LXR linux/fs/proc/devices.c

   1#include <linux/fs.h>
   2#include <linux/init.h>
   3#include <linux/proc_fs.h>
   4#include <linux/seq_file.h>
   5
   6static int devinfo_show(struct seq_file *f, void *v)
   7{
   8        int i = *(loff_t *) v;
   9
  10        if (i < CHRDEV_MAJOR_HASH_SIZE) {
  11                if (i == 0)
  12                        seq_printf(f, "Character devices:\n");
  13                chrdev_show(f, i);
  14        }
  15#ifdef CONFIG_BLOCK
  16        else {
  17                i -= CHRDEV_MAJOR_HASH_SIZE;
  18                if (i == 0)
  19                        seq_printf(f, "\nBlock devices:\n");
  20                blkdev_show(f, i);
  21        }
  22#endif
  23        return 0;
  24}
  25
  26static void *devinfo_start(struct seq_file *f, loff_t *pos)
  27{
  28        if (*pos < (BLKDEV_MAJOR_HASH_SIZE + CHRDEV_MAJOR_HASH_SIZE))
  29                return pos;
  30        return NULL;
  31}
  32
  33static void *devinfo_next(struct seq_file *f, void *v, loff_t *pos)
  34{
  35        (*pos)++;
  36        if (*pos >= (BLKDEV_MAJOR_HASH_SIZE + CHRDEV_MAJOR_HASH_SIZE))
  37                return NULL;
  38        return pos;
  39}
  40
  41static void devinfo_stop(struct seq_file *f, void *v)
  42{
  43        /* Nothing to do */
  44}
  45
  46static const struct seq_operations devinfo_ops = {
  47        .start = devinfo_start,
  48        .next  = devinfo_next,
  49        .stop  = devinfo_stop,
  50        .show  = devinfo_show
  51};
  52
  53static int devinfo_open(struct inode *inode, struct file *filp)
  54{
  55        return seq_open(filp, &devinfo_ops);
  56}
  57
  58static const struct file_operations proc_devinfo_operations = {
  59        .open           = devinfo_open,
  60        .read           = seq_read,
  61        .llseek         = seq_lseek,
  62        .release        = seq_release,
  63};
  64
  65static int __init proc_devices_init(void)
  66{
  67        proc_create("devices", 0, NULL, &proc_devinfo_operations);
  68        return 0;
  69}
  70module_init(proc_devices_init);
  71