gzipfs.c revision 83610
1/* 2 * Copyright (c) 1998 Michael Smith. 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 17 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 24 * SUCH DAMAGE. 25 * 26 * $FreeBSD: head/lib/libstand/gzipfs.c 83610 2001-09-18 13:01:12Z sobomax $ 27 * 28 */ 29 30#include "stand.h" 31 32#include <sys/stat.h> 33#include <string.h> 34#include <zlib.h> 35 36#define Z_BUFSIZE 2048 /* XXX larger? */ 37 38struct z_file 39{ 40 int zf_rawfd; 41 z_stream zf_zstream; 42 char zf_buf[Z_BUFSIZE]; 43}; 44 45static int zf_fill(struct z_file *z); 46static int zf_open(const char *path, struct open_file *f); 47static int zf_close(struct open_file *f); 48static int zf_read(struct open_file *f, void *buf, size_t size, size_t *resid); 49static off_t zf_seek(struct open_file *f, off_t offset, int where); 50static int zf_stat(struct open_file *f, struct stat *sb); 51 52struct fs_ops zipfs_fsops = { 53 "zip", 54 zf_open, 55 zf_close, 56 zf_read, 57 null_write, 58 zf_seek, 59 zf_stat, 60 null_readdir 61}; 62 63#if 0 64void * 65calloc(int items, size_t size) 66{ 67 return(malloc(items * size)); 68} 69#endif 70 71static int 72zf_fill(struct z_file *zf) 73{ 74 int result; 75 int req; 76 77 req = Z_BUFSIZE - zf->zf_zstream.avail_in; 78 result = 0; 79 80 /* If we need more */ 81 if (req > 0) { 82 /* move old data to bottom of buffer */ 83 if (req < Z_BUFSIZE) 84 bcopy(zf->zf_buf + req, zf->zf_buf, Z_BUFSIZE - req); 85 86 /* read to fill buffer and update availibility data */ 87 result = read(zf->zf_rawfd, zf->zf_buf + zf->zf_zstream.avail_in, req); 88 zf->zf_zstream.next_in = zf->zf_buf; 89 if (result >= 0) 90 zf->zf_zstream.avail_in += result; 91 } 92 return(result); 93} 94 95/* 96 * Adapted from get_byte/check_header in libz 97 * 98 * Returns 0 if the header is OK, nonzero if not. 99 */ 100static int 101get_byte(struct z_file *zf) 102{ 103 if ((zf->zf_zstream.avail_in == 0) && (zf_fill(zf) == -1)) 104 return(-1); 105 zf->zf_zstream.avail_in--; 106 return(*(zf->zf_zstream.next_in)++); 107} 108 109static int gz_magic[2] = {0x1f, 0x8b}; /* gzip magic header */ 110 111/* gzip flag byte */ 112#define ASCII_FLAG 0x01 /* bit 0 set: file probably ascii text */ 113#define HEAD_CRC 0x02 /* bit 1 set: header CRC present */ 114#define EXTRA_FIELD 0x04 /* bit 2 set: extra field present */ 115#define ORIG_NAME 0x08 /* bit 3 set: original file name present */ 116#define COMMENT 0x10 /* bit 4 set: file comment present */ 117#define RESERVED 0xE0 /* bits 5..7: reserved */ 118 119static int 120check_header(struct z_file *zf) 121{ 122 int method; /* method byte */ 123 int flags; /* flags byte */ 124 uInt len; 125 int c; 126 127 /* Check the gzip magic header */ 128 for (len = 0; len < 2; len++) { 129 c = get_byte(zf); 130 if (c != gz_magic[len]) { 131 return(1); 132 } 133 } 134 method = get_byte(zf); 135 flags = get_byte(zf); 136 if (method != Z_DEFLATED || (flags & RESERVED) != 0) { 137 return(1); 138 } 139 140 /* Discard time, xflags and OS code: */ 141 for (len = 0; len < 6; len++) (void)get_byte(zf); 142 143 if ((flags & EXTRA_FIELD) != 0) { /* skip the extra field */ 144 len = (uInt)get_byte(zf); 145 len += ((uInt)get_byte(zf))<<8; 146 /* len is garbage if EOF but the loop below will quit anyway */ 147 while (len-- != 0 && get_byte(zf) != -1) ; 148 } 149 if ((flags & ORIG_NAME) != 0) { /* skip the original file name */ 150 while ((c = get_byte(zf)) != 0 && c != -1) ; 151 } 152 if ((flags & COMMENT) != 0) { /* skip the .gz file comment */ 153 while ((c = get_byte(zf)) != 0 && c != -1) ; 154 } 155 if ((flags & HEAD_CRC) != 0) { /* skip the header crc */ 156 for (len = 0; len < 2; len++) c = get_byte(zf); 157 } 158 /* if there's data left, we're in business */ 159 return((c == -1) ? 1 : 0); 160} 161 162static int 163zf_open(const char *fname, struct open_file *f) 164{ 165 static char *zfname; 166 int rawfd; 167 struct z_file *zf; 168 char *cp; 169 int error; 170 struct stat sb; 171 172 /* Have to be in "just read it" mode */ 173 if (f->f_flags != F_READ) 174 return(EPERM); 175 176 /* If the name already ends in .gz or .bz2, ignore it */ 177 if ((cp = strrchr(fname, '.')) && (!strcmp(cp, ".gz") 178 || !strcmp(cp, ".bz2"))) 179 return(ENOENT); 180 181 /* Construct new name */ 182 zfname = malloc(strlen(fname) + 4); 183 if (zfname == NULL) 184 return(ENOMEM); 185 sprintf(zfname, "%s.gz", fname); 186 187 /* Try to open the compressed datafile */ 188 rawfd = open(zfname, O_RDONLY); 189 free(zfname); 190 if (rawfd == -1) 191 return(ENOENT); 192 193 if (fstat(rawfd, &sb) < 0) { 194 printf("zf_open: stat failed\n"); 195 close(rawfd); 196 return(ENOENT); 197 } 198 if (!S_ISREG(sb.st_mode)) { 199 printf("zf_open: not a file\n"); 200 close(rawfd); 201 return(EISDIR); /* best guess */ 202 } 203 204 /* Allocate a z_file structure, populate it */ 205 zf = malloc(sizeof(struct z_file)); 206 if (zf == NULL) 207 return(ENOMEM); 208 bzero(zf, sizeof(struct z_file)); 209 zf->zf_rawfd = rawfd; 210 211 /* Verify that the file is gzipped (XXX why do this afterwards?) */ 212 if (check_header(zf)) { 213 close(zf->zf_rawfd); 214 inflateEnd(&(zf->zf_zstream)); 215 free(zf); 216 return(EFTYPE); 217 } 218 219 /* Initialise the inflation engine */ 220 if ((error = inflateInit2(&(zf->zf_zstream), -15)) != Z_OK) { 221 printf("zf_open: inflateInit returned %d : %s\n", error, zf->zf_zstream.msg); 222 close(zf->zf_rawfd); 223 free(zf); 224 return(EIO); 225 } 226 227 /* Looks OK, we'll take it */ 228 f->f_fsdata = zf; 229 return(0); 230} 231 232static int 233zf_close(struct open_file *f) 234{ 235 struct z_file *zf = (struct z_file *)f->f_fsdata; 236 237 inflateEnd(&(zf->zf_zstream)); 238 close(zf->zf_rawfd); 239 free(zf); 240 return(0); 241} 242 243static int 244zf_read(struct open_file *f, void *buf, size_t size, size_t *resid) 245{ 246 struct z_file *zf = (struct z_file *)f->f_fsdata; 247 int error; 248 249 zf->zf_zstream.next_out = buf; /* where and how much */ 250 zf->zf_zstream.avail_out = size; 251 252 while (zf->zf_zstream.avail_out) { 253 if ((zf->zf_zstream.avail_in == 0) && (zf_fill(zf) == -1)) { 254 printf("zf_read: fill error\n"); 255 return(-1); 256 } 257 if (zf->zf_zstream.avail_in == 0) { /* oops, unexpected EOF */ 258 printf("zf_read: unexpected EOF\n"); 259 break; 260 } 261 262 error = inflate(&zf->zf_zstream, Z_SYNC_FLUSH); /* decompression pass */ 263 if (error == Z_STREAM_END) { /* EOF, all done */ 264 break; 265 } 266 if (error != Z_OK) { /* argh, decompression error */ 267 printf("inflate: %s\n", zf->zf_zstream.msg); 268 errno = EIO; 269 return(-1); 270 } 271 } 272 if (resid != NULL) 273 *resid = zf->zf_zstream.avail_out; 274 return(0); 275} 276 277static off_t 278zf_seek(struct open_file *f, off_t offset, int where) 279{ 280 struct z_file *zf = (struct z_file *)f->f_fsdata; 281 off_t target; 282 char discard[16]; 283 284 switch (where) { 285 case SEEK_SET: 286 target = offset; 287 break; 288 case SEEK_CUR: 289 target = offset + zf->zf_zstream.total_out; 290 break; 291 default: 292 target = -1; 293 } 294 295 /* Can we get there from here? */ 296 if (target < zf->zf_zstream.total_out) { 297 errno = EOFFSET; 298 return -1; 299 } 300 301 /* skip forwards if required */ 302 while (target > zf->zf_zstream.total_out) { 303 if (zf_read(f, discard, min(sizeof(discard), target - zf->zf_zstream.total_out), NULL) == -1) 304 return(-1); 305 } 306 /* This is where we are (be honest if we overshot) */ 307 return (zf->zf_zstream.total_out); 308} 309 310 311static int 312zf_stat(struct open_file *f, struct stat *sb) 313{ 314 struct z_file *zf = (struct z_file *)f->f_fsdata; 315 int result; 316 317 /* stat as normal, but indicate that size is unknown */ 318 if ((result = fstat(zf->zf_rawfd, sb)) == 0) 319 sb->st_size = -1; 320 return(result); 321} 322 323 324 325