share/examples/refuse/fanoutfs/fanoutfs.c

   1 /*
   2  * Copyright © 2007 Alistair Crooks.  All rights reserved.
   3  *
   4  * Redistribution and use in source and binary forms, with or without
   5  * modification, are permitted provided that the following conditions
   6  * are met:
   7  * 1. Redistributions of source code must retain the above copyright
   8  *    notice, this list of conditions and the following disclaimer.
   9  * 2. Redistributions in binary form must reproduce the above copyright
  10  *    notice, this list of conditions and the following disclaimer in the
  11  *    documentation and/or other materials provided with the distribution.
  12  * 3. The name of the author may not be used to endorse or promote
  13  *    products derived from this software without specific prior written
  14  *    permission.
  15  *
  16  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS
  17  * OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
  18  * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  19  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
  20  * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  21  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
  22  * GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  23  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
  24  * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
  25  * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
  26  * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  27  */
  28 #include <sys/types.h>
  29 #include <sys/stat.h>
  30
  31 #include <ctype.h>
  32 #include <dirent.h>
  33 #include <err.h>
  34 #include <errno.h>
  35 #include <fcntl.h>
  36 #include <fuse.h>
  37 #include <signal.h>
  38 #include <stdio.h>
  39 #include <stdlib.h>
  40 #include <string.h>
  41 #include <time.h>
  42 #include <unistd.h>
  43
  44 #include "defs.h"
  45
  46 #ifndef PREFIX
  47 #define PREFIX          ""
  48 #endif
  49
  50 #ifndef DEF_CONF_FILE
  51 #define DEF_CONF_FILE   "/etc/fanoutfs.conf"
  52 #endif
  53
  54 DEFINE_ARRAY(strv_t, char *);
  55
  56 static struct stat       vfs;           /* stat info of directory */
  57 static strv_t            dirs;          /* the directories, in order */
  58 static char             *conffile;      /* configuration file name */
  59 static int               verbose;       /* how chatty are we? */
  60
  61
  62
  63
  64
  65 /********************************************************************/
  66
  67 static int
  68 readconf(const char *f)
  69 {
  70         char     buf[BUFSIZ];
  71         char    *cp;
  72         FILE    *fp;
  73         int      line;
  74
  75         if ((fp = fopen((f) ? f : PREFIX DEF_CONF_FILE, "r")) == NULL) {
  76                 warn("can't read configuration file `%s'\n", f);
  77                 return 0;
  78         }
  79         for (line = 1 ;  fgets(buf, sizeof(buf), fp) != NULL ; line += 1) {
  80                 buf[strlen(buf) - 1] = 0x0;
  81                 for (cp = buf ; *cp && isspace((unsigned)*cp) ; cp++) {
  82                 }
  83                 if (*cp == '\n' || *cp == 0x0 || *cp == '#') {
  84                         continue;
  85                 }
  86                 ALLOC(char *, dirs.v, dirs.size, dirs.c, 10, 10,
  87                         "readconf", exit(EXIT_FAILURE));
  88                 dirs.v[dirs.c++] = strdup(cp);
  89         }
  90         (void) fclose(fp);
  91         return 1;
  92 }
  93
  94 /* yes, this does too much work */
  95 static void
  96 sighup(int n)
  97 {
  98         int     i;
  99
 100         printf("Reading configuration file `%s'\n", conffile);
 101         for (i = 0 ; i < dirs.c ; i++) {
 102                 FREE(dirs.v[i]);
 103         }
 104         dirs.c = 0;
 105         readconf(conffile);
 106 }
 107
 108 /* find the correct entry in the list of directories */
 109 static int
 110 findentry(const char *path, char *name, size_t namesize, struct stat *sp)
 111 {
 112         struct stat     st;
 113         int             i;
 114
 115         if (sp == NULL) {
 116                 sp = &st;
 117         }
 118         for (i = 0 ; i < dirs.c ; i++) {
 119                 (void) snprintf(name, namesize, "%s%s", dirs.v[i], path);
 120                 if (stat(name, sp) == 0) {
 121                         return i;
 122                 }
 123         }
 124         return -1;
 125 }
 126
 127 /* return 1 if the string `s' is present in the array */
 128 static int
 129 present(char *s, strv_t *sp)
 130 {
 131         int     i;
 132
 133         for (i = 0 ; i < sp->c && strcmp(s, sp->v[i]) != 0 ; i++) {
 134         }
 135         return (i < sp->c);
 136 }
 137
 138 /* make sure the directory hierarchy exists */
 139 static int
 140 mkdirs(char *path)
 141 {
 142         char     name[MAXPATHLEN];
 143         char    *slash;
 144
 145         (void) snprintf(name, sizeof(name), "%s%s", dirs.v[0], path);
 146         slash = &name[strlen(path) + 1];
 147         while ((slash = strchr(slash, '/')) != NULL) {
 148                 *slash = 0x0;
 149 printf("mkdirs: dir `%s'\n", name);
 150                 if (mkdir(name, 0777) < 0) {
 151                         return 0;
 152                 }
 153                 *slash = '/';
 154         }
 155         return 1;
 156 }
 157
 158 /* copy a file, preserving mode, to make it writable */
 159 static int
 160 copyfile(char *from, char *to)
 161 {
 162         struct stat     st;
 163         char            buf[BUFSIZ * 10];
 164         int             fdfrom;
 165         int             fdto;
 166         int             ret;
 167         int             cc;
 168
 169         if ((fdfrom = open(from, O_RDONLY, 0666)) < 0) {
 170                 warn("can't open file `%s' for reading", from);
 171                 return 0;
 172         }
 173         (void) fstat(fdfrom, &st);
 174         if ((fdto = open(to, O_WRONLY | O_CREAT | O_EXCL, st.st_mode & 07777)) < 0) {
 175                 warn("can't open file `%s' for reading", from);
 176                 close(fdfrom);
 177                 return 0;
 178         }
 179         for (ret = 1 ; ret && (cc = read(fdfrom, buf, sizeof(buf))) > 0 ; ) {
 180                 if (write(fdto, buf, cc) != cc) {
 181                         warn("short write");
 182                         ret = 0;
 183                 }
 184         }
 185         if (fchown(fdto, st.st_uid, st.st_gid) < 0) {
 186                 warn("bad fchown");
 187                 ret = 0;
 188         }
 189         (void) close(fdfrom);
 190         (void) close(fdto);
 191         return ret;
 192 }
 193
 194 /* file system operations start here */
 195
 196 /* perform the stat operation */
 197 static int
 198 fanoutfs_getattr(const char *path, struct stat *st)
 199 {
 200         char    name[MAXPATHLEN];
 201
 202         (void) memset(st, 0x0, sizeof(*st));
 203         if (strcmp(path, "/") == 0) {
 204                 st->st_mode = S_IFDIR | 0755;
 205                 st->st_nlink = 2;
 206                 return 0;
 207         }
 208         if (findentry(path, name, sizeof(name), st) < 0) {
 209                 return -ENOENT;
 210         }
 211         return 0;
 212 }
 213
 214 /* readdir operation */
 215 static int
 216 fanoutfs_readdir(const char *path, void *buf, fuse_fill_dir_t filler,
 217               off_t offset, struct fuse_file_info *fi)
 218 {
 219         struct dirent   *dp;
 220         strv_t           names;
 221         char             name[MAXPATHLEN];
 222         DIR             *dirp;
 223         int              i;
 224
 225         (void) fi;
 226
 227         (void) memset(&names, 0x0, sizeof(names));
 228         for (i = 0 ; i < dirs.c ; i++) {
 229                 (void) snprintf(name, sizeof(name), "%s%s", dirs.v[i], path);
 230                 if ((dirp = opendir(name)) == NULL) {
 231                         continue;
 232                 }
 233                 while ((dp = readdir(dirp)) != NULL) {
 234                         if (!present(dp->d_name, &names)) {
 235                                 ALLOC(char *, names.v, names.size, names.c,
 236                                         10, 10, "readdir", exit(EXIT_FAILURE));
 237                                 names.v[names.c++] = strdup(dp->d_name);
 238                         }
 239                 }
 240                 (void) closedir(dirp);
 241         }
 242         for (i = 0 ; i < names.c ; i++) {
 243                 (void) filler(buf, names.v[i], NULL, 0);
 244                 FREE(names.v[i]);
 245         }
 246         if (i > 0) {
 247                 FREE(names.v);
 248         }
 249         return 0;
 250 }
 251
 252 /* open the file in the file system */
 253 static int
 254 fanoutfs_open(const char *path, struct fuse_file_info *fi)
 255 {
 256         char    newname[MAXPATHLEN];
 257         char    name[MAXPATHLEN];
 258         int     d;
 259
 260         if ((d = findentry(path, name, sizeof(name), NULL)) < 0) {
 261                 return -ENOENT;
 262         }
 263         if (d > 0 && (fi->flags & 0x3) != O_RDONLY) {
 264                 /* need to copy file to writable dir */
 265                 (void) snprintf(newname, sizeof(newname), "%s%s", dirs.v[0], path);
 266                 if (!mkdirs(newname)) {
 267                         return -ENOENT;
 268                 }
 269                 if (!copyfile(name, newname)) {
 270                         return -EPERM;
 271                 }
 272         }
 273         return 0;
 274 }
 275
 276 /* read the file's contents in the file system */
 277 static int
 278 fanoutfs_read(const char *path, char *buf, size_t size, off_t offset,
 279            struct fuse_file_info * fi)
 280 {
 281         char    name[MAXPATHLEN];
 282         int     fd;
 283         int     cc;
 284
 285         (void) fi;
 286
 287         if (findentry(path, name, sizeof(name), NULL) < 0) {
 288                 return -ENOENT;
 289         }
 290         if ((fd = open(name, O_RDONLY, 0666)) < 0) {
 291                 return -ENOENT;
 292         }
 293         if (lseek(fd, offset, SEEK_SET) < 0) {
 294                 (void) close(fd);
 295                 return -EBADF;
 296         }
 297         if ((cc = read(fd, buf, size)) < 0) {
 298                 (void) close(fd);
 299                 return -errno;
 300         }
 301         (void) close(fd);
 302         return cc;
 303 }
 304
 305 /* write the file's contents in the file system */
 306 static int
 307 fanoutfs_write(const char *path, const char *buf, size_t size, off_t offset,
 308            struct fuse_file_info * fi)
 309 {
 310         char    name[MAXPATHLEN];
 311         int     fd;
 312         int     cc;
 313
 314         (void) fi;
 315
 316         if (findentry(path, name, sizeof(name), NULL) < 0) {
 317                 return -ENOENT;
 318         }
 319         if ((fd = open(name, O_WRONLY, 0666)) < 0) {
 320                 return -ENOENT;
 321         }
 322         if (lseek(fd, offset, SEEK_SET) < 0) {
 323                 (void) close(fd);
 324                 return -EBADF;
 325         }
 326         if ((cc = write(fd, buf, size)) < 0) {
 327                 (void) close(fd);
 328                 return -errno;
 329         }
 330         (void) close(fd);
 331         return cc;
 332 }
 333
 334 /* fill in the statvfs struct */
 335 static int
 336 fanoutfs_statfs(const char *path, struct statvfs *st)
 337 {
 338         (void) memset(st, 0x0, sizeof(*st));
 339         st->f_bsize = st->f_frsize = st->f_iosize = 512;
 340         st->f_owner = vfs.st_uid;
 341         st->f_files = 1;
 342         return 0;
 343 }
 344
 345 /* "remove" a file */
 346 static int
 347 fanoutfs_unlink(const char *path)
 348 {
 349         char    name[MAXPATHLEN];
 350
 351         if (findentry(path, name, sizeof(name), NULL) < 0) {
 352                 return -ENOENT;
 353         }
 354         if (unlink(name) < 0) {
 355                 return -errno;
 356         }
 357         return 0;
 358 }
 359
 360 /* check the access on a file */
 361 static int
 362 fanoutfs_access(const char *path, int acc)
 363 {
 364         char    name[MAXPATHLEN];
 365
 366         if (findentry(path, name, sizeof(name), NULL) < 0) {
 367                 return -ENOENT;
 368         }
 369         if (access(name, acc) < 0) {
 370                 return -errno;
 371         }
 372         return 0;
 373 }
 374
 375 /* change the mode of a file */
 376 static int
 377 fanoutfs_chmod(const char *path, mode_t mode)
 378 {
 379         char    name[MAXPATHLEN];
 380
 381         if (findentry(path, name, sizeof(name), NULL) < 0) {
 382                 return -ENOENT;
 383         }
 384         if (chmod(name, mode) < 0) {
 385                 return -errno;
 386         }
 387         return 0;
 388 }
 389
 390 /* change the owner and group of a file */
 391 static int
 392 fanoutfs_chown(const char *path, uid_t uid, gid_t gid)
 393 {
 394         char    name[MAXPATHLEN];
 395
 396         if (findentry(path, name, sizeof(name), NULL) < 0) {
 397                 return -ENOENT;
 398         }
 399         if (lchown(name, uid, gid) < 0) {
 400                 return -errno;
 401         }
 402         return 0;
 403 }
 404
 405 /* "rename" a file */
 406 static int
 407 fanoutfs_rename(const char *from, const char *to)
 408 {
 409         char    fromname[MAXPATHLEN];
 410         char    toname[MAXPATHLEN];
 411
 412         if (findentry(from, fromname, sizeof(fromname), NULL) < 0) {
 413                 return -ENOENT;
 414         }
 415         (void) snprintf(toname, sizeof(toname), "%s%s", dirs.v[0], to);
 416         if (!mkdirs(toname)) {
 417                 return -ENOENT;
 418         }
 419         if (rename(fromname, toname) < 0) {
 420                 return -EPERM;
 421         }
 422         return 0;
 423 }
 424
 425 /* create a file */
 426 static int
 427 fanoutfs_create(const char *path, mode_t mode, struct fuse_file_info *fi)
 428 {
 429         struct stat     st;
 430         char            name[MAXPATHLEN];
 431         int             fd;
 432
 433         if (findentry(path, name, sizeof(name), &st) >= 0) {
 434                 return -EEXIST;
 435         }
 436         if ((fd = open(name, O_RDWR | O_CREAT | O_EXCL, 0666)) < 0) {
 437                 return -EPERM;
 438         }
 439         (void) close(fd);
 440         return 0;
 441 }
 442
 443 /* create a special node */
 444 static int
 445 fanoutfs_mknod(const char *path, mode_t mode, dev_t d)
 446 {
 447         struct stat     st;
 448         char            name[MAXPATHLEN];
 449
 450         if (findentry(path, name, sizeof(name), &st) >= 0) {
 451                 return -EEXIST;
 452         }
 453         if (mknod(name, mode, d) < 0) {
 454                 return -EPERM;
 455         }
 456         return 0;
 457 }
 458
 459 /* create a directory */
 460 static int
 461 fanoutfs_mkdir(const char *path, mode_t mode)
 462 {
 463         char    name[MAXPATHLEN];
 464
 465         (void) snprintf(name, sizeof(name), "%s%s", dirs.v[0], path);
 466         if (!mkdirs(name)) {
 467                 return -ENOENT;
 468         }
 469         if (mkdir(name, mode) < 0) {
 470                 return -EPERM;
 471         }
 472         return 0;
 473 }
 474
 475 /* create a symbolic link */
 476 static int
 477 fanoutfs_symlink(const char *path, const char *tgt)
 478 {
 479         char    name[MAXPATHLEN];
 480
 481         (void) snprintf(name, sizeof(name), "%s%s", dirs.v[0], path);
 482         if (!mkdirs(name)) {
 483                 return -ENOENT;
 484         }
 485         if (symlink(name, tgt) < 0) {
 486                 return -EPERM;
 487         }
 488         return 0;
 489 }
 490
 491 /* create a link */
 492 static int
 493 fanoutfs_link(const char *path, const char *tgt)
 494 {
 495         char    name[MAXPATHLEN];
 496
 497         (void) snprintf(name, sizeof(name), "%s%s", dirs.v[0], path);
 498         if (!mkdirs(name)) {
 499                 return -ENOENT;
 500         }
 501         if (link(name, tgt) < 0) {
 502                 return -errno;
 503         }
 504         return 0;
 505 }
 506
 507 /* read the contents of a symbolic link */
 508 static int
 509 fanoutfs_readlink(const char *path, char *buf, size_t size)
 510 {
 511         char    name[MAXPATHLEN];
 512
 513         if (findentry(path, name, sizeof(name), NULL) < 0) {
 514                 return -ENOENT;
 515         }
 516         if (readlink(name, buf, size) < 0) {
 517                 return -errno;
 518         }
 519         return 0;
 520 }
 521
 522 /* remove a directory */
 523 static int
 524 fanoutfs_rmdir(const char *path)
 525 {
 526         char    name[MAXPATHLEN];
 527
 528         if (findentry(path, name, sizeof(name), NULL) < 0) {
 529                 return -ENOENT;
 530         }
 531         if (rmdir(name) < 0) {
 532                 return -errno;
 533         }
 534         return 0;
 535 }
 536
 537 /* truncate a file */
 538 static int
 539 fanoutfs_truncate(const char *path, off_t size)
 540 {
 541         char    name[MAXPATHLEN];
 542
 543         if (findentry(path, name, sizeof(name), NULL) < 0) {
 544                 return -ENOENT;
 545         }
 546         if (truncate(name, size) < 0) {
 547                 return -errno;
 548         }
 549         return 0;
 550 }
 551
 552 /* set utimes on a file */
 553 static int
 554 fanoutfs_utime(const char *path, struct utimbuf *t)
 555 {
 556         char    name[MAXPATHLEN];
 557
 558         if (findentry(path, name, sizeof(name), NULL) < 0) {
 559                 return -ENOENT;
 560         }
 561         if (utime(name, t) < 0) {
 562                 return -errno;
 563         }
 564         return 0;
 565 }
 566
 567 /* operations struct */
 568 static struct fuse_operations fanoutfs_oper = {
 569         .getattr = fanoutfs_getattr,
 570         .readlink = fanoutfs_readlink,
 571         .mknod = fanoutfs_mknod,
 572         .mkdir = fanoutfs_mkdir,
 573         .unlink = fanoutfs_unlink,
 574         .rmdir = fanoutfs_rmdir,
 575         .symlink = fanoutfs_symlink,
 576         .rename = fanoutfs_rename,
 577         .link = fanoutfs_link,
 578         .chmod = fanoutfs_chmod,
 579         .chown = fanoutfs_chown,
 580         .truncate = fanoutfs_truncate,
 581         .utime = fanoutfs_utime,
 582         .open = fanoutfs_open,
 583         .read = fanoutfs_read,
 584         .write = fanoutfs_write,
 585         .statfs = fanoutfs_statfs,
 586         .readdir = fanoutfs_readdir,
 587         .access = fanoutfs_access,
 588         .create = fanoutfs_create
 589 };
 590
 591 int
 592 main(int argc, char **argv)
 593 {
 594         int      i;
 595
 596         while ((i = getopt(argc, argv, "f:v")) != -1) {
 597                 switch(i) {
 598                 case 'f':
 599                         conffile = optarg;
 600                         break;
 601                 case 'v':
 602                         verbose = 1;
 603                         break;
 604                 }
 605         }
 606         (void) signal(SIGHUP, sighup);
 607         readconf(conffile);
 608         (void) daemon(1, 1);
 609         return fuse_main(argc, argv, &fanoutfs_oper, NULL);
 610 }