Module Name: src
Committed By: gutteridge
Date: Tue Sep 6 22:54:41 UTC 2022
Modified Files:
src/lib/libc/stdlib: posix_openpt.3
Log Message:
posix_openpt.3: add caveats about oflags
The NetBSD implementation differs from other BSDs in that it does not
return EINVAL if invalid oflags are submitted, since it completely
ignores them. This is surprising to upstream projects that may expect
otherwise.
To generate a diff of this commit:
cvs rdiff -u -r1.6 -r1.7 src/lib/libc/stdlib/posix_openpt.3
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
Modified files:
Index: src/lib/libc/stdlib/posix_openpt.3
diff -u src/lib/libc/stdlib/posix_openpt.3:1.6 src/lib/libc/stdlib/posix_openpt.3:1.7
--- src/lib/libc/stdlib/posix_openpt.3:1.6 Thu May 5 07:36:44 2011
+++ src/lib/libc/stdlib/posix_openpt.3 Tue Sep 6 22:54:41 2022
@@ -1,4 +1,4 @@
-.\" $NetBSD: posix_openpt.3,v 1.6 2011/05/05 07:36:44 wiz Exp $
+.\" $NetBSD: posix_openpt.3,v 1.7 2022/09/06 22:54:41 gutteridge Exp $
.\"
.\" Copyright (c) 2004 The NetBSD Foundation, Inc.
.\" All rights reserved.
@@ -27,7 +27,7 @@
.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
.\" POSSIBILITY OF SUCH DAMAGE.
.\"
-.Dd May 25, 2004
+.Dd September 6, 2022
.Dt POSIX_OPENPT 3
.Os
.Sh NAME
@@ -51,6 +51,9 @@ The
argument has the same meaning as in the
.Xr open 2
call.
+However, the value of
+.Fa oflag
+is ignored; it exists for compatibility reasons only.
.Sh RETURN VALUES
If successful,
.Fn posix_openpt
@@ -59,6 +62,19 @@ pointing to the master pseudo-terminal d
Otherwise, a value of \-1 is returned and
.Va errno
is set to indicate the error.
+.Pp
+Note that unlike implementations on some other operating systems,
+.Fn posix_openpt
+does not return
+.Er EINVAL
+if the value of
+.Fa oflag
+would be deemed invalid, instead it is simply ignored.
+This means it is not possible to dynamically test which
+.Xr open 2
+flags are possible to set, and apply a fallback if
+.Er EINVAL
+is received.
.Sh SEE ALSO
.Xr ioctl 2 ,
.Xr open 2 ,
