lib/fuse_kern_chan.c

   1 /*
   2   FUSE: Filesystem in Userspace
   3   Copyright (C) 2001-2007  Miklos Szeredi <miklos@szeredi.hu>
   4
   5   This program can be distributed under the terms of the GNU LGPLv2.
   6   See the file COPYING.LIB
   7 */
   8
   9 #include "fuse_lowlevel.h"
  10 #include "fuse_kernel.h"
  11 #include "fuse_i.h"
  12
  13 #include <stdio.h>
  14 #include <errno.h>
  15 #include <unistd.h>
  16 #include <assert.h>
  17
  18 static int fuse_kern_chan_receive(struct fuse_chan **chp, char *buf,
  19                                   size_t size)
  20 {
  21         struct fuse_chan *ch = *chp;
  22         int err;
  23         ssize_t res;
  24         struct fuse_session *se = fuse_chan_session(ch);
  25         assert(se != NULL);
  26
  27 restart:
  28         res = read(fuse_chan_fd(ch), buf, size);
  29         err = errno;
  30
  31         if (fuse_session_exited(se))
  32                 return 0;
  33         if (res == -1) {
  34                 /* ENOENT means the operation was interrupted, it's safe
  35                    to restart */
  36                 if (err == ENOENT)
  37                         goto restart;
  38
  39                 if (err == ENODEV) {
  40                         fuse_session_exit(se);
  41                         return 0;
  42                 }
  43                 /* Errors occurring during normal operation: EINTR (read
  44                    interrupted), EAGAIN (nonblocking I/O), ENODEV (filesystem
  45                    umounted) */
  46                 if (err != EINTR && err != EAGAIN)
  47                         perror("fuse: reading device");
  48                 return -err;
  49         }
  50         if ((size_t) res < sizeof(struct fuse_in_header)) {
  51                 fprintf(stderr, "short read on fuse device\n");
  52                 return -EIO;
  53         }
  54         return res;
  55 }
  56
  57 static int fuse_kern_chan_send(struct fuse_chan *ch, const struct iovec iov[],
  58                                size_t count)
  59 {
  60         if (iov) {
  61                 ssize_t res = writev(fuse_chan_fd(ch), iov, count);
  62                 int err = errno;
  63
  64                 if (res == -1) {
  65                         struct fuse_session *se = fuse_chan_session(ch);
  66
  67                         assert(se != NULL);
  68
  69                         /* ENOENT means the operation was interrupted */
  70                         if (!fuse_session_exited(se) && err != ENOENT)
  71                                 perror("fuse: writing device");
  72                         return -err;
  73                 }
  74         }
  75         return 0;
  76 }
  77
  78 static void fuse_kern_chan_destroy(struct fuse_chan *ch)
  79 {
  80         close(fuse_chan_fd(ch));
  81 }
  82
  83 #define MIN_BUFSIZE 0x21000
  84
  85 struct fuse_chan *fuse_kern_chan_new(int fd)
  86 {
  87         struct fuse_chan_ops op = {
  88                 .receive = fuse_kern_chan_receive,
  89                 .send = fuse_kern_chan_send,
  90                 .destroy = fuse_kern_chan_destroy,
  91         };
  92         size_t bufsize = getpagesize() + 0x1000;
  93         bufsize = bufsize < MIN_BUFSIZE ? MIN_BUFSIZE : bufsize;
  94         return fuse_chan_new(&op, fd, bufsize, NULL);
  95 }