[PATCH] fcntl: document some F_SETLK errno variations

[Paul Eggert]

* doc/posix-functions/fcntl.texi (fcntl): Document
OpenIndiana, GNU/Linux, FreeBSD on NFS files.
---
 ChangeLog                      | 6 ++++++
 doc/posix-functions/fcntl.texi | 8 ++++++++
 2 files changed, 14 insertions(+)

diff --git a/ChangeLog b/ChangeLog
index cec93905a..b078da4d3 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+2020-08-02  Paul Eggert  <eggert@cs.ucla.edu>
+
+       fcntl: document some F_SETLK errno variations
+       * doc/posix-functions/fcntl.texi (fcntl): Document
+       OpenIndiana, GNU/Linux, FreeBSD on NFS files.
+
 2020-08-02  Bruno Haible  <bruno@clisp.org>
 
        oset: Add an 'iterator_atleast' operation.
diff --git a/doc/posix-functions/fcntl.texi b/doc/posix-functions/fcntl.texi
index 8696704ac..30500e83c 100644
--- a/doc/posix-functions/fcntl.texi
+++ b/doc/posix-functions/fcntl.texi
@@ -43,4 +43,12 @@ The replacement function does not support @code{F_SETFD},
 @code{F_GETFL}, @code{F_SETFL}, @code{F_GETOWN}, @code{F_SETOWN},
 @code{F_GETLK}, @code{F_SETLK}, and @code{F_SETLKW} on some platforms:
 mingw, MSVC 14.
+
+@item
+When a file does not support locking (such as on an NFS file system
+that does not support file locking), calls with @code{F_SETLK} and
+@code{F_SETLKW} fail with @code{errno} set to different values on
+different systems: @code{EINVAL} on OpenIndiana (as suggested by the
+POSIX 1003.1-2017 @code{fcntl} specification), @code{ENOLCK} on
+GNU/Linux, and @code{EOPNOTSUPP} on FreeBSD.
 @end itemize
-- 
2.25.4