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-rw-r--r--example/hello_ll_uds.c358
1 files changed, 358 insertions, 0 deletions
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;
+}
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