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
17static char rcsid[] = "$Id: unzip.c 3476 2003-06-11 15:56:10Z darkwyrm $";
18#endif
19
20#include "tailor.h"
21#include "gzip.h"
22#include "crypt.h"
23
24/* PKZIP header definitions */
25#define LOCSIG 0x04034b50L      /* four-byte lead-in (lsb first) */
26#define LOCFLG 6                /* offset of bit flag */
27#define  CRPFLG 1               /*  bit for encrypted entry */
28#define  EXTFLG 8               /*  bit for extended local header */
29#define LOCHOW 8                /* offset of compression method */
30#define LOCTIM 10               /* file mod time (for decryption) */
31#define LOCCRC 14               /* offset of crc */
32#define LOCSIZ 18               /* offset of compressed size */
33#define LOCLEN 22               /* offset of uncompressed length */
34#define LOCFIL 26               /* offset of file name field length */
35#define LOCEXT 28               /* offset of extra field length */
36#define LOCHDR 30               /* size of local header, including sig */
37#define EXTHDR 16               /* size of extended local header, inc sig */
38
39
40/* Globals */
41
42int decrypt;        /* flag to turn on decryption */
43char *key;          /* not used--needed to link crypt.c */
44int pkzip = 0;      /* set for a pkzip file */
45int ext_header = 0; /* set if extended local header */
46
47/* ===========================================================================
48 * Check zip file and advance inptr to the start of the compressed data.
49 * Get ofname from the local header if necessary.
50 */
51int check_zipfile(in)
52    int in;   /* input file descriptors */
53{
54    uch *h = inbuf + inptr; /* first local header */
55
56    ifd = in;
57
58    /* Check validity of local header, and skip name and extra fields */
59    inptr += LOCHDR + SH(h + LOCFIL) + SH(h + LOCEXT);
60
61    if (inptr > insize || LG(h) != LOCSIG) {
62	fprintf(stderr, "\n%s: %s: not a valid zip file\n",
63		progname, ifname);
64	exit_code = ERROR;
65	return ERROR;
66    }
67    method = h[LOCHOW];
68    if (method != STORED && method != DEFLATED) {
69	fprintf(stderr,
70		"\n%s: %s: first entry not deflated or stored -- use unzip\n",
71		progname, ifname);
72	exit_code = ERROR;
73	return ERROR;
74    }
75
76    /* If entry encrypted, decrypt and validate encryption header */
77    if ((decrypt = h[LOCFLG] & CRPFLG) != 0) {
78	fprintf(stderr, "\n%s: %s: encrypted file -- use unzip\n",
79		progname, ifname);
80	exit_code = ERROR;
81	return ERROR;
82    }
83
84    /* Save flags for unzip() */
85    ext_header = (h[LOCFLG] & EXTFLG) != 0;
86    pkzip = 1;
87
88    /* Get ofname and time stamp from local header (to be done) */
89    return OK;
90}
91
92/* ===========================================================================
93 * Unzip in to out.  This routine works on both gzip and pkzip files.
94 *
95 * IN assertions: the buffer inbuf contains already the beginning of
96 *   the compressed data, from offsets inptr to insize-1 included.
97 *   The magic header has already been checked. The output buffer is cleared.
98 */
99int unzip(in, out)
100    int in, out;   /* input and output file descriptors */
101{
102    ulg orig_crc = 0;       /* original crc */
103    ulg orig_len = 0;       /* original uncompressed length */
104    int n;
105    uch buf[EXTHDR];        /* extended local header */
106
107    ifd = in;
108    ofd = out;
109
110    updcrc(NULL, 0);           /* initialize crc */
111
112    if (pkzip && !ext_header) {  /* crc and length at the end otherwise */
113	orig_crc = LG(inbuf + LOCCRC);
114	orig_len = LG(inbuf + LOCLEN);
115    }
116
117    /* Decompress */
118    if (method == DEFLATED)  {
119
120	int res = inflate();
121
122	if (res == 3) {
123	    error("out of memory");
124	} else if (res != 0) {
125	    error("invalid compressed data--format violated");
126	}
127
128    } else if (pkzip && method == STORED) {
129
130	register ulg n = LG(inbuf + LOCLEN);
131
132	if (n != LG(inbuf + LOCSIZ) - (decrypt ? RAND_HEAD_LEN : 0)) {
133
134	    fprintf(stderr, "len %ld, siz %ld\n", n, LG(inbuf + LOCSIZ));
135	    error("invalid compressed data--length mismatch");
136	}
137	while (n--) {
138	    uch c = (uch)get_byte();
139#ifdef CRYPT
140	    if (decrypt) zdecode(c);
141#endif
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	error("invalid compressed data--crc error");
176    }
177    if (orig_len != (ulg)bytes_out) {
178	error("invalid compressed data--length error");
179    }
180
181    /* Check if there are more entries in a pkzip file */
182    if (pkzip && inptr + 4 < insize && LG(inbuf+inptr) == LOCSIG) {
183	if (to_stdout) {
184	    WARN((stderr,
185		  "%s: %s has more than one entry--rest ignored\n",
186		  progname, ifname));
187	} else {
188	    /* Don't destroy the input zip file */
189	    fprintf(stderr,
190		    "%s: %s has more than one entry -- unchanged\n",
191		    progname, ifname);
192	    exit_code = ERROR;
193	    ext_header = pkzip = 0;
194	    return ERROR;
195	}
196    }
197    ext_header = pkzip = 0; /* for next file */
198    return OK;
199}
200