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 "config.h"
10#include "fuse_lowlevel.h"
11#include "fuse_kernel.h"
12#include "fuse_i.h"
13
14#include <stdio.h>
15#include <errno.h>
16#include <unistd.h>
17#include <assert.h>
18
19static int fuse_kern_chan_receive(struct fuse_chan **chp, char *buf,
20                                  size_t size)
21{
22    struct fuse_chan *ch = *chp;
23    int err;
24    ssize_t res;
25    struct fuse_session *se = fuse_chan_session(ch);
26    assert(se != NULL);
27
28 restart:
29    res = read(fuse_chan_fd(ch), buf, size);
30    err = errno;
31
32    if (fuse_session_exited(se))
33        return 0;
34    if (res == -1) {
35        /* ENOENT means the operation was interrupted, it's safe
36           to restart */
37        if (err == ENOENT)
38            goto restart;
39
40        if (err == ENODEV) {
41            fuse_session_exit(se);
42            return 0;
43        }
44        /* Errors occuring during normal operation: EINTR (read
45           interrupted), EAGAIN (nonblocking I/O), ENODEV (filesystem
46           umounted) */
47        if (err != EINTR && err != EAGAIN)
48            perror("fuse: reading device");
49        return -err;
50    }
51    if ((size_t) res < sizeof(struct fuse_in_header)) {
52        fprintf(stderr, "short read on fuse device\n");
53        return -EIO;
54    }
55    return res;
56}
57
58static int fuse_kern_chan_send(struct fuse_chan *ch, const struct iovec iov[],
59                               size_t count)
60{
61    if (iov) {
62        ssize_t res = writev(fuse_chan_fd(ch), iov, count);
63        int err = errno;
64
65        if (res == -1) {
66            struct fuse_session *se = fuse_chan_session(ch);
67
68            assert(se != NULL);
69
70            /* ENOENT means the operation was interrupted */
71            if (!fuse_session_exited(se) && err != ENOENT)
72                perror("fuse: writing device");
73            return -err;
74        }
75    }
76    return 0;
77}
78
79static void fuse_kern_chan_destroy(struct fuse_chan *ch)
80{
81    close(fuse_chan_fd(ch));
82}
83
84#define MIN_BUFSIZE 0x21000
85
86struct fuse_chan *fuse_kern_chan_new(int fd)
87{
88    struct fuse_chan_ops op = {
89        .receive = fuse_kern_chan_receive,
90        .send = fuse_kern_chan_send,
91        .destroy = fuse_kern_chan_destroy,
92    };
93    size_t bufsize = getpagesize() + 0x1000;
94    bufsize = bufsize < MIN_BUFSIZE ? MIN_BUFSIZE : bufsize;
95    return fuse_chan_new(&op, fd, bufsize, NULL);
96}
97