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 /*
  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 */
  30 static 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
  39 static QemuMutex  synth_mutex;
  40 static int synth_node_count;
  41 /* set to 1 when the synth fs is ready */
  42 static int synth_fs;
  43
  44 static 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
  72 int 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
 105 int 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
 145 static 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
 162 static 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
 171 static 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
 179 static 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
 192 static 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
 203 static off_t synth_telldir(FsContext *ctx, V9fsFidOpenState *fs)
 204 {
 205     V9fsSynthOpenState *synth_open = fs->private;
 206     return synth_open->offset;
 207 }
 208
 209 static void synth_seekdir(FsContext *ctx, V9fsFidOpenState *fs, off_t off)
 210 {
 211     V9fsSynthOpenState *synth_open = fs->private;
 212     synth_open->offset = off;
 213 }
 214
 215 static void synth_rewinddir(FsContext *ctx, V9fsFidOpenState *fs)
 216 {
 217     synth_seekdir(ctx, fs, 0);
 218 }
 219
 220 static 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
 228 static 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
 251 static 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
 263 static 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
 276 static 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
 284 static 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
 295 static 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
 319 static 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
 343 static int synth_truncate(FsContext *ctx, V9fsPath *path, off_t offset)
 344 {
 345     errno = ENOSYS;
 346     return -1;
 347 }
 348
 349 static int synth_chmod(FsContext *fs_ctx, V9fsPath *path, FsCred *credp)
 350 {
 351     errno = EPERM;
 352     return -1;
 353 }
 354
 355 static int synth_mknod(FsContext *fs_ctx, V9fsPath *path,
 356                        const char *buf, FsCred *credp)
 357 {
 358     errno = EPERM;
 359     return -1;
 360 }
 361
 362 static int synth_mkdir(FsContext *fs_ctx, V9fsPath *path,
 363                        const char *buf, FsCred *credp)
 364 {
 365     errno = EPERM;
 366     return -1;
 367 }
 368
 369 static ssize_t synth_readlink(FsContext *fs_ctx, V9fsPath *path,
 370                                    char *buf, size_t bufsz)
 371 {
 372     errno = ENOSYS;
 373     return -1;
 374 }
 375
 376 static 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
 383 static int synth_link(FsContext *fs_ctx, V9fsPath *oldpath,
 384                            V9fsPath *newpath, const char *buf)
 385 {
 386     errno = EPERM;
 387     return -1;
 388 }
 389
 390 static int synth_rename(FsContext *ctx, const char *oldpath,
 391                              const char *newpath)
 392 {
 393     errno = EPERM;
 394     return -1;
 395 }
 396
 397 static int synth_chown(FsContext *fs_ctx, V9fsPath *path, FsCred *credp)
 398 {
 399     errno = EPERM;
 400     return -1;
 401 }
 402
 403 static int synth_utimensat(FsContext *fs_ctx, V9fsPath *path,
 404                                 const struct timespec *buf)
 405 {
 406     errno = EPERM;
 407     return 0;
 408 }
 409
 410 static int synth_remove(FsContext *ctx, const char *path)
 411 {
 412     errno = EPERM;
 413     return -1;
 414 }
 415
 416 static int synth_fsync(FsContext *ctx, int fid_type,
 417                             V9fsFidOpenState *fs, int datasync)
 418 {
 419     errno = ENOSYS;
 420     return 0;
 421 }
 422
 423 static 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
 434 static 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
 441 static ssize_t synth_llistxattr(FsContext *ctx, V9fsPath *path,
 442                                      void *value, size_t size)
 443 {
 444     errno = ENOTSUP;
 445     return -1;
 446 }
 447
 448 static 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
 456 static int synth_lremovexattr(FsContext *ctx,
 457                                    V9fsPath *path, const char *name)
 458 {
 459     errno = ENOTSUP;
 460     return -1;
 461 }
 462
 463 static 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     }
 497 out:
 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
 505 static 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
 513 static int synth_unlinkat(FsContext *ctx, V9fsPath *dir,
 514                                const char *name, int flags)
 515 {
 516     errno = EPERM;
 517     return -1;
 518 }
 519
 520 static ssize_t v9fs_synth_qtest_write(void *buf, int len, off_t offset,
 521                                       void *arg)
 522 {
 523     return 1;
 524 }
 525
 526 static 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
 540 static 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
 606 FileOperations 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 };