LXR RHEL4/mm/util.c

   1#include <linux/slab.h>
   2#include <linux/string.h>
   3#include <linux/module.h>
   4#include <linux/err.h>
   5#include <asm/uaccess.h>
   6
   7/*
   8 * strndup_user - duplicate an existing string from user space
   9 *
  10 * @s: The string to duplicate
  11 * @n: Maximum number of bytes to copy, including the trailing NUL.
  12 */
  13char *strndup_user(const char __user *s, long n)
  14{
  15        char *p;
  16        long length;
  17
  18        length = strnlen_user(s, n);
  19
  20        if (!length)
  21                return ERR_PTR(-EFAULT);
  22
  23        if (length > n)
  24                return ERR_PTR(-EINVAL);
  25
  26        p = kmalloc(length, GFP_KERNEL);
  27
  28        if (!p)
  29                return ERR_PTR(-ENOMEM);
  30
  31        if (copy_from_user(p, s, length)) {
  32                kfree(p);
  33                return ERR_PTR(-EFAULT);
  34        }
  35
  36        p[length - 1] = '\0';
  37
  38        return p;
  39}
  40EXPORT_SYMBOL(strndup_user);
  41