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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 `\0' 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 `\0' 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 `\0' 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\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:

           (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 .


HISTORY

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

BSD                            February 28, 2009                           BSD

Mac OS X 10.9.1 - Generated Thu Jan 9 06:36:43 CST 2014