linux howto - fabio de lorenzo personal informations and experiences

[root]

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/device.h>
#include <linux/vmalloc.h>
#include <linux/syscalls.h>
#include <linux/file.h>
#include <linux/fs.h>
#include <linux/fcntl.h>
#include <asm/uaccess.h>

MODULE_LICENSE("GPL");



/**
* Reads give buffer to file.
*
* GPL'd code.
* FOR DEBUGGING PURPOSES ONLY.
*/
ssize_t fabio_gpl_read_file(char *filename, unsigned char *data, int data_size)
{
struct file *file;
loff_t pos = 0;
int fd;
ssize_t ret = -EBADF;
mm_segment_t old_fs = get_fs();
set_fs(KERNEL_DS);
fd = sys_open(filename, O_RDONLY, 0644);
if (fd >= 0) {
ret = __sys_read(fd, data, data_size);
file = fget(fd);
if (file) {
ret = vfs_read(file, data, data_size, &pos);
fput(file);
}
sys_close(fd);
}
set_fs(old_fs);
return ret;
}



/**
* Writes give buffer to file.
*
* GPL'd code.
* FOR DEBUGGING PURPOSES ONLY.
*/
ssize_t fabio_gpl_write_file(char *filename, unsigned char *data, int data_size, bool append)
{
struct file *file;
loff_t pos = 0;
int fd;
ssize_t ret = -EBADF;
mm_segment_t old_fs = get_fs();
set_fs(KERNEL_DS);
fd = sys_open(filename, O_WRONLY|O_CREAT|(append ? O_APPEND : 0), 0644);
if (fd >= 0) {
ret = __sys_write(fd, data, data_size);
file = fget(fd);
if (file) {
ret = vfs_write(file, data, data_size, &pos);
fput(file);
}
sys_close(fd);
}
set_fs(old_fs);
return ret;
}