diff options
| -rw-r--r-- | ChangeLog.rst | 6 | ||||
| -rw-r--r-- | example/hello_ll_uds.c | 358 | ||||
| -rw-r--r-- | example/meson.build | 6 | ||||
| -rw-r--r-- | include/fuse_lowlevel.h | 41 | ||||
| -rw-r--r-- | lib/fuse_i.h | 1 | ||||
| -rw-r--r-- | lib/fuse_lowlevel.c | 84 | ||||
| -rw-r--r-- | lib/fuse_versionscript | 1 | ||||
| -rw-r--r-- | test/meson.build | 2 | ||||
| -rw-r--r-- | test/test_custom_io.py | 81 |
9 files changed, 567 insertions, 13 deletions
diff --git a/ChangeLog.rst b/ChangeLog.rst index 5c2ec39..226a801 100644 --- a/ChangeLog.rst +++ b/ChangeLog.rst @@ -1,3 +1,9 @@ +libfuse next.release.version (xxxx-xx-xx) +========================================= +* There is a new low-level API function `fuse_session_custom_io` that allows to implement + a daemon with a custom io. This can be used to create a daemon that can process incoming + FUSE requests to other destinations than `/dev/fuse`. + libfuse 3.12.0 (2022-09-08) =========================== diff --git a/example/hello_ll_uds.c b/example/hello_ll_uds.c new file mode 100644 index 0000000..c1f64d7 --- /dev/null +++ b/example/hello_ll_uds.c @@ -0,0 +1,358 @@ +/* + FUSE: Filesystem in Userspace + Copyright (C) 2001-2007 Miklos Szeredi <miklos@szeredi.hu> + Copyright (C) 2022 Tofik Sonono <tofik.sonono@intel.com> + + This program can be distributed under the terms of the GNU GPLv2. + See the file COPYING. +*/ + +/** @file + * + * 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 ## + * \include hello_ll.c + */ + +#define FUSE_USE_VERSION 34 + + +#ifndef _GNU_SOURCE +#define _GNU_SOURCE +#endif + +#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> + +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_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 const struct fuse_lowlevel_ops hello_ll_oper = { + .lookup = hello_ll_lookup, + .getattr = hello_ll_getattr, + .readdir = hello_ll_readdir, + .open = hello_ll_open, + .read = hello_ll_read, +}; + +static int create_socket(const char *socket_path) { + struct sockaddr_un addr; + + if (strnlen(socket_path, sizeof(addr.sun_path)) >= + sizeof(addr.sun_path)) { + printf("Socket path may not be longer than %lu characters\n", + sizeof(addr.sun_path) - 1); + return -1; + } + + if (remove(socket_path) == -1 && errno != ENOENT) { + printf("Could not delete previous socket file entry at %s. Error: " + "%s\n", socket_path, strerror(errno)); + return -1; + } + + memset(&addr, 0, sizeof(struct sockaddr_un)); + strcpy(addr.sun_path, socket_path); + + int sfd = socket(AF_UNIX, SOCK_STREAM, 0); + if (sfd == -1) { + printf("Could not create socket. Error: %s\n", strerror(errno)); + return -1; + } + + addr.sun_family = AF_UNIX; + if (bind(sfd, (struct sockaddr *) &addr, + sizeof(struct sockaddr_un)) == -1) { + printf("Could not bind socket. Error: %s\n", strerror(errno)); + return -1; + } + + if (listen(sfd, 1) == -1) + return -1; + + printf("Awaiting connection on socket at %s...\n", socket_path); + int cfd = accept(sfd, NULL, NULL); + if (cfd == -1) { + printf("Could not accept connection. Error: %s\n", + strerror(errno)); + return -1; + } else { + printf("Accepted connection!\n"); + } + return cfd; +} + +static ssize_t stream_writev(int fd, struct iovec *iov, int count, + void *userdata) { + (void)userdata; + + ssize_t written = 0; + int cur = 0; + for (;;) { + written = writev(fd, iov+cur, count-cur); + if (written < 0) + return written; + + while (cur < count && written >= iov[cur].iov_len) + written -= iov[cur++].iov_len; + if (cur == count) + break; + + iov[cur].iov_base = (char *)iov[cur].iov_base + written; + iov[cur].iov_len -= written; + } + return written; +} + + +static ssize_t readall(int fd, void *buf, size_t len) { + size_t count = 0; + + while (count < len) { + int i = read(fd, (char *)buf + count, len - count); + if (!i) + break; + + if (i < 0) + return i; + + count += i; + } + return count; +} + +static ssize_t stream_read(int fd, void *buf, size_t buf_len, void *userdata) { + (void)userdata; + + int res = readall(fd, buf, sizeof(struct fuse_in_header)); + if (res == -1) + return res; + + + uint32_t packet_len = ((struct fuse_in_header *)buf)->len; + if (packet_len > buf_len) + return -1; + + int prev_res = res; + + res = readall(fd, (char *)buf + sizeof(struct fuse_in_header), + packet_len - sizeof(struct fuse_in_header)); + + return (res == -1) ? res : (res + prev_res); +} + +static ssize_t stream_splice_send(int fdin, __off64_t *offin, int fdout, + __off64_t *offout, size_t len, + unsigned int flags, void *userdata) { + (void)userdata; + + size_t count = 0; + while (count < len) { + int i = splice(fdin, offin, fdout, offout, len - count, flags); + if (i < 1) + return i; + + count += i; + } + return count; +} + +static void fuse_cmdline_help_uds(void) +{ + printf(" -h --help print help\n" + " -V --version print version\n" + " -d -o debug enable debug output (implies -f)\n"); +} + +int main(int argc, char *argv[]) +{ + struct fuse_args args = FUSE_ARGS_INIT(argc, argv); + struct fuse_session *se; + struct fuse_cmdline_opts opts; + const struct fuse_custom_io io = { + .writev = stream_writev, + .read = stream_read, + .splice_receive = NULL, + .splice_send = stream_splice_send, + }; + int cfd = -1; + int ret = -1; + + if (fuse_parse_cmdline(&args, &opts) != 0) + return 1; + if (opts.show_help) { + printf("usage: %s [options]\n\n", argv[0]); + fuse_cmdline_help_uds(); + 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; + } + + 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; + + cfd = create_socket("/tmp/libfuse-hello-ll.sock"); + if (cfd == -1) + goto err_out3; + + if (fuse_session_custom_io(se, &io, cfd) != 0) + goto err_out3; + + /* Block until ctrl+c */ + ret = fuse_session_loop(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; +} diff --git a/example/meson.build b/example/meson.build index 2342df9..e641543 100644 --- a/example/meson.build +++ b/example/meson.build @@ -1,7 +1,7 @@ examples = [ 'passthrough', 'passthrough_fh', - 'hello', 'hello_ll', 'printcap', - 'ioctl_client', 'poll_client', 'ioctl', - 'cuse', 'cuse_client' ] + 'hello', 'hello_ll', 'hello_ll_uds', + 'printcap', 'ioctl_client', 'poll_client', + 'ioctl', 'cuse', 'cuse_client' ] if not platform.endswith('bsd') and platform != 'dragonfly' examples += 'passthrough_ll' diff --git a/include/fuse_lowlevel.h b/include/fuse_lowlevel.h index 6bad70e..ff0d966 100644 --- a/include/fuse_lowlevel.h +++ b/include/fuse_lowlevel.h @@ -127,6 +127,17 @@ struct fuse_forget_data { uint64_t nlookup; }; +struct fuse_custom_io { + ssize_t (*writev)(int fd, struct iovec *iov, int count, void *userdata); + ssize_t (*read)(int fd, void *buf, size_t buf_len, void *userdata); + ssize_t (*splice_receive)(int fdin, __off64_t *offin, int fdout, + __off64_t *offout, size_t len, + unsigned int flags, void *userdata); + ssize_t (*splice_send)(int fdin, __off64_t *offin, int fdout, + __off64_t *offout, size_t len, + unsigned int flags, void *userdata); +}; + /** * Flags for fuse_lowlevel_notify_expire_entry() * 0 = invalidate entry @@ -1995,6 +2006,36 @@ struct fuse_session *fuse_session_new(struct fuse_args *args, size_t op_size, void *userdata); /** + * Set a file descriptor for the session. + * + * This function can be used if you want to have a custom communication + * interface instead of using a mountpoint. In practice, this means that instead + * of calling fuse_session_mount() and fuse_session_unmount(), one could call + * fuse_session_custom_io() where fuse_session_mount() would have otherwise been + * called. + * + * In `io`, implementations for read and writev MUST be provided. Otherwise -1 + * will be returned and `fd` will not be used. Implementations for `splice_send` + * and `splice_receive` are optional. If they are not provided splice will not + * be used for send or receive respectively. + * + * The provided file descriptor `fd` will be closed when fuse_session_destroy() + * is called. + * + * @param se session object + * @param io Custom io to use when retrieving/sending requests/responses + * @param fd file descriptor for the session + * + * @return 0 on success + * @return -EINVAL if `io`, `io->read` or `ìo->writev` are NULL + * @return -EBADF if `fd` was smaller than 0 + * @return -errno if failed to allocate memory to store `io` + * + **/ +int fuse_session_custom_io(struct fuse_session *se, + const struct fuse_custom_io *io, int fd); + +/** * Mount a FUSE file system. * * @param mountpoint the mount point path diff --git a/lib/fuse_i.h b/lib/fuse_i.h index 42f0e5f..74cfe36 100644 --- a/lib/fuse_i.h +++ b/lib/fuse_i.h @@ -45,6 +45,7 @@ struct fuse_session { char *mountpoint; volatile int exited; int fd; + struct fuse_custom_io *io; struct mount_opts *mo; int debug; int deny_others; diff --git a/lib/fuse_lowlevel.c b/lib/fuse_lowlevel.c index 7d76309..8fe47db 100644 --- a/lib/fuse_lowlevel.c +++ b/lib/fuse_lowlevel.c @@ -186,8 +186,15 @@ static int fuse_send_msg(struct fuse_session *se, struct fuse_chan *ch, } } - ssize_t res = writev(ch ? ch->fd : se->fd, - iov, count); + ssize_t res; + if (se->io != NULL) + /* se->io->writev is never NULL if se->io is not NULL as + specified by fuse_session_custom_io()*/ + res = se->io->writev(ch ? ch->fd : se->fd, iov, count, + se->userdata); + else + res = writev(ch ? ch->fd : se->fd, iov, count); + int err = errno; if (res == -1) { @@ -817,8 +824,14 @@ static int fuse_send_data_iov(struct fuse_session *se, struct fuse_chan *ch, (se->conn.want & FUSE_CAP_SPLICE_MOVE)) splice_flags |= SPLICE_F_MOVE; - res = splice(llp->pipe[0], NULL, ch ? ch->fd : se->fd, - NULL, out->len, splice_flags); + if (se->io != NULL && se->io->splice_send != NULL) { + res = se->io->splice_send(llp->pipe[0], NULL, + ch ? ch->fd : se->fd, NULL, out->len, + splice_flags, se->userdata); + } else { + res = splice(llp->pipe[0], NULL, ch ? ch->fd : se->fd, NULL, + out->len, splice_flags); + } if (res == -1) { res = -errno; perror("fuse: splice from pipe"); @@ -2000,9 +2013,13 @@ void do_init(fuse_req_t req, fuse_ino_t nodeid, const void *inarg) if (se->conn.proto_minor >= 14) { #ifdef HAVE_SPLICE #ifdef HAVE_VMSPLICE - se->conn.capable |= FUSE_CAP_SPLICE_WRITE | FUSE_CAP_SPLICE_MOVE; + if ((se->io == NULL) || (se->io->splice_send != NULL)) { + se->conn.capable |= FUSE_CAP_SPLICE_WRITE | FUSE_CAP_SPLICE_MOVE; + } #endif - se->conn.capable |= FUSE_CAP_SPLICE_READ; + if ((se->io == NULL) || (se->io->splice_receive != NULL)) { + se->conn.capable |= FUSE_CAP_SPLICE_READ; + } #endif } if (se->conn.proto_minor >= 18) @@ -2755,6 +2772,8 @@ void fuse_session_destroy(struct fuse_session *se) free(se->cuse_data); if (se->fd != -1) close(se->fd); + if (se->io != NULL) + free(se->io); destroy_mount_opts(se->mo); free(se); } @@ -2804,8 +2823,14 @@ int fuse_session_receive_buf_int(struct fuse_session *se, struct fuse_buf *buf, goto fallback; } - res = splice(ch ? ch->fd : se->fd, - NULL, llp->pipe[1], NULL, bufsize, 0); + if (se->io != NULL && se->io->splice_receive != NULL) { + res = se->io->splice_receive(ch ? ch->fd : se->fd, NULL, + llp->pipe[1], NULL, bufsize, 0, + se->userdata); + } else { + res = splice(ch ? ch->fd : se->fd, NULL, llp->pipe[1], NULL, + bufsize, 0); + } err = errno; if (fuse_session_exited(se)) @@ -2891,7 +2916,14 @@ fallback: } restart: - res = read(ch ? ch->fd : se->fd, buf->mem, se->bufsize); + if (se->io != NULL) { + /* se->io->read is never NULL if se->io is not NULL as + specified by fuse_session_custom_io()*/ + res = se->io->read(ch ? ch->fd : se->fd, buf->mem, se->bufsize, + se->userdata); + } else { + res = read(ch ? ch->fd : se->fd, buf->mem, se->bufsize); + } err = errno; if (fuse_session_exited(se)) @@ -3021,6 +3053,40 @@ out1: return NULL; } +int fuse_session_custom_io(struct fuse_session *se, const struct fuse_custom_io *io, + int fd) +{ + if (fd < 0) { + fuse_log(FUSE_LOG_ERR, "Invalid file descriptor value %d passed to " + "fuse_session_custom_io()\n", fd); + return -EBADF; + } + if (io == NULL) { + fuse_log(FUSE_LOG_ERR, "No custom IO passed to " + "fuse_session_custom_io()\n"); + return -EINVAL; + } else if (io->read == NULL || io->writev == NULL) { + /* If the user provides their own file descriptor, we can't + guarantee that the default behavior of the io operations made + in libfuse will function properly. Therefore, we enforce the + user to implement these io operations when using custom io. */ + fuse_log(FUSE_LOG_ERR, "io passed to fuse_session_custom_io() must " + "implement both io->read() and io->writev\n"); + return -EINVAL; + } + + se->io = malloc(sizeof(struct fuse_custom_io)); + if (se->io == NULL) { + fuse_log(FUSE_LOG_ERR, "Failed to allocate memory for custom io. " + "Error: %s\n", strerror(errno)); + return -errno; + } + + se->fd = fd; + *se->io = *io; + return 0; +} + int fuse_session_mount(struct fuse_session *se, const char *mountpoint) { int fd; diff --git a/lib/fuse_versionscript b/lib/fuse_versionscript index 114f592..55ab9e5 100644 --- a/lib/fuse_versionscript +++ b/lib/fuse_versionscript @@ -39,6 +39,7 @@ FUSE_3.0 { fuse_session_new; fuse_main_real; fuse_mount; + fuse_session_custom_io; fuse_session_mount; fuse_new; fuse_opt_insert_arg; diff --git a/test/meson.build b/test/meson.build index 12d3c41..1f5cb53 100644 --- a/test/meson.build +++ b/test/meson.build @@ -15,7 +15,7 @@ td += executable('readdir_inode', 'readdir_inode.c', install: false) test_scripts = [ 'conftest.py', 'pytest.ini', 'test_examples.py', - 'util.py', 'test_ctests.py' ] + 'util.py', 'test_ctests.py', 'test_custom_io.py' ] td += custom_target('test_scripts', input: test_scripts, output: test_scripts, build_by_default: true, command: ['cp', '-fPp', diff --git a/test/test_custom_io.py b/test/test_custom_io.py new file mode 100644 index 0000000..737b939 --- /dev/null +++ b/test/test_custom_io.py @@ -0,0 +1,81 @@ +#!/usr/bin/env python3 + +if __name__ == '__main__': + import sys + + import pytest + sys.exit(pytest.main([__file__] + sys.argv[1:])) + +import os +import socket +import struct +import subprocess +import sys +import time +from os.path import join as pjoin + +import pytest + +from util import base_cmdline, basename + +FUSE_OP_INIT = 26 + +FUSE_MAJOR_VERSION = 7 +FUSE_MINOR_VERSION = 38 + +fuse_in_header_fmt = '<IIQQIIII' +fuse_out_header_fmt = '<IiQ' + +fuse_init_in_fmt = '<IIIII44x' +fuse_init_out_fmt = '<IIIIHHIIHHI28x' + + +def sock_recvall(sock: socket.socket, bufsize: int) -> bytes: + buf = bytes() + while len(buf) < bufsize: + buf += sock.recv(bufsize - len(buf)) + return buf + + +def tst_init(sock: socket.socket): + unique_req = 10 + dummy_init_req_header = struct.pack( + fuse_in_header_fmt, struct.calcsize(fuse_in_header_fmt) + + struct.calcsize(fuse_init_in_fmt), FUSE_OP_INIT, unique_req, 0, 0, 0, + 0, 0) + dummy_init_req_payload = struct.pack( + fuse_init_in_fmt, FUSE_MAJOR_VERSION, FUSE_MINOR_VERSION, 0, 0, 0) + dummy_init_req = dummy_init_req_header + dummy_init_req_payload + + sock.sendall(dummy_init_req) + + response_header = sock_recvall(sock, struct.calcsize(fuse_out_header_fmt)) + packet_len, _, unique_res = struct.unpack( + fuse_out_header_fmt, response_header) + assert unique_res == unique_req + + response_payload = sock_recvall(sock, packet_len - len(response_header)) + response_payload = struct.unpack(fuse_init_out_fmt, response_payload) + assert response_payload[0] == FUSE_MAJOR_VERSION + + +def test_hello_uds(output_checker): + cmdline = base_cmdline + [pjoin(basename, 'example', 'hello_ll_uds')] + print(cmdline) + uds_process = subprocess.Popen(cmdline, stdout=output_checker.fd, + stderr=output_checker.fd) + time.sleep(1) + + sock = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM) + sock.settimeout(1) + sock.connect("/tmp/libfuse-hello-ll.sock") + + tst_init(sock) + + sock.close() + uds_process.terminate() + try: + uds_process.wait(1) + except subprocess.TimeoutExpired: + uds_process.kill() + os.remove("/tmp/libfuse-hello-ll.sock") |