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 <asm/uaccess.h>
  14
  15 /*****************************************************************************/
  16 /*
  17  * copy a null terminated string from userspace
  18  */
  19 long strncpy_from_user(char *dst, const char *src, long count)
  20 {
  21         unsigned long max;
  22         char *p, ch;
  23         long err = -EFAULT;
  24
  25         if (count < 0)
  26                 BUG();
  27
  28         p = dst;
  29
  30 #ifndef CONFIG_MMU
  31         if ((unsigned long) src < memory_start)
  32                 goto error;
  33 #endif
  34
  35         if ((unsigned long) src >= get_addr_limit())
  36                 goto error;
  37
  38         max = get_addr_limit() - (unsigned long) src;
  39         if ((unsigned long) count > max) {
  40                 memset(dst + max, 0, count - max);
  41                 count = max;
  42         }
  43
  44         err = 0;
  45         for (; count > 0; count--, p++, src++) {
  46                 __get_user_asm(err, ch, src, "ub", "=r");
  47                 if (err < 0)
  48                         goto error;
  49                 if (!ch)
  50                         break;
  51                 *p = ch;
  52         }
  53
  54         err = p - dst; /* return length excluding NUL */
  55
  56  error:
  57         if (count > 0)
  58                 memset(p, 0, count); /* clear remainder of buffer [security] */
  59
  60         return err;
  61 } /* end strncpy_from_user() */
  62
  63 /*****************************************************************************/
  64 /*
  65  * Return the size of a string (including the ending 0)
  66  *
  67  * Return 0 on exception, a value greater than N if too long
  68  */
  69 long strnlen_user(const char *src, long count)
  70 {
  71         const char *p;
  72         long err = 0;
  73         char ch;
  74
  75         if (count < 0)
  76                 BUG();
  77
  78 #ifndef CONFIG_MMU
  79         if ((unsigned long) src < memory_start)
  80                 return 0;
  81 #endif
  82
  83         if ((unsigned long) src >= get_addr_limit())
  84                 return 0;
  85
  86         for (p = src; count > 0; count--, p++) {
  87                 __get_user_asm(err, ch, p, "ub", "=r");
  88                 if (err < 0)
  89                         return 0;
  90                 if (!ch)
  91                         break;
  92         }
  93
  94         return p - src + 1; /* return length including NUL */
  95 } /* end strnlen_user() */