9p-synth.c (17304B)
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/* 16 * Not so fast! You might want to read the 9p developer docs first: 17 * https://wiki.qemu.org/Documentation/9p 18 */ 19 20#include "qemu/osdep.h" 21#include "9p.h" 22#include "fsdev/qemu-fsdev.h" 23#include "9p-synth.h" 24#include "qemu/rcu.h" 25#include "qemu/rcu_queue.h" 26#include "qemu/cutils.h" 27#include "sysemu/qtest.h" 28 29/* Root node for synth file system */ 30static V9fsSynthNode synth_root = { 31 .name = "/", 32 .actual_attr = { 33 .mode = 0555 | S_IFDIR, 34 .nlink = 1, 35 }, 36 .attr = &synth_root.actual_attr, 37}; 38 39static QemuMutex synth_mutex; 40static int synth_node_count; 41/* set to 1 when the synth fs is ready */ 42static int synth_fs; 43 44static V9fsSynthNode *v9fs_add_dir_node(V9fsSynthNode *parent, int mode, 45 const char *name, 46 V9fsSynthNodeAttr *attr, int inode) 47{ 48 V9fsSynthNode *node; 49 50 /* Add directory type and remove write bits */ 51 mode = ((mode & 0777) | S_IFDIR) & ~(S_IWUSR | S_IWGRP | S_IWOTH); 52 node = g_malloc0(sizeof(V9fsSynthNode)); 53 if (attr) { 54 /* We are adding .. or . entries */ 55 node->attr = attr; 56 node->attr->nlink++; 57 } else { 58 node->attr = &node->actual_attr; 59 node->attr->inode = inode; 60 node->attr->nlink = 1; 61 /* We don't allow write to directories */ 62 node->attr->mode = mode; 63 node->attr->write = NULL; 64 node->attr->read = NULL; 65 } 66 node->private = node; 67 pstrcpy(node->name, sizeof(node->name), name); 68 QLIST_INSERT_HEAD_RCU(&parent->child, node, sibling); 69 return node; 70} 71 72int qemu_v9fs_synth_mkdir(V9fsSynthNode *parent, int mode, 73 const char *name, V9fsSynthNode **result) 74{ 75 int ret; 76 V9fsSynthNode *node, *tmp; 77 78 if (!synth_fs) { 79 return EAGAIN; 80 } 81 if (!name || (strlen(name) >= NAME_MAX)) { 82 return EINVAL; 83 } 84 if (!parent) { 85 parent = &synth_root; 86 } 87 QEMU_LOCK_GUARD(&synth_mutex); 88 QLIST_FOREACH(tmp, &parent->child, sibling) { 89 if (!strcmp(tmp->name, name)) { 90 ret = EEXIST; 91 return ret; 92 } 93 } 94 /* Add the name */ 95 node = v9fs_add_dir_node(parent, mode, name, NULL, synth_node_count++); 96 v9fs_add_dir_node(node, parent->attr->mode, "..", 97 parent->attr, parent->attr->inode); 98 v9fs_add_dir_node(node, node->attr->mode, ".", 99 node->attr, node->attr->inode); 100 *result = node; 101 ret = 0; 102 return ret; 103} 104 105int qemu_v9fs_synth_add_file(V9fsSynthNode *parent, int mode, 106 const char *name, v9fs_synth_read read, 107 v9fs_synth_write write, void *arg) 108{ 109 int ret; 110 V9fsSynthNode *node, *tmp; 111 112 if (!synth_fs) { 113 return EAGAIN; 114 } 115 if (!name || (strlen(name) >= NAME_MAX)) { 116 return EINVAL; 117 } 118 if (!parent) { 119 parent = &synth_root; 120 } 121 122 QEMU_LOCK_GUARD(&synth_mutex); 123 QLIST_FOREACH(tmp, &parent->child, sibling) { 124 if (!strcmp(tmp->name, name)) { 125 ret = EEXIST; 126 return ret; 127 } 128 } 129 /* Add file type and remove write bits */ 130 mode = ((mode & 0777) | S_IFREG); 131 node = g_malloc0(sizeof(V9fsSynthNode)); 132 node->attr = &node->actual_attr; 133 node->attr->inode = synth_node_count++; 134 node->attr->nlink = 1; 135 node->attr->read = read; 136 node->attr->write = write; 137 node->attr->mode = mode; 138 node->private = arg; 139 pstrcpy(node->name, sizeof(node->name), name); 140 QLIST_INSERT_HEAD_RCU(&parent->child, node, sibling); 141 ret = 0; 142 return ret; 143} 144 145static void synth_fill_statbuf(V9fsSynthNode *node, struct stat *stbuf) 146{ 147 stbuf->st_dev = 0; 148 stbuf->st_ino = node->attr->inode; 149 stbuf->st_mode = node->attr->mode; 150 stbuf->st_nlink = node->attr->nlink; 151 stbuf->st_uid = 0; 152 stbuf->st_gid = 0; 153 stbuf->st_rdev = 0; 154 stbuf->st_size = 0; 155 stbuf->st_blksize = 0; 156 stbuf->st_blocks = 0; 157 stbuf->st_atime = 0; 158 stbuf->st_mtime = 0; 159 stbuf->st_ctime = 0; 160} 161 162static int synth_lstat(FsContext *fs_ctx, 163 V9fsPath *fs_path, struct stat *stbuf) 164{ 165 V9fsSynthNode *node = *(V9fsSynthNode **)fs_path->data; 166 167 synth_fill_statbuf(node, stbuf); 168 return 0; 169} 170 171static int synth_fstat(FsContext *fs_ctx, int fid_type, 172 V9fsFidOpenState *fs, struct stat *stbuf) 173{ 174 V9fsSynthOpenState *synth_open = fs->private; 175 synth_fill_statbuf(synth_open->node, stbuf); 176 return 0; 177} 178 179static int synth_opendir(FsContext *ctx, 180 V9fsPath *fs_path, V9fsFidOpenState *fs) 181{ 182 V9fsSynthOpenState *synth_open; 183 V9fsSynthNode *node = *(V9fsSynthNode **)fs_path->data; 184 185 synth_open = g_malloc(sizeof(*synth_open)); 186 synth_open->node = node; 187 node->open_count++; 188 fs->private = synth_open; 189 return 0; 190} 191 192static int synth_closedir(FsContext *ctx, V9fsFidOpenState *fs) 193{ 194 V9fsSynthOpenState *synth_open = fs->private; 195 V9fsSynthNode *node = synth_open->node; 196 197 node->open_count--; 198 g_free(synth_open); 199 fs->private = NULL; 200 return 0; 201} 202 203static off_t synth_telldir(FsContext *ctx, V9fsFidOpenState *fs) 204{ 205 V9fsSynthOpenState *synth_open = fs->private; 206 return synth_open->offset; 207} 208 209static void synth_seekdir(FsContext *ctx, V9fsFidOpenState *fs, off_t off) 210{ 211 V9fsSynthOpenState *synth_open = fs->private; 212 synth_open->offset = off; 213} 214 215static void synth_rewinddir(FsContext *ctx, V9fsFidOpenState *fs) 216{ 217 synth_seekdir(ctx, fs, 0); 218} 219 220static void synth_direntry(V9fsSynthNode *node, 221 struct dirent *entry, off_t off) 222{ 223 strcpy(entry->d_name, node->name); 224 entry->d_ino = node->attr->inode; 225 entry->d_off = off + 1; 226} 227 228static struct dirent *synth_get_dentry(V9fsSynthNode *dir, 229 struct dirent *entry, off_t off) 230{ 231 int i = 0; 232 V9fsSynthNode *node; 233 234 rcu_read_lock(); 235 QLIST_FOREACH(node, &dir->child, sibling) { 236 /* This is the off child of the directory */ 237 if (i == off) { 238 break; 239 } 240 i++; 241 } 242 rcu_read_unlock(); 243 if (!node) { 244 /* end of directory */ 245 return NULL; 246 } 247 synth_direntry(node, entry, off); 248 return entry; 249} 250 251static struct dirent *synth_readdir(FsContext *ctx, V9fsFidOpenState *fs) 252{ 253 struct dirent *entry; 254 V9fsSynthOpenState *synth_open = fs->private; 255 V9fsSynthNode *node = synth_open->node; 256 entry = synth_get_dentry(node, &synth_open->dent, synth_open->offset); 257 if (entry) { 258 synth_open->offset++; 259 } 260 return entry; 261} 262 263static int synth_open(FsContext *ctx, V9fsPath *fs_path, 264 int flags, V9fsFidOpenState *fs) 265{ 266 V9fsSynthOpenState *synth_open; 267 V9fsSynthNode *node = *(V9fsSynthNode **)fs_path->data; 268 269 synth_open = g_malloc(sizeof(*synth_open)); 270 synth_open->node = node; 271 node->open_count++; 272 fs->private = synth_open; 273 return 0; 274} 275 276static int synth_open2(FsContext *fs_ctx, V9fsPath *dir_path, 277 const char *name, int flags, 278 FsCred *credp, V9fsFidOpenState *fs) 279{ 280 errno = ENOSYS; 281 return -1; 282} 283 284static int synth_close(FsContext *ctx, V9fsFidOpenState *fs) 285{ 286 V9fsSynthOpenState *synth_open = fs->private; 287 V9fsSynthNode *node = synth_open->node; 288 289 node->open_count--; 290 g_free(synth_open); 291 fs->private = NULL; 292 return 0; 293} 294 295static ssize_t synth_pwritev(FsContext *ctx, V9fsFidOpenState *fs, 296 const struct iovec *iov, 297 int iovcnt, off_t offset) 298{ 299 int i, count = 0, wcount; 300 V9fsSynthOpenState *synth_open = fs->private; 301 V9fsSynthNode *node = synth_open->node; 302 if (!node->attr->write) { 303 errno = EPERM; 304 return -1; 305 } 306 for (i = 0; i < iovcnt; i++) { 307 wcount = node->attr->write(iov[i].iov_base, iov[i].iov_len, 308 offset, node->private); 309 offset += wcount; 310 count += wcount; 311 /* If we wrote less than requested. we are done */ 312 if (wcount < iov[i].iov_len) { 313 break; 314 } 315 } 316 return count; 317} 318 319static ssize_t synth_preadv(FsContext *ctx, V9fsFidOpenState *fs, 320 const struct iovec *iov, 321 int iovcnt, off_t offset) 322{ 323 int i, count = 0, rcount; 324 V9fsSynthOpenState *synth_open = fs->private; 325 V9fsSynthNode *node = synth_open->node; 326 if (!node->attr->read) { 327 errno = EPERM; 328 return -1; 329 } 330 for (i = 0; i < iovcnt; i++) { 331 rcount = node->attr->read(iov[i].iov_base, iov[i].iov_len, 332 offset, node->private); 333 offset += rcount; 334 count += rcount; 335 /* If we read less than requested. we are done */ 336 if (rcount < iov[i].iov_len) { 337 break; 338 } 339 } 340 return count; 341} 342 343static int synth_truncate(FsContext *ctx, V9fsPath *path, off_t offset) 344{ 345 errno = ENOSYS; 346 return -1; 347} 348 349static int synth_chmod(FsContext *fs_ctx, V9fsPath *path, FsCred *credp) 350{ 351 errno = EPERM; 352 return -1; 353} 354 355static int synth_mknod(FsContext *fs_ctx, V9fsPath *path, 356 const char *buf, FsCred *credp) 357{ 358 errno = EPERM; 359 return -1; 360} 361 362static int synth_mkdir(FsContext *fs_ctx, V9fsPath *path, 363 const char *buf, FsCred *credp) 364{ 365 errno = EPERM; 366 return -1; 367} 368 369static ssize_t synth_readlink(FsContext *fs_ctx, V9fsPath *path, 370 char *buf, size_t bufsz) 371{ 372 errno = ENOSYS; 373 return -1; 374} 375 376static int synth_symlink(FsContext *fs_ctx, const char *oldpath, 377 V9fsPath *newpath, const char *buf, FsCred *credp) 378{ 379 errno = EPERM; 380 return -1; 381} 382 383static int synth_link(FsContext *fs_ctx, V9fsPath *oldpath, 384 V9fsPath *newpath, const char *buf) 385{ 386 errno = EPERM; 387 return -1; 388} 389 390static int synth_rename(FsContext *ctx, const char *oldpath, 391 const char *newpath) 392{ 393 errno = EPERM; 394 return -1; 395} 396 397static int synth_chown(FsContext *fs_ctx, V9fsPath *path, FsCred *credp) 398{ 399 errno = EPERM; 400 return -1; 401} 402 403static int synth_utimensat(FsContext *fs_ctx, V9fsPath *path, 404 const struct timespec *buf) 405{ 406 errno = EPERM; 407 return 0; 408} 409 410static int synth_remove(FsContext *ctx, const char *path) 411{ 412 errno = EPERM; 413 return -1; 414} 415 416static int synth_fsync(FsContext *ctx, int fid_type, 417 V9fsFidOpenState *fs, int datasync) 418{ 419 errno = ENOSYS; 420 return 0; 421} 422 423static int synth_statfs(FsContext *s, V9fsPath *fs_path, 424 struct statfs *stbuf) 425{ 426 stbuf->f_type = 0xABCD; 427 stbuf->f_bsize = 512; 428 stbuf->f_blocks = 0; 429 stbuf->f_files = synth_node_count; 430 stbuf->f_namelen = NAME_MAX; 431 return 0; 432} 433 434static ssize_t synth_lgetxattr(FsContext *ctx, V9fsPath *path, 435 const char *name, void *value, size_t size) 436{ 437 errno = ENOTSUP; 438 return -1; 439} 440 441static ssize_t synth_llistxattr(FsContext *ctx, V9fsPath *path, 442 void *value, size_t size) 443{ 444 errno = ENOTSUP; 445 return -1; 446} 447 448static int synth_lsetxattr(FsContext *ctx, V9fsPath *path, 449 const char *name, void *value, 450 size_t size, int flags) 451{ 452 errno = ENOTSUP; 453 return -1; 454} 455 456static int synth_lremovexattr(FsContext *ctx, 457 V9fsPath *path, const char *name) 458{ 459 errno = ENOTSUP; 460 return -1; 461} 462 463static int synth_name_to_path(FsContext *ctx, V9fsPath *dir_path, 464 const char *name, V9fsPath *target) 465{ 466 V9fsSynthNode *node; 467 V9fsSynthNode *dir_node; 468 469 /* "." and ".." are not allowed */ 470 if (!strcmp(name, ".") || !strcmp(name, "..")) { 471 errno = EINVAL; 472 return -1; 473 474 } 475 if (!dir_path) { 476 dir_node = &synth_root; 477 } else { 478 dir_node = *(V9fsSynthNode **)dir_path->data; 479 } 480 if (!strcmp(name, "/")) { 481 node = dir_node; 482 goto out; 483 } 484 /* search for the name in the childern */ 485 rcu_read_lock(); 486 QLIST_FOREACH(node, &dir_node->child, sibling) { 487 if (!strcmp(node->name, name)) { 488 break; 489 } 490 } 491 rcu_read_unlock(); 492 493 if (!node) { 494 errno = ENOENT; 495 return -1; 496 } 497out: 498 /* Copy the node pointer to fid */ 499 g_free(target->data); 500 target->data = g_memdup(&node, sizeof(void *)); 501 target->size = sizeof(void *); 502 return 0; 503} 504 505static int synth_renameat(FsContext *ctx, V9fsPath *olddir, 506 const char *old_name, V9fsPath *newdir, 507 const char *new_name) 508{ 509 errno = EPERM; 510 return -1; 511} 512 513static int synth_unlinkat(FsContext *ctx, V9fsPath *dir, 514 const char *name, int flags) 515{ 516 errno = EPERM; 517 return -1; 518} 519 520static ssize_t v9fs_synth_qtest_write(void *buf, int len, off_t offset, 521 void *arg) 522{ 523 return 1; 524} 525 526static ssize_t v9fs_synth_qtest_flush_write(void *buf, int len, off_t offset, 527 void *arg) 528{ 529 bool should_block = !!*(uint8_t *)buf; 530 531 if (should_block) { 532 /* This will cause the server to call us again until we're cancelled */ 533 errno = EINTR; 534 return -1; 535 } 536 537 return 1; 538} 539 540static int synth_init(FsContext *ctx, Error **errp) 541{ 542 QLIST_INIT(&synth_root.child); 543 qemu_mutex_init(&synth_mutex); 544 545 /* Add "." and ".." entries for root */ 546 v9fs_add_dir_node(&synth_root, synth_root.attr->mode, 547 "..", synth_root.attr, synth_root.attr->inode); 548 v9fs_add_dir_node(&synth_root, synth_root.attr->mode, 549 ".", synth_root.attr, synth_root.attr->inode); 550 551 /* Mark the subsystem is ready for use */ 552 synth_fs = 1; 553 554 if (qtest_enabled()) { 555 V9fsSynthNode *node = NULL; 556 int i, ret; 557 558 /* Directory hierarchy for WALK test */ 559 for (i = 0; i < P9_MAXWELEM; i++) { 560 char *name = g_strdup_printf(QTEST_V9FS_SYNTH_WALK_FILE, i); 561 562 ret = qemu_v9fs_synth_mkdir(node, 0700, name, &node); 563 assert(!ret); 564 g_free(name); 565 } 566 567 /* File for LOPEN test */ 568 ret = qemu_v9fs_synth_add_file(NULL, 0, QTEST_V9FS_SYNTH_LOPEN_FILE, 569 NULL, NULL, ctx); 570 assert(!ret); 571 572 /* File for WRITE test */ 573 ret = qemu_v9fs_synth_add_file(NULL, 0, QTEST_V9FS_SYNTH_WRITE_FILE, 574 NULL, v9fs_synth_qtest_write, ctx); 575 assert(!ret); 576 577 /* File for FLUSH test */ 578 ret = qemu_v9fs_synth_add_file(NULL, 0, QTEST_V9FS_SYNTH_FLUSH_FILE, 579 NULL, v9fs_synth_qtest_flush_write, 580 ctx); 581 assert(!ret); 582 583 /* Directory for READDIR test */ 584 { 585 V9fsSynthNode *dir = NULL; 586 ret = qemu_v9fs_synth_mkdir( 587 NULL, 0700, QTEST_V9FS_SYNTH_READDIR_DIR, &dir 588 ); 589 assert(!ret); 590 for (i = 0; i < QTEST_V9FS_SYNTH_READDIR_NFILES; ++i) { 591 char *name = g_strdup_printf( 592 QTEST_V9FS_SYNTH_READDIR_FILE, i 593 ); 594 ret = qemu_v9fs_synth_add_file( 595 dir, 0, name, NULL, NULL, ctx 596 ); 597 assert(!ret); 598 g_free(name); 599 } 600 } 601 } 602 603 return 0; 604} 605 606FileOperations synth_ops = { 607 .init = synth_init, 608 .lstat = synth_lstat, 609 .readlink = synth_readlink, 610 .close = synth_close, 611 .closedir = synth_closedir, 612 .open = synth_open, 613 .opendir = synth_opendir, 614 .rewinddir = synth_rewinddir, 615 .telldir = synth_telldir, 616 .readdir = synth_readdir, 617 .seekdir = synth_seekdir, 618 .preadv = synth_preadv, 619 .pwritev = synth_pwritev, 620 .chmod = synth_chmod, 621 .mknod = synth_mknod, 622 .mkdir = synth_mkdir, 623 .fstat = synth_fstat, 624 .open2 = synth_open2, 625 .symlink = synth_symlink, 626 .link = synth_link, 627 .truncate = synth_truncate, 628 .rename = synth_rename, 629 .chown = synth_chown, 630 .utimensat = synth_utimensat, 631 .remove = synth_remove, 632 .fsync = synth_fsync, 633 .statfs = synth_statfs, 634 .lgetxattr = synth_lgetxattr, 635 .llistxattr = synth_llistxattr, 636 .lsetxattr = synth_lsetxattr, 637 .lremovexattr = synth_lremovexattr, 638 .name_to_path = synth_name_to_path, 639 .renameat = synth_renameat, 640 .unlinkat = synth_unlinkat, 641};