usr/src/boot/lib/libstand/splitfs.c

   1 /*
   2  * Copyright (c) 2002 Maxim Sobolev
   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 #define NTRIES          (3)
  33 #define CONF_BUF        (512)
  34 #define SEEK_BUF        (512)
  35
  36 struct split_file
  37 {
  38     char  **filesv;     /* Filenames */
  39     char  **descsv;     /* Descriptions */
  40     int   filesc;       /* Number of parts */
  41     int   curfile;      /* Current file number */
  42     int   curfd;        /* Current file descriptor */
  43     off_t tot_pos;      /* Offset from the beginning of the sequence */
  44     off_t file_pos;     /* Offset from the beginning of the slice */
  45 };
  46
  47 static int      split_openfile(struct split_file *sf);
  48 static int      splitfs_open(const char *path, struct open_file *f);
  49 static int      splitfs_close(struct open_file *f);
  50 static int      splitfs_read(struct open_file *f, void *buf, size_t size, size_t *resid);
  51 static off_t    splitfs_seek(struct open_file *f, off_t offset, int where);
  52 static int      splitfs_stat(struct open_file *f, struct stat *sb);
  53
  54 struct fs_ops splitfs_fsops = {
  55     "split",
  56     splitfs_open,
  57     splitfs_close,
  58     splitfs_read,
  59     null_write,
  60     splitfs_seek,
  61     splitfs_stat,
  62     null_readdir
  63 };
  64
  65 static void
  66 split_file_destroy(struct split_file *sf)
  67 {
  68     int i;
  69
  70     if (sf->filesc > 0) {
  71         for (i = 0; i < sf->filesc; i++) {
  72             free(sf->filesv[i]);
  73             free(sf->descsv[i]);
  74         }
  75         free(sf->filesv);
  76         free(sf->descsv);
  77     }
  78     free(sf);
  79 }
  80
  81 static int
  82 split_openfile(struct split_file *sf)
  83 {
  84     int i;
  85
  86     for (i = 0;; i++) {
  87         sf->curfd = open(sf->filesv[sf->curfile], O_RDONLY);
  88         if (sf->curfd >= 0)
  89             break;
  90         if ((sf->curfd == -1) && (errno != ENOENT))
  91             return (errno);
  92         if (i == NTRIES)
  93             return (EIO);
  94         printf("\nInsert disk labelled %s and press any key...",
  95             sf->descsv[sf->curfile]);
  96         getchar();
  97         putchar('\n');
  98     }
  99     sf->file_pos = 0;
 100     return (0);
 101 }
 102
 103 static int
 104 splitfs_open(const char *fname, struct open_file *f)
 105 {
 106     char *buf, *confname, *cp;
 107     int conffd;
 108     struct split_file *sf;
 109     struct stat sb;
 110
 111     /* Have to be in "just read it" mode */
 112     if (f->f_flags != F_READ)
 113         return(EPERM);
 114
 115     /* If the name already ends in `.split', ignore it */
 116     if ((cp = strrchr(fname, '.')) && (!strcmp(cp, ".split")))
 117         return(ENOENT);
 118
 119     /* Construct new name */
 120     confname = malloc(strlen(fname) + 7);
 121     sprintf(confname, "%s.split", fname);
 122
 123     /* Try to open the configuration file */
 124     conffd = open(confname, O_RDONLY);
 125     free(confname);
 126     if (conffd == -1)
 127         return(ENOENT);
 128
 129     if (fstat(conffd, &sb) < 0) {
 130         printf("splitfs_open: stat failed\n");
 131         close(conffd);
 132         return(ENOENT);
 133     }
 134     if (!S_ISREG(sb.st_mode)) {
 135         printf("splitfs_open: not a file\n");
 136         close(conffd);
 137         return(EISDIR);                 /* best guess */
 138     }
 139
 140     /* Allocate a split_file structure, populate it from the config file */
 141     sf = malloc(sizeof(struct split_file));
 142     bzero(sf, sizeof(struct split_file));
 143     buf = malloc(CONF_BUF);
 144     while (fgetstr(buf, CONF_BUF, conffd) > 0) {
 145         cp = buf;
 146         while ((*cp != '\0') && (isspace(*cp) == 0))
 147             cp++;
 148         if (*cp != '\0') {
 149             *cp = '\0';
 150             cp++;
 151         }
 152         while ((*cp != '\0') && (isspace(*cp) != 0))
 153             cp++;
 154         if (*cp == '\0')
 155             cp = buf;
 156         sf->filesc++;
 157         sf->filesv = realloc(sf->filesv, sizeof(*(sf->filesv)) * sf->filesc);
 158         sf->descsv = realloc(sf->descsv, sizeof(*(sf->descsv)) * sf->filesc);
 159         sf->filesv[sf->filesc - 1] = strdup(buf);
 160         sf->descsv[sf->filesc - 1] = strdup(cp);
 161     }
 162     free(buf);
 163     close(conffd);
 164
 165     if (sf->filesc == 0) {
 166         split_file_destroy(sf);
 167         return(ENOENT);
 168     }
 169     errno = split_openfile(sf);
 170     if (errno != 0) {
 171         split_file_destroy(sf);
 172         return(ENOENT);
 173     }
 174
 175     /* Looks OK, we'll take it */
 176     f->f_fsdata = sf;
 177     return (0);
 178 }
 179
 180 static int
 181 splitfs_close(struct open_file *f)
 182 {
 183     int fd;
 184     struct split_file *sf;
 185
 186     sf = (struct split_file *)f->f_fsdata;
 187     fd = sf->curfd;
 188     split_file_destroy(sf);
 189     return(close(fd));
 190 }
 191
 192 static int
 193 splitfs_read(struct open_file *f, void *buf, size_t size, size_t *resid)
 194 {
 195     ssize_t nread;
 196     size_t totread;
 197     struct split_file *sf;
 198
 199     sf = (struct split_file *)f->f_fsdata;
 200     totread = 0;
 201     do {
 202         nread = read(sf->curfd, buf, size - totread);
 203
 204         /* Error? */
 205         if (nread == -1)
 206             return (errno);
 207
 208         sf->tot_pos += nread;
 209         sf->file_pos += nread;
 210         totread += nread;
 211         buf = (char *)buf + nread;
 212
 213         if (totread < size) {                           /* EOF */
 214             if (sf->curfile == (sf->filesc - 1))        /* Last slice */
 215                 break;
 216
 217             /* Close previous slice */
 218             if (close(sf->curfd) != 0)
 219                 return (errno);
 220
 221             sf->curfile++;
 222             errno = split_openfile(sf);
 223             if (errno)
 224                     return (errno);
 225         }
 226     } while (totread < size);
 227
 228     if (resid != NULL)
 229         *resid = size - totread;
 230
 231     return (0);
 232 }
 233
 234 static off_t
 235 splitfs_seek(struct open_file *f, off_t offset, int where)
 236 {
 237     int nread;
 238     size_t resid;
 239     off_t new_pos, seek_by;
 240     struct split_file *sf;
 241
 242     sf = (struct split_file *)f->f_fsdata;
 243
 244     seek_by = offset;
 245     switch (where) {
 246     case SEEK_SET:
 247         seek_by -= sf->tot_pos;
 248         break;
 249     case SEEK_CUR:
 250         break;
 251     case SEEK_END:
 252         panic("splitfs_seek: SEEK_END not supported");
 253         break;
 254     default:
 255         errno = EINVAL;
 256         return (-1);
 257     }
 258
 259     if (seek_by > 0) {
 260         /*
 261          * Seek forward - implemented using splitfs_read(), because otherwise we'll be
 262          * unable to detect that we have crossed slice boundary and hence
 263          * unable to do a long seek crossing that boundary.
 264          */
 265         void *tmp;
 266
 267         tmp = malloc(SEEK_BUF);
 268         if (tmp == NULL) {
 269             errno = ENOMEM;
 270             return (-1);
 271         }
 272
 273         nread = 0;
 274         for (; seek_by > 0; seek_by -= nread) {
 275             resid = 0;
 276             errno = splitfs_read(f, tmp, min(seek_by, SEEK_BUF), &resid);
 277             nread = min(seek_by, SEEK_BUF) - resid;
 278             if ((errno != 0) || (nread == 0))
 279                 /* Error or EOF */
 280                 break;
 281         }
 282         free(tmp);
 283         if (errno != 0)
 284             return (-1);
 285     }
 286
 287     if (seek_by != 0) {
 288         /* Seek backward or seek past the boundary of the last slice */
 289         if (sf->file_pos + seek_by < 0)
 290             panic("splitfs_seek: can't seek past the beginning of the slice");
 291         new_pos = lseek(sf->curfd, seek_by, SEEK_CUR);
 292         if (new_pos < 0) {
 293             errno = EINVAL;
 294             return (-1);
 295         }
 296         sf->tot_pos += new_pos - sf->file_pos;
 297         sf->file_pos = new_pos;
 298     }
 299
 300     return (sf->tot_pos);
 301 }
 302
 303 static int
 304 splitfs_stat(struct open_file *f, struct stat *sb)
 305 {
 306     int result;
 307     struct split_file *sf = (struct split_file *)f->f_fsdata;
 308
 309     /* stat as normal, but indicate that size is unknown */
 310     if ((result = fstat(sf->curfd, sb)) == 0)
 311         sb->st_size = -1;
 312     return (result);
 313 }