hw/9pfs/9p-synth.c

   1 /*
   2  * Virtio 9p synthetic file system support
   3  *
   4  * Copyright IBM, Corp. 2011
   5  *
   6  * Authors:
   7  *  Malahal Naineni <malahal@us.ibm.com>
   8  *  Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
   9  *
  10  * This work is licensed under the terms of the GNU GPL, version 2.  See
  11  * the COPYING file in the top-level directory.
  12  *
  13  */
  14
  15 #include "qemu/osdep.h"
  16 #include "hw/virtio/virtio.h"
  17 #include "9p.h"
  18 #include "9p-xattr.h"
  19 #include "fsdev/qemu-fsdev.h"
  20 #include "9p-synth.h"
  21 #include "qemu/rcu.h"
  22 #include "qemu/rcu_queue.h"
  23
  24 /* Root node for synth file system */
  25 static V9fsSynthNode v9fs_synth_root = {
  26     .name = "/",
  27     .actual_attr = {
  28         .mode = 0555 | S_IFDIR,
  29         .nlink = 1,
  30     },
  31     .attr = &v9fs_synth_root.actual_attr,
  32 };
  33
  34 static QemuMutex  v9fs_synth_mutex;
  35 static int v9fs_synth_node_count;
  36 /* set to 1 when the synth fs is ready */
  37 static int v9fs_synth_fs;
  38
  39 static V9fsSynthNode *v9fs_add_dir_node(V9fsSynthNode *parent, int mode,
  40                                         const char *name,
  41                                         V9fsSynthNodeAttr *attr, int inode)
  42 {
  43     V9fsSynthNode *node;
  44
  45     /* Add directory type and remove write bits */
  46     mode = ((mode & 0777) | S_IFDIR) & ~(S_IWUSR | S_IWGRP | S_IWOTH);
  47     node = g_malloc0(sizeof(V9fsSynthNode));
  48     if (attr) {
  49         /* We are adding .. or . entries */
  50         node->attr = attr;
  51         node->attr->nlink++;
  52     } else {
  53         node->attr = &node->actual_attr;
  54         node->attr->inode = inode;
  55         node->attr->nlink = 1;
  56         /* We don't allow write to directories */
  57         node->attr->mode   = mode;
  58         node->attr->write = NULL;
  59         node->attr->read  = NULL;
  60     }
  61     node->private = node;
  62     pstrcpy(node->name, sizeof(node->name), name);
  63     QLIST_INSERT_HEAD_RCU(&parent->child, node, sibling);
  64     return node;
  65 }
  66
  67 int qemu_v9fs_synth_mkdir(V9fsSynthNode *parent, int mode,
  68                           const char *name, V9fsSynthNode **result)
  69 {
  70     int ret;
  71     V9fsSynthNode *node, *tmp;
  72
  73     if (!v9fs_synth_fs) {
  74         return EAGAIN;
  75     }
  76     if (!name || (strlen(name) >= NAME_MAX)) {
  77         return EINVAL;
  78     }
  79     if (!parent) {
  80         parent = &v9fs_synth_root;
  81     }
  82     qemu_mutex_lock(&v9fs_synth_mutex);
  83     QLIST_FOREACH(tmp, &parent->child, sibling) {
  84         if (!strcmp(tmp->name, name)) {
  85             ret = EEXIST;
  86             goto err_out;
  87         }
  88     }
  89     /* Add the name */
  90     node = v9fs_add_dir_node(parent, mode, name, NULL, v9fs_synth_node_count++);
  91     v9fs_add_dir_node(node, parent->attr->mode, "..",
  92                       parent->attr, parent->attr->inode);
  93     v9fs_add_dir_node(node, node->attr->mode, ".",
  94                       node->attr, node->attr->inode);
  95     *result = node;
  96     ret = 0;
  97 err_out:
  98     qemu_mutex_unlock(&v9fs_synth_mutex);
  99     return ret;
 100 }
 101
 102 int qemu_v9fs_synth_add_file(V9fsSynthNode *parent, int mode,
 103                              const char *name, v9fs_synth_read read,
 104                              v9fs_synth_write write, void *arg)
 105 {
 106     int ret;
 107     V9fsSynthNode *node, *tmp;
 108
 109     if (!v9fs_synth_fs) {
 110         return EAGAIN;
 111     }
 112     if (!name || (strlen(name) >= NAME_MAX)) {
 113         return EINVAL;
 114     }
 115     if (!parent) {
 116         parent = &v9fs_synth_root;
 117     }
 118
 119     qemu_mutex_lock(&v9fs_synth_mutex);
 120     QLIST_FOREACH(tmp, &parent->child, sibling) {
 121         if (!strcmp(tmp->name, name)) {
 122             ret = EEXIST;
 123             goto err_out;
 124         }
 125     }
 126     /* Add file type and remove write bits */
 127     mode = ((mode & 0777) | S_IFREG);
 128     node = g_malloc0(sizeof(V9fsSynthNode));
 129     node->attr         = &node->actual_attr;
 130     node->attr->inode  = v9fs_synth_node_count++;
 131     node->attr->nlink  = 1;
 132     node->attr->read   = read;
 133     node->attr->write  = write;
 134     node->attr->mode   = mode;
 135     node->private      = arg;
 136     pstrcpy(node->name, sizeof(node->name), name);
 137     QLIST_INSERT_HEAD_RCU(&parent->child, node, sibling);
 138     ret = 0;
 139 err_out:
 140     qemu_mutex_unlock(&v9fs_synth_mutex);
 141     return ret;
 142 }
 143
 144 static void v9fs_synth_fill_statbuf(V9fsSynthNode *node, struct stat *stbuf)
 145 {
 146     stbuf->st_dev = 0;
 147     stbuf->st_ino = node->attr->inode;
 148     stbuf->st_mode = node->attr->mode;
 149     stbuf->st_nlink = node->attr->nlink;
 150     stbuf->st_uid = 0;
 151     stbuf->st_gid = 0;
 152     stbuf->st_rdev = 0;
 153     stbuf->st_size = 0;
 154     stbuf->st_blksize = 0;
 155     stbuf->st_blocks = 0;
 156     stbuf->st_atime = 0;
 157     stbuf->st_mtime = 0;
 158     stbuf->st_ctime = 0;
 159 }
 160
 161 static int v9fs_synth_lstat(FsContext *fs_ctx,
 162                             V9fsPath *fs_path, struct stat *stbuf)
 163 {
 164     V9fsSynthNode *node = *(V9fsSynthNode **)fs_path->data;
 165
 166     v9fs_synth_fill_statbuf(node, stbuf);
 167     return 0;
 168 }
 169
 170 static int v9fs_synth_fstat(FsContext *fs_ctx, int fid_type,
 171                             V9fsFidOpenState *fs, struct stat *stbuf)
 172 {
 173     V9fsSynthOpenState *synth_open = fs->private;
 174     v9fs_synth_fill_statbuf(synth_open->node, stbuf);
 175     return 0;
 176 }
 177
 178 static int v9fs_synth_opendir(FsContext *ctx,
 179                              V9fsPath *fs_path, V9fsFidOpenState *fs)
 180 {
 181     V9fsSynthOpenState *synth_open;
 182     V9fsSynthNode *node = *(V9fsSynthNode **)fs_path->data;
 183
 184     synth_open = g_malloc(sizeof(*synth_open));
 185     synth_open->node = node;
 186     node->open_count++;
 187     fs->private = synth_open;
 188     return 0;
 189 }
 190
 191 static int v9fs_synth_closedir(FsContext *ctx, V9fsFidOpenState *fs)
 192 {
 193     V9fsSynthOpenState *synth_open = fs->private;
 194     V9fsSynthNode *node = synth_open->node;
 195
 196     node->open_count--;
 197     g_free(synth_open);
 198     fs->private = NULL;
 199     return 0;
 200 }
 201
 202 static off_t v9fs_synth_telldir(FsContext *ctx, V9fsFidOpenState *fs)
 203 {
 204     V9fsSynthOpenState *synth_open = fs->private;
 205     return synth_open->offset;
 206 }
 207
 208 static void v9fs_synth_seekdir(FsContext *ctx, V9fsFidOpenState *fs, off_t off)
 209 {
 210     V9fsSynthOpenState *synth_open = fs->private;
 211     synth_open->offset = off;
 212 }
 213
 214 static void v9fs_synth_rewinddir(FsContext *ctx, V9fsFidOpenState *fs)
 215 {
 216     v9fs_synth_seekdir(ctx, fs, 0);
 217 }
 218
 219 static void v9fs_synth_direntry(V9fsSynthNode *node,
 220                                 struct dirent *entry, off_t off)
 221 {
 222     strcpy(entry->d_name, node->name);
 223     entry->d_ino = node->attr->inode;
 224     entry->d_off = off + 1;
 225 }
 226
 227 static int v9fs_synth_get_dentry(V9fsSynthNode *dir, struct dirent *entry,
 228                                  struct dirent **result, off_t off)
 229 {
 230     int i = 0;
 231     V9fsSynthNode *node;
 232
 233     rcu_read_lock();
 234     QLIST_FOREACH(node, &dir->child, sibling) {
 235         /* This is the off child of the directory */
 236         if (i == off) {
 237             break;
 238         }
 239         i++;
 240     }
 241     rcu_read_unlock();
 242     if (!node) {
 243         /* end of directory */
 244         *result = NULL;
 245         return 0;
 246     }
 247     v9fs_synth_direntry(node, entry, off);
 248     *result = entry;
 249     return 0;
 250 }
 251
 252 static int v9fs_synth_readdir_r(FsContext *ctx, V9fsFidOpenState *fs,
 253                                 struct dirent *entry, struct dirent **result)
 254 {
 255     int ret;
 256     V9fsSynthOpenState *synth_open = fs->private;
 257     V9fsSynthNode *node = synth_open->node;
 258     ret = v9fs_synth_get_dentry(node, entry, result, synth_open->offset);
 259     if (!ret && *result != NULL) {
 260         synth_open->offset++;
 261     }
 262     return ret;
 263 }
 264
 265 static int v9fs_synth_open(FsContext *ctx, V9fsPath *fs_path,
 266                            int flags, V9fsFidOpenState *fs)
 267 {
 268     V9fsSynthOpenState *synth_open;
 269     V9fsSynthNode *node = *(V9fsSynthNode **)fs_path->data;
 270
 271     synth_open = g_malloc(sizeof(*synth_open));
 272     synth_open->node = node;
 273     node->open_count++;
 274     fs->private = synth_open;
 275     return 0;
 276 }
 277
 278 static int v9fs_synth_open2(FsContext *fs_ctx, V9fsPath *dir_path,
 279                             const char *name, int flags,
 280                             FsCred *credp, V9fsFidOpenState *fs)
 281 {
 282     errno = ENOSYS;
 283     return -1;
 284 }
 285
 286 static int v9fs_synth_close(FsContext *ctx, V9fsFidOpenState *fs)
 287 {
 288     V9fsSynthOpenState *synth_open = fs->private;
 289     V9fsSynthNode *node = synth_open->node;
 290
 291     node->open_count--;
 292     g_free(synth_open);
 293     fs->private = NULL;
 294     return 0;
 295 }
 296
 297 static ssize_t v9fs_synth_pwritev(FsContext *ctx, V9fsFidOpenState *fs,
 298                                   const struct iovec *iov,
 299                                   int iovcnt, off_t offset)
 300 {
 301     int i, count = 0, wcount;
 302     V9fsSynthOpenState *synth_open = fs->private;
 303     V9fsSynthNode *node = synth_open->node;
 304     if (!node->attr->write) {
 305         errno = EPERM;
 306         return -1;
 307     }
 308     for (i = 0; i < iovcnt; i++) {
 309         wcount = node->attr->write(iov[i].iov_base, iov[i].iov_len,
 310                                    offset, node->private);
 311         offset += wcount;
 312         count  += wcount;
 313         /* If we wrote less than requested. we are done */
 314         if (wcount < iov[i].iov_len) {
 315             break;
 316         }
 317     }
 318     return count;
 319 }
 320
 321 static ssize_t v9fs_synth_preadv(FsContext *ctx, V9fsFidOpenState *fs,
 322                                  const struct iovec *iov,
 323                                  int iovcnt, off_t offset)
 324 {
 325     int i, count = 0, rcount;
 326     V9fsSynthOpenState *synth_open = fs->private;
 327     V9fsSynthNode *node = synth_open->node;
 328     if (!node->attr->read) {
 329         errno = EPERM;
 330         return -1;
 331     }
 332     for (i = 0; i < iovcnt; i++) {
 333         rcount = node->attr->read(iov[i].iov_base, iov[i].iov_len,
 334                                   offset, node->private);
 335         offset += rcount;
 336         count  += rcount;
 337         /* If we read less than requested. we are done */
 338         if (rcount < iov[i].iov_len) {
 339             break;
 340         }
 341     }
 342     return count;
 343 }
 344
 345 static int v9fs_synth_truncate(FsContext *ctx, V9fsPath *path, off_t offset)
 346 {
 347     errno = ENOSYS;
 348     return -1;
 349 }
 350
 351 static int v9fs_synth_chmod(FsContext *fs_ctx, V9fsPath *path, FsCred *credp)
 352 {
 353     errno = EPERM;
 354     return -1;
 355 }
 356
 357 static int v9fs_synth_mknod(FsContext *fs_ctx, V9fsPath *path,
 358                        const char *buf, FsCred *credp)
 359 {
 360     errno = EPERM;
 361     return -1;
 362 }
 363
 364 static int v9fs_synth_mkdir(FsContext *fs_ctx, V9fsPath *path,
 365                        const char *buf, FsCred *credp)
 366 {
 367     errno = EPERM;
 368     return -1;
 369 }
 370
 371 static ssize_t v9fs_synth_readlink(FsContext *fs_ctx, V9fsPath *path,
 372                                    char *buf, size_t bufsz)
 373 {
 374     errno = ENOSYS;
 375     return -1;
 376 }
 377
 378 static int v9fs_synth_symlink(FsContext *fs_ctx, const char *oldpath,
 379                               V9fsPath *newpath, const char *buf, FsCred *credp)
 380 {
 381     errno = EPERM;
 382     return -1;
 383 }
 384
 385 static int v9fs_synth_link(FsContext *fs_ctx, V9fsPath *oldpath,
 386                            V9fsPath *newpath, const char *buf)
 387 {
 388     errno = EPERM;
 389     return -1;
 390 }
 391
 392 static int v9fs_synth_rename(FsContext *ctx, const char *oldpath,
 393                              const char *newpath)
 394 {
 395     errno = EPERM;
 396     return -1;
 397 }
 398
 399 static int v9fs_synth_chown(FsContext *fs_ctx, V9fsPath *path, FsCred *credp)
 400 {
 401     errno = EPERM;
 402     return -1;
 403 }
 404
 405 static int v9fs_synth_utimensat(FsContext *fs_ctx, V9fsPath *path,
 406                                 const struct timespec *buf)
 407 {
 408     errno = EPERM;
 409     return 0;
 410 }
 411
 412 static int v9fs_synth_remove(FsContext *ctx, const char *path)
 413 {
 414     errno = EPERM;
 415     return -1;
 416 }
 417
 418 static int v9fs_synth_fsync(FsContext *ctx, int fid_type,
 419                             V9fsFidOpenState *fs, int datasync)
 420 {
 421     errno = ENOSYS;
 422     return 0;
 423 }
 424
 425 static int v9fs_synth_statfs(FsContext *s, V9fsPath *fs_path,
 426                              struct statfs *stbuf)
 427 {
 428     stbuf->f_type = 0xABCD;
 429     stbuf->f_bsize = 512;
 430     stbuf->f_blocks = 0;
 431     stbuf->f_files = v9fs_synth_node_count;
 432     stbuf->f_namelen = NAME_MAX;
 433     return 0;
 434 }
 435
 436 static ssize_t v9fs_synth_lgetxattr(FsContext *ctx, V9fsPath *path,
 437                                     const char *name, void *value, size_t size)
 438 {
 439     errno = ENOTSUP;
 440     return -1;
 441 }
 442
 443 static ssize_t v9fs_synth_llistxattr(FsContext *ctx, V9fsPath *path,
 444                                      void *value, size_t size)
 445 {
 446     errno = ENOTSUP;
 447     return -1;
 448 }
 449
 450 static int v9fs_synth_lsetxattr(FsContext *ctx, V9fsPath *path,
 451                                 const char *name, void *value,
 452                                 size_t size, int flags)
 453 {
 454     errno = ENOTSUP;
 455     return -1;
 456 }
 457
 458 static int v9fs_synth_lremovexattr(FsContext *ctx,
 459                                    V9fsPath *path, const char *name)
 460 {
 461     errno = ENOTSUP;
 462     return -1;
 463 }
 464
 465 static int v9fs_synth_name_to_path(FsContext *ctx, V9fsPath *dir_path,
 466                                    const char *name, V9fsPath *target)
 467 {
 468     V9fsSynthNode *node;
 469     V9fsSynthNode *dir_node;
 470
 471     /* "." and ".." are not allowed */
 472     if (!strcmp(name, ".") || !strcmp(name, "..")) {
 473         errno = EINVAL;
 474         return -1;
 475
 476     }
 477     if (!dir_path) {
 478         dir_node = &v9fs_synth_root;
 479     } else {
 480         dir_node = *(V9fsSynthNode **)dir_path->data;
 481     }
 482     if (!strcmp(name, "/")) {
 483         node = dir_node;
 484         goto out;
 485     }
 486     /* search for the name in the childern */
 487     rcu_read_lock();
 488     QLIST_FOREACH(node, &dir_node->child, sibling) {
 489         if (!strcmp(node->name, name)) {
 490             break;
 491         }
 492     }
 493     rcu_read_unlock();
 494
 495     if (!node) {
 496         errno = ENOENT;
 497         return -1;
 498     }
 499 out:
 500     /* Copy the node pointer to fid */
 501     target->data = g_malloc(sizeof(void *));
 502     memcpy(target->data, &node, sizeof(void *));
 503     target->size = sizeof(void *);
 504     return 0;
 505 }
 506
 507 static int v9fs_synth_renameat(FsContext *ctx, V9fsPath *olddir,
 508                                const char *old_name, V9fsPath *newdir,
 509                                const char *new_name)
 510 {
 511     errno = EPERM;
 512     return -1;
 513 }
 514
 515 static int v9fs_synth_unlinkat(FsContext *ctx, V9fsPath *dir,
 516                                const char *name, int flags)
 517 {
 518     errno = EPERM;
 519     return -1;
 520 }
 521
 522 static int v9fs_synth_init(FsContext *ctx)
 523 {
 524     QLIST_INIT(&v9fs_synth_root.child);
 525     qemu_mutex_init(&v9fs_synth_mutex);
 526
 527     /* Add "." and ".." entries for root */
 528     v9fs_add_dir_node(&v9fs_synth_root, v9fs_synth_root.attr->mode,
 529                       "..", v9fs_synth_root.attr, v9fs_synth_root.attr->inode);
 530     v9fs_add_dir_node(&v9fs_synth_root, v9fs_synth_root.attr->mode,
 531                       ".", v9fs_synth_root.attr, v9fs_synth_root.attr->inode);
 532
 533     /* Mark the subsystem is ready for use */
 534     v9fs_synth_fs = 1;
 535     return 0;
 536 }
 537
 538 FileOperations synth_ops = {
 539     .init         = v9fs_synth_init,
 540     .lstat        = v9fs_synth_lstat,
 541     .readlink     = v9fs_synth_readlink,
 542     .close        = v9fs_synth_close,
 543     .closedir     = v9fs_synth_closedir,
 544     .open         = v9fs_synth_open,
 545     .opendir      = v9fs_synth_opendir,
 546     .rewinddir    = v9fs_synth_rewinddir,
 547     .telldir      = v9fs_synth_telldir,
 548     .readdir_r    = v9fs_synth_readdir_r,
 549     .seekdir      = v9fs_synth_seekdir,
 550     .preadv       = v9fs_synth_preadv,
 551     .pwritev      = v9fs_synth_pwritev,
 552     .chmod        = v9fs_synth_chmod,
 553     .mknod        = v9fs_synth_mknod,
 554     .mkdir        = v9fs_synth_mkdir,
 555     .fstat        = v9fs_synth_fstat,
 556     .open2        = v9fs_synth_open2,
 557     .symlink      = v9fs_synth_symlink,
 558     .link         = v9fs_synth_link,
 559     .truncate     = v9fs_synth_truncate,
 560     .rename       = v9fs_synth_rename,
 561     .chown        = v9fs_synth_chown,
 562     .utimensat    = v9fs_synth_utimensat,
 563     .remove       = v9fs_synth_remove,
 564     .fsync        = v9fs_synth_fsync,
 565     .statfs       = v9fs_synth_statfs,
 566     .lgetxattr    = v9fs_synth_lgetxattr,
 567     .llistxattr   = v9fs_synth_llistxattr,
 568     .lsetxattr    = v9fs_synth_lsetxattr,
 569     .lremovexattr = v9fs_synth_lremovexattr,
 570     .name_to_path = v9fs_synth_name_to_path,
 571     .renameat     = v9fs_synth_renameat,
 572     .unlinkat     = v9fs_synth_unlinkat,
 573 };