/*    FUSE: Filesystem in Userspace    Copyright (C) 2001-2006  Miklos Szeredi <miklos@szeredi.hu>    This program can be distributed under the terms of the GNU LGPL.    See the file COPYING.LIB*/#include "fuse_lowlevel.h"#include "fuse_kernel.h"#include <stdio.h>#include <errno.h>#include <unistd.h>#include <assert.h>static int fuse_kern_chan_receive(struct fuse_chan *ch, char *buf, size_t size){    ssize_t res = read(fuse_chan_fd(ch), buf, size);    int err = errno;    struct fuse_session *se = fuse_chan_session(ch);    assert(se != NULL);    if (fuse_session_exited(se))        return 0;    if (res == -1) {        /* EINTR means, the read() was interrupted, ENOENT means the           operation was interrupted */        if (err == EINTR || err == ENOENT)            return 0;        /* ENODEV means we got unmounted, so we silently return failure */        if (err != ENODEV)            perror("fuse: reading device");        return -1;    }    if ((size_t) res < sizeof(struct fuse_in_header)) {        fprintf(stderr, "short read on fuse device\n");        return -1;    }    return res;}static int fuse_kern_chan_send(struct fuse_chan *ch, const struct iovec iov[],                               size_t count){    ssize_t res = writev(fuse_chan_fd(ch), iov, count);    int err = errno;    if (res == -1) {        struct fuse_session *se = fuse_chan_session(ch);        assert(se != NULL);        /* ENOENT means the operation was interrupted */        if (!fuse_session_exited(se) && err != ENOENT)            perror("fuse: writing device");        return -err;    }    return 0;}static void fuse_kern_chan_destroy(struct fuse_chan *ch){    close(fuse_chan_fd(ch));}#define MIN_BUFSIZE 0x21000struct fuse_chan *fuse_kern_chan_new(int fd){    struct fuse_chan_ops op = {        .receive = fuse_kern_chan_receive,        .send = fuse_kern_chan_send,        .destroy = fuse_kern_chan_destroy,    };    size_t bufsize = getpagesize() + 0x1000;    bufsize = bufsize < MIN_BUFSIZE ? MIN_BUFSIZE : bufsize;    return fuse_chan_new(&op, fd, bufsize, NULL);}