Linux驱动中读写文件

最近做了一个TF卡烧写MAC地址，方法额外增加一个驱动，驱动中实现对TF卡和本地mac文件的读写功能，让以太网驱动加载时调用读写函数进行设置mac地址，代码比较简单，如下：

/* * setmac one chip USB 2.0 ethernet devices * * Author : yubo.wang  * Date : 2017-08-25 * * This file is licensed under the terms of the GNU General Public License * version 2.  This program is licensed "as is" without any warranty of any * kind, whether express or implied. */#include #include #include #include #include #include #include #include #include #include #include #include "setmac.h"#define SET_MAC_FILE "/system/etc/mac"#define SET_MAC_MOUNT "/system/etc/tf_mac/mac"int setmac_read_tf_mac(u8 *mac_addr){  u8 mac_buf[12] = {0,};int i = 0;struct file *fp;  mm_segment_t fs;  loff_t pos;  fp = filp_open(SET_MAC_MOUNT, O_RDONLY, 0);if (IS_ERR(fp)) {  printk(KERN_ERR "read tf mac addr file error,return!\n");return -1;}  fs = get_fs();set_fs(KERNEL_DS);pos = 0;  vfs_read(fp, mac_buf, sizeof(mac_buf), &pos);if(strlen(mac_buf) < 12){printk(KERN_ERR "read tf mac addr len < 12,return!\n");  return -1;}mac_buf[12] = '\0';printk(KERN_INFO "read tf mac:%s",mac_buf);for (i=0; i<6; i++){ u8 mac_tmp[3]= {0,};memcpy(mac_tmp, (char *)(mac_buf+i*2), 2);mac_addr[i] = simple_strtoul(mac_tmp, NULL, 16);}filp_close(fp, NULL);  set_fs(fs);  return 0;  }EXPORT_SYMBOL_GPL(setmac_read_tf_mac);int setmac_write_tf_mac(u8 *mac_addr){  u8 mac_buf[12] = {0,};int i = 0;struct file *fp;  mm_segment_t fs;  loff_t pos;  fp = filp_open(SET_MAC_FILE, O_RDWR | O_CREAT, 0644);if (IS_ERR(fp)) {  printk(KERN_ERR "write tf mac addr file error,return!\n"); return -1;}  fs = get_fs();set_fs(KERNEL_DS);for (i=0; i<6; i++){ u8 mac_tmp[3]= {0,};sprintf(mac_tmp, "%02x", mac_addr[i]);strncat(mac_buf, mac_tmp, 2);}mac_buf[12] = '\0';printk(KERN_INFO "write mac:%s",mac_buf);pos = 0;vfs_write(fp, mac_buf, sizeof(mac_buf), &pos);vfs_fsync(fp, 0);filp_close(fp, NULL);set_fs(fs);return 0;}EXPORT_SYMBOL_GPL(setmac_write_tf_mac);int setmac_read_mac_addr(u8 *mac_addr){  u8 mac_buf[12] = {0,};int i = 0;struct file *fp;  mm_segment_t fs;  loff_t pos;  fp = filp_open(SET_MAC_FILE, O_RDONLY, 0);if (IS_ERR(fp)) {  printk(KERN_ERR "read mac addr file error,return!\n");return -1;}  fs = get_fs();set_fs(KERNEL_DS);pos = 0;  vfs_read(fp, mac_buf, sizeof(mac_buf), &pos);if(strlen(mac_buf) < 12){printk(KERN_ERR "read mac addr len < 12,return!\n");  return -1;}mac_buf[12] = '\0';printk(KERN_INFO "read mac:%s",mac_buf);for (i=0; i<6; i++){ u8 mac_tmp[3]= {0,};memcpy(mac_tmp, (char *)(mac_buf+i*2), 2);mac_addr[i] = simple_strtoul(mac_tmp, NULL, 16);}filp_close(fp, NULL);  set_fs(fs);  return 0;  }EXPORT_SYMBOL_GPL(setmac_read_mac_addr);int setmac_write_mac_addr(u8 *mac_addr) {  u8 mac_buf[12] = {0,};int i = 0;struct file *fp;  mm_segment_t fs;  loff_t pos;  fp = filp_open(SET_MAC_FILE, O_RDWR | O_CREAT, 0644);if (IS_ERR(fp)) {  printk(KERN_ERR "write mac addr file error,return!\n");return -1;}  fs = get_fs();set_fs(KERNEL_DS);for (i=0; i<6; i++){ u8 mac_tmp[3]= {0,};sprintf(mac_tmp, "%02x", mac_addr[i]);strncat(mac_buf, mac_tmp, 2);}mac_buf[12] = '\0';printk(KERN_INFO "write mac:%s",mac_buf);pos = 0;vfs_write(fp, mac_buf, sizeof(mac_buf), &pos);vfs_fsync(fp, 0);filp_close(fp, NULL);set_fs(fs);return 0;}EXPORT_SYMBOL_GPL(setmac_write_mac_addr);MODULE_AUTHOR("yubo.wang ");MODULE_DESCRIPTION("SETMAC one chip USB 2.0 ethernet devices");MODULE_LICENSE("GPL");

预留问题：

1、量产多个mac地址递增还未实现，发现ops文件指针偏移不准导致读数据异常

2、没有对mac地址有效性检查，只检查了位数，且单播多播和OUI也没有检查