STRCPY(3)						   BSD Library Functions Manual 						 STRCPY(3)

NAME

     stpcpy, stpncpy, strcpy, strncpy -- copy strings

LIBRARY

     Standard C Library (libc, -lc)

SYNOPSIS

     #include <string.h>

     char *
     stpcpy(char *dst, const char *src);

     char *
     stpncpy(char *restrict dst, const char *restrict src, size_t n);

     char *
     strcpy(char *restrict dst, const char *restrict src);

     char *
     strncpy(char *restrict dst, const char *restrict src, size_t n);

DESCRIPTION

     The stpcpy() and strcpy() functions copy the string src to dst (including the terminating '' character).

     The stpncpy() and strncpy() functions copy at most n characters from src into dst.  If src is less than n characters long, the remainder of
     dst is filled with '' characters.  Otherwise, dst is not terminated.

     The source and destination strings should not overlap, as the behavior is undefined.

RETURN VALUES

     The strcpy() and strncpy() functions return dst.  The stpcpy() and stpncpy() functions return a pointer to the terminating '' character of
     dst.  If stpncpy() does not terminate dst with a NUL character, it instead returns a pointer to dst[n] (which does not necessarily refer to a
     valid memory location.)

EXAMPLES

     The following sets chararray to ``abc'':

	   char chararray[6];

	   (void)strncpy(chararray, "abc", sizeof(chararray));

     The following sets chararray to ``abcdef'':

	   char chararray[6];

	   (void)strncpy(chararray, "abcdefgh", sizeof(chararray));

     Note that it does not NUL terminate chararray, because the length of the source string is greater than or equal to the length argument.

     The following copies as many characters from input to buf as will fit and NUL terminates the result.  Because strncpy() does not guarantee to
     NUL terminate the string itself, this must be done explicitly.

	   char buf[1024];

	   (void)strncpy(buf, input, sizeof(buf) - 1);
	   buf[sizeof(buf) - 1] = '';

     This could be better achieved using strlcpy(3), as shown in the following example:

	   (void)strlcpy(buf, input, sizeof(buf));

SECURITY CONSIDERATIONS

     The strcpy(), strncpy(), stpcpy(), and stpncpy() functions are easily misused in a manner which enables malicious users to arbitrarily change
     a running program's functionality through a buffer overflow attack.  (See the FSA and EXAMPLES.)

     It is recommended that strlcpy(3) be used instead as a way to avoid such problems.  strlcpy(3) is not defined in any standards, but it has
     been adopted by most major libc implementations.

SEE ALSO

     bcopy(3), memccpy(3), memcpy(3), memmove(3), strlcpy(3), wcscpy(3)

STANDARDS

     The strcpy() and strncpy() functions conform to ISO/IEC 9899:1990 (``ISO C90'').  The stpcpy() and stpncpy() functions conform to IEEE Std
     1003.1-2008 (``POSIX.1'').

HISTORY

     The stpcpy() function first appeared in FreeBSD 4.4, and stpncpy() was added in FreeBSD 8.0.

BSD
								 February 28, 2009							       BSD