginning of
  98  *   the compressed data, from offsets inptr to insize-1 included.
  99  *   The magic header has already been checked. The output buffer is cleared.
 100  */
 101 int unzip(in, out)
 102     int in, out;   /* input and output file descriptors */
 103 {
 104     ulg orig_crc = 0;       /* original crc */
 105     ulg orig_len = 0;       /* original uncompressed length */
 106     int n;
 107     uch buf[EXTHDR];        /* extended local header */
 108     int err = OK;
 109
 110     ifd = in;
 111     ofd = out;
 112
 113     updcrc(NULL, 0);           /* initialize crc */
 114
 115     if (pkzip && !ext_header) {  /* crc and length at the end otherwise */
 116         orig_crc = LG(inbuf + LOCCRC);
 117         orig_len = LG(inbuf + LOCLEN);
 118     }
 119
 120     /* Decompress */
 121     if (method == DEFLATED)  {
 122
 123         int res = inflate();
 124
 125         if (res == 3) {
 126             error("out of memory");
 127         } else if (res != 0) {
 128             error("invalid compressed data--format violated");
 129         }
 130
 131     } else if (pkzip && method == STORED) {
 132
 133         register ulg n = LG(inbuf + LOCLEN);
 134
 135         if (n != LG(inbuf + LOCSIZ) - (decrypt ? RAND_HEAD_LEN : 0)) {
 136
 137             fprintf(stderr, "len %ld, siz %ld\n", n, LG(inbuf + LOCSIZ));
 138             error("invalid compressed data--length mismatch");
 139         }
 140         while (n--) {
 141             uch c = (uch)get_byte();
 142             put_ubyte(c);
 143         }
 144         flush_window();
 145     } else {
 146         error("internal error, invalid method");
 147     }
 148
 149     /* Get the crc and original length */
 150     if (!pkzip) {
 151         /* crc32  (see algorithm.doc)
 152          * uncompressed input size modulo 2^32
 153          */
 154         for (n = 0; n < 8; n++) {
 155             buf[n] = (uch)get_byte(); /* may cause an error if EOF */
 156         }
 157         orig_crc = LG(buf);
 158         orig_len = LG(buf+4);
 159
 160     } else if (ext_header) {  /* If extended header, check it */
 161         /* signature - 4bytes: 0x50 0x4b 0x07 0x08
 162          * CRC-32 value
 163          * compressed size 4-bytes
 164          * uncompressed size 4-bytes
 165          */
 166         for (n = 0; n < EXTHDR; n++) {
 167             buf[n] = (uch)get_byte(); /* may cause an error if EOF */
 168         }
 169         orig_crc = LG(buf+4);
 170         orig_len = LG(buf+12);
 171     }
 172
 173     /* Validate decompression */
 174     if (orig_crc != updcrc(outbuf, 0)) {
 175         fprintf(stderr, "\n%s: %s: invalid compressed data--crc error\n",
 176                 progname, ifname);
 177         err = ERROR;
 178     }
 179     if (orig_len != (ulg)(bytes_out & 0xffffffff)) {
 180         fprintf(stderr, "\n%s: %s: invalid compressed data--length error\n",
 181                 progname, ifname);
 182         err = ERROR;
 183     }
 184
 185     /* Check if there are more entries in a pkzip file */
 186     if (pkzip && inptr + 4 < insize && LG(inbuf+inptr) == LOCSIG) {
 187         if (to_stdout) {
 188             WARN((stderr,
 189                   "%s: %s has more than one entry--rest ignored\n",
 190                   progname, ifname));
 191         } else {
 192             /* Don't destroy the input zip file */
 193             fprintf(stderr,
 194                     "%s: %s has more than one entry -- unchanged\n",
 195                     progname, ifname);
 196             err = ERROR;
 197         }
 198     }
 199     ext_header = pkzip = 0; /* for next file */
 200     if (err == OK) return OK;
 201     exit_code = ERROR;
 202     if (!test) abort_gzip();
 203     return err;
 204 }