StdLib/LibC/String/Concatenation.c

   1 /** @file
   2     Concatenation Functions for <string.h>.
   3
   4     Copyright (c) 2010, Intel Corporation. All rights reserved.<BR>
   5     This program and the accompanying materials are licensed and made available under
   6     the terms and conditions of the BSD License that accompanies this distribution.
   7     The full text of the license may be found at
   8     http://opensource.org/licenses/bsd-license.php.
   9
  10     THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
  11     WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
  12 **/
  13 #include  <Uefi.h>
  14 #include  <Library/BaseLib.h>
  15
  16 #include  <LibConfig.h>
  17
  18 #include  <string.h>
  19
  20 /** The strcat function appends a copy of the string pointed to by s2
  21     (including the terminating null character) to the end of the string pointed
  22     to by s1. The initial character of s2 overwrites the null character at the
  23     end of s1. If copying takes place between objects that overlap, the
  24     behavior is undefined.
  25
  26     @return   The strcat function returns the value of s1.
  27 **/
  28 char *
  29 strcat(char * __restrict s1, const char * __restrict s2)
  30 {
  31   return AsciiStrCat( s1, s2);
  32 }
  33
  34 /** The strncat function appends not more than n characters (a null character
  35     and characters that follow it are not appended) from the array pointed to
  36     by s2 to the end of the string pointed to by s1. The initial character of
  37     s2 overwrites the null character at the end of s1. A terminating null
  38     character is always appended to the result. If copying takes place
  39     between objects that overlap, the behavior is undefined.
  40
  41     @return   The strncat function returns the value of s1.
  42 **/
  43 char *
  44 strncat(char * __restrict s1, const char * __restrict s2, size_t n)
  45 {
  46   return AsciiStrnCat( s1, s2, n);
  47 }
  48
  49 /** The strncatX function appends not more than n characters (a null character
  50     and characters that follow it are not appended) from the array pointed to
  51     by s2 to the end of the string pointed to by s1. The initial character of
  52     s2 overwrites the null character at the end of s1. The result is always
  53     terminated with a null character. If copying takes place between objects
  54     that overlap, the behavior is undefined.
  55
  56     strncatX exists because normal strncat does not indicate if the operation
  57     was terminated because of exhausting n or reaching the end of s2.
  58
  59     @return   The strncatX function returns 0 if the operation was terminated
  60               because it reached the end of s1.  Otherwise, a non-zero value is
  61               returned indicating how many characters remain in s1.
  62 **/
  63 int
  64 strncatX(char * __restrict s1, const char * __restrict s2, size_t n)
  65 {
  66   int NumLeft;
  67
  68   // Find s1's terminating NUL
  69   for( ; n != 0; --n) {
  70     if( *s1++ == '\0')  break;
  71   }
  72
  73   // Now copy *s2 into s1, overwriting s1's terminating NUL
  74   for( --s1; n != 0; --n) {
  75     if((*s1++ = *s2++) == '\0')  break;
  76   }
  77   NumLeft = (int)n;
  78
  79   // Guarantee that s1 is NUL terminated.
  80   *--s1 = '\0';
  81
  82   return NumLeft;   // Zero if we ran out of buffer ( strlen(s1) < strlen(s2) )
  83 }