libfuse

hello_ll_uds.c File Reference
`#include <fuse_lowlevel.h>`
`#include <fuse_kernel.h>`
`#include <stdio.h>`
`#include <stdlib.h>`
`#include <string.h>`
`#include <errno.h>`
`#include <fcntl.h>`
`#include <unistd.h>`
`#include <assert.h>`
`#include <sys/socket.h>`
`#include <sys/un.h>`

Go to the source code of this file.

## Detailed Description

minimal example filesystem using low-level API and a custom io. This custom io is implemented using UNIX domain sockets (of type SOCK_STREAM)

Compile with:

    gcc -Wall hello_ll_uds.c `pkg-config fuse3 --cflags --libs` -o hello_ll_uds

## Source code

/*
FUSE: Filesystem in Userspace
Copyright (C) 2001-2007 Miklos Szeredi <miklos@szeredi.hu>
This program can be distributed under the terms of the GNU GPLv2.
See the file COPYING.
*/
#define FUSE_USE_VERSION FUSE_MAKE_VERSION(3, 12)
#include <fuse_lowlevel.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <fcntl.h>
#include <unistd.h>
#include <assert.h>
static const char *hello_str = "Hello World!\n";
static const char *hello_name = "hello";
static int hello_stat(fuse_ino_t ino, struct stat *stbuf)
{
stbuf->st_ino = ino;
switch (ino) {
case 1:
stbuf->st_mode = S_IFDIR | 0755;
stbuf->st_nlink = 2;
break;
case 2:
stbuf->st_mode = S_IFREG | 0444;
stbuf->st_nlink = 1;
stbuf->st_size = strlen(hello_str);
break;
default:
return -1;
}
return 0;
}
static void hello_ll_init(void *userdata, struct fuse_conn_info *conn)
{
(void)userdata;
/* Disable the receiving and processing of FUSE_INTERRUPT requests */
conn->no_interrupt = 1;
}
static void hello_ll_getattr(fuse_req_t req, fuse_ino_t ino,
struct fuse_file_info *fi)
{
struct stat stbuf;
(void) fi;
memset(&stbuf, 0, sizeof(stbuf));
if (hello_stat(ino, &stbuf) == -1)
fuse_reply_err(req, ENOENT);
else
fuse_reply_attr(req, &stbuf, 1.0);
}
static void hello_ll_lookup(fuse_req_t req, fuse_ino_t parent, const char *name)
{
struct fuse_entry_param e;
if (parent != 1 || strcmp(name, hello_name) != 0)
fuse_reply_err(req, ENOENT);
else {
memset(&e, 0, sizeof(e));
e.ino = 2;
e.attr_timeout = 1.0;
e.entry_timeout = 1.0;
hello_stat(e.ino, &e.attr);
fuse_reply_entry(req, &e);
}
}
struct dirbuf {
char *p;
size_t size;
};
static void dirbuf_add(fuse_req_t req, struct dirbuf *b, const char *name,
fuse_ino_t ino)
{
struct stat stbuf;
size_t oldsize = b->size;
b->size += fuse_add_direntry(req, NULL, 0, name, NULL, 0);
b->p = (char *) realloc(b->p, b->size);
memset(&stbuf, 0, sizeof(stbuf));
stbuf.st_ino = ino;
fuse_add_direntry(req, b->p + oldsize, b->size - oldsize, name, &stbuf,
b->size);
}
#define min(x, y) ((x) < (y) ? (x) : (y))
static int reply_buf_limited(fuse_req_t req, const char *buf, size_t bufsize,
off_t off, size_t maxsize)
{
if (off < bufsize)
return fuse_reply_buf(req, buf + off,
min(bufsize - off, maxsize));
else
return fuse_reply_buf(req, NULL, 0);
}
static void hello_ll_readdir(fuse_req_t req, fuse_ino_t ino, size_t size,
off_t off, struct fuse_file_info *fi)
{
(void) fi;
if (ino != 1)
fuse_reply_err(req, ENOTDIR);
else {
struct dirbuf b;
memset(&b, 0, sizeof(b));
dirbuf_add(req, &b, ".", 1);
dirbuf_add(req, &b, "..", 1);
dirbuf_add(req, &b, hello_name, 2);
reply_buf_limited(req, b.p, b.size, off, size);
free(b.p);
}
}
static void hello_ll_open(fuse_req_t req, fuse_ino_t ino,
struct fuse_file_info *fi)
{
if (ino != 2)
fuse_reply_err(req, EISDIR);
else if ((fi->flags & O_ACCMODE) != O_RDONLY)
fuse_reply_err(req, EACCES);
else
fuse_reply_open(req, fi);
}
static void hello_ll_read(fuse_req_t req, fuse_ino_t ino, size_t size,
off_t off, struct fuse_file_info *fi)
{
(void) fi;
assert(ino == 2);
reply_buf_limited(req, hello_str, strlen(hello_str), off, size);
}
static void hello_ll_getxattr(fuse_req_t req, fuse_ino_t ino, const char *name,
size_t size)
{
(void)size;
assert(ino == 1 || ino == 2);
if (strcmp(name, "hello_ll_getxattr_name") == 0)
{
const char *buf = "hello_ll_getxattr_value";
fuse_reply_buf(req, buf, strlen(buf));
}
else
{
fuse_reply_err(req, ENOTSUP);
}
}
static void hello_ll_setxattr(fuse_req_t req, fuse_ino_t ino, const char *name,
const char *value, size_t size, int flags)
{
(void)flags;
(void)size;
assert(ino == 1 || ino == 2);
const char* exp_val = "hello_ll_setxattr_value";
if (strcmp(name, "hello_ll_setxattr_name") == 0 &&
strlen(exp_val) == size &&
strncmp(value, exp_val, size) == 0)
{
fuse_reply_err(req, 0);
}
else
{
fuse_reply_err(req, ENOTSUP);
}
}
static void hello_ll_removexattr(fuse_req_t req, fuse_ino_t ino, const char *name)
{
assert(ino == 1 || ino == 2);
if (strcmp(name, "hello_ll_removexattr_name") == 0)
{
fuse_reply_err(req, 0);
}
else
{
fuse_reply_err(req, ENOTSUP);
}
}
static const struct fuse_lowlevel_ops hello_ll_oper = {
.init = hello_ll_init,
.lookup = hello_ll_lookup,
.getattr = hello_ll_getattr,
.readdir = hello_ll_readdir,
.open = hello_ll_open,
.read = hello_ll_read,
.setxattr = hello_ll_setxattr,
.getxattr = hello_ll_getxattr,
.removexattr = hello_ll_removexattr,
};
int main(int argc, char *argv[])
{
struct fuse_args args = FUSE_ARGS_INIT(argc, argv);
struct fuse_session *se;
struct fuse_cmdline_opts opts;
struct fuse_loop_config *config;
int ret = -1;
if (fuse_parse_cmdline(&args, &opts) != 0)
return 1;
if (opts.show_help) {
printf("usage: %s [options] <mountpoint>\n\n", argv[0]);
fuse_cmdline_help();
fuse_lowlevel_help();
ret = 0;
goto err_out1;
} else if (opts.show_version) {
printf("FUSE library version %s\n", fuse_pkgversion());
fuse_lowlevel_version();
ret = 0;
goto err_out1;
}
if(opts.mountpoint == NULL) {
printf("usage: %s [options] <mountpoint>\n", argv[0]);
printf(" %s --help\n", argv[0]);
ret = 1;
goto err_out1;
}
se = fuse_session_new(&args, &hello_ll_oper,
sizeof(hello_ll_oper), NULL);
if (se == NULL)
goto err_out1;
if (fuse_set_signal_handlers(se) != 0)
goto err_out2;
if (fuse_session_mount(se, opts.mountpoint) != 0)
goto err_out3;
fuse_daemonize(opts.foreground);
/* Block until ctrl+c or fusermount -u */
if (opts.singlethread)
ret = fuse_session_loop(se);
else {
config = fuse_loop_cfg_create();
fuse_loop_cfg_set_clone_fd(config, opts.clone_fd);
fuse_loop_cfg_set_max_threads(config, opts.max_threads);
ret = fuse_session_loop_mt(se, config);
fuse_loop_cfg_destroy(config);
config = NULL;
}
fuse_session_unmount(se);
err_out3:
fuse_remove_signal_handlers(se);
err_out2:
fuse_session_destroy(se);
err_out1:
free(opts.mountpoint);
fuse_opt_free_args(&args);
return ret ? 1 : 0;
}
fuse_set_signal_handlers
int fuse_set_signal_handlers(struct fuse_session *se)
Definition fuse_signals.c:138
fuse_pkgversion
const char * fuse_pkgversion(void)
Definition fuse.c:5218
fuse_remove_signal_handlers
void fuse_remove_signal_handlers(struct fuse_session *se)
Definition fuse_signals.c:180
fuse_daemonize
int fuse_daemonize(int foreground)
Definition helper.c:253
fuse_session_destroy
void fuse_session_destroy(struct fuse_session *se)
Definition fuse_lowlevel.c:2967
fuse_reply_open
int fuse_reply_open(fuse_req_t req, const struct fuse_file_info *fi)
Definition fuse_lowlevel.c:508
fuse_reply_err
int fuse_reply_err(fuse_req_t req, int err)
Definition fuse_lowlevel.c:334
fuse_reply_buf
int fuse_reply_buf(fuse_req_t req, const char *buf, size_t size)
Definition fuse_lowlevel.c:527
fuse_req_t
struct fuse_req * fuse_req_t
Definition fuse_lowlevel.h:50
fuse_session_loop
int fuse_session_loop(struct fuse_session *se)
Definition fuse_loop.c:19
fuse_reply_entry
int fuse_reply_entry(fuse_req_t req, const struct fuse_entry_param *e)
Definition fuse_lowlevel.c:431
fuse_session_unmount
void fuse_session_unmount(struct fuse_session *se)
Definition fuse_lowlevel.c:3479
fuse_cmdline_help
void fuse_cmdline_help(void)
Definition helper.c:130
fuse_lowlevel_help
void fuse_lowlevel_help(void)
Definition fuse_lowlevel.c:2957
fuse_session_mount
int fuse_session_mount(struct fuse_session *se, const char *mountpoint)
Definition fuse_lowlevel.c:3419
fuse_lowlevel_version
void fuse_lowlevel_version(void)
Definition fuse_lowlevel.c:2950
fuse_ino_t
uint64_t fuse_ino_t
Definition fuse_lowlevel.h:47
fuse_add_direntry
size_t fuse_add_direntry(fuse_req_t req, char *buf, size_t bufsize, const char *name, const struct stat *stbuf, off_t off)
Definition fuse_lowlevel.c:289
fuse_reply_attr
int fuse_reply_attr(fuse_req_t req, const struct stat *attr, double attr_timeout)
Definition fuse_lowlevel.c:463
fuse_opt_free_args
void fuse_opt_free_args(struct fuse_args *args)
Definition fuse_opt.c:34
FUSE_ARGS_INIT
#define FUSE_ARGS_INIT(argc, argv)
Definition fuse_opt.h:123
fuse_args
Definition fuse_opt.h:109
fuse_args::argc
int argc
Definition fuse_opt.h:111
fuse_args::argv
char ** argv
Definition fuse_opt.h:114
fuse_cmdline_opts
Definition fuse_lowlevel.h:2001
fuse_conn_info
Definition fuse_common.h:555
fuse_conn_info::no_interrupt
uint32_t no_interrupt
Definition fuse_common.h:694
fuse_entry_param
Definition fuse_lowlevel.h:60
fuse_file_info
Definition fuse_common.h:58
fuse_file_info::flags
int32_t flags
Definition fuse_common.h:60
fuse_loop_config
Definition fuse_common.h:149
fuse_lowlevel_ops
Definition fuse_lowlevel.h:206
fuse_lowlevel_ops::init
void(* init)(void *userdata, struct fuse_conn_info *conn)
Definition fuse_lowlevel.h:223

Definition in file hello_ll_uds.c.