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, see <https://www.gnu.org/licenses/>.  */
  18
  19 /*
  20  * The code in this file is derived from the file funzip.c written
  21  * and put in the public domain by Mark Adler.
  22  */
  23
  24 /*
  25    This version can extract files in gzip or pkzip format.
  26    For the latter, only the first entry is extracted, and it has to be
  27    either deflated or stored.
  28  */
  29
  30 #include <config.h>
  31 #include "tailor.h"
  32 #include "gzip.h"
  33
  34 /* PKZIP header definitions */
  35 #define LOCSIG 0x04034b50L      /* four-byte lead-in (lsb first) */
  36 #define LOCFLG 6                /* offset of bit flag */
  37 #define  CRPFLG 1               /*  bit for encrypted entry */
  38 #define  EXTFLG 8               /*  bit for extended local header */
  39 #define LOCHOW 8                /* offset of compression method */
  40 /* #define LOCTIM 10               UNUSED file mod time (for decryption) */
  41 #define LOCCRC 14               /* offset of crc */
  42 #define LOCSIZ 18               /* offset of compressed size */
  43 #define LOCLEN 22               /* offset of uncompressed length */
  44 #define LOCFIL 26               /* offset of file name field length */
  45 #define LOCEXT 28               /* offset of extra field length */
  46 #define LOCHDR 30               /* size of local header, including sig */
  47 #define EXTHDR 16               /* size of extended local header, inc sig */
  48 #define RAND_HEAD_LEN  12       /* length of encryption random header */
  49
  50
  51 /* Globals */
  52
  53 ulg unzip_crc;  /* CRC found by 'unzip'.  */
  54
  55 static int decrypt;        /* flag to turn on decryption */
  56 static int pkzip = 0;      /* set for a pkzip file */
  57 static int ext_header = 0; /* set if extended local header */
  58
  59 /* ===========================================================================
  60  * Check zip file and advance inptr to the start of the compressed data.
  61  * Get ofname from the local header if necessary.
  62  * IN is the input file descriptor.
  63  */
  64 int
  65 check_zipfile (int in)
  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  * 'in' and 'out' are the input and output file descriptors.
 113  */
 114 int
 115 unzip (int in, int out)
 116 {
 117     ulg orig_crc = 0;       /* original crc */
 118     ulg orig_len = 0;       /* original uncompressed length */
 119     off_t orig_bytes_out = bytes_out;
 120     int n;
 121     uch buf[EXTHDR];        /* extended local header */
 122     int err = OK;
 123
 124     ifd = in;
 125     ofd = out;
 126
 127     updcrc(NULL, 0);           /* initialize crc */
 128
 129     if (pkzip && !ext_header) {  /* crc and length at the end otherwise */
 130         orig_crc = LG(inbuf + LOCCRC);
 131         orig_len = LG(inbuf + LOCLEN);
 132     }
 133
 134     /* Decompress */
 135     if (method == DEFLATED)  {
 136
 137 #ifdef IBM_Z_DFLTCC
 138         int res = dfltcc_inflate ();
 139 #else
 140         int res = gzip_inflate ();
 141 #endif
 142
 143         if (res == 3) {
 144             xalloc_die ();
 145         } else if (res != 0) {
 146             gzip_error ("invalid compressed data--format violated");
 147         }
 148
 149     } else if (pkzip && method == STORED) {
 150
 151         register ulg n = LG(inbuf + LOCLEN);
 152
 153         if (n != LG(inbuf + LOCSIZ) - (decrypt ? RAND_HEAD_LEN : 0)) {
 154
 155             fprintf(stderr, "len %lu, siz %lu\n", n, LG(inbuf + LOCSIZ));
 156             gzip_error ("invalid compressed data--length mismatch");
 157         }
 158         while (n--) {
 159             uch c = (uch)get_byte();
 160             put_ubyte(c);
 161         }
 162         flush_window();
 163     } else {
 164         gzip_error ("internal error, invalid method");
 165     }
 166
 167     /* Get the crc and original length */
 168     if (!pkzip) {
 169         /* crc32  (see algorithm.doc)
 170          * uncompressed input size modulo 2^32
 171          */
 172         for (n = 0; n < 8; n++) {
 173             buf[n] = (uch)get_byte(); /* may cause an error if EOF */
 174         }
 175         orig_crc = LG(buf);
 176         orig_len = LG(buf+4);
 177
 178     } else if (ext_header) {  /* If extended header, check it */
 179         /* signature - 4bytes: 0x50 0x4b 0x07 0x08
 180          * CRC-32 value
 181          * compressed size 4-bytes
 182          * uncompressed size 4-bytes
 183          */
 184         for (n = 0; n < EXTHDR; n++) {
 185             buf[n] = (uch)get_byte(); /* may cause an error if EOF */
 186         }
 187         orig_crc = LG(buf+4);
 188         orig_len = LG(buf+12);
 189     }
 190
 191     /* Validate decompression */
 192     if (orig_crc != updcrc(outbuf, 0)) {
 193         fprintf(stderr, "\n%s: %s: invalid compressed data--crc error\n",
 194                 program_name, ifname);
 195         err = ERROR;
 196     }
 197     if (orig_len != (ulg)((bytes_out - orig_bytes_out) & 0xffffffff)) {
 198         fprintf(stderr, "\n%s: %s: invalid compressed data--length error\n",
 199                 program_name, ifname);
 200         err = ERROR;
 201     }
 202
 203     /* Check if there are more entries in a pkzip file */
 204     if (pkzip && inptr + 4 < insize && LG(inbuf+inptr) == LOCSIG) {
 205         if (to_stdout) {
 206             WARN((stderr,
 207                   "%s: %s has more than one entry--rest ignored\n",
 208                   program_name, ifname));
 209         } else {
 210             /* Don't destroy the input zip file */
 211             fprintf(stderr,
 212                     "%s: %s has more than one entry -- unchanged\n",
 213                     program_name, ifname);
 214             err = ERROR;
 215         }
 216     }
 217     ext_header = pkzip = 0; /* for next file */
 218     unzip_crc = orig_crc;
 219     if (err == OK) return OK;
 220     exit_code = ERROR;
 221     if (!test) abort_gzip();
 222     return err;
 223 }