lib/cuse_lowlevel.c

   1 /*
   2   CUSE: Character device in Userspace
   3   Copyright (C) 2008       SUSE Linux Products GmbH
   4   Copyright (C) 2008       Tejun Heo <teheo@suse.de>
   5
   6   This program can be distributed under the terms of the GNU LGPLv2.
   7   See the file COPYING.LIB.
   8 */
   9
  10 #include "cuse_lowlevel.h"
  11 #include "fuse_kernel.h"
  12 #include "fuse_i.h"
  13 #include "fuse_opt.h"
  14 #include "fuse_misc.h"
  15
  16 #include <stdio.h>
  17 #include <string.h>
  18 #include <stdlib.h>
  19 #include <stddef.h>
  20 #include <errno.h>
  21 #include <unistd.h>
  22
  23 struct cuse_data {
  24         struct cuse_lowlevel_ops        clop;
  25         unsigned                        max_read;
  26         unsigned                        dev_major;
  27         unsigned                        dev_minor;
  28         unsigned                        flags;
  29         unsigned                        dev_info_len;
  30         char                            dev_info[];
  31 };
  32
  33 static struct cuse_lowlevel_ops *req_clop(fuse_req_t req)
  34 {
  35         return &req->f->cuse_data->clop;
  36 }
  37
  38 static void cuse_fll_open(fuse_req_t req, fuse_ino_t ino,
  39                           struct fuse_file_info *fi)
  40 {
  41         (void)ino;
  42         req_clop(req)->open(req, fi);
  43 }
  44
  45 static void cuse_fll_read(fuse_req_t req, fuse_ino_t ino, size_t size,
  46                           off_t off, struct fuse_file_info *fi)
  47 {
  48         (void)ino;
  49         req_clop(req)->read(req, size, off, fi);
  50 }
  51
  52 static void cuse_fll_write(fuse_req_t req, fuse_ino_t ino, const char *buf,
  53                            size_t size, off_t off, struct fuse_file_info *fi)
  54 {
  55         (void)ino;
  56         req_clop(req)->write(req, buf, size, off, fi);
  57 }
  58
  59 static void cuse_fll_flush(fuse_req_t req, fuse_ino_t ino,
  60                            struct fuse_file_info *fi)
  61 {
  62         (void)ino;
  63         req_clop(req)->flush(req, fi);
  64 }
  65
  66 static void cuse_fll_release(fuse_req_t req, fuse_ino_t ino,
  67                              struct fuse_file_info *fi)
  68 {
  69         (void)ino;
  70         req_clop(req)->release(req, fi);
  71 }
  72
  73 static void cuse_fll_fsync(fuse_req_t req, fuse_ino_t ino, int datasync,
  74                            struct fuse_file_info *fi)
  75 {
  76         (void)ino;
  77         req_clop(req)->fsync(req, datasync, fi);
  78 }
  79
  80 static void cuse_fll_ioctl(fuse_req_t req, fuse_ino_t ino, int cmd, void *arg,
  81                        struct fuse_file_info *fi, unsigned int flags,
  82                        const void *in_buf, size_t in_bufsz, size_t out_bufsz)
  83 {
  84         (void)ino;
  85         req_clop(req)->ioctl(req, cmd, arg, fi, flags, in_buf, in_bufsz,
  86                              out_bufsz);
  87 }
  88
  89 static void cuse_fll_poll(fuse_req_t req, fuse_ino_t ino,
  90                           struct fuse_file_info *fi, struct fuse_pollhandle *ph)
  91 {
  92         (void)ino;
  93         req_clop(req)->poll(req, fi, ph);
  94 }
  95
  96 static size_t cuse_pack_info(int argc, const char **argv, char *buf)
  97 {
  98         size_t size = 0;
  99         int i;
 100
 101         for (i = 0; i < argc; i++) {
 102                 size_t len;
 103
 104                 len = strlen(argv[i]) + 1;
 105                 size += len;
 106                 if (buf) {
 107                         memcpy(buf, argv[i], len);
 108                         buf += len;
 109                 }
 110         }
 111
 112         return size;
 113 }
 114
 115 static struct cuse_data *cuse_prep_data(const struct cuse_info *ci,
 116                                         const struct cuse_lowlevel_ops *clop)
 117 {
 118         struct cuse_data *cd;
 119         size_t dev_info_len;
 120
 121         dev_info_len = cuse_pack_info(ci->dev_info_argc, ci->dev_info_argv,
 122                                       NULL);
 123
 124         if (dev_info_len > CUSE_INIT_INFO_MAX) {
 125                 fprintf(stderr, "cuse: dev_info (%zu) too large, limit=%u\n",
 126                         dev_info_len, CUSE_INIT_INFO_MAX);
 127                 return NULL;
 128         }
 129
 130         cd = calloc(1, sizeof(*cd) + dev_info_len);
 131         if (!cd) {
 132                 fprintf(stderr, "cuse: failed to allocate cuse_data\n");
 133                 return NULL;
 134         }
 135
 136         memcpy(&cd->clop, clop, sizeof(cd->clop));
 137         cd->max_read = 131072;
 138         cd->dev_major = ci->dev_major;
 139         cd->dev_minor = ci->dev_minor;
 140         cd->dev_info_len = dev_info_len;
 141         cd->flags = ci->flags;
 142         cuse_pack_info(ci->dev_info_argc, ci->dev_info_argv, cd->dev_info);
 143
 144         return cd;
 145 }
 146
 147 struct fuse_session *cuse_lowlevel_new(struct fuse_args *args,
 148                                        const struct cuse_info *ci,
 149                                        const struct cuse_lowlevel_ops *clop,
 150                                        void *userdata)
 151 {
 152         struct fuse_lowlevel_ops lop;
 153         struct cuse_data *cd;
 154         struct fuse_session *se;
 155         struct fuse_ll *ll;
 156
 157         cd = cuse_prep_data(ci, clop);
 158         if (!cd)
 159                 return NULL;
 160
 161         memset(&lop, 0, sizeof(lop));
 162         lop.init        = clop->init;
 163         lop.destroy     = clop->destroy;
 164         lop.open        = clop->open            ? cuse_fll_open         : NULL;
 165         lop.read        = clop->read            ? cuse_fll_read         : NULL;
 166         lop.write       = clop->write           ? cuse_fll_write        : NULL;
 167         lop.flush       = clop->flush           ? cuse_fll_flush        : NULL;
 168         lop.release     = clop->release         ? cuse_fll_release      : NULL;
 169         lop.fsync       = clop->fsync           ? cuse_fll_fsync        : NULL;
 170         lop.ioctl       = clop->ioctl           ? cuse_fll_ioctl        : NULL;
 171         lop.poll        = clop->poll            ? cuse_fll_poll         : NULL;
 172
 173         se = fuse_lowlevel_new_common(args, &lop, sizeof(lop), userdata);
 174         if (!se) {
 175                 free(cd);
 176                 return NULL;
 177         }
 178         ll = se->data;
 179         ll->cuse_data = cd;
 180
 181         return se;
 182 }
 183
 184 static int cuse_reply_init(fuse_req_t req, struct cuse_init_out *arg,
 185                            char *dev_info, unsigned dev_info_len)
 186 {
 187         struct iovec iov[3];
 188
 189         iov[1].iov_base = arg;
 190         iov[1].iov_len = sizeof(struct cuse_init_out);
 191         iov[2].iov_base = dev_info;
 192         iov[2].iov_len = dev_info_len;
 193
 194         return fuse_send_reply_iov_nofree(req, 0, iov, 3);
 195 }
 196
 197 void cuse_lowlevel_init(fuse_req_t req, fuse_ino_t nodeid, const void *inarg)
 198 {
 199         struct fuse_init_in *arg = (struct fuse_init_in *) inarg;
 200         struct cuse_init_out outarg;
 201         struct fuse_ll *f = req->f;
 202         struct cuse_data *cd = f->cuse_data;
 203         size_t bufsize = fuse_chan_bufsize(req->ch);
 204         struct cuse_lowlevel_ops *clop = req_clop(req);
 205
 206         (void) nodeid;
 207         if (f->debug) {
 208                 fprintf(stderr, "CUSE_INIT: %u.%u\n", arg->major, arg->minor);
 209                 fprintf(stderr, "flags=0x%08x\n", arg->flags);
 210         }
 211         f->conn.proto_major = arg->major;
 212         f->conn.proto_minor = arg->minor;
 213         f->conn.capable = 0;
 214         f->conn.want = 0;
 215
 216         if (arg->major < 7) {
 217                 fprintf(stderr, "cuse: unsupported protocol version: %u.%u\n",
 218                         arg->major, arg->minor);
 219                 fuse_reply_err(req, EPROTO);
 220                 return;
 221         }
 222
 223         if (bufsize < FUSE_MIN_READ_BUFFER) {
 224                 fprintf(stderr, "cuse: warning: buffer size too small: %zu\n",
 225                         bufsize);
 226                 bufsize = FUSE_MIN_READ_BUFFER;
 227         }
 228
 229         bufsize -= 4096;
 230         if (bufsize < f->conn.max_write)
 231                 f->conn.max_write = bufsize;
 232
 233         f->got_init = 1;
 234         if (f->op.init)
 235                 f->op.init(f->userdata, &f->conn);
 236
 237         memset(&outarg, 0, sizeof(outarg));
 238         outarg.major = FUSE_KERNEL_VERSION;
 239         outarg.minor = FUSE_KERNEL_MINOR_VERSION;
 240         outarg.flags = cd->flags;
 241         outarg.max_read = cd->max_read;
 242         outarg.max_write = f->conn.max_write;
 243         outarg.dev_major = cd->dev_major;
 244         outarg.dev_minor = cd->dev_minor;
 245
 246         if (f->debug) {
 247                 fprintf(stderr, "   CUSE_INIT: %u.%u\n",
 248                         outarg.major, outarg.minor);
 249                 fprintf(stderr, "   flags=0x%08x\n", outarg.flags);
 250                 fprintf(stderr, "   max_read=0x%08x\n", outarg.max_read);
 251                 fprintf(stderr, "   max_write=0x%08x\n", outarg.max_write);
 252                 fprintf(stderr, "   dev_major=%u\n", outarg.dev_major);
 253                 fprintf(stderr, "   dev_minor=%u\n", outarg.dev_minor);
 254                 fprintf(stderr, "   dev_info: %.*s\n", cd->dev_info_len,
 255                         cd->dev_info);
 256         }
 257
 258         cuse_reply_init(req, &outarg, cd->dev_info, cd->dev_info_len);
 259
 260         if (clop->init_done)
 261                 clop->init_done(f->userdata);
 262
 263         fuse_free_req(req);
 264 }
 265
 266 struct fuse_session *cuse_lowlevel_setup(int argc, char *argv[],
 267                                          const struct cuse_info *ci,
 268                                          const struct cuse_lowlevel_ops *clop,
 269                                          int *multithreaded, void *userdata)
 270 {
 271         const char *devname = "/dev/cuse";
 272         static const struct fuse_opt kill_subtype_opts[] = {
 273                 FUSE_OPT_KEY("subtype=",  FUSE_OPT_KEY_DISCARD),
 274                 FUSE_OPT_END
 275         };
 276         struct fuse_args args = FUSE_ARGS_INIT(argc, argv);
 277         struct fuse_session *se;
 278         struct fuse_chan *ch;
 279         int fd;
 280         int foreground;
 281         int res;
 282
 283         res = fuse_parse_cmdline(&args, NULL, multithreaded, &foreground);
 284         if (res == -1)
 285                 goto err_args;
 286
 287         res = fuse_opt_parse(&args, NULL, kill_subtype_opts, NULL);
 288         if (res == -1)
 289                 goto err_args;
 290
 291         /*
 292          * Make sure file descriptors 0, 1 and 2 are open, otherwise chaos
 293          * would ensue.
 294          */
 295         do {
 296                 fd = open("/dev/null", O_RDWR);
 297                 if (fd > 2)
 298                         close(fd);
 299         } while (fd >= 0 && fd <= 2);
 300
 301         se = cuse_lowlevel_new(&args, ci, clop, userdata);
 302         fuse_opt_free_args(&args);
 303         if (se == NULL)
 304                 goto err_args;
 305
 306         fd = open(devname, O_RDWR);
 307         if (fd == -1) {
 308                 if (errno == ENODEV || errno == ENOENT)
 309                         fprintf(stderr, "cuse: device not found, try 'modprobe cuse' first\n");
 310                 else
 311                         fprintf(stderr, "cuse: failed to open %s: %s\n",
 312                                 devname, strerror(errno));
 313                 goto err_se;
 314         }
 315
 316         ch = fuse_kern_chan_new(fd);
 317         if (!ch) {
 318                 close(fd);
 319                 goto err_se;
 320         }
 321
 322         fuse_session_add_chan(se, ch);
 323
 324         res = fuse_set_signal_handlers(se);
 325         if (res == -1)
 326                 goto err_se;
 327
 328         res = fuse_daemonize(foreground);
 329         if (res == -1)
 330                 goto err_sig;
 331
 332         return se;
 333
 334 err_sig:
 335         fuse_remove_signal_handlers(se);
 336 err_se:
 337         fuse_session_destroy(se);
 338 err_args:
 339         fuse_opt_free_args(&args);
 340         return NULL;
 341 }
 342
 343 void cuse_lowlevel_teardown(struct fuse_session *se)
 344 {
 345         fuse_remove_signal_handlers(se);
 346         fuse_session_destroy(se);
 347 }
 348
 349 int cuse_lowlevel_main(int argc, char *argv[], const struct cuse_info *ci,
 350                        const struct cuse_lowlevel_ops *clop, void *userdata)
 351 {
 352         struct fuse_session *se;
 353         int multithreaded;
 354         int res;
 355
 356         se = cuse_lowlevel_setup(argc, argv, ci, clop, &multithreaded,
 357                                  userdata);
 358         if (se == NULL)
 359                 return 1;
 360
 361         if (multithreaded)
 362                 res = fuse_session_loop_mt(se);
 363         else
 364                 res = fuse_session_loop(se);
 365
 366         cuse_lowlevel_teardown(se);
 367         if (res == -1)
 368                 return 1;
 369
 370         return 0;
 371 }