.\" 2007-06-15, Marc Boyer <marc.boyer@enseeiht.fr> + mtk
.\" Improve discussion of strncpy().
.\"
-.TH STRCPY 3 2015-08-08 "GNU" "Linux Programmer's Manual"
+.TH STRCPY 3 2019-03-06 "GNU" "Linux Programmer's Manual"
.SH NAME
strcpy, strncpy \- copy a string
.SH SYNOPSIS
.BR strcpy ()
function copies the string pointed to by
.IR src ,
-including the terminating null byte (\(aq\\0\(aq),
+including the terminating null byte (\(aq\e0\(aq),
to the buffer pointed to by
.IR dest .
The strings may not overlap, and the destination string
A simple implementation of
.BR strncpy ()
might be:
+.PP
.in +4n
-.nf
-
+.EX
char *
strncpy(char *dest, const char *src, size_t n)
{
size_t i;
- for (i = 0; i < n && src[i] != \(aq\\0\(aq; i++)
+ for (i = 0; i < n && src[i] != \(aq\e0\(aq; i++)
dest[i] = src[i];
for ( ; i < n; i++)
- dest[i] = \(aq\\0\(aq;
+ dest[i] = \(aq\e0\(aq;
return dest;
}
-.fi
+.EE
.in
.SH RETURN VALUE
The
.BR strncpy ()
is to copy a C string to a fixed-length buffer
while ensuring both that the buffer is not overflowed
-and that unused bytes in the target buffer are zeroed out
+and that unused bytes in the destination buffer are zeroed out
(perhaps to prevent information leaks if the buffer is to be
written to media or transmitted to another process via an
interprocess communication technique).
has length
.IR buflen ,
you can force termination using something like the following:
+.PP
.in +4n
-.nf
-
-strncpy(buf, str, buflen \- 1);
-if (buflen > 0)
- buf[buflen \- 1]= \(aq\\0\(aq;
-.fi
+.EX
+if (buflen > 0) {
+ strncpy(buf, str, buflen \- 1);
+ buf[buflen \- 1]= \(aq\e0\(aq;
+}
+.EE
.in
.PP
(Of course, the above technique ignores the fact that, if
bytes to
.IR dest ,
always adds a terminating null byte,
-and does not pad the target with (further) null bytes.
+and does not pad the destination with (further) null bytes.
This function fixes some of the problems of
.BR strcpy ()
and