proc文件(OLD)

写一个模块测试proc文件的读写：

#include linux/module.h  
#include linux/kernel.h  
#include linux/proc_fs.h  
#include linux/sched.h  
#include asm/uaccess.h  
 
#define STRINGLEN 1024  
 
char global_buffer[STRINGLEN];  
 
struct proc_dir_entry *example_dir, *hello_file;  
 
int proc_read_hello(char *page, char **start, off_t off, int count, int *eof,  
                void *data) {  
        int len;  
        len = sprintf(page, global_buffer); //把global_buffer的内容显示给访问者  
        return len;  
}  
 
int proc_write_hello(struct file *file, const char *buffer, unsigned long count,  
                void *data) {  
        int len;  
 
        if (count = STRINGLEN)  
                len = STRINGLEN – 1;  
        else  
                len = count;  
 
        copy_from_user(global_buffer, buffer, len);  
        global_buffer[len] = 0′;  
        return len;  
}  
 
static int __init proc_test_init(void) {  
        example_dir = proc_mkdir("proc_test", NULL);  
        hello_file = create_proc_entry("hello", S_IRUGO, example_dir);  
        strcpy(global_buffer, "hello");  
        hello_file->read_proc = proc_read_hello;  
        hello_file->write_proc = proc_write_hello;  
        return 0;  
}  
 
static void __exit proc_test_exit(void) {  
        remove_proc_entry("hello", example_dir);  
        remove_proc_entry(“proc_test”, NULL);  
}  
 
module_init(proc_test_init);  
module_exit(proc_test_exit);  

写入proc文件

echo "Hello from kernel" /proc/proc_test/hello'

读取proc文件内容，将看到屏幕上显示了我们写入的字符串:Hello from kernel

cat /proc/proc_test/hello