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strncpy(3)

NAME

     strcpy, strncpy -- copy strings

LIBRARY

     Standard C Library (libc, -lc)

SYNOPSIS

     #include <string.h>

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

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

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

DESCRIPTION

     The stpcpy() and strcpy() functions copy the string src to dst (including
     the terminating `\0' character.)

     The strncpy() function copies at most len characters from src into dst.
     If src is less than len characters long, the remainder of dst is filled
     with `\0' characters.  Otherwise, dst is not terminated.

RETURN VALUES

     The strcpy() and strncpy() functions return dst.  The stpcpy() function
     returns a pointer to the terminating `\0' character of dst.

EXAMPLES

     The following sets chararray to ``abc\0\0\0'':

	   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] = '\0';

     This could be better achieved using strlcpy(3), as shown in the following
     example:
     cious users to arbitrarily change a running program's functionality
     through a buffer overflow attack.	(See the FSA and EXAMPLES.)

SEE ALSO

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

     The FreeBSD Security Architecture.  (See /usr/share/doc/{to be decided}.)

STANDARDS

     The strcpy() and strncpy() functions conform to ISO/IEC 9899:1990
     (``ISO C90'').  The stpcpy() function is an MS-DOS and GNUism.  The
     stpcpy() function conforms to no standard.

HISTORY

     The stpcpy() function first appeared in FreeBSD 4.4, coming from
     1998-vintage Linux.

FreeBSD 5.4			August 9, 2001			   FreeBSD 5.4

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