Энциклопедия разработчика модулей ядра Linux

Померанц Ори

 if (op == 4 || (op == 2 && current->euid == 0)) return 0;

 /* If it's anything else, access is denied */

 return -EACCES;

}

/* The file is opened - we don't really care about

* that, but it does mean we need to increment the

* module's reference count. */

int module_open(struct inode *inode, struct file *file) {

 MOD_INC_USE_COUNT;

 return 0;

}

/* The file is closed - again, interesting only because of the reference count. */

#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,2,0)

int module_close(struct inode *inode, struct file *file)

#else

void module_close(struct inode *inode, struct file *file)

#endif

{

 MOD_DEC_USE_COUNT;

#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,2,0)

 return 0; /* success */

#endif

}

/* Structures to register as the /proc file, with

* pointers to all the relevant functions. ********** */

/* File operations for our proc file. This is where we

* place pointers to all the functions called when

* somebody tries to do something to our file. NULL

* means we don't want to deal with something. */

static struct file_operations File_Ops_4_Our_Proc_File = {

 NULL, /* lseek */

 module_output, /* "read" from the file */

 module_input, /* "write" to the file */

 NULL, /* readdir */

 NULL, /* select */

 NULL, /* ioctl */

 NULL, /* mmap */

 module_open, /* Somebody opened the file */

 #if LINUX_VERSION_CODE >= KERNEL_VERSION(2,2,0)

 NULL, /* flush, added here in version 2.2 */

#endif

 module_close, /* Somebody closed the file */

 /* etc. etc. etc. (they are all given in

 * /usr/include/linux/fs.h). Since we don't put

 * anything here, the system will keep the default

 * data, which in Unix is zeros (NULLs when taken as pointers). */

};

/* Inode operations for our proc file. We need it so

* we'll have some place to specify the file operations

* structure we want to use, and the function we use for

* permissions. It's also possible to specify functions

* to be called for anything else which could be done to

* an inode (although we don't bother, we just put NULL). */

static struct inode_operations Inode_Ops_4_Our_Proc_File = {

 &File_Ops_4_Our_Proc_File,

 NULL, /* create */

 NULL, /* lookup */

 NULL, /* link */

 NULL, /* unlink */

 NULL, /* symlink */

 NULL, /* mkdir */

 NULL, /* rmdir */

 NULL, /* mknod */

 NULL, /* rename */

 NULL, /* readlink */

 NULL, /* follow_link */

 NULL, /* readpage */

 NULL, /* writepage */

 NULL, /* bmap */

 NULL, /* truncate */

 module_permission /* check for permissions */

};

/* Directory entry */

static struct proc_dir_entry Our_Proc_File = {

 0, /* Inode number - ignore, it will be filled by proc_register[_dynamic] */

 7, /* Length of the file name */

 "rw_test", /* The file name */

 S_IFREG | S_IRUGO | S_IWUSR,

 /* File mode - this is a regular file which

 * can be read by its owner, its group, and everybody

 * else. Also, its owner can write to it.

 *

 * Actually, this field is just for reference, it's

 * module_permission that does the actual check. It

 * could use this field, but in our implementation it

 * doesn't, for simplicity. */

 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. */

 &Inode_Ops_4_Our_Proc_File,

 /* A pointer to the inode structure for