工作拾遗

1 string -> num

1) atoi(int)

2)sscanf(const char *buffer,const char *format,[argument ]...)

#include <stdio.h>

int main(void)
{
        int value;
        sscanf("0x11", "%x", &value);
        printf("%d\n", value);

        return 0;
}

 

2 sed\awk

#!/bin/sh
##!/system/bin/sh

INPUT_FILE=$1
# sed 正则表达式选择行, awk 处理列
sed -n '/^REG/p' ${INPUT_FILE} | awk -F'0x|\t' '{print $2 $3}' | sed 's/ //'

 

3 open_filp

#include <linux/uaccess.h>
#include <linux/fs.h>
#include <linux/proc_fs.h> 

   struct file *fp; 
    mm_segment_t fs;
    loff_t pos; 
    char buf[] = "VVVVVVVVV"; 
    char buf1[16] = {0}; 

    fp = filp_open("/test", O_RDWR | O_CREAT, 0644);

    if (IS_ERR(fp)) {
        pr_0("open file error");

        return -1;
    }    

    fs = get_fs();
    set_fs(KERNEL_DS);
    pos = 0; 
    vfs_write(fp, buf, sizeof(buf), &pos);
    pos = 0; 
    vfs_read(fp, buf1, sizeof(buf), &pos);
    pr_0("read : %s", buf1);
    filp_close(fp, NULL);
    set_fs(fs);