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

NAME
     stpcpy, strcpy, strncpy -- copy strings

LIBRARY
     Standard C Library (libc, -lc)

SYNOPSIS
     #include <string.h>

     char *
     stpcpy(char *s1, const char *s2);

     char *
     strcpy(char *restrict s1, const char *restrict s2);

     char *
     strncpy(char *restrict s1, const char *restrict s2, size_t n);

DESCRIPTION
     The stpcpy() and strcpy() functions copy the string s2 to s1 (including
     the terminating `\0' character).

     The strncpy() function copies at most n characters from s2 into s1.  If
     s2 is less than n characters long, the remainder of s1 is filled with
     `\0' characters.  Otherwise, s1 is not terminated.

RETURN VALUES
     The strcpy() and strncpy() functions return s1.  The stpcpy() function
     returns a pointer to the terminating `\0' character of s1.

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));

     Note that, because strlcpy(3) is not defined in any standards, it should
     only be used when portability is not a concern.

SECURITY CONSIDERATIONS
     The strcpy() function is easily misused in a manner which enables mali-cious malicious
     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)

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.

BSD                             August 9, 2001                             BSD