procfs信息读取实现案例
/********************************************** * Author: lewiyon@hotmail.com * File name: proc_sample.c * Description: create a file "proc_example" in the /proc, * which allows read. * Date: 2011-12-11 * Version: V1.0 *********************************************/ #include <linux/kernel.h> /* We're doing kernel work */ #include <linux/module.h> /* Specifically, a module */ #include <linux/proc_fs.h> /* Necessary because we use proc fs */ #include <asm/uaccess.h> /* for get_user and put_user */ #define MESSAGE_LENGTH 80 #define PROC_NAME "proc_sample" unsigned int flag = 100; static struct proc_dir_entry *proc_sample; static struct proc_dir_entry *sample, *sample_r; /** * proc_read_data() * @page - buffer to write the data in * @start - where the actual data has been written in page * @offset - same meaning as the read system call * @count - same meaning as the read system call * @eof - set if no more data needs to be returned * @data - pointer to our soft state */ static int proc_read_data(char *page, char **stat, off_t off, int count, int *eof, void *data) { int len; len = sprintf(page, "jiffies = %ld\n", jiffies); return len; } /* * 模块初始化 */ static int __init sample_init(void) { int ret = 0; /* * proc_mkdir(name, parent) * 在parent对应的目录下创建name目录 * 返回目录对应的proc_dir_dentry */ proc_sample = proc_mkdir(PROC_NAME, NULL); if (NULL == proc_sample) { ret = -ENOMEM; goto proc_sample_err; } /* * create_proc_entry(name, mode,parent) * 在parent对应的目录下创建name文件 * 返回目录对应的proc_dir_dentry */ sample = create_proc_entry("sample", 0644, proc_sample); if (NULL == sample) { ret = -ENOMEM; goto sample_err; } sample_r = create_proc_read_entry("sample_r", 0444, proc_sample, proc_read_data, NULL); if (NULL == sample_r) { ret = -ENOMEM; goto sample_r_err; } printk(KERN_INFO "Create sample\n"); return ret; sample_r_err: remove_proc_entry("sample", proc_sample); sample_err: remove_proc_entry(PROC_NAME, NULL); proc_sample_err: return ret; } /* * 模块清理 */ static void __exit sample_exit(void) { remove_proc_entry("sample", proc_sample); remove_proc_entry("sample_r", proc_sample); remove_proc_entry(PROC_NAME, NULL); printk(KERN_INFO "Remove /proc/proc_sample\n"); } module_init(sample_init); module_exit(sample_exit); MODULE_LICENSE("GPL"); MODULE_AUTHOR("lewiyon <lewiyon@hotmail.com>");在/proc/创建文件目录proc_sampe,然后在其下创建了两个文件。其中sample_r可读取数据
posted on 2011-12-12 01:00 YoungerChina 阅读(231) 评论(0) 编辑 收藏 举报