/* We give all of our information in one go, so if the
* user asks us if we have more information the
* answer should always be no.
*
* This is important because the standard read
* function from the library would continue to issue
* the read system call until the kernel replies
* that it has no more information, or until its * buffer is filled. */
if (offset > 0) return 0;
/* Fill the buffer and get its length */
len = sprintf(my_buffer, "For the %d%s time, go away!\n", count,
(count % 100 > 10 && count % 100 < 14) ? "th" :
(count % 10 == 1) ? "st" : (count % 10 == 2) ? "nd" :
(count % 10 == 3) ? "rd" : "th" );
count++;
/* Tell the function which called us where the buffer is */
*buffer_location = my_buffer;
/* Return the length */
return len;
}
struct proc_dir_entry Our_Proc_File = {
0, /* Inode number - ignore, it will be filled by proc_register[_dynamic] */
4, /* Length of the file name */
"test", /* The file name */
S_IFREG | S_IRUGO, /* File mode - this is a regular file which can be read by its owner, its group, and everybody else */
1, /* Number of links (directories where the file is referenced) */
0, 0, /* The uid and gid for the file - we give it * to root */
80, /* The size of the file reported by ls. */
NULL, /* functions which can be done on the inode (linking, removing, etc.) - we don't support any. */
procfile_read, /* The read function for this file, the function called when somebody tries to read something from it. */
NULL /* We could have here a function to fill the file's inode, to enable us to play with permissions, ownership, etc. */
};
/* Initialize the module - register the proc file */
int init_module() {
/* Success if proc_register[_dynamic] is a success, failure otherwise. */
#if LINUX_VERSION_CODE > KERNEL_VERSION(2,2,0)
/* In version 2.2, proc_register assign a dynamic
* inode number automatically if it is zero in the
* structure, so there's no more need for
* proc_register_dynamic */
return proc_register(&proc_root, &Our_Proc_File);
#else
return proc_register_dynamic(&proc_root, &Our_Proc_File);
#endif
/* proc_root is the root directory for the proc fs (/proc). This is where we want our file to be located. */
}
/* Cleanup - unregister our file from /proc */
void cleanup_module() {
proc_unregister(&proc_root, Our_Proc_File.low_ino);
}
Пока мы имеем два способа генерировать вывод из модулей: мы можем зарегистрировать драйвер устройства и создать mknod файл устройства, или мы можем создать /proc файл. Это позволяет модулю сообщать нам что-нибудь. Единственная проблема в том, что не имеется никакого пути для нас, чтобы возразить. Первый путем, которым мы пошлем ввод модулям, будет запись обратно в файл в системе /proc.
