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  * $FreeBSD: src/lib/libstand/gzipfs.c,v 1.11 2002/12/19 19:34:58 jake Exp $
  27  * $DragonFly: src/lib/libstand/gzipfs.c,v 1.1 2003/11/10 06:14:44 dillon Exp $
  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
  38 struct z_file
  39 {
  40     int                 zf_rawfd;
  41     z_stream            zf_zstream;
  42     char                zf_buf[Z_BUFSIZE];
  43 };
  44
  45 static int      zf_fill(struct z_file *z);
  46 static int      zf_open(const char *path, struct open_file *f);
  47 static int      zf_close(struct open_file *f);
  48 static int      zf_read(struct open_file *f, void *buf, size_t size, size_t *resid);
  49 static off_t    zf_seek(struct open_file *f, off_t offset, int where);
  50 static int      zf_stat(struct open_file *f, struct stat *sb);
  51
  52 struct fs_ops gzipfs_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
  64 void *
  65 calloc(int items, size_t size)
  66 {
  67     return(malloc(items * size));
  68 }
  69 #endif
  70
  71 static int
  72 zf_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  */
 100 static int
 101 get_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
 109 static 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
 119 static int
 120 check_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
 162 static int
 163 zf_open(const char *fname, struct open_file *f)
 164 {
 165     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") || !strcmp(cp, ".split")))
 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     /* Try to open the compressed datafile */
 187     rawfd = open(zfname, O_RDONLY);
 188     free(zfname);
 189     if (rawfd == -1)
 190         return(ENOENT);
 191
 192     if (fstat(rawfd, &sb) < 0) {
 193         printf("zf_open: stat failed\n");
 194         close(rawfd);
 195         return(ENOENT);
 196     }
 197     if (!S_ISREG(sb.st_mode)) {
 198         printf("zf_open: not a file\n");
 199         close(rawfd);
 200         return(EISDIR);                 /* best guess */
 201     }
 202
 203     /* Allocate a z_file structure, populate it */
 204     zf = malloc(sizeof(struct z_file));
 205     if (zf == NULL)
 206         return(ENOMEM);
 207     bzero(zf, sizeof(struct z_file));
 208     zf->zf_rawfd = rawfd;
 209
 210     /* Verify that the file is gzipped (XXX why do this afterwards?) */
 211     if (check_header(zf)) {
 212         close(zf->zf_rawfd);
 213         inflateEnd(&(zf->zf_zstream));
 214         free(zf);
 215         return(EFTYPE);
 216     }
 217
 218     /* Initialise the inflation engine */
 219     if ((error = inflateInit2(&(zf->zf_zstream), -15)) != Z_OK) {
 220         printf("zf_open: inflateInit returned %d : %s\n", error, zf->zf_zstream.msg);
 221         close(zf->zf_rawfd);
 222         free(zf);
 223         return(EIO);
 224     }
 225
 226     /* Looks OK, we'll take it */
 227     f->f_fsdata = zf;
 228     return(0);
 229 }
 230
 231 static int
 232 zf_close(struct open_file *f)
 233 {
 234     struct z_file       *zf = (struct z_file *)f->f_fsdata;
 235
 236     f->f_fsdata = NULL;
 237     if (zf) {
 238         inflateEnd(&(zf->zf_zstream));
 239         close(zf->zf_rawfd);
 240         free(zf);
 241     }
 242     return(0);
 243 }
 244
 245 static int
 246 zf_read(struct open_file *f, void *buf, size_t size, size_t *resid)
 247 {
 248     struct z_file       *zf = (struct z_file *)f->f_fsdata;
 249     int                 error;
 250
 251     zf->zf_zstream.next_out = buf;                      /* where and how much */
 252     zf->zf_zstream.avail_out = size;
 253
 254     while (zf->zf_zstream.avail_out) {
 255         if ((zf->zf_zstream.avail_in == 0) && (zf_fill(zf) == -1)) {
 256             printf("zf_read: fill error\n");
 257             return(-1);
 258         }
 259         if (zf->zf_zstream.avail_in == 0) {             /* oops, unexpected EOF */
 260             printf("zf_read: unexpected EOF\n");
 261             break;
 262         }
 263
 264         error = inflate(&zf->zf_zstream, Z_SYNC_FLUSH); /* decompression pass */
 265         if (error == Z_STREAM_END) {                    /* EOF, all done */
 266             break;
 267         }
 268         if (error != Z_OK) {                            /* argh, decompression error */
 269             printf("inflate: %s\n", zf->zf_zstream.msg);
 270             errno = EIO;
 271             return(-1);
 272         }
 273     }
 274     if (resid != NULL)
 275         *resid = zf->zf_zstream.avail_out;
 276     return(0);
 277 }
 278
 279 static off_t
 280 zf_seek(struct open_file *f, off_t offset, int where)
 281 {
 282     struct z_file       *zf = (struct z_file *)f->f_fsdata;
 283     off_t               target;
 284     char                discard[16];
 285
 286     switch (where) {
 287     case SEEK_SET:
 288         target = offset;
 289         break;
 290     case SEEK_CUR:
 291         target = offset + zf->zf_zstream.total_out;
 292         break;
 293     default:
 294         target = -1;
 295     }
 296
 297     /* Can we get there from here? */
 298     if (target < zf->zf_zstream.total_out) {
 299         errno = EOFFSET;
 300         return -1;
 301     }
 302
 303     /* skip forwards if required */
 304     while (target > zf->zf_zstream.total_out) {
 305         if (zf_read(f, discard, min(sizeof(discard), target - zf->zf_zstream.total_out), NULL) == -1)
 306             return(-1);
 307     }
 308     /* This is where we are (be honest if we overshot) */
 309     return (zf->zf_zstream.total_out);
 310 }
 311
 312
 313 static int
 314 zf_stat(struct open_file *f, struct stat *sb)
 315 {
 316     struct z_file       *zf = (struct z_file *)f->f_fsdata;
 317     int                 result;
 318
 319     /* stat as normal, but indicate that size is unknown */
 320     if ((result = fstat(zf->zf_rawfd, sb)) == 0)
 321         sb->st_size = -1;
 322     return(result);
 323 }
 324
 325
 326