1 files changed, 56 insertions, 27 deletions

diff --git a/src/lib/libc/string/strcpy.3 b/src/lib/libc/string/strcpy.3
index 1ca12c2707..428e474d43 100644
--- a/src/lib/libc/string/strcpy.3
+++ b/src/lib/libc/string/strcpy.3
@@ -13,11 +13,7 @@
 .\" 2. Redistributions in binary form must reproduce the above copyright
 .\"    notice, this list of conditions and the following disclaimer in the
 .\"    documentation and/or other materials provided with the distribution.
-.\" 3. All advertising materials mentioning features or use of this software
-.\"    must display the following acknowledgement:
-.\"     This product includes software developed by the University of
-.\"     California, Berkeley and its contributors.
-.\" 4. Neither the name of the University nor the names of its contributors
+.\" 3. Neither the name of the University nor the names of its contributors
 .\"    may be used to endorse or promote products derived from this software
 .\"    without specific prior written permission.
 .\"
@@ -33,14 +29,14 @@
 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 .\" SUCH DAMAGE.
 .\"
-.\"     from: @(#)strcpy.3      5.4 (Berkeley) 6/29/91
-.\"     $Id: strcpy.3,v 1.1.1.1 1995/10/18 08:42:22 deraadt Exp $
+.\"     $OpenBSD: strcpy.3,v 1.15 2007/05/31 19:19:32 jmc Exp $
 .\"
-.Dd June 29, 1991
+.Dd $Mdocdate: May 31 2007 $
 .Dt STRCPY 3
-.Os BSD 4
+.Os
 .Sh NAME
-.Nm strcpy
+.Nm strcpy ,
+.Nm strncpy
 .Nd copy strings
 .Sh SYNOPSIS
 .Fd #include <string.h>
@@ -53,8 +49,7 @@ The
 .Fn strcpy
 and
 .Fn strncpy
-functions
-copy the string
+functions copy the string
 .Fa src
 to
 .Fa dst
@@ -62,7 +57,6 @@ to
 .Ql \e0
 character).
 .Pp
-The
 .Fn strncpy
 copies not more than
 .Fa len
@@ -78,45 +72,80 @@ characters long, and
 .Em not
 terminating
 .Fa dst
-if
+if the length of
 .Fa src
-is more than
-.Fa len
-characters long.
+is greater than or equal to
+.Fa len .
 .Sh RETURN VALUES
 The
 .Fn strcpy
 and
 .Fn strncpy
-functions
-return
+functions return
 .Fa dst .
 .Sh EXAMPLES
 The following sets
-.Dq Li chararray
+.Va chararray
 to
-.Dq Li abc\e0\e0\e0 :
+.Dq abc\e0\e0\e0 :
 .Bd -literal -offset indent
-(void)strncpy(chararray, "abc", 6).
+(void)strncpy(chararray, "abc", 6);
 .Ed
 .Pp
 The following sets
-.Dq Li chararray
+.Va chararray
 to
-.Dq Li abcdef :
+.Dq abcdef
+and does
+.Em not
+NUL terminate
+.Va chararray
+because the length of the source string is greater than or equal to the
+length parameter.
+.Fn strncpy
+.Em only
+NUL terminates the destination string when the length of the source
+string is less than the length parameter.
 .Bd -literal -offset indent
 (void)strncpy(chararray, "abcdefgh", 6);
 .Ed
+.Pp
+The following copies as many characters from
+.Va input
+to
+.Va buf
+as will fit and NUL terminates the result.
+Because
+.Fn strncpy
+does
+.Em not
+guarantee to NUL terminate the string itself, it must be done by hand.
+.Bd -literal -offset indent
+char buf[BUFSIZ];
+
+(void)strncpy(buf, input, sizeof(buf) - 1);
+buf[sizeof(buf) - 1] = '\e0';
+.Ed
+.Pp
+Note that
+.Xr strlcpy 3
+is a better choice for this kind of operation.
+The equivalent using
+.Xr strlcpy 3
+is simply:
+.Bd -literal -offset indent
+(void)strlcpy(buf, input, sizeof(buf));
+.Ed
 .Sh SEE ALSO
 .Xr bcopy 3 ,
 .Xr memccpy 3 ,
 .Xr memcpy 3 ,
-.Xr memmove 3
+.Xr memmove 3 ,
+.Xr strlcpy 3
 .Sh STANDARDS
 The
 .Fn strcpy
 and
 .Fn strncpy
-functions
-conform to
+functions conform to
 .St -ansiC .