libsyscall/mach/mig_strncpy.c

   1 /*
   2  * Copyright (c) 1999-2010 Apple Inc. All rights reserved.
   3  *
   4  * @APPLE_OSREFERENCE_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. The rights granted to you under the License
  10  * may not be used to create, or enable the creation or redistribution of,
  11  * unlawful or unlicensed copies of an Apple operating system, or to
  12  * circumvent, violate, or enable the circumvention or violation of, any
  13  * terms of an Apple operating system software license agreement.
  14  *
  15  * Please obtain a copy of the License at
  16  * http://www.opensource.apple.com/apsl/ and read it before using this file.
  17  *
  18  * The Original Code and all software distributed under the License are
  19  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  20  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  21  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
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  23  * Please see the License for the specific language governing rights and
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  27  */
  28 /*
  29  * Mach Operating System
  30  * Copyright (c) 1991,1990,1989 Carnegie Mellon University
  31  * All Rights Reserved.
  32  *
  33  * Permission to use, copy, modify and distribute this software and its
  34  * documentation is hereby granted, provided that both the copyright
  35  * notice and this permission notice appear in all copies of the
  36  * software, derivative works or modified versions, and any portions
  37  * thereof, and that both notices appear in supporting documentation.
  38  *
  39  * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
  40  * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
  41  * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
  42  *
  43  * Carnegie Mellon requests users of this software to return to
  44  *
  45  *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
  46  *  School of Computer Science
  47  *  Carnegie Mellon University
  48  *  Pittsburgh PA 15213-3890
  49  *
  50  * any improvements or extensions that they make and grant Carnegie Mellon
  51  * the rights to redistribute these changes.
  52  */
  53 /*
  54  * mig_strncpy.c - by Joshua Block
  55  *
  56  * mig_strncpy -- Bounded string copy.  Does what the library routine strncpy
  57  * OUGHT to do:  Copies the (null terminated) string in src into dest, a
  58  * buffer of length len.  Assures that the copy is still null terminated
  59  * and doesn't overflow the buffer, truncating the copy if necessary.
  60  *
  61  * Parameters:
  62  *
  63  *     dest - Pointer to destination buffer.
  64  *
  65  *     src - Pointer to source string.
  66  *
  67  *     len - Length of destination buffer.
  68  *
  69  * Result:
  70  *      length of string copied, INCLUDING the trailing 0.
  71  */
  72 #include <mach/mig_errors.h>
  73
  74 int
  75 mig_strncpy(
  76     char *dest,
  77     const char *src,
  78     int len)
  79 {
  80     int i;
  81
  82     if (len <= 0) {
  83                 return 0;
  84         }
  85
  86     for (i = 1; i < len; i++) {
  87                 if (!(*dest++ = *src++)) {
  88                         return i;
  89                 }
  90         }
  91
  92     *dest = '\0';
  93     return i;
  94 }