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libfuse
null.c
Go to the documentation of this file.
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 
25 #define FUSE_USE_VERSION 31
26 
27 #include <fuse.h>
28 #include <fuse_lowlevel.h>
29 #include <stdio.h>
30 #include <stdlib.h>
31 #include <string.h>
32 #include <unistd.h>
33 #include <time.h>
34 #include <errno.h>
35 
36 static int null_getattr(const char *path, struct stat *stbuf,
37  struct fuse_file_info *fi)
38 {
39  (void) fi;
40 
41  if(strcmp(path, "/") != 0)
42  return -ENOENT;
43 
44  stbuf->st_mode = S_IFREG | 0644;
45  stbuf->st_nlink = 1;
46  stbuf->st_uid = getuid();
47  stbuf->st_gid = getgid();
48  stbuf->st_size = (1ULL << 32); /* 4G */
49  stbuf->st_blocks = 0;
50  stbuf->st_atime = stbuf->st_mtime = stbuf->st_ctime = time(NULL);
51 
52  return 0;
53 }
54 
55 static int null_truncate(const char *path, off_t size,
56  struct fuse_file_info *fi)
57 {
58  (void) size;
59  (void) fi;
60 
61  if(strcmp(path, "/") != 0)
62  return -ENOENT;
63 
64  return 0;
65 }
66 
67 static int null_open(const char *path, struct fuse_file_info *fi)
68 {
69  (void) fi;
70 
71  if(strcmp(path, "/") != 0)
72  return -ENOENT;
73 
74  return 0;
75 }
76 
77 static int null_read(const char *path, char *buf, size_t size,
78  off_t offset, struct fuse_file_info *fi)
79 {
80  (void) buf;
81  (void) offset;
82  (void) fi;
83 
84  if(strcmp(path, "/") != 0)
85  return -ENOENT;
86 
87  if (offset >= (1ULL << 32))
88  return 0;
89 
90  memset(buf, 0, size);
91  return size;
92 }
93 
94 static int null_write(const char *path, const char *buf, size_t size,
95  off_t offset, struct fuse_file_info *fi)
96 {
97  (void) buf;
98  (void) offset;
99  (void) fi;
100 
101  if(strcmp(path, "/") != 0)
102  return -ENOENT;
103 
104  return size;
105 }
106 
107 static struct fuse_operations null_oper = {
108  .getattr = null_getattr,
109  .truncate = null_truncate,
110  .open = null_open,
111  .read = null_read,
112  .write = null_write,
113 };
114 
115 int main(int argc, char *argv[])
116 {
117  struct fuse_args args = FUSE_ARGS_INIT(argc, argv);
118  struct fuse_cmdline_opts opts;
119  struct stat stbuf;
120 
121  if (fuse_parse_cmdline(&args, &opts) != 0)
122  return 1;
123  fuse_opt_free_args(&args);
124 
125  if (!opts.mountpoint) {
126  fprintf(stderr, "missing mountpoint parameter\n");
127  return 1;
128  }
129 
130  if (stat(opts.mountpoint, &stbuf) == -1) {
131  fprintf(stderr ,"failed to access mountpoint %s: %s\n",
132  opts.mountpoint, strerror(errno));
133  free(opts.mountpoint);
134  return 1;
135  }
136  free(opts.mountpoint);
137  if (!S_ISREG(stbuf.st_mode)) {
138  fprintf(stderr, "mountpoint is not a regular file\n");
139  return 1;
140  }
141 
142  return fuse_main(argc, argv, &null_oper, NULL);
143 }
int fuse_parse_cmdline(struct fuse_args *args, struct fuse_cmdline_opts *opts)
Definition: helper.c:202
void fuse_opt_free_args(struct fuse_args *args)
Definition: fuse_opt.c:33
int(* getattr)(const char *, struct stat *, struct fuse_file_info *fi)
Definition: fuse.h:311
#define FUSE_ARGS_INIT(argc, argv)
Definition: fuse_opt.h:123
#define fuse_main(argc, argv, op, private_data)
Definition: fuse.h:838