unzip.c

   1 /* unzip.c -- decompress files in gzip or pkzip format.
   2
   3    Copyright (C) 1997-1999, 2009-2024 Free Software Foundation, Inc.
   4    Copyright (C) 1992-1993 Jean-loup Gailly
   5
   6    This program is free software; you can redistribute it and/or modify
   7    it under the terms of the GNU General Public License as published by
   8    the Free Software Foundation; either version 3, or (at your option)
   9    any later version.
  10
  11    This program is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14    GNU General Public License for more details.
  15
  16    You should have received a copy of the GNU General Public License
  17    along with this program; if not, write to the Free Software Foundation,
  18    Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.  */
  19
  20 /*
  21  * The code in this file is derived from the file funzip.c written
  22  * and put in the public domain by Mark Adler.
  23  */
  24
  25 /*
  26    This version can extract files in gzip or pkzip format.
  27    For the latter, only the first entry is extracted, and it has to be
  28    either deflated or stored.
  29  */
  30
  31 #include <config.h>
  32 #include "tailor.h"
  33 #include "gzip.h"
  34
  35 /* PKZIP header definitions */
  36 #define LOCSIG 0x04034b50L      /* four-byte lead-in (lsb first) */
  37 #define LOCFLG 6                /* offset of bit flag */
  38 #define  CRPFLG 1               /*  bit for encrypted entry */
  39 #define  EXTFLG 8               /*  bit for extended local header */
  40 #define LOCHOW 8                /* offset of compression method */
  41 /* #define LOCTIM 10               UNUSED file mod time (for decryption) */
  42 #define LOCCRC 14               /* offset of crc */
  43 #define LOCSIZ 18               /* offset of compressed size */
  44 #define LOCLEN 22               /* offset of uncompressed length */
  45 #define LOCFIL 26               /* offset of file name field length */
  46 #define LOCEXT 28               /* offset of extra field length */
  47 #define LOCHDR 30               /* size of local header, including sig */
  48 #define EXTHDR 16               /* size of extended local header, inc sig */
  49 #define RAND_HEAD_LEN  12       /* length of encryption random header */
  50
  51
  52 /* Globals */
  53
  54 ulg unzip_crc;  /* CRC found by 'unzip'.  */
  55
  56 static int decrypt;        /* flag to turn on decryption */
  57 static int pkzip = 0;      /* set for a pkzip file */
  58 static int ext_header = 0; /* set if extended local header */
  59
  60 /* ===========================================================================
  61  * Check zip file and advance inptr to the start of the compressed data.
  62  * Get ofname from the local header if necessary.
  63  * IN is the input file descriptor.
  64  */
  65 int
  66 check_zipfile (int in)
  67 {
  68     uch *h = inbuf + inptr; /* first local header */
  69
  70     ifd = in;
  71
  72     /* Check validity of local header, and skip name and extra fields */
  73     inptr += LOCHDR + SH(h + LOCFIL) + SH(h + LOCEXT);
  74
  75     if (inptr > insize || LG(h) != LOCSIG) {
  76         fprintf(stderr, "\n%s: %s: not a valid zip file\n",
  77                 program_name, ifname);
  78         exit_code = ERROR;
  79         return ERROR;
  80     }
  81     method = h[LOCHOW];
  82     if (method != STORED && method != DEFLATED) {
  83         fprintf(stderr,
  84                 "\n%s: %s: first entry not deflated or stored -- use unzip\n",
  85                 program_name, ifname);
  86         exit_code = ERROR;
  87         return ERROR;
  88     }
  89
  90     /* If entry encrypted, decrypt and validate encryption header */
  91     if ((decrypt = h[LOCFLG] & CRPFLG) != 0) {
  92         fprintf(stderr, "\n%s: %s: encrypted file -- use unzip\n",
  93                 program_name, ifname);
  94         exit_code = ERROR;
  95         return ERROR;
  96     }
  97
  98     /* Save flags for unzip() */
  99     ext_header = (h[LOCFLG] & EXTFLG) != 0;
 100     pkzip = 1;
 101
 102     /* Get ofname and timestamp from local header (to be done) */
 103     return OK;
 104 }
 105
 106 /* ===========================================================================
 107  * Unzip in to out.  This routine works on both gzip and pkzip files.
 108  *
 109  * IN assertions: the buffer inbuf contains already the beginning of
 110  *   the compressed data, from offsets inptr to insize-1 included.
 111  *   The magic header has already been checked. The output buffer is cleared.
 112  *
 113  * 'in' and 'out' are the input and output file descriptors.
 114  */
 115 int
 116 unzip (int in, int out)
 117 {
 118     ulg orig_crc = 0;       /* original crc */
 119     ulg orig_len = 0;       /* original uncompressed length */
 120     off_t orig_bytes_out = bytes_out;
 121     int n;
 122     uch buf[EXTHDR];        /* extended local header */
 123     int err = OK;
 124
 125     ifd = in;
 126     ofd = out;
 127
 128     updcrc(NULL, 0);           /* initialize crc */
 129
 130     if (pkzip && !ext_header) {  /* crc and length at the end otherwise */
 131         orig_crc = LG(inbuf + LOCCRC);
 132         orig_len = LG(inbuf + LOCLEN);
 133     }
 134
 135     /* Decompress */
 136     if (method == DEFLATED)  {
 137
 138 #ifdef IBM_Z_DFLTCC
 139         int res = dfltcc_inflate ();
 140 #else
 141         int res = inflate();
 142 #endif
 143
 144         if (res == 3) {
 145             xalloc_die ();
 146         } else if (res != 0) {
 147             gzip_error ("invalid compressed data--format violated");
 148         }
 149
 150     } else if (pkzip && method == STORED) {
 151
 152         register ulg n = LG(inbuf + LOCLEN);
 153
 154         if (n != LG(inbuf + LOCSIZ) - (decrypt ? RAND_HEAD_LEN : 0)) {
 155
 156             fprintf(stderr, "len %lu, siz %lu\n", n, LG(inbuf + LOCSIZ));
 157             gzip_error ("invalid compressed data--length mismatch");
 158         }
 159         while (n--) {
 160             uch c = (uch)get_byte();
 161             put_ubyte(c);
 162         }
 163         flush_window();
 164     } else {
 165         gzip_error ("internal error, invalid method");
 166     }
 167
 168     /* Get the crc and original length */
 169     if (!pkzip) {
 170         /* crc32  (see algorithm.doc)
 171          * uncompressed input size modulo 2^32
 172          */
 173         for (n = 0; n < 8; n++) {
 174             buf[n] = (uch)get_byte(); /* may cause an error if EOF */
 175         }
 176         orig_crc = LG(buf);
 177         orig_len = LG(buf+4);
 178
 179     } else if (ext_header) {  /* If extended header, check it */
 180         /* signature - 4bytes: 0x50 0x4b 0x07 0x08
 181          * CRC-32 value
 182          * compressed size 4-bytes
 183          * uncompressed size 4-bytes
 184          */
 185         for (n = 0; n < EXTHDR; n++) {
 186             buf[n] = (uch)get_byte(); /* may cause an error if EOF */
 187         }
 188         orig_crc = LG(buf+4);
 189         orig_len = LG(buf+12);
 190     }
 191
 192     /* Validate decompression */
 193     if (orig_crc != updcrc(outbuf, 0)) {
 194         fprintf(stderr, "\n%s: %s: invalid compressed data--crc error\n",
 195                 program_name, ifname);
 196         err = ERROR;
 197     }
 198     if (orig_len != (ulg)((bytes_out - orig_bytes_out) & 0xffffffff)) {
 199         fprintf(stderr, "\n%s: %s: invalid compressed data--length error\n",
 200                 program_name, ifname);
 201         err = ERROR;
 202     }
 203
 204     /* Check if there are more entries in a pkzip file */
 205     if (pkzip && inptr + 4 < insize && LG(inbuf+inptr) == LOCSIG) {
 206         if (to_stdout) {
 207             WARN((stderr,
 208                   "%s: %s has more than one entry--rest ignored\n",
 209                   program_name, ifname));
 210         } else {
 211             /* Don't destroy the input zip file */
 212             fprintf(stderr,
 213                     "%s: %s has more than one entry -- unchanged\n",
 214                     program_name, ifname);
 215             err = ERROR;
 216         }
 217     }
 218     ext_header = pkzip = 0; /* for next file */
 219     unzip_crc = orig_crc;
 220     if (err == OK) return OK;
 221     exit_code = ERROR;
 222     if (!test) abort_gzip();
 223     return err;
 224 }