unzip.c

   1 /* unzip.c -- decompress files in gzip or pkzip format.
   2
   3    Copyright (C) 1997-1999, 2009-2022 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  */
  64 int check_zipfile(in)
  65     int in;   /* input file descriptors */
  66 {
  67     uch *h = inbuf + inptr; /* first local header */
  68
  69     ifd = in;
  70
  71     /* Check validity of local header, and skip name and extra fields */
  72     inptr += LOCHDR + SH(h + LOCFIL) + SH(h + LOCEXT);
  73
  74     if (inptr > insize || LG(h) != LOCSIG) {
  75         fprintf(stderr, "\n%s: %s: not a valid zip file\n",
  76                 program_name, ifname);
  77         exit_code = ERROR;
  78         return ERROR;
  79     }
  80     method = h[LOCHOW];
  81     if (method != STORED && method != DEFLATED) {
  82         fprintf(stderr,
  83                 "\n%s: %s: first entry not deflated or stored -- use unzip\n",
  84                 program_name, ifname);
  85         exit_code = ERROR;
  86         return ERROR;
  87     }
  88
  89     /* If entry encrypted, decrypt and validate encryption header */
  90     if ((decrypt = h[LOCFLG] & CRPFLG) != 0) {
  91         fprintf(stderr, "\n%s: %s: encrypted file -- use unzip\n",
  92                 program_name, ifname);
  93         exit_code = ERROR;
  94         return ERROR;
  95     }
  96
  97     /* Save flags for unzip() */
  98     ext_header = (h[LOCFLG] & EXTFLG) != 0;
  99     pkzip = 1;
 100
 101     /* Get ofname and timestamp from local header (to be done) */
 102     return OK;
 103 }
 104
 105 /* ===========================================================================
 106  * Unzip in to out.  This routine works on both gzip and pkzip files.
 107  *
 108  * IN assertions: the buffer inbuf contains already the beginning of
 109  *   the compressed data, from offsets inptr to insize-1 included.
 110  *   The magic header has already been checked. The output buffer is cleared.
 111  */
 112 int unzip(in, out)
 113     int in, out;   /* input and output file descriptors */
 114 {
 115     ulg orig_crc = 0;       /* original crc */
 116     ulg orig_len = 0;       /* original uncompressed length */
 117     int n;
 118     uch buf[EXTHDR];        /* extended local header */
 119     int err = OK;
 120
 121     ifd = in;
 122     ofd = out;
 123
 124     updcrc(NULL, 0);           /* initialize crc */
 125
 126     if (pkzip && !ext_header) {  /* crc and length at the end otherwise */
 127         orig_crc = LG(inbuf + LOCCRC);
 128         orig_len = LG(inbuf + LOCLEN);
 129     }
 130
 131     /* Decompress */
 132     if (method == DEFLATED)  {
 133
 134 #ifdef IBM_Z_DFLTCC
 135         int res = dfltcc_inflate ();
 136 #else
 137         int res = inflate();
 138 #endif
 139
 140         if (res == 3) {
 141             xalloc_die ();
 142         } else if (res != 0) {
 143             gzip_error ("invalid compressed data--format violated");
 144         }
 145
 146     } else if (pkzip && method == STORED) {
 147
 148         register ulg n = LG(inbuf + LOCLEN);
 149
 150         if (n != LG(inbuf + LOCSIZ) - (decrypt ? RAND_HEAD_LEN : 0)) {
 151
 152             fprintf(stderr, "len %lu, siz %lu\n", n, LG(inbuf + LOCSIZ));
 153             gzip_error ("invalid compressed data--length mismatch");
 154         }
 155         while (n--) {
 156             uch c = (uch)get_byte();
 157             put_ubyte(c);
 158         }
 159         flush_window();
 160     } else {
 161         gzip_error ("internal error, invalid method");
 162     }
 163
 164     /* Get the crc and original length */
 165     if (!pkzip) {
 166         /* crc32  (see algorithm.doc)
 167          * uncompressed input size modulo 2^32
 168          */
 169         for (n = 0; n < 8; n++) {
 170             buf[n] = (uch)get_byte(); /* may cause an error if EOF */
 171         }
 172         orig_crc = LG(buf);
 173         orig_len = LG(buf+4);
 174
 175     } else if (ext_header) {  /* If extended header, check it */
 176         /* signature - 4bytes: 0x50 0x4b 0x07 0x08
 177          * CRC-32 value
 178          * compressed size 4-bytes
 179          * uncompressed size 4-bytes
 180          */
 181         for (n = 0; n < EXTHDR; n++) {
 182             buf[n] = (uch)get_byte(); /* may cause an error if EOF */
 183         }
 184         orig_crc = LG(buf+4);
 185         orig_len = LG(buf+12);
 186     }
 187
 188     /* Validate decompression */
 189     if (orig_crc != updcrc(outbuf, 0)) {
 190         fprintf(stderr, "\n%s: %s: invalid compressed data--crc error\n",
 191                 program_name, ifname);
 192         err = ERROR;
 193     }
 194     if (orig_len != (ulg)(bytes_out & 0xffffffff)) {
 195         fprintf(stderr, "\n%s: %s: invalid compressed data--length error\n",
 196                 program_name, ifname);
 197         err = ERROR;
 198     }
 199
 200     /* Check if there are more entries in a pkzip file */
 201     if (pkzip && inptr + 4 < insize && LG(inbuf+inptr) == LOCSIG) {
 202         if (to_stdout) {
 203             WARN((stderr,
 204                   "%s: %s has more than one entry--rest ignored\n",
 205                   program_name, ifname));
 206         } else {
 207             /* Don't destroy the input zip file */
 208             fprintf(stderr,
 209                     "%s: %s has more than one entry -- unchanged\n",
 210                     program_name, ifname);
 211             err = ERROR;
 212         }
 213     }
 214     ext_header = pkzip = 0; /* for next file */
 215     unzip_crc = orig_crc;
 216     if (err == OK) return OK;
 217     exit_code = ERROR;
 218     if (!test) abort_gzip();
 219     return err;
 220 }