Fops attempt, but noticed that /proc is not getting mounted.

This commit is contained in:
Ciro Santilli
2017-05-12 16:30:10 +01:00
parent 0279ae3bad
commit 401666d221
2 changed files with 75 additions and 1 deletions

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@@ -1,4 +1,4 @@
obj-m += debugfs.o hello.o hello2.o
obj-m += debugfs.o fops.o hello.o hello2.o
ccflags-y := -Wno-declaration-after-statement -std=gnu99
.PHONY: all clean

74
kernel_module/fops.c Normal file
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@@ -0,0 +1,74 @@
/*
dmesg stuff when fops happen.
fops define what the kernel will do on filesystem system calls on all of
/dev, /proc, /sys, and consistute the main method of userland communication
in drivers (syscalls being the other one).
Here we use debugfs.
*/
#include <linux/debugfs.h>
#include <linux/fs.h>
#include <linux/kernel.h>
#include <linux/module.h>
MODULE_LICENSE("GPL");
static struct dentry *dir = 0;
int fop_open(struct inode *inode, struct file *file)
{
printk(KERN_INFO "open");
return 0;
}
ssize_t fop_read(struct file *file, char __user *buf, size_t len, loff_t *off)
{
printk(KERN_INFO "read");
return 0;
}
ssize_t fop_write(struct file *file, const char __user *buf, size_t len, loff_t *off)
{
printk(KERN_INFO "write");
return 0;
}
/*
Called on the last close:
http://stackoverflow.com/questions/11393674/why-is-the-close-function-is-called-release-in-struct-file-operations-in-the-l
*/
int fop_release (struct inode *inode, struct file *file)
{
printk(KERN_INFO "release");
return 0;
}
const struct file_operations fops = {
.open = fop_open,
.read = fop_read,
.release = fop_release,
.write = fop_write,
};
int init_module(void)
{
struct dentry *file;
dir = debugfs_create_dir("kernel_module_cheat", 0);
if (!dir) {
printk(KERN_ALERT "debugfs_create_dir failed");
return -1;
}
file = debugfs_create_file("fops", 0666, dir, NULL, &fops);
if (!file) {
printk(KERN_ALERT "debugfs_create_file failed");
return -1;
}
return 0;
}
void cleanup_module(void)
{
debugfs_remove_recursive(dir);
}