hw/9pfs/9p-synth.c

   1 /*
   2  * 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 "9p.h"
  17 #include "fsdev/qemu-fsdev.h"
  18 #include "9p-synth.h"
  19 #include "qemu/rcu.h"
  20 #include "qemu/rcu_queue.h"
  21 #include "qemu/cutils.h"
  22 #include "sysemu/qtest.h"
  23
  24 /* Root node for synth file system */
  25 static V9fsSynthNode synth_root = {
  26     .name = "/",
  27     .actual_attr = {
  28         .mode = 0555 | S_IFDIR,
  29         .nlink = 1,
  30     },
  31     .attr = &synth_root.actual_attr,
  32 };
  33
  34 static QemuMutex  synth_mutex;
  35 static int synth_node_count;
  36 /* set to 1 when the synth fs is ready */
  37 static int 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 (!synth_fs) {
  74         return EAGAIN;
  75     }
  76     if (!name || (strlen(name) >= NAME_MAX)) {
  77         return EINVAL;
  78     }
  79     if (!parent) {
  80         parent = &synth_root;
  81     }
  82     qemu_mutex_lock(&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, 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(&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 (!synth_fs) {
 110         return EAGAIN;
 111     }
 112     if (!name || (strlen(name) >= NAME_MAX)) {
 113         return EINVAL;
 114     }
 115     if (!parent) {
 116         parent = &synth_root;
 117     }
 118
 119     qemu_mutex_lock(&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  = 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(&synth_mutex);
 141     return ret;
 142 }
 143
 144 static void 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 synth_lstat(FsContext *fs_ctx,
 162                             V9fsPath *fs_path, struct stat *stbuf)
 163 {
 164     V9fsSynthNode *node = *(V9fsSynthNode **)fs_path->data;
 165
 166     synth_fill_statbuf(node, stbuf);
 167     return 0;
 168 }
 169
 170 static int synth_fstat(FsContext *fs_ctx, int fid_type,
 171                             V9fsFidOpenState *fs, struct stat *stbuf)
 172 {
 173     V9fsSynthOpenState *synth_open = fs->private;
 174     synth_fill_statbuf(synth_open->node, stbuf);
 175     return 0;
 176 }
 177
 178 static int 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 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 synth_telldir(FsContext *ctx, V9fsFidOpenState *fs)
 203 {
 204     V9fsSynthOpenState *synth_open = fs->private;
 205     return synth_open->offset;
 206 }
 207
 208 static void 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 synth_rewinddir(FsContext *ctx, V9fsFidOpenState *fs)
 215 {
 216     synth_seekdir(ctx, fs, 0);
 217 }
 218
 219 static void 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 struct dirent *synth_get_dentry(V9fsSynthNode *dir,
 228                                             struct dirent *entry, 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         return NULL;
 245     }
 246     synth_direntry(node, entry, off);
 247     return entry;
 248 }
 249
 250 static struct dirent *synth_readdir(FsContext *ctx, V9fsFidOpenState *fs)
 251 {
 252     struct dirent *entry;
 253     V9fsSynthOpenState *synth_open = fs->private;
 254     V9fsSynthNode *node = synth_open->node;
 255     entry = synth_get_dentry(node, &synth_open->dent, synth_open->offset);
 256     if (entry) {
 257         synth_open->offset++;
 258     }
 259     return entry;
 260 }
 261
 262 static int synth_open(FsContext *ctx, V9fsPath *fs_path,
 263                            int flags, V9fsFidOpenState *fs)
 264 {
 265     V9fsSynthOpenState *synth_open;
 266     V9fsSynthNode *node = *(V9fsSynthNode **)fs_path->data;
 267
 268     synth_open = g_malloc(sizeof(*synth_open));
 269     synth_open->node = node;
 270     node->open_count++;
 271     fs->private = synth_open;
 272     return 0;
 273 }
 274
 275 static int synth_open2(FsContext *fs_ctx, V9fsPath *dir_path,
 276                             const char *name, int flags,
 277                             FsCred *credp, V9fsFidOpenState *fs)
 278 {
 279     errno = ENOSYS;
 280     return -1;
 281 }
 282
 283 static int synth_close(FsContext *ctx, V9fsFidOpenState *fs)
 284 {
 285     V9fsSynthOpenState *synth_open = fs->private;
 286     V9fsSynthNode *node = synth_open->node;
 287
 288     node->open_count--;
 289     g_free(synth_open);
 290     fs->private = NULL;
 291     return 0;
 292 }
 293
 294 static ssize_t synth_pwritev(FsContext *ctx, V9fsFidOpenState *fs,
 295                                   const struct iovec *iov,
 296                                   int iovcnt, off_t offset)
 297 {
 298     int i, count = 0, wcount;
 299     V9fsSynthOpenState *synth_open = fs->private;
 300     V9fsSynthNode *node = synth_open->node;
 301     if (!node->attr->write) {
 302         errno = EPERM;
 303         return -1;
 304     }
 305     for (i = 0; i < iovcnt; i++) {
 306         wcount = node->attr->write(iov[i].iov_base, iov[i].iov_len,
 307                                    offset, node->private);
 308         offset += wcount;
 309         count  += wcount;
 310         /* If we wrote less than requested. we are done */
 311         if (wcount < iov[i].iov_len) {
 312             break;
 313         }
 314     }
 315     return count;
 316 }
 317
 318 static ssize_t synth_preadv(FsContext *ctx, V9fsFidOpenState *fs,
 319                                  const struct iovec *iov,
 320                                  int iovcnt, off_t offset)
 321 {
 322     int i, count = 0, rcount;
 323     V9fsSynthOpenState *synth_open = fs->private;
 324     V9fsSynthNode *node = synth_open->node;
 325     if (!node->attr->read) {
 326         errno = EPERM;
 327         return -1;
 328     }
 329     for (i = 0; i < iovcnt; i++) {
 330         rcount = node->attr->read(iov[i].iov_base, iov[i].iov_len,
 331                                   offset, node->private);
 332         offset += rcount;
 333         count  += rcount;
 334         /* If we read less than requested. we are done */
 335         if (rcount < iov[i].iov_len) {
 336             break;
 337         }
 338     }
 339     return count;
 340 }
 341
 342 static int synth_truncate(FsContext *ctx, V9fsPath *path, off_t offset)
 343 {
 344     errno = ENOSYS;
 345     return -1;
 346 }
 347
 348 static int synth_chmod(FsContext *fs_ctx, V9fsPath *path, FsCred *credp)
 349 {
 350     errno = EPERM;
 351     return -1;
 352 }
 353
 354 static int synth_mknod(FsContext *fs_ctx, V9fsPath *path,
 355                        const char *buf, FsCred *credp)
 356 {
 357     errno = EPERM;
 358     return -1;
 359 }
 360
 361 static int synth_mkdir(FsContext *fs_ctx, V9fsPath *path,
 362                        const char *buf, FsCred *credp)
 363 {
 364     errno = EPERM;
 365     return -1;
 366 }
 367
 368 static ssize_t synth_readlink(FsContext *fs_ctx, V9fsPath *path,
 369                                    char *buf, size_t bufsz)
 370 {
 371     errno = ENOSYS;
 372     return -1;
 373 }
 374
 375 static int synth_symlink(FsContext *fs_ctx, const char *oldpath,
 376                               V9fsPath *newpath, const char *buf, FsCred *credp)
 377 {
 378     errno = EPERM;
 379     return -1;
 380 }
 381
 382 static int synth_link(FsContext *fs_ctx, V9fsPath *oldpath,
 383                            V9fsPath *newpath, const char *buf)
 384 {
 385     errno = EPERM;
 386     return -1;
 387 }
 388
 389 static int synth_rename(FsContext *ctx, const char *oldpath,
 390                              const char *newpath)
 391 {
 392     errno = EPERM;
 393     return -1;
 394 }
 395
 396 static int synth_chown(FsContext *fs_ctx, V9fsPath *path, FsCred *credp)
 397 {
 398     errno = EPERM;
 399     return -1;
 400 }
 401
 402 static int synth_utimensat(FsContext *fs_ctx, V9fsPath *path,
 403                                 const struct timespec *buf)
 404 {
 405     errno = EPERM;
 406     return 0;
 407 }
 408
 409 static int synth_remove(FsContext *ctx, const char *path)
 410 {
 411     errno = EPERM;
 412     return -1;
 413 }
 414
 415 static int synth_fsync(FsContext *ctx, int fid_type,
 416                             V9fsFidOpenState *fs, int datasync)
 417 {
 418     errno = ENOSYS;
 419     return 0;
 420 }
 421
 422 static int synth_statfs(FsContext *s, V9fsPath *fs_path,
 423                              struct statfs *stbuf)
 424 {
 425     stbuf->f_type = 0xABCD;
 426     stbuf->f_bsize = 512;
 427     stbuf->f_blocks = 0;
 428     stbuf->f_files = synth_node_count;
 429     stbuf->f_namelen = NAME_MAX;
 430     return 0;
 431 }
 432
 433 static ssize_t synth_lgetxattr(FsContext *ctx, V9fsPath *path,
 434                                     const char *name, void *value, size_t size)
 435 {
 436     errno = ENOTSUP;
 437     return -1;
 438 }
 439
 440 static ssize_t synth_llistxattr(FsContext *ctx, V9fsPath *path,
 441                                      void *value, size_t size)
 442 {
 443     errno = ENOTSUP;
 444     return -1;
 445 }
 446
 447 static int synth_lsetxattr(FsContext *ctx, V9fsPath *path,
 448                                 const char *name, void *value,
 449                                 size_t size, int flags)
 450 {
 451     errno = ENOTSUP;
 452     return -1;
 453 }
 454
 455 static int synth_lremovexattr(FsContext *ctx,
 456                                    V9fsPath *path, const char *name)
 457 {
 458     errno = ENOTSUP;
 459     return -1;
 460 }
 461
 462 static int synth_name_to_path(FsContext *ctx, V9fsPath *dir_path,
 463                                    const char *name, V9fsPath *target)
 464 {
 465     V9fsSynthNode *node;
 466     V9fsSynthNode *dir_node;
 467
 468     /* "." and ".." are not allowed */
 469     if (!strcmp(name, ".") || !strcmp(name, "..")) {
 470         errno = EINVAL;
 471         return -1;
 472
 473     }
 474     if (!dir_path) {
 475         dir_node = &synth_root;
 476     } else {
 477         dir_node = *(V9fsSynthNode **)dir_path->data;
 478     }
 479     if (!strcmp(name, "/")) {
 480         node = dir_node;
 481         goto out;
 482     }
 483     /* search for the name in the childern */
 484     rcu_read_lock();
 485     QLIST_FOREACH(node, &dir_node->child, sibling) {
 486         if (!strcmp(node->name, name)) {
 487             break;
 488         }
 489     }
 490     rcu_read_unlock();
 491
 492     if (!node) {
 493         errno = ENOENT;
 494         return -1;
 495     }
 496 out:
 497     /* Copy the node pointer to fid */
 498     g_free(target->data);
 499     target->data = g_memdup(&node, sizeof(void *));
 500     target->size = sizeof(void *);
 501     return 0;
 502 }
 503
 504 static int synth_renameat(FsContext *ctx, V9fsPath *olddir,
 505                                const char *old_name, V9fsPath *newdir,
 506                                const char *new_name)
 507 {
 508     errno = EPERM;
 509     return -1;
 510 }
 511
 512 static int synth_unlinkat(FsContext *ctx, V9fsPath *dir,
 513                                const char *name, int flags)
 514 {
 515     errno = EPERM;
 516     return -1;
 517 }
 518
 519 static ssize_t v9fs_synth_qtest_write(void *buf, int len, off_t offset,
 520                                       void *arg)
 521 {
 522     return 1;
 523 }
 524
 525 static ssize_t v9fs_synth_qtest_flush_write(void *buf, int len, off_t offset,
 526                                             void *arg)
 527 {
 528     bool should_block = !!*(uint8_t *)buf;
 529
 530     if (should_block) {
 531         /* This will cause the server to call us again until we're cancelled */
 532         errno = EINTR;
 533         return -1;
 534     }
 535
 536     return 1;
 537 }
 538
 539 static int synth_init(FsContext *ctx, Error **errp)
 540 {
 541     QLIST_INIT(&synth_root.child);
 542     qemu_mutex_init(&synth_mutex);
 543
 544     /* Add "." and ".." entries for root */
 545     v9fs_add_dir_node(&synth_root, synth_root.attr->mode,
 546                       "..", synth_root.attr, synth_root.attr->inode);
 547     v9fs_add_dir_node(&synth_root, synth_root.attr->mode,
 548                       ".", synth_root.attr, synth_root.attr->inode);
 549
 550     /* Mark the subsystem is ready for use */
 551     synth_fs = 1;
 552
 553     if (qtest_enabled()) {
 554         V9fsSynthNode *node = NULL;
 555         int i, ret;
 556
 557         /* Directory hierarchy for WALK test */
 558         for (i = 0; i < P9_MAXWELEM; i++) {
 559             char *name = g_strdup_printf(QTEST_V9FS_SYNTH_WALK_FILE, i);
 560
 561             ret = qemu_v9fs_synth_mkdir(node, 0700, name, &node);
 562             assert(!ret);
 563             g_free(name);
 564         }
 565
 566         /* File for LOPEN test */
 567         ret = qemu_v9fs_synth_add_file(NULL, 0, QTEST_V9FS_SYNTH_LOPEN_FILE,
 568                                        NULL, NULL, ctx);
 569         assert(!ret);
 570
 571         /* File for WRITE test */
 572         ret = qemu_v9fs_synth_add_file(NULL, 0, QTEST_V9FS_SYNTH_WRITE_FILE,
 573                                        NULL, v9fs_synth_qtest_write, ctx);
 574         assert(!ret);
 575
 576         /* File for FLUSH test */
 577         ret = qemu_v9fs_synth_add_file(NULL, 0, QTEST_V9FS_SYNTH_FLUSH_FILE,
 578                                        NULL, v9fs_synth_qtest_flush_write,
 579                                        ctx);
 580         assert(!ret);
 581     }
 582
 583     return 0;
 584 }
 585
 586 FileOperations synth_ops = {
 587     .init         = synth_init,
 588     .lstat        = synth_lstat,
 589     .readlink     = synth_readlink,
 590     .close        = synth_close,
 591     .closedir     = synth_closedir,
 592     .open         = synth_open,
 593     .opendir      = synth_opendir,
 594     .rewinddir    = synth_rewinddir,
 595     .telldir      = synth_telldir,
 596     .readdir      = synth_readdir,
 597     .seekdir      = synth_seekdir,
 598     .preadv       = synth_preadv,
 599     .pwritev      = synth_pwritev,
 600     .chmod        = synth_chmod,
 601     .mknod        = synth_mknod,
 602     .mkdir        = synth_mkdir,
 603     .fstat        = synth_fstat,
 604     .open2        = synth_open2,
 605     .symlink      = synth_symlink,
 606     .link         = synth_link,
 607     .truncate     = synth_truncate,
 608     .rename       = synth_rename,
 609     .chown        = synth_chown,
 610     .utimensat    = synth_utimensat,
 611     .remove       = synth_remove,
 612     .fsync        = synth_fsync,
 613     .statfs       = synth_statfs,
 614     .lgetxattr    = synth_lgetxattr,
 615     .llistxattr   = synth_llistxattr,
 616     .lsetxattr    = synth_lsetxattr,
 617     .lremovexattr = synth_lremovexattr,
 618     .name_to_path = synth_name_to_path,
 619     .renameat     = synth_renameat,
 620     .unlinkat     = synth_unlinkat,
 621 };