【内核】：一个使用 seq_file 接口的 proc_fs 例子

#include <linux/module.h>

#include <linux/proc_fs.h>

#include <linux/seq_file.h>

#include <asm/uaccess.h>

static struct proc_dir_entry *pfile;

static char *myfruits[5] = {"apple", "orange", "banana", "watermelon", "pear"};

static void *my_seq_start(struct seq_file *s, loff_t *pos)

{

if (*pos >= 5)

return NULL;

return myfruits[*pos];

}

static void *my_seq_next(struct seq_file *s, void *v, loff_t *pos)

{

if (++*pos >= 5)

return NULL;

return myfruits[*pos];

}

static void my_seq_stop(struct seq_file *s, void *v)

{

// nothing to do;

}

static int my_seq_show(struct seq_file *s, void *v)

{

seq_printf(s, "%s ", (char *)v);

return 0;

}

static struct seq_operations proc_seq_ops = {

.start = my_seq_start,

.next = my_seq_next,

.stop = my_seq_stop,

.show = my_seq_show,

};

static int my_seq_open(struct inode *inode, struct file *file)

{

return seq_open(file, &proc_seq_ops);

}

static struct file_operations proc_fops = {

.open = my_seq_open,

.read = seq_read,

.llseek = seq_lseek,

.release = seq_release,

};

static int __init myproc_init(void)

{

pfile = proc_create("fruits", 0666, NULL, &proc_fops);

if (!pfile) {

printk(KERN_ERR "Can't create /proc/fruits/n");

remove_proc_entry("mydir", NULL);

return -1;

}

return 0;

}

static void __exit myproc_exit(void)

{

remove_proc_entry("fruits", NULL);

}

module_init(myproc_init);

module_exit(myproc_exit);