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