Re: ptsname_r on Cygwin

[Bruno Haible]

> While https://www.kernel.org/doc/man-pages/online/pages/man3/ptsname_r.3.html
> says that ptsname_r, upon failure, should return an error code, on Cygwin,
> it returns 0 and stores the empty string in 'buffer'.

Let me document this issue.


2021-01-20  Bruno Haible  <bruno@clisp.org>

        doc: Document ptsname_r bug on Cygwin.
        * doc/glibc-functions/ptsname_r.texi: Mention Cygwin bug.

diff --git a/doc/glibc-functions/ptsname_r.texi 
b/doc/glibc-functions/ptsname_r.texi
index 0bfd05b..a79e751 100644
--- a/doc/glibc-functions/ptsname_r.texi
+++ b/doc/glibc-functions/ptsname_r.texi
@@ -25,13 +25,17 @@ Mac OS X 10.5, FreeBSD 6.0, NetBSD 5.0, OpenBSD 6.7, Minix 
3.1.8,
 AIX 5.1, HP-UX 11, IRIX 6.5, Solaris 11.4, Cygwin 1.7.9, mingw,
 MSVC 14.
 @item
-When this functions fails, it returns -1 instead of the error code
+When this function fails, it returns -1 instead of the error code
 on some platforms:
 Mac OS X 10.13, Android 4.3.
 @end itemize
 
 Portability problems not fixed by Gnulib:
 @itemize
+@item
+When this function fails, it returns 0 and stores an empty string as result
+on some platforms:
+Cygwin 2.9.
 @end itemize
 
 Note: Portable programs should expect to find the error code as the