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Bug #20587 » hello.c

ivoanjo (Ivo Anjo), 07/12/2024 11:33 AM

 
/*
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.
*/

/** @file
*
* minimal example filesystem using high-level API
*
* Compile with:
*
* gcc -Wall hello.c `pkg-config fuse3 --cflags --libs` -o hello
*
* ## Source code ##
* \include hello.c
*/


#define FUSE_USE_VERSION 31

#include <fuse.h>
#include <stdio.h>
#include <string.h>
#include <errno.h>
#include <fcntl.h>
#include <stddef.h>
#include <assert.h>

/*
* Command line options
*
* We can't set default values for the char* fields here because
* fuse_opt_parse would attempt to free() them when the user specifies
* different values on the command line.
*/
static struct options {
const char *filename;
const char *contents;
int show_help;
} options;

#define OPTION(t, p) \
{ t, offsetof(struct options, p), 1 }
static const struct fuse_opt option_spec[] = {
OPTION("--name=%s", filename),
OPTION("--contents=%s", contents),
OPTION("-h", show_help),
OPTION("--help", show_help),
FUSE_OPT_END
};

static void *hello_init(struct fuse_conn_info *conn,
struct fuse_config *cfg)
{
(void) conn;
cfg->kernel_cache = 1;
return NULL;
}

static int hello_getattr(const char *path, struct stat *stbuf,
struct fuse_file_info *fi)
{
fprintf(stderr, "hello_getattr sleeping...\n");
sleep(2);
fprintf(stderr, "hello_getattr woke up!\n");
(void) fi;
int res = 0;

memset(stbuf, 0, sizeof(struct stat));
if (strcmp(path, "/") == 0) {
stbuf->st_mode = S_IFDIR | 0755;
stbuf->st_nlink = 2;
} else if (strcmp(path+1, options.filename) == 0) {
stbuf->st_mode = S_IFREG | 0444;
stbuf->st_nlink = 1;
stbuf->st_size = strlen(options.contents);
} else
res = -ENOENT;

return res;
}

static int hello_readdir(const char *path, void *buf, fuse_fill_dir_t filler,
off_t offset, struct fuse_file_info *fi,
enum fuse_readdir_flags flags)
{
(void) offset;
(void) fi;
(void) flags;

if (strcmp(path, "/") != 0)
return -ENOENT;

fprintf(stderr, "hello_readdir sleeping...\n");
sleep(2);
fprintf(stderr, "hello_readdir woke up!\n");

filler(buf, ".", NULL, 0, FUSE_FILL_DIR_DEFAULTS);
filler(buf, "..", NULL, 0, FUSE_FILL_DIR_DEFAULTS);
filler(buf, options.filename, NULL, 0, FUSE_FILL_DIR_DEFAULTS);

return 0;
}

static int hello_open(const char *path, struct fuse_file_info *fi)
{
if (strcmp(path+1, options.filename) != 0)
return -ENOENT;

if ((fi->flags & O_ACCMODE) != O_RDONLY)
return -EACCES;

return 0;
}

static int hello_read(const char *path, char *buf, size_t size, off_t offset,
struct fuse_file_info *fi)
{
size_t len;
(void) fi;
if(strcmp(path+1, options.filename) != 0)
return -ENOENT;

len = strlen(options.contents);
if (offset < len) {
if (offset + size > len)
size = len - offset;
memcpy(buf, options.contents + offset, size);
} else
size = 0;

return size;
}

static int hello_opendir(const char *path, struct fuse_file_info *fi) {
fprintf(stderr, "hello_opendir sleeping...\n");
sleep(2);
fprintf(stderr, "hello_opendir woke up!\n");

return 0;
}

static int hello_access(const char *, int) {
fprintf(stderr, "hello_access sleeping...\n");
sleep(2);
fprintf(stderr, "hello_access woke up!\n");

return 0;
}

static const struct fuse_operations hello_oper = {
.init = hello_init,
.getattr = hello_getattr,
.readdir = hello_readdir,
.open = hello_open,
.read = hello_read,
.opendir = hello_opendir,
.access = hello_access,
};

static void show_help(const char *progname)
{
printf("usage: %s [options] <mountpoint>\n\n", progname);
printf("File-system specific options:\n"
" --name=<s> Name of the \"hello\" file\n"
" (default: \"hello\")\n"
" --contents=<s> Contents \"hello\" file\n"
" (default \"Hello, World!\\n\")\n"
"\n");
}

int main(int argc, char *argv[])
{
int ret;
struct fuse_args args = FUSE_ARGS_INIT(argc, argv);

/* Set defaults -- we have to use strdup so that
fuse_opt_parse can free the defaults if other
values are specified */
options.filename = strdup("hello");
options.contents = strdup("Hello World!\n");

/* Parse options */
if (fuse_opt_parse(&args, &options, option_spec, NULL) == -1)
return 1;

/* When --help is specified, first print our own file-system
specific help text, then signal fuse_main to show
additional help (by adding `--help` to the options again)
without usage: line (by setting argv[0] to the empty
string) */
if (options.show_help) {
show_help(argv[0]);
assert(fuse_opt_add_arg(&args, "--help") == 0);
args.argv[0][0] = '\0';
}

ret = fuse_main(args.argc, args.argv, &hello_oper, NULL);
fuse_opt_free_args(&args);
return ret;
}
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