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glibc  2.9
Functions
strncat_chk.c File Reference
#include <string.h>
#include <memcopy.h>

Go to the source code of this file.

Functions

char * __strncat_chk (char *s1, const char *s2, size_t n, size_t s1len)

Function Documentation

char* __strncat_chk ( char *  s1,
const char *  s2,
size_t  n,
size_t  s1len 
)

Definition at line 25 of file strncat_chk.c.

{
  reg_char c;
  char *s = s1;

  /* Find the end of S1.  */
  do
    {
      if (__builtin_expect (s1len-- == 0, 0))
       __chk_fail ();
      c = *s1++;
    }
  while (c != '\0');

  /* Make S1 point before next character, so we can increment
     it while memory is read (wins on pipelined cpus).  */
  ++s1len;
  s1 -= 2;

  if (n >= 4)
    {
      size_t n4 = n >> 2;
      do
       {
         if (__builtin_expect (s1len-- == 0, 0))
           __chk_fail ();
         c = *s2++;
         *++s1 = c;
         if (c == '\0')
           return s;
         if (__builtin_expect (s1len-- == 0, 0))
           __chk_fail ();
         c = *s2++;
         *++s1 = c;
         if (c == '\0')
           return s;
         if (__builtin_expect (s1len-- == 0, 0))
           __chk_fail ();
         c = *s2++;
         *++s1 = c;
         if (c == '\0')
           return s;
         if (__builtin_expect (s1len-- == 0, 0))
           __chk_fail ();
         c = *s2++;
         *++s1 = c;
         if (c == '\0')
           return s;
       } while (--n4 > 0);
      n &= 3;
    }

  while (n > 0)
    {
      if (__builtin_expect (s1len-- == 0, 0))
       __chk_fail ();
      c = *s2++;
      *++s1 = c;
      if (c == '\0')
       return s;
      n--;
    }

  if (c != '\0')
    {
      if (__builtin_expect (s1len-- == 0, 0))
       __chk_fail ();
      *++s1 = '\0';
    }

  return s;
}

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