string2.h

它通过提供glibc兼容使得应用程序移植到较小的c 库时相当得容易. 它能够应用到带虚拟存储的Linux和uClinux上.在大多数带MMU部件的平台上为使它更加紧凑,它也能够编译成共享库.uClib

{
  union {
    __uint32_t __ui;
    __uint16_t __usi;
    unsigned char __uc;
  } *__u = (void *) __dest;
  switch ((unsigned int) __srclen)
    {
    case 1:
      __u->__uc = '\0';
      break;
    case 2:
      __u->__usi = __src0_2;
      break;
    case 3:
      __u->__usi = __src0_2;
      __u = __extension__ (void *)((char *) __u + 2);
      __u->__uc = '\0';
      break;
    case 4:
      __u->__ui = __src0_4;
      break;
    case 5:
      __u->__ui = __src0_4;
      __u = __extension__ (void *)((char *) __u + 4);
      __u->__uc = '\0';
      break;
    case 6:
      __u->__ui = __src0_4;
      __u = __extension__ (void *)((char *) __u + 4);
      __u->__usi = __src4_2;
      break;
    case 7:
      __u->__ui = __src0_4;
      __u = __extension__ (void *)((char *) __u + 4);
      __u->__usi = __src4_2;
      __u = __extension__ (void *)((char *) __u + 2);
      __u->__uc = '\0';
      break;
    case 8:
      __u->__ui = __src0_4;
      __u = __extension__ (void *)((char *) __u + 4);
      __u->__ui = __src4_4;
      break;
    }
  return __dest;
}
# else
#  ifndef _FORCE_INLINES
#   define __strcpy_args(src) \
     __extension__ ((__STRING2_COPY_ARR2)				      \
      { { ((__const char *) (src))[0], '\0' } }),			      \
     __extension__ ((__STRING2_COPY_ARR3)				      \
      { { ((__const char *) (src))[0], ((__const char *) (src))[1],	      \
	  '\0' } }),							      \
     __extension__ ((__STRING2_COPY_ARR4)				      \
      { { ((__const char *) (src))[0], ((__const char *) (src))[1],	      \
	  ((__const char *) (src))[2], '\0' } }),			      \
     __extension__ ((__STRING2_COPY_ARR5)				      \
      { { ((__const char *) (src))[0], ((__const char *) (src))[1],	      \
	  ((__const char *) (src))[2], ((__const char *) (src))[3],	      \
	  '\0' } }),							      \
     __extension__ ((__STRING2_COPY_ARR6)				      \
      { { ((__const char *) (src))[0], ((__const char *) (src))[1],	      \
	  ((__const char *) (src))[2], ((__const char *) (src))[3],	      \
	  ((__const char *) (src))[4], '\0' } }),			      \
     __extension__ ((__STRING2_COPY_ARR7)				      \
      { { ((__const char *) (src))[0], ((__const char *) (src))[1],	      \
	  ((__const char *) (src))[2], ((__const char *) (src))[3],	      \
	  ((__const char *) (src))[4], ((__const char *) (src))[5],	      \
	  '\0' } }),							      \
     __extension__ ((__STRING2_COPY_ARR8)				      \
      { { ((__const char *) (src))[0], ((__const char *) (src))[1],	      \
	  ((__const char *) (src))[2], ((__const char *) (src))[3],	      \
	  ((__const char *) (src))[4], ((__const char *) (src))[5],	      \
	  ((__const char *) (src))[6], '\0' } })
#  endif
__STRING_INLINE char *__strcpy_small (char *, __STRING2_COPY_ARR2,
				      __STRING2_COPY_ARR3,
				      __STRING2_COPY_ARR4,
				      __STRING2_COPY_ARR5,
				      __STRING2_COPY_ARR6,
				      __STRING2_COPY_ARR7,
				      __STRING2_COPY_ARR8, size_t);
__STRING_INLINE char *
__strcpy_small (char *__dest,
		__STRING2_COPY_ARR2 __src2, __STRING2_COPY_ARR3 __src3,
		__STRING2_COPY_ARR4 __src4, __STRING2_COPY_ARR5 __src5,
		__STRING2_COPY_ARR6 __src6, __STRING2_COPY_ARR7 __src7,
		__STRING2_COPY_ARR8 __src8, size_t __srclen)
{
  union {
    char __c;
    __STRING2_COPY_ARR2 __sca2;
    __STRING2_COPY_ARR3 __sca3;
    __STRING2_COPY_ARR4 __sca4;
    __STRING2_COPY_ARR5 __sca5;
    __STRING2_COPY_ARR6 __sca6;
    __STRING2_COPY_ARR7 __sca7;
    __STRING2_COPY_ARR8 __sca8;
  } *__u = (void *) __dest;
  switch ((unsigned int) __srclen)
    {
    case 1:
      __u->__c = '\0';
      break;
    case 2:
      __extension__ __u->__sca2 = __src2;
      break;
    case 3:
      __extension__ __u->__sca3 = __src3;
      break;
    case 4:
      __extension__ __u->__sca4 = __src4;
      break;
    case 5:
      __extension__ __u->__sca5 = __src5;
      break;
    case 6:
      __extension__ __u->__sca6 = __src6;
      break;
    case 7:
      __extension__ __u->__sca7 = __src7;
      break;
    case 8:
      __extension__ __u->__sca8 = __src8;
      break;
  }
  return __dest;
}
# endif
#endif


/* Copy SRC to DEST, returning pointer to final NUL byte.  */
#ifdef __USE_GNU
# if !defined _HAVE_STRING_ARCH_stpcpy || defined _FORCE_INLINES
#  ifndef _HAVE_STRING_ARCH_stpcpy
#   if __GNUC_PREREQ (3, 0)
#    define __stpcpy(dest, src) \
  (__extension__ (__builtin_constant_p (src)				      \
		  ? (__string2_1bptr_p (src) && strlen (src) + 1 <= 8	      \
		     ? __builtin_strcpy (dest, src) + strlen (src)	      \
		     : ((char *) (__mempcpy) (dest, src, strlen (src) + 1)    \
			- 1))						      \
		  : __stpcpy (dest, src)))
#   else
#    define __stpcpy(dest, src) \
  (__extension__ (__builtin_constant_p (src)				      \
		  ? (__string2_1bptr_p (src) && strlen (src) + 1 <= 8	      \
		     ? __stpcpy_small (dest, __stpcpy_args (src),	      \
				       strlen (src) + 1)		      \
		     : ((char *) (__mempcpy) (dest, src, strlen (src) + 1)    \
			- 1))						      \
		  : __stpcpy (dest, src)))
#   endif
/* In glibc we use this function frequently but for namespace reasons
   we have to use the name `__stpcpy'.  */
#   define stpcpy(dest, src) __stpcpy (dest, src)
#  endif

#  if !__GNUC_PREREQ (3, 0) || defined _FORCE_INLINES
#   if _STRING_ARCH_unaligned
#    ifndef _FORCE_INLINES
#     define __stpcpy_args(src) \
     __extension__ __STRING2_SMALL_GET16 (src, 0),			      \
     __extension__ __STRING2_SMALL_GET16 (src, 4),			      \
     __extension__ __STRING2_SMALL_GET32 (src, 0),			      \
     __extension__ __STRING2_SMALL_GET32 (src, 4)
#    endif
__STRING_INLINE char *__stpcpy_small (char *, __uint16_t, __uint16_t,
				      __uint32_t, __uint32_t, size_t);
__STRING_INLINE char *
__stpcpy_small (char *__dest,
		__uint16_t __src0_2, __uint16_t __src4_2,
		__uint32_t __src0_4, __uint32_t __src4_4,
		size_t __srclen)
{
  union {
    unsigned int __ui;
    unsigned short int __usi;
    unsigned char __uc;
    char __c;
  } *__u = (void *) __dest;
  switch ((unsigned int) __srclen)
    {
    case 1:
      __u->__uc = '\0';
      break;
    case 2:
      __u->__usi = __src0_2;
      __u = __extension__ (void *)((char *) __u + 1);
      break;
    case 3:
      __u->__usi = __src0_2;
      __u = __extension__ (void *)((char *) __u + 2);
      __u->__uc = '\0';
      break;
    case 4:
      __u->__ui = __src0_4;
      __u = __extension__ (void *)((char *) __u + 3);
      break;
    case 5:
      __u->__ui = __src0_4;
      __u = __extension__ (void *)((char *) __u + 4);
      __u->__uc = '\0';
      break;
    case 6:
      __u->__ui = __src0_4;
      __u = __extension__ (void *)((char *) __u + 4);
      __u->__usi = __src4_2;
      __u = __extension__ (void *)((char *) __u + 1);
      break;
    case 7:
      __u->__ui = __src0_4;
      __u = __extension__ (void *)((char *) __u + 4);
      __u->__usi = __src4_2;
      __u = __extension__ (void *)((char *) __u + 2);
      __u->__uc = '\0';
      break;
    case 8:
      __u->__ui = __src0_4;
      __u = __extension__ (void *)((char *) __u + 4);
      __u->__ui = __src4_4;
      __u = __extension__ (void *)((char *) __u + 3);
      break;
    }
  return &__u->__c;
}
#   else
#    ifndef _FORCE_INLINES
#     define __stpcpy_args(src) \
     __extension__ ((__STRING2_COPY_ARR2)				      \
      { { ((__const char *) (src))[0], '\0' } }),			      \
     __extension__ ((__STRING2_COPY_ARR3)				      \
      { { ((__const char *) (src))[0], ((__const char *) (src))[1],	      \
	  '\0' } }),							      \
     __extension__ ((__STRING2_COPY_ARR4)				      \
      { { ((__const char *) (src))[0], ((__const char *) (src))[1],	      \
	  ((__const char *) (src))[2], '\0' } }),			      \
     __extension__ ((__STRING2_COPY_ARR5)				      \
      { { ((__const char *) (src))[0], ((__const char *) (src))[1],	      \
	  ((__const char *) (src))[2], ((__const char *) (src))[3],	      \
	  '\0' } }),							      \
     __extension__ ((__STRING2_COPY_ARR6)				      \
      { { ((__const char *) (src))[0], ((__const char *) (src))[1],	      \
	  ((__const char *) (src))[2], ((__const char *) (src))[3],	      \
	  ((__const char *) (src))[4], '\0' } }),			      \
     __extension__ ((__STRING2_COPY_ARR7)				      \
      { { ((__const char *) (src))[0], ((__const char *) (src))[1],	      \
	  ((__const char *) (src))[2], ((__const char *) (src))[3],	      \
	  ((__const char *) (src))[4], ((__const char *) (src))[5],	      \
	  '\0' } }),							      \
     __extension__ ((__STRING2_COPY_ARR8)				      \
      { { ((__const char *) (src))[0], ((__const char *) (src))[1],	      \
	  ((__const char *) (src))[2], ((__const char *) (src))[3],	      \
	  ((__const char *) (src))[4], ((__const char *) (src))[5],	      \
	  ((__const char *) (src))[6], '\0' } })
#    endif
__STRING_INLINE char *__stpcpy_small (char *, __STRING2_COPY_ARR2,
				      __STRING2_COPY_ARR3,
				      __STRING2_COPY_ARR4,
				      __STRING2_COPY_ARR5,
				      __STRING2_COPY_ARR6,
				      __STRING2_COPY_ARR7,
				      __STRING2_COPY_ARR8, size_t);
__STRING_INLINE char *
__stpcpy_small (char *__dest,
		__STRING2_COPY_ARR2 __src2, __STRING2_COPY_ARR3 __src3,
		__STRING2_COPY_ARR4 __src4, __STRING2_COPY_ARR5 __src5,
		__STRING2_COPY_ARR6 __src6, __STRING2_COPY_ARR7 __src7,
		__STRING2_COPY_ARR8 __src8, size_t __srclen)
{
  union {
    char __c;
    __STRING2_COPY_ARR2 __sca2;
    __STRING2_COPY_ARR3 __sca3;
    __STRING2_COPY_ARR4 __sca4;
    __STRING2_COPY_ARR5 __sca5;
    __STRING2_COPY_ARR6 __sca6;
    __STRING2_COPY_ARR7 __sca7;
    __STRING2_COPY_ARR8 __sca8;
  } *__u = (void *) __dest;
  switch ((unsigned int) __srclen)
    {
    case 1:
      __u->__c = '\0';
      break;
    case 2:
      __extension__ __u->__sca2 = __src2;
      break;
    case 3:
      __extension__ __u->__sca3 = __src3;
      break;
    case 4:
      __extension__ __u->__sca4 = __src4;
      break;
    case 5:
      __extension__ __u->__sca5 = __src5;
      break;
    case 6:
      __extension__ __u->__sca6 = __src6;
      break;
    case 7:
      __extension__ __u->__sca7 = __src7;
      break;
    case 8:
      __extension__ __u->__sca8 = __src8;
      break;
  }
  return __dest + __srclen - 1;
}
#   endif
#  endif
# endif
#endif


/* Copy no more than N characters of SRC to DEST.  */
#ifndef _HAVE_STRING_ARCH_strncpy
# if defined _USE_STRING_ARCH_memset && defined _USE_STRING_ARCH_mempcpy
#  define strncpy(dest, src, n) \
  (__extension__ ({ char *__dest = (dest);				      \
		    __builtin_constant_p (src) && __builtin_constant_p (n)    \
		    ? (strlen (src) + 1 >= ((size_t) (n))		      \
		       ? (char *) memcpy (__dest, src, n)		      \
		       : (memset (__mempcpy (__dest, src, strlen (src)),      \
				  '\0', n - strlen (src)),		      \
			  __dest))					      \
		    : strncpy (__dest, src, n); }))
# else
#  define strncpy(dest, src, n) \
  (__extension__ (__builtin_constant_p (src) && __builtin_constant_p (n)      \
		  ? (strlen (src) + 1 >= ((size_t) (n))			      \
		     ? (char *) memcpy (dest, src, n)			      \
		     : strncpy (dest, src, n))				      \
		  : strncpy (dest, src, n)))
# endif
#endif


/* Append no more than N characters from SRC onto DEST.  */
#ifndef _HAVE_STRING_ARCH_strncat
# ifdef _USE_STRING_ARCH_strchr
#  define strncat(dest, src, n) \
  (__extension__ ({ char *__dest = (dest);				      \
		    __builtin_constant_p (src) && __builtin_constant_p (n)    \
		    ? (strlen (src) < ((size_t) (n))			      \
		       ? strcat (__dest, src)				      \
		       : (*((char *) __mempcpy (strchr (__dest, '\0'),	      \
						src, n)) = '\0', __dest))     \
		    : strncat (dest, src, n); }))
# else
#  define strncat(dest, src, n) \
  (__extension__ (__builtin_constant_p (src) && __builtin_constant_p (n)      \
		  ? (strlen (src) < ((size_t) (n))			      \
		     ? strcat (dest, src)				      \
		     : strncat (dest, src, n))				      \
		  : strncat (dest, src, n)))
# endif
#endif


/* Compare characters of S1 and S2.  */
#ifndef _HAVE_STRING_ARCH_strcmp
# define strcmp(s1, s2) \
  __extension__								      \
  ({ size_t __s1_len, __s2_len;						      \
     (__builtin_constant_p (s1) && __builtin_constant_p (s2)		      \
      && (__s1_len = strlen (s1), __s2_len = strlen (s2),		      \
	  (!__string2_1bptr_p (s1) || __s1_len >= 4)			      \
	  && (!__string2_1bptr_p (s2) || __s2_len >= 4))		      \
      ? memcmp ((__const char *) (s1), (__const char *) (s2),		      \
		(__s1_len < __s2_len ? __s1_len : __s2_len) + 1)	      \
      : (__builtin_constant_p (s1) && __string2_1bptr_p (s1)		      \
	 && (__s1_len = strlen (s1), __s1_len < 4)			      \
	 ? (__builtin_constant_p (s2) && __string2_1bptr_p (s2)		      \
	    ? __strcmp_cc (s1, s2, __s1_len)				      \
	    : __strcmp_cg (s1, s2, __s1_len))				      \
	 : (__builtin_constant_p (s2) && __string2_1bptr_p (s2)		      \
	    && (__s2_len = strlen (s2), __s2_len < 4)			      \
	    ? (__builtin_constant_p (s1) && __string2_1bptr_p (s1)	      \
	       ? __strcmp_cc (s1, s2, __s2_len)				      \
	       : __strcmp_gc (s1, s2, __s2_len))			      \
	    : strcmp (s1, s2)))); })

# define __strcmp_cc(s1, s2, l) \
  (__extension__ ({ register int __result =				      \
		      (((__const unsigned char *) (__const char *) (s1))[0]   \
		       - ((__const unsigned char *) (__const char *)(s2))[0]);\
		    if (l > 0 && __result == 0)				      \
		      {							      \
			__result = (((__const unsigned char *)		      \
				     (__const char *) (s1))[1]		      \
				    - ((__const unsigned char *)	      \
				       (__const char *) (s2))[1]);	      \
			if (l > 1 && __result == 0)			      \
			  {						      \
			    __result =					      \
			      (((__const unsigned char *)		      \
				(__const char *) (s1))[2]		      \
			       - ((__const unsigned char *)		      \
				  (__const char *) (s2))[2]);		      \
			    if (l > 2 && __result == 0)			      \
			      __result =				      \
				(((__const unsigned char *)		      \
				  (__const char *) (s1))[3]		      \
				 - ((__const unsigned char *)		      \
				    (__const char *) (s2))[3]);		      \
			  }						      \
		      }							      \
		    __result; }))

# define __strcmp_cg(s1, s2, l1) \
  (__extension__ ({ __const unsigned char *__s2 =			      \
		      (__const unsigned char *) (__const char *) (s2);	      \
		    register int __result =				      \
		      (((__const unsigned char *) (__const char *) (s1))[0]   \
		       - __s2[0]);					      \
		    if (l1 > 0 && __result == 0)			      \
		      {							      \
			__result = (((__const unsigned char *)		      \