头文件
#include <linux/fs.h>
#include <asm/segment.h>
#include <asm/uaccess.h>
#include <linux/buffer_head.h>
打开文件
struct file* file_open(const char* path, int flags, int rights) {
struct file* filp = NULL;
mm_segment_t oldfs;
int err = 0;
oldfs = get_fs();
set_fs(get_ds());
filp = filp_open(path, flags, rights);
set_fs(oldfs);
if(IS_ERR(filp)) {
err = PTR_ERR(filp);
return NULL;
}
return filp;
}
关闭文件
void file_close(struct file* file) {
filp_close(file, NULL);
}
读文件
int file_read(struct file* file, unsigned long long offset, unsigned char* data, unsigned int size) {
mm_segment_t oldfs;
int ret;
oldfs = get_fs();
set_fs(get_ds());
ret = vfs_read(file, data, size, &offset);
set_fs(oldfs);
return ret;
}
写文件
int file_write(struct file* file,vunsigned long long offset, unsigned char* data, unsigned int size) {
mm_segment_t oldfs;
int ret;
oldfs = get_fs();
set_fs(get_ds());
ret = vfs_write(file, data, size, &offset);
set_fs(oldfs);
return ret;
}
同步文件
int file_sync(struct file* file) {
vfs_fsync(file, 0);
return 0;
}
备注：
get_ds(): 获得kernel的内存访问地址范围
get_fs(): 取得当前的地址访问限制值
set_fs(): 设置当前的地址访问值
