Проект OpenNet: MAN strncpy (3) Библиотечные вызовы (FreeBSD и Linux)

Интерактивная система просмотра системных руководств (man-ов)

strncpy (3)

>> strncpy (3) ( FreeBSD man: Библиотечные вызовы )

strncpy (3) ( Русские man: Библиотечные вызовы )

strncpy (3) ( Linux man: Библиотечные вызовы )

strncpy (3) ( POSIX man: Библиотечные вызовы )

BSD mandoc

NAME



strcpy , strncpy

 - copy strings

LIBRARY

Lb libc

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 Fa src to Fa dst (including the terminating `\0' character.)

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

RETURN VALUES

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

"(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 malicious users to arbitrarily change a running program's functionality through a buffer overflow attack. (See the FSA and Sx EXAMPLES . )

STANDARDS

The strcpy ();
and strncpy ();
functions conform to St -isoC . The stpcpy ();
function is an MS-DOS and GNUism. The stpcpy ();
function conforms to no standard.