arch/frv/kernel/uaccess.c

   1 /* uaccess.c: userspace access functions
   2  *
   3  * Copyright (C) 2004 Red Hat, Inc. All Rights Reserved.
   4  * Written by David Howells (dhowells@redhat.com)
   5  *
   6  * This program is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU General Public License
   8  * as published by the Free Software Foundation; either version
   9  * 2 of the License, or (at your option) any later version.
  10  */
  11
  12 #include <linux/mm.h>
  13 #include <linux/module.h>
  14 #include <asm/uaccess.h>
  15
  16 /*****************************************************************************/
  17 /*
  18  * copy a null terminated string from userspace
  19  */
  20 long strncpy_from_user(char *dst, const char __user *src, long count)
  21 {
  22         unsigned long max;
  23         char *p, ch;
  24         long err = -EFAULT;
  25
  26         if (count < 0)
  27                 BUG();
  28
  29         p = dst;
  30
  31 #ifndef CONFIG_MMU
  32         if ((unsigned long) src < memory_start)
  33                 goto error;
  34 #endif
  35
  36         if ((unsigned long) src >= get_addr_limit())
  37                 goto error;
  38
  39         max = get_addr_limit() - (unsigned long) src;
  40         if ((unsigned long) count > max) {
  41                 memset(dst + max, 0, count - max);
  42                 count = max;
  43         }
  44
  45         err = 0;
  46         for (; count > 0; count--, p++, src++) {
  47                 __get_user_asm(err, ch, src, "ub", "=r");
  48                 if (err < 0)
  49                         goto error;
  50                 if (!ch)
  51                         break;
  52                 *p = ch;
  53         }
  54
  55         err = p - dst; /* return length excluding NUL */
  56
  57  error:
  58         if (count > 0)
  59                 memset(p, 0, count); /* clear remainder of buffer [security] */
  60
  61         return err;
  62
  63 } /* end strncpy_from_user() */
  64
  65 EXPORT_SYMBOL(strncpy_from_user);
  66
  67 /*****************************************************************************/
  68 /*
  69  * Return the size of a string (including the ending 0)
  70  *
  71  * Return 0 on exception, a value greater than N if too long
  72  */
  73 long strnlen_user(const char __user *src, long count)
  74 {
  75         const char __user *p;
  76         long err = 0;
  77         char ch;
  78
  79         if (count < 0)
  80                 BUG();
  81
  82 #ifndef CONFIG_MMU
  83         if ((unsigned long) src < memory_start)
  84                 return 0;
  85 #endif
  86
  87         if ((unsigned long) src >= get_addr_limit())
  88                 return 0;
  89
  90         for (p = src; count > 0; count--, p++) {
  91                 __get_user_asm(err, ch, p, "ub", "=r");
  92                 if (err < 0)
  93                         return 0;
  94                 if (!ch)
  95                         break;
  96         }
  97
  98         return p - src + 1; /* return length including NUL */
  99
 100 } /* end strnlen_user() */
 101
 102 EXPORT_SYMBOL(strnlen_user);