hw/9pfs/cofs.c

   1 /*
   2  * 9p backend
   3  *
   4  * Copyright IBM, Corp. 2011
   5  *
   6  * Authors:
   7  *  Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
   8  *
   9  * This work is licensed under the terms of the GNU GPL, version 2.  See
  10  * the COPYING file in the top-level directory.
  11  *
  12  */
  13
  14 /*
  15  * Not so fast! You might want to read the 9p developer docs first:
  16  * https://wiki.qemu.org/Documentation/9p
  17  */
  18
  19 #include "qemu/osdep.h"
  20 #include "fsdev/qemu-fsdev.h"
  21 #include "qemu/thread.h"
  22 #include "qemu/coroutine.h"
  23 #include "qemu/main-loop.h"
  24 #include "coth.h"
  25
  26 static ssize_t __readlink(V9fsState *s, V9fsPath *path, V9fsString *buf)
  27 {
  28     ssize_t len, maxlen = PATH_MAX;
  29
  30     buf->data = g_malloc(PATH_MAX);
  31     for (;;) {
  32         len = s->ops->readlink(&s->ctx, path, buf->data, maxlen);
  33         if (len < 0) {
  34             g_free(buf->data);
  35             buf->data = NULL;
  36             buf->size = 0;
  37             break;
  38         } else if (len == maxlen) {
  39             /*
  40              * We dodn't have space to put the NULL or we have more
  41              * to read. Increase the size and try again
  42              */
  43             maxlen *= 2;
  44             g_free(buf->data);
  45             buf->data = g_malloc(maxlen);
  46             continue;
  47         }
  48         /*
  49          * Null terminate the readlink output
  50          */
  51         buf->data[len] = '\0';
  52         buf->size = len;
  53         break;
  54     }
  55     return len;
  56 }
  57
  58 int coroutine_fn v9fs_co_readlink(V9fsPDU *pdu, V9fsPath *path, V9fsString *buf)
  59 {
  60     int err;
  61     V9fsState *s = pdu->s;
  62
  63     if (v9fs_request_cancelled(pdu)) {
  64         return -EINTR;
  65     }
  66     v9fs_path_read_lock(s);
  67     v9fs_co_run_in_worker(
  68         {
  69             err = __readlink(s, path, buf);
  70             if (err < 0) {
  71                 err = -errno;
  72             }
  73         });
  74     v9fs_path_unlock(s);
  75     return err;
  76 }
  77
  78 int coroutine_fn v9fs_co_statfs(V9fsPDU *pdu, V9fsPath *path,
  79                                 struct statfs *stbuf)
  80 {
  81     int err;
  82     V9fsState *s = pdu->s;
  83
  84     if (v9fs_request_cancelled(pdu)) {
  85         return -EINTR;
  86     }
  87     v9fs_path_read_lock(s);
  88     v9fs_co_run_in_worker(
  89         {
  90             err = s->ops->statfs(&s->ctx, path, stbuf);
  91             if (err < 0) {
  92                 err = -errno;
  93             }
  94         });
  95     v9fs_path_unlock(s);
  96     return err;
  97 }
  98
  99 int coroutine_fn v9fs_co_chmod(V9fsPDU *pdu, V9fsPath *path, mode_t mode)
 100 {
 101     int err;
 102     FsCred cred;
 103     V9fsState *s = pdu->s;
 104
 105     if (v9fs_request_cancelled(pdu)) {
 106         return -EINTR;
 107     }
 108     cred_init(&cred);
 109     cred.fc_mode = mode;
 110     v9fs_path_read_lock(s);
 111     v9fs_co_run_in_worker(
 112         {
 113             err = s->ops->chmod(&s->ctx, path, &cred);
 114             if (err < 0) {
 115                 err = -errno;
 116             }
 117         });
 118     v9fs_path_unlock(s);
 119     return err;
 120 }
 121
 122 int coroutine_fn v9fs_co_utimensat(V9fsPDU *pdu, V9fsPath *path,
 123                                    struct timespec times[2])
 124 {
 125     int err;
 126     V9fsState *s = pdu->s;
 127
 128     if (v9fs_request_cancelled(pdu)) {
 129         return -EINTR;
 130     }
 131     v9fs_path_read_lock(s);
 132     v9fs_co_run_in_worker(
 133         {
 134             err = s->ops->utimensat(&s->ctx, path, times);
 135             if (err < 0) {
 136                 err = -errno;
 137             }
 138         });
 139     v9fs_path_unlock(s);
 140     return err;
 141 }
 142
 143 int coroutine_fn v9fs_co_chown(V9fsPDU *pdu, V9fsPath *path, uid_t uid,
 144                                gid_t gid)
 145 {
 146     int err;
 147     FsCred cred;
 148     V9fsState *s = pdu->s;
 149
 150     if (v9fs_request_cancelled(pdu)) {
 151         return -EINTR;
 152     }
 153     cred_init(&cred);
 154     cred.fc_uid = uid;
 155     cred.fc_gid = gid;
 156     v9fs_path_read_lock(s);
 157     v9fs_co_run_in_worker(
 158         {
 159             err = s->ops->chown(&s->ctx, path, &cred);
 160             if (err < 0) {
 161                 err = -errno;
 162             }
 163         });
 164     v9fs_path_unlock(s);
 165     return err;
 166 }
 167
 168 int coroutine_fn v9fs_co_truncate(V9fsPDU *pdu, V9fsPath *path, off_t size)
 169 {
 170     int err;
 171     V9fsState *s = pdu->s;
 172
 173     if (v9fs_request_cancelled(pdu)) {
 174         return -EINTR;
 175     }
 176     v9fs_path_read_lock(s);
 177     v9fs_co_run_in_worker(
 178         {
 179             err = s->ops->truncate(&s->ctx, path, size);
 180             if (err < 0) {
 181                 err = -errno;
 182             }
 183         });
 184     v9fs_path_unlock(s);
 185     return err;
 186 }
 187
 188 int coroutine_fn v9fs_co_mknod(V9fsPDU *pdu, V9fsFidState *fidp,
 189                                V9fsString *name, uid_t uid, gid_t gid,
 190                                dev_t dev, mode_t mode, struct stat *stbuf)
 191 {
 192     int err;
 193     V9fsPath path;
 194     FsCred cred;
 195     V9fsState *s = pdu->s;
 196
 197     if (v9fs_request_cancelled(pdu)) {
 198         return -EINTR;
 199     }
 200     cred_init(&cred);
 201     cred.fc_uid  = uid;
 202     cred.fc_gid  = gid;
 203     cred.fc_mode = mode;
 204     cred.fc_rdev = dev;
 205     v9fs_path_read_lock(s);
 206     v9fs_co_run_in_worker(
 207         {
 208             err = s->ops->mknod(&s->ctx, &fidp->path, name->data, &cred);
 209             if (err < 0) {
 210                 err = -errno;
 211             } else {
 212                 v9fs_path_init(&path);
 213                 err = v9fs_name_to_path(s, &fidp->path, name->data, &path);
 214                 if (!err) {
 215                     err = s->ops->lstat(&s->ctx, &path, stbuf);
 216                     if (err < 0) {
 217                         err = -errno;
 218                     }
 219                 }
 220                 v9fs_path_free(&path);
 221             }
 222         });
 223     v9fs_path_unlock(s);
 224     return err;
 225 }
 226
 227 /* Only works with path name based fid */
 228 int coroutine_fn v9fs_co_remove(V9fsPDU *pdu, V9fsPath *path)
 229 {
 230     int err;
 231     V9fsState *s = pdu->s;
 232
 233     if (v9fs_request_cancelled(pdu)) {
 234         return -EINTR;
 235     }
 236     v9fs_path_read_lock(s);
 237     v9fs_co_run_in_worker(
 238         {
 239             err = s->ops->remove(&s->ctx, path->data);
 240             if (err < 0) {
 241                 err = -errno;
 242             }
 243         });
 244     v9fs_path_unlock(s);
 245     return err;
 246 }
 247
 248 int coroutine_fn v9fs_co_unlinkat(V9fsPDU *pdu, V9fsPath *path,
 249                                   V9fsString *name, int flags)
 250 {
 251     int err;
 252     V9fsState *s = pdu->s;
 253
 254     if (v9fs_request_cancelled(pdu)) {
 255         return -EINTR;
 256     }
 257     v9fs_path_read_lock(s);
 258     v9fs_co_run_in_worker(
 259         {
 260             err = s->ops->unlinkat(&s->ctx, path, name->data, flags);
 261             if (err < 0) {
 262                 err = -errno;
 263             }
 264         });
 265     v9fs_path_unlock(s);
 266     return err;
 267 }
 268
 269 /* Only work with path name based fid */
 270 int coroutine_fn v9fs_co_rename(V9fsPDU *pdu, V9fsPath *oldpath,
 271                                 V9fsPath *newpath)
 272 {
 273     int err;
 274     V9fsState *s = pdu->s;
 275
 276     if (v9fs_request_cancelled(pdu)) {
 277         return -EINTR;
 278     }
 279     v9fs_co_run_in_worker(
 280         {
 281             err = s->ops->rename(&s->ctx, oldpath->data, newpath->data);
 282             if (err < 0) {
 283                 err = -errno;
 284             }
 285         });
 286     return err;
 287 }
 288
 289 int coroutine_fn v9fs_co_renameat(V9fsPDU *pdu, V9fsPath *olddirpath,
 290                                   V9fsString *oldname, V9fsPath *newdirpath,
 291                                   V9fsString *newname)
 292 {
 293     int err;
 294     V9fsState *s = pdu->s;
 295
 296     if (v9fs_request_cancelled(pdu)) {
 297         return -EINTR;
 298     }
 299     v9fs_co_run_in_worker(
 300         {
 301             err = s->ops->renameat(&s->ctx, olddirpath, oldname->data,
 302                                    newdirpath, newname->data);
 303             if (err < 0) {
 304                 err = -errno;
 305             }
 306         });
 307     return err;
 308 }
 309
 310 int coroutine_fn v9fs_co_symlink(V9fsPDU *pdu, V9fsFidState *dfidp,
 311                                  V9fsString *name, const char *oldpath,
 312                                  gid_t gid, struct stat *stbuf)
 313 {
 314     int err;
 315     FsCred cred;
 316     V9fsPath path;
 317     V9fsState *s = pdu->s;
 318
 319     if (v9fs_request_cancelled(pdu)) {
 320         return -EINTR;
 321     }
 322     cred_init(&cred);
 323     cred.fc_uid = dfidp->uid;
 324     cred.fc_gid = gid;
 325     cred.fc_mode = 0777;
 326     v9fs_path_read_lock(s);
 327     v9fs_co_run_in_worker(
 328         {
 329             err = s->ops->symlink(&s->ctx, oldpath, &dfidp->path,
 330                                   name->data, &cred);
 331             if (err < 0) {
 332                 err = -errno;
 333             } else {
 334                 v9fs_path_init(&path);
 335                 err = v9fs_name_to_path(s, &dfidp->path, name->data, &path);
 336                 if (!err) {
 337                     err = s->ops->lstat(&s->ctx, &path, stbuf);
 338                     if (err < 0) {
 339                         err = -errno;
 340                     }
 341                 }
 342                 v9fs_path_free(&path);
 343             }
 344         });
 345     v9fs_path_unlock(s);
 346     return err;
 347 }
 348
 349 /*
 350  * For path name based fid we don't block. So we can
 351  * directly call the fs driver ops.
 352  */
 353 int coroutine_fn v9fs_co_name_to_path(V9fsPDU *pdu, V9fsPath *dirpath,
 354                                       const char *name, V9fsPath *path)
 355 {
 356     int err;
 357     V9fsState *s = pdu->s;
 358
 359     if (s->ctx.export_flags & V9FS_PATHNAME_FSCONTEXT) {
 360         err = s->ops->name_to_path(&s->ctx, dirpath, name, path);
 361         if (err < 0) {
 362             err = -errno;
 363         }
 364     } else {
 365         if (v9fs_request_cancelled(pdu)) {
 366             return -EINTR;
 367         }
 368         v9fs_co_run_in_worker(
 369             {
 370                 err = s->ops->name_to_path(&s->ctx, dirpath, name, path);
 371                 if (err < 0) {
 372                     err = -errno;
 373                 }
 374             });
 375     }
 376     return err;
 377 }