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
fuse_kern_chan_receive(struct fuse_chan ** chp,char * buf,size_t size)19 static 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
fuse_kern_chan_send(struct fuse_chan * ch,const struct iovec iov[],size_t count)58 static 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
fuse_kern_chan_destroy(struct fuse_chan * ch)79 static void fuse_kern_chan_destroy(struct fuse_chan *ch)
80 {
81 close(fuse_chan_fd(ch));
82 }
83
84 #define MIN_BUFSIZE 0x21000
85
fuse_kern_chan_new(int fd)86 struct 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