lib/libstand/gzipfs.c

   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
  27 #include <sys/cdefs.h>
  28 __FBSDID("$FreeBSD$");
  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
  38 struct z_file
  39 {
  40     int                 zf_rawfd;
  41     off_t               zf_dataoffset;
  42     z_stream            zf_zstream;
  43     char                zf_buf[Z_BUFSIZE];
  44     int                 zf_endseen;
  45 };
  46
  47 static int      zf_fill(struct z_file *z);
  48 static int      zf_open(const char *path, struct open_file *f);
  49 static int      zf_close(struct open_file *f);
  50 static int      zf_read(struct open_file *f, void *buf, size_t size, size_t *resid);
  51 static off_t    zf_seek(struct open_file *f, off_t offset, int where);
  52 static int      zf_stat(struct open_file *f, struct stat *sb);
  53
  54 struct fs_ops gzipfs_fsops = {
  55     "zip",
  56     zf_open,
  57     zf_close,
  58     zf_read,
  59     null_write,
  60     zf_seek,
  61     zf_stat,
  62     null_readdir
  63 };
  64
  65 static int
  66 zf_fill(struct z_file *zf)
  67 {
  68     int         result;
  69     int         req;
  70
  71     req = Z_BUFSIZE - zf->zf_zstream.avail_in;
  72     result = 0;
  73
  74     /* If we need more */
  75     if (req > 0) {
  76         /* move old data to bottom of buffer */
  77         if (req < Z_BUFSIZE)
  78             bcopy(zf->zf_buf + req, zf->zf_buf, Z_BUFSIZE - req);
  79
  80         /* read to fill buffer and update availibility data */
  81         result = read(zf->zf_rawfd, zf->zf_buf + zf->zf_zstream.avail_in, req);
  82         zf->zf_zstream.next_in = zf->zf_buf;
  83         if (result >= 0)
  84             zf->zf_zstream.avail_in += result;
  85     }
  86     return(result);
  87 }
  88
  89 /*
  90  * Adapted from get_byte/check_header in libz
  91  *
  92  * Returns 0 if the header is OK, nonzero if not.
  93  */
  94 static int
  95 get_byte(struct z_file *zf, off_t *curoffp)
  96 {
  97     if ((zf->zf_zstream.avail_in == 0) && (zf_fill(zf) == -1))
  98         return(-1);
  99     zf->zf_zstream.avail_in--;
 100     ++*curoffp;
 101     return(*(zf->zf_zstream.next_in)++);
 102 }
 103
 104 static int gz_magic[2] = {0x1f, 0x8b}; /* gzip magic header */
 105
 106 /* gzip flag byte */
 107 #define ASCII_FLAG      0x01 /* bit 0 set: file probably ascii text */
 108 #define HEAD_CRC        0x02 /* bit 1 set: header CRC present */
 109 #define EXTRA_FIELD     0x04 /* bit 2 set: extra field present */
 110 #define ORIG_NAME       0x08 /* bit 3 set: original file name present */
 111 #define COMMENT         0x10 /* bit 4 set: file comment present */
 112 #define RESERVED        0xE0 /* bits 5..7: reserved */
 113
 114 static int
 115 check_header(struct z_file *zf)
 116 {
 117     int         method; /* method byte */
 118     int         flags;  /* flags byte */
 119     uInt        len;
 120     int         c;
 121
 122     zf->zf_dataoffset = 0;
 123     /* Check the gzip magic header */
 124     for (len = 0; len < 2; len++) {
 125         c = get_byte(zf, &zf->zf_dataoffset);
 126         if (c != gz_magic[len]) {
 127             return(1);
 128         }
 129     }
 130     method = get_byte(zf, &zf->zf_dataoffset);
 131     flags = get_byte(zf, &zf->zf_dataoffset);
 132     if (method != Z_DEFLATED || (flags & RESERVED) != 0) {
 133         return(1);
 134     }
 135
 136     /* Discard time, xflags and OS code: */
 137     for (len = 0; len < 6; len++) (void)get_byte(zf, &zf->zf_dataoffset);
 138
 139     if ((flags & EXTRA_FIELD) != 0) { /* skip the extra field */
 140         len  =  (uInt)get_byte(zf, &zf->zf_dataoffset);
 141         len += ((uInt)get_byte(zf, &zf->zf_dataoffset))<<8;
 142         /* len is garbage if EOF but the loop below will quit anyway */
 143         while (len-- != 0 && get_byte(zf, &zf->zf_dataoffset) != -1) ;
 144     }
 145     if ((flags & ORIG_NAME) != 0) { /* skip the original file name */
 146         while ((c = get_byte(zf, &zf->zf_dataoffset)) != 0 && c != -1) ;
 147     }
 148     if ((flags & COMMENT) != 0) {   /* skip the .gz file comment */
 149         while ((c = get_byte(zf, &zf->zf_dataoffset)) != 0 && c != -1) ;
 150     }
 151     if ((flags & HEAD_CRC) != 0) {  /* skip the header crc */
 152         for (len = 0; len < 2; len++) c = get_byte(zf, &zf->zf_dataoffset);
 153     }
 154     /* if there's data left, we're in business */
 155     return((c == -1) ? 1 : 0);
 156 }
 157
 158 static int
 159 zf_open(const char *fname, struct open_file *f)
 160 {
 161     static char         *zfname;
 162     int                 rawfd;
 163     struct z_file       *zf;
 164     char                *cp;
 165     int                 error;
 166     struct stat         sb;
 167
 168     /* Have to be in "just read it" mode */
 169     if (f->f_flags != F_READ)
 170         return(EPERM);
 171
 172     /* If the name already ends in .gz or .bz2, ignore it */
 173     if ((cp = strrchr(fname, '.')) && (!strcmp(cp, ".gz")
 174             || !strcmp(cp, ".bz2") || !strcmp(cp, ".split")))
 175         return(ENOENT);
 176
 177     /* Construct new name */
 178     zfname = malloc(strlen(fname) + 4);
 179     if (zfname == NULL)
 180         return(ENOMEM);
 181     sprintf(zfname, "%s.gz", fname);
 182
 183     /* Try to open the compressed datafile */
 184     rawfd = open(zfname, O_RDONLY);
 185     free(zfname);
 186     if (rawfd == -1)
 187         return(ENOENT);
 188
 189     if (fstat(rawfd, &sb) < 0) {
 190         printf("zf_open: stat failed\n");
 191         close(rawfd);
 192         return(ENOENT);
 193     }
 194     if (!S_ISREG(sb.st_mode)) {
 195         printf("zf_open: not a file\n");
 196         close(rawfd);
 197         return(EISDIR);                 /* best guess */
 198     }
 199
 200     /* Allocate a z_file structure, populate it */
 201     zf = malloc(sizeof(struct z_file));
 202     if (zf == NULL)
 203         return(ENOMEM);
 204     bzero(zf, sizeof(struct z_file));
 205     zf->zf_rawfd = rawfd;
 206
 207     /* Verify that the file is gzipped */
 208     if (check_header(zf)) {
 209         close(zf->zf_rawfd);
 210         free(zf);
 211         return(EFTYPE);
 212     }
 213
 214     /* Initialise the inflation engine */
 215     if ((error = inflateInit2(&(zf->zf_zstream), -15)) != Z_OK) {
 216         printf("zf_open: inflateInit returned %d : %s\n", error, zf->zf_zstream.msg);
 217         close(zf->zf_rawfd);
 218         free(zf);
 219         return(EIO);
 220     }
 221
 222     /* Looks OK, we'll take it */
 223     f->f_fsdata = zf;
 224     return(0);
 225 }
 226
 227 static int
 228 zf_close(struct open_file *f)
 229 {
 230     struct z_file       *zf = (struct z_file *)f->f_fsdata;
 231
 232     inflateEnd(&(zf->zf_zstream));
 233     close(zf->zf_rawfd);
 234     free(zf);
 235     return(0);
 236 }
 237
 238 static int
 239 zf_read(struct open_file *f, void *buf, size_t size, size_t *resid)
 240 {
 241     struct z_file       *zf = (struct z_file *)f->f_fsdata;
 242     int                 error;
 243
 244     zf->zf_zstream.next_out = buf;                      /* where and how much */
 245     zf->zf_zstream.avail_out = size;
 246
 247     while (zf->zf_zstream.avail_out && zf->zf_endseen == 0) {
 248         if ((zf->zf_zstream.avail_in == 0) && (zf_fill(zf) == -1)) {
 249             printf("zf_read: fill error\n");
 250             return(EIO);
 251         }
 252         if (zf->zf_zstream.avail_in == 0) {             /* oops, unexpected EOF */
 253             printf("zf_read: unexpected EOF\n");
 254             if (zf->zf_zstream.avail_out == size)
 255                 return(EIO);
 256             break;
 257         }
 258
 259         error = inflate(&zf->zf_zstream, Z_SYNC_FLUSH); /* decompression pass */
 260         if (error == Z_STREAM_END) {                    /* EOF, all done */
 261             zf->zf_endseen = 1;
 262             break;
 263         }
 264         if (error != Z_OK) {                            /* argh, decompression error */
 265             printf("inflate: %s\n", zf->zf_zstream.msg);
 266             return(EIO);
 267         }
 268     }
 269     if (resid != NULL)
 270         *resid = zf->zf_zstream.avail_out;
 271     return(0);
 272 }
 273
 274 static int
 275 zf_rewind(struct open_file *f)
 276 {
 277     struct z_file       *zf = (struct z_file *)f->f_fsdata;
 278
 279     if (lseek(zf->zf_rawfd, zf->zf_dataoffset, SEEK_SET) == -1)
 280         return(-1);
 281     zf->zf_zstream.avail_in = 0;
 282     zf->zf_zstream.next_in = NULL;
 283     zf->zf_endseen = 0;
 284     (void)inflateReset(&zf->zf_zstream);
 285
 286     return(0);
 287 }
 288
 289 static off_t
 290 zf_seek(struct open_file *f, off_t offset, int where)
 291 {
 292     struct z_file       *zf = (struct z_file *)f->f_fsdata;
 293     off_t               target;
 294     char                discard[16];
 295
 296     switch (where) {
 297     case SEEK_SET:
 298         target = offset;
 299         break;
 300     case SEEK_CUR:
 301         target = offset + zf->zf_zstream.total_out;
 302         break;
 303     case SEEK_END:
 304         target = -1;
 305     default:
 306         errno = EINVAL;
 307         return(-1);
 308     }
 309
 310     /* rewind if required */
 311     if (target < zf->zf_zstream.total_out && zf_rewind(f) != 0)
 312         return(-1);
 313
 314     /* skip forwards if required */
 315     while (target > zf->zf_zstream.total_out) {
 316         errno = zf_read(f, discard, min(sizeof(discard),
 317             target - zf->zf_zstream.total_out), NULL);
 318         if (errno)
 319             return(-1);
 320     }
 321     /* This is where we are (be honest if we overshot) */
 322     return(zf->zf_zstream.total_out);
 323 }
 324
 325
 326 static int
 327 zf_stat(struct open_file *f, struct stat *sb)
 328 {
 329     struct z_file       *zf = (struct z_file *)f->f_fsdata;
 330     int                 result;
 331
 332     /* stat as normal, but indicate that size is unknown */
 333     if ((result = fstat(zf->zf_rawfd, sb)) == 0)
 334         sb->st_size = -1;
 335     return(result);
 336 }
 337
 338
 339