mach/mig_strncpy.c

   1 /*
   2  * Copyright (c) 1999 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * This file contains Original Code and/or Modifications of Original Code
   7  * as defined in and that are subject to the Apple Public Source License
   8  * Version 2.0 (the 'License'). You may not use this file except in
   9  * compliance with the License. Please obtain a copy of the License at
  10  * http://www.opensource.apple.com/apsl/ and read it before using this
  11  * file.
  12  *
  13  * The Original Code and all software distributed under the License are
  14  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  15  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  16  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  17  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  18  * Please see the License for the specific language governing rights and
  19  * limitations under the License.
  20  *
  21  * @APPLE_LICENSE_HEADER_END@
  22  */
  23 /*
  24  * Mach Operating System
  25  * Copyright (c) 1991,1990,1989 Carnegie Mellon University
  26  * All Rights Reserved.
  27  *
  28  * Permission to use, copy, modify and distribute this software and its
  29  * documentation is hereby granted, provided that both the copyright
  30  * notice and this permission notice appear in all copies of the
  31  * software, derivative works or modified versions, and any portions
  32  * thereof, and that both notices appear in supporting documentation.
  33  *
  34  * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
  35  * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
  36  * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
  37  *
  38  * Carnegie Mellon requests users of this software to return to
  39  *
  40  *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
  41  *  School of Computer Science
  42  *  Carnegie Mellon University
  43  *  Pittsburgh PA 15213-3890
  44  *
  45  * any improvements or extensions that they make and grant Carnegie Mellon
  46  * the rights to redistribute these changes.
  47  */
  48 /*
  49  * mig_strncpy.c - by Joshua Block
  50  *
  51  * mig_strncpy -- Bounded string copy.  Does what the library routine strncpy
  52  * OUGHT to do:  Copies the (null terminated) string in src into dest, a
  53  * buffer of length len.  Assures that the copy is still null terminated
  54  * and doesn't overflow the buffer, truncating the copy if necessary.
  55  *
  56  * Parameters:
  57  *
  58  *     dest - Pointer to destination buffer.
  59  *
  60  *     src - Pointer to source string.
  61  *
  62  *     len - Length of destination buffer.
  63  *
  64  * Result:
  65  *      length of string copied, INCLUDING the trailing 0.
  66  */
  67 #include <mach/mig_errors.h>
  68
  69 int
  70 mig_strncpy(
  71     register char *dest,
  72     register const char *src,
  73     register int len)
  74 {
  75     register int i;
  76
  77     if (len <= 0)
  78         return 0;
  79
  80     for (i=1; i<len; i++)
  81         if (! (*dest++ = *src++))
  82             return i;
  83
  84     *dest = '\0';
  85     return i;
  86 }