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