stand/lib/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  * $FreeBSD: src/lib/libstand/gzipfs.c,v 1.11 2002/12/19 19:34:58 jake Exp $
  27  */
  28
  29 #include "stand.h"
  30
  31 #include <sys/stat.h>
  32 #include <string.h>
  33 #include <zlib.h>
  34
  35 #define Z_BUFSIZE 2048  /* XXX larger? */
  36
  37 struct z_file
  38 {
  39     int                 zf_rawfd;
  40     z_stream            zf_zstream;
  41     char                zf_buf[Z_BUFSIZE];
  42 };
  43
  44 static int      zf_fill(struct z_file *z);
  45 static int      zf_open(const char *path, struct open_file *f);
  46 static int      zf_close(struct open_file *f);
  47 static int      zf_read(struct open_file *f, void *buf, size_t size, size_t *resid);
  48 static off_t    zf_seek(struct open_file *f, off_t offset, int where);
  49 static int      zf_stat(struct open_file *f, struct stat *sb);
  50
  51 struct fs_ops gzipfs_fsops = {
  52     "zip",
  53     zf_open,
  54     zf_close,
  55     zf_read,
  56     null_write,
  57     zf_seek,
  58     zf_stat,
  59     null_readdir
  60 };
  61
  62 static int
  63 zf_fill(struct z_file *zf)
  64 {
  65     int         result;
  66     int         req;
  67
  68     req = Z_BUFSIZE - zf->zf_zstream.avail_in;
  69     result = 0;
  70
  71     /* If we need more */
  72     if (req > 0) {
  73         /* move old data to bottom of buffer */
  74         if (req < Z_BUFSIZE)
  75             bcopy(zf->zf_buf + req, zf->zf_buf, Z_BUFSIZE - req);
  76
  77         /* read to fill buffer and update availibility data */
  78         result = read(zf->zf_rawfd, zf->zf_buf + zf->zf_zstream.avail_in, req);
  79         zf->zf_zstream.next_in = zf->zf_buf;
  80         if (result >= 0)
  81             zf->zf_zstream.avail_in += result;
  82     }
  83     return(result);
  84 }
  85
  86 /*
  87  * Adapted from get_byte/check_header in libz
  88  *
  89  * Returns 0 if the header is OK, nonzero if not.
  90  */
  91 static int
  92 get_byte(struct z_file *zf)
  93 {
  94     if ((zf->zf_zstream.avail_in == 0) && (zf_fill(zf) == -1))
  95         return(-1);
  96     zf->zf_zstream.avail_in--;
  97     return(*(zf->zf_zstream.next_in)++);
  98 }
  99
 100 static int gz_magic[2] = {0x1f, 0x8b}; /* gzip magic header */
 101
 102 /* gzip flag byte */
 103 #define ASCII_FLAG      0x01 /* bit 0 set: file probably ascii text */
 104 #define HEAD_CRC        0x02 /* bit 1 set: header CRC present */
 105 #define EXTRA_FIELD     0x04 /* bit 2 set: extra field present */
 106 #define ORIG_NAME       0x08 /* bit 3 set: original file name present */
 107 #define COMMENT         0x10 /* bit 4 set: file comment present */
 108 #define RESERVED        0xE0 /* bits 5..7: reserved */
 109
 110 static int
 111 check_header(struct z_file *zf)
 112 {
 113     int         method; /* method byte */
 114     int         flags;  /* flags byte */
 115     uInt        len;
 116     int         c;
 117
 118     /* Check the gzip magic header */
 119     for (len = 0; len < 2; len++) {
 120         c = get_byte(zf);
 121         if (c != gz_magic[len]) {
 122             return(1);
 123         }
 124     }
 125     method = get_byte(zf);
 126     flags = get_byte(zf);
 127     if (method != Z_DEFLATED || (flags & RESERVED) != 0) {
 128         return(1);
 129     }
 130
 131     /* Discard time, xflags and OS code: */
 132     for (len = 0; len < 6; len++) (void)get_byte(zf);
 133
 134     if ((flags & EXTRA_FIELD) != 0) { /* skip the extra field */
 135         len  =  (uInt)get_byte(zf);
 136         len += ((uInt)get_byte(zf))<<8;
 137         /* len is garbage if EOF but the loop below will quit anyway */
 138         while (len-- != 0 && get_byte(zf) != -1) ;
 139     }
 140     if ((flags & ORIG_NAME) != 0) { /* skip the original file name */
 141         while ((c = get_byte(zf)) != 0 && c != -1) ;
 142     }
 143     if ((flags & COMMENT) != 0) {   /* skip the .gz file comment */
 144         while ((c = get_byte(zf)) != 0 && c != -1) ;
 145     }
 146     if ((flags & HEAD_CRC) != 0) {  /* skip the header crc */
 147         for (len = 0; len < 2; len++) c = get_byte(zf);
 148     }
 149     /* if there's data left, we're in business */
 150     return((c == -1) ? 1 : 0);
 151 }
 152
 153 static int
 154 zf_open(const char *fname, struct open_file *f)
 155 {
 156     char                *zfname;
 157     int                 rawfd;
 158     struct z_file       *zf;
 159     char                *cp;
 160     int                 error;
 161     struct stat         sb;
 162
 163     /* Have to be in "just read it" mode */
 164     if ((f->f_flags & (F_READ | F_WRITE)) != F_READ)
 165         return(EPERM);
 166
 167     /* If the name already ends in .gz or .bz2, ignore it */
 168     if ((cp = strrchr(fname, '.')) && (!strcmp(cp, ".gz")
 169             || !strcmp(cp, ".bz2") || !strcmp(cp, ".split")))
 170         return(ENOENT);
 171
 172     /* Construct new name */
 173     zfname = malloc(strlen(fname) + 4);
 174     if (zfname == NULL)
 175         return(ENOMEM);
 176     sprintf(zfname, "%s.gz", fname);
 177
 178     /* Try to open the compressed datafile */
 179     rawfd = open(zfname, O_RDONLY);
 180     free(zfname);
 181     if (rawfd == -1)
 182         return(ENOENT);
 183
 184     if (fstat(rawfd, &sb) < 0) {
 185         printf("zf_open: stat failed\n");
 186         close(rawfd);
 187         return(ENOENT);
 188     }
 189     if (!S_ISREG(sb.st_mode)) {
 190         printf("zf_open: not a file\n");
 191         close(rawfd);
 192         return(EISDIR);                 /* best guess */
 193     }
 194
 195     /* Allocate a z_file structure, populate it */
 196     zf = malloc(sizeof(struct z_file));
 197     if (zf == NULL)
 198         return(ENOMEM);
 199     bzero(zf, sizeof(struct z_file));
 200     zf->zf_rawfd = rawfd;
 201
 202     /* Verify that the file is gzipped (XXX why do this afterwards?) */
 203     if (check_header(zf)) {
 204         close(zf->zf_rawfd);
 205         inflateEnd(&(zf->zf_zstream));
 206         free(zf);
 207         return(EFTYPE);
 208     }
 209
 210     /* Initialise the inflation engine */
 211     if ((error = inflateInit2(&(zf->zf_zstream), -15)) != Z_OK) {
 212         printf("zf_open: inflateInit returned %d : %s\n", error, zf->zf_zstream.msg);
 213         close(zf->zf_rawfd);
 214         free(zf);
 215         return(EIO);
 216     }
 217
 218     /* Looks OK, we'll take it */
 219     f->f_fsdata = zf;
 220     return(0);
 221 }
 222
 223 static int
 224 zf_close(struct open_file *f)
 225 {
 226     struct z_file       *zf = (struct z_file *)f->f_fsdata;
 227
 228     f->f_fsdata = NULL;
 229     if (zf) {
 230         inflateEnd(&(zf->zf_zstream));
 231         close(zf->zf_rawfd);
 232         free(zf);
 233     }
 234     return(0);
 235 }
 236
 237 static int
 238 zf_read(struct open_file *f, void *buf, size_t size, size_t *resid)
 239 {
 240     struct z_file       *zf = (struct z_file *)f->f_fsdata;
 241     int                 error;
 242
 243     zf->zf_zstream.next_out = buf;                      /* where and how much */
 244     zf->zf_zstream.avail_out = size;
 245
 246     while (zf->zf_zstream.avail_out) {
 247         if ((zf->zf_zstream.avail_in == 0) && (zf_fill(zf) == -1)) {
 248             printf("zf_read: fill error\n");
 249             return(-1);
 250         }
 251         if (zf->zf_zstream.avail_in == 0) {             /* oops, unexpected EOF */
 252             printf("zf_read: unexpected EOF\n");
 253             break;
 254         }
 255
 256         error = inflate(&zf->zf_zstream, Z_SYNC_FLUSH); /* decompression pass */
 257         if (error == Z_STREAM_END) {                    /* EOF, all done */
 258             break;
 259         }
 260         if (error != Z_OK) {                            /* argh, decompression error */
 261             printf("inflate: %s\n", zf->zf_zstream.msg);
 262             errno = EIO;
 263             return(-1);
 264         }
 265     }
 266     if (resid != NULL)
 267         *resid = zf->zf_zstream.avail_out;
 268     return(0);
 269 }
 270
 271 static off_t
 272 zf_seek(struct open_file *f, off_t offset, int where)
 273 {
 274     struct z_file       *zf = (struct z_file *)f->f_fsdata;
 275     off_t               target;
 276     char                discard[16];
 277
 278     switch (where) {
 279     case SEEK_SET:
 280         target = offset;
 281         break;
 282     case SEEK_CUR:
 283         target = offset + zf->zf_zstream.total_out;
 284         break;
 285     default:
 286         target = -1;
 287     }
 288
 289     /* Can we get there from here? */
 290     if (target < zf->zf_zstream.total_out) {
 291         errno = EOFFSET;
 292         return -1;
 293     }
 294
 295     /* skip forwards if required */
 296     while (target > zf->zf_zstream.total_out) {
 297         if (zf_read(f, discard, min(sizeof(discard), target - zf->zf_zstream.total_out), NULL) == -1)
 298             return(-1);
 299     }
 300     /* This is where we are (be honest if we overshot) */
 301     return (zf->zf_zstream.total_out);
 302 }
 303
 304 static int
 305 zf_stat(struct open_file *f, struct stat *sb)
 306 {
 307     struct z_file       *zf = (struct z_file *)f->f_fsdata;
 308     int                 result;
 309
 310     /* stat as normal, but indicate that size is unknown */
 311     if ((result = fstat(zf->zf_rawfd, sb)) == 0)
 312         sb->st_size = -1;
 313     return(result);
 314 }