40 #include <sys/types.h>    43 #include <sys/ioctl.h>    52 "Usage: cuse_client FIOC_FILE COMMAND\n"    55 "  s [SIZE]     : get size if SIZE is omitted, set size otherwise\n"    56 "  r SIZE [OFF] : read SIZE bytes @ OFF (dfl 0) and output to stdout\n"    57 "  w SIZE [OFF] : write SIZE bytes @ OFF (dfl 0) from stdin\n"    60 static int do_rw(
int fd, 
int is_read, 
size_t size, off_t offset,
    61                  size_t *prev_size, 
size_t *new_size)
    63         struct fioc_rw_arg arg = { .offset = offset };
    66         arg.buf = calloc(1, size);
    68                 fprintf(stderr, 
"failed to allocated %zu bytes\n", size);
    74                 ret = ioctl(fd, FIOC_READ, &arg);
    76                         fwrite(arg.buf, 1, ret, stdout);
    78                 arg.size = fread(arg.buf, 1, size, stdin);
    79                 fprintf(stderr, 
"Writing %zu bytes\n", arg.size);
    80                 ret = ioctl(fd, FIOC_WRITE, &arg);
    84                 *prev_size = arg.prev_size;
    85                 *new_size = arg.new_size;
    93 int main(
int argc, 
char **argv)
    95         size_t param[2] = { };
    96         size_t size, prev_size = 0, new_size = 0;
   103         fd = open(argv[1], O_RDWR);
   109         cmd = tolower(argv[2][0]);
   113         for (i = 0; i < argc; i++) {
   115                 param[i] = strtoul(argv[i], &endp, 0);
   116                 if (endp == argv[i] || *endp != 
'\0')
   123                         if (ioctl(fd, FIOC_GET_SIZE, &size)) {
   127                         printf(
"%zu\n", size);
   130                         if (ioctl(fd, FIOC_SET_SIZE, &size)) {
   140                 rc = do_rw(fd, cmd == 
'r', param[0], param[1],
   141                            &prev_size, &new_size);
   144                 fprintf(stderr, 
"transferred %d bytes (%zu -> %zu)\n",
   145                         rc, prev_size, new_size);
   151         fprintf(stderr, 
"%s", usage);