example/hello.c

   1 /*
   2   FUSE: Filesystem in Userspace
   3   Copyright (C) 2001-2007  Miklos Szeredi <miklos@szeredi.hu>
   4
   5   This program can be distributed under the terms of the GNU GPL.
   6   See the file COPYING.
   7 */
   8
   9 /** @file
  10  *
  11  * hello.c - minimal FUSE example featuring fuse_main usage
  12  *
  13  * \section section_compile compiling this example
  14  *
  15  * gcc -Wall hello.c `pkg-config fuse3 --cflags --libs` -o hello
  16  *
  17  * \section section_usage usage
  18  \verbatim
  19  % mkdir mnt
  20  % ./hello mnt        # program will vanish into the background
  21  % ls -la mnt
  22    total 4
  23    drwxr-xr-x 2 root root      0 Jan  1  1970 ./
  24    drwxrwx--- 1 root vboxsf 4096 Jun 16 23:12 ../
  25    -r--r--r-- 1 root root     13 Jan  1  1970 hello
  26  % cat mnt/hello
  27    Hello World!
  28  % fusermount -u mnt
  29  \endverbatim
  30  *
  31  * \section section_source the complete source
  32  * \include hello.c
  33  */
  34
  35
  36 #define FUSE_USE_VERSION 30
  37
  38 #include <config.h>
  39
  40 #include <fuse.h>
  41 #include <stdio.h>
  42 #include <string.h>
  43 #include <errno.h>
  44 #include <fcntl.h>
  45
  46 static const char *hello_str = "Hello World!\n";
  47 static const char *hello_path = "/hello";
  48
  49 static int hello_getattr(const char *path, struct stat *stbuf)
  50 {
  51         int res = 0;
  52
  53         memset(stbuf, 0, sizeof(struct stat));
  54         if (strcmp(path, "/") == 0) {
  55                 stbuf->st_mode = S_IFDIR | 0755;
  56                 stbuf->st_nlink = 2;
  57         } else if (strcmp(path, hello_path) == 0) {
  58                 stbuf->st_mode = S_IFREG | 0444;
  59                 stbuf->st_nlink = 1;
  60                 stbuf->st_size = strlen(hello_str);
  61         } else
  62                 res = -ENOENT;
  63
  64         return res;
  65 }
  66
  67 static int hello_readdir(const char *path, void *buf, fuse_fill_dir_t filler,
  68                          off_t offset, struct fuse_file_info *fi,
  69                          enum fuse_readdir_flags flags)
  70 {
  71         (void) offset;
  72         (void) fi;
  73         (void) flags;
  74
  75         if (strcmp(path, "/") != 0)
  76                 return -ENOENT;
  77
  78         filler(buf, ".", NULL, 0, 0);
  79         filler(buf, "..", NULL, 0, 0);
  80         filler(buf, hello_path + 1, NULL, 0, 0);
  81
  82         return 0;
  83 }
  84
  85 static int hello_open(const char *path, struct fuse_file_info *fi)
  86 {
  87         if (strcmp(path, hello_path) != 0)
  88                 return -ENOENT;
  89
  90         if ((fi->flags & 3) != O_RDONLY)
  91                 return -EACCES;
  92
  93         return 0;
  94 }
  95
  96 static int hello_read(const char *path, char *buf, size_t size, off_t offset,
  97                       struct fuse_file_info *fi)
  98 {
  99         size_t len;
 100         (void) fi;
 101         if(strcmp(path, hello_path) != 0)
 102                 return -ENOENT;
 103
 104         len = strlen(hello_str);
 105         if (offset < len) {
 106                 if (offset + size > len)
 107                         size = len - offset;
 108                 memcpy(buf, hello_str + offset, size);
 109         } else
 110                 size = 0;
 111
 112         return size;
 113 }
 114
 115 static struct fuse_operations hello_oper = {
 116         .getattr        = hello_getattr,
 117         .readdir        = hello_readdir,
 118         .open           = hello_open,
 119         .read           = hello_read,
 120 };
 121
 122 int main(int argc, char *argv[])
 123 {
 124         return fuse_main(argc, argv, &hello_oper, NULL);
 125 }