[PATCH] Cygwin: redefine some macros for Linux compatibility

Ken Brown kbrown@cornell.edu
Wed Jul 6 20:25:27 GMT 2022


Patch attached.

I wasn't sure whether the API bump was warranted for such a trivial change.  But 
the fact is that some programs compiled prior to the patch will behave 
differently if they are recompiled after the patch.  For example, emacs limits 
the number of open subprocesses to FD_SETSIZE, so this number will change when 
emacs is recompiled for Cygwin 3.4.0.  Is that a good enough reason to bump the API?

Ken
-------------- next part --------------
From 6d6c1ed356e3e8f39aa9b6447982f3fccbdabfad Mon Sep 17 00:00:00 2001
From: Ken Brown <kbrown@cornell.edu>
Date: Wed, 6 Jul 2022 14:43:16 -0400
Subject: [PATCH] Cygwin: redefine some macros for Linux compatibility

Define FD_SETSIZE (<sys/select.h>) to be 1024 by default, and define
NOFILE (<sys/param.h>) to be OPEN_MAX (== 3200) by default.

Remove the comment in <sys/select.h> that FD_SETSIZE should be >=
NOFILE.

Bump API minor.

Addresses: https://cygwin.com/pipermail/cygwin/2022-July/251839.html
---
 newlib/libc/include/sys/select.h       | 10 +++++++---
 winsup/cygwin/include/cygwin/version.h |  3 ++-
 winsup/cygwin/include/sys/param.h      |  4 +++-
 winsup/cygwin/release/3.4.0            |  4 ++++
 winsup/doc/new-features.xml            |  5 +++++
 5 files changed, 21 insertions(+), 5 deletions(-)

diff --git a/newlib/libc/include/sys/select.h b/newlib/libc/include/sys/select.h
index a5cd6c3fe..93d0b79bf 100644
--- a/newlib/libc/include/sys/select.h
+++ b/newlib/libc/include/sys/select.h
@@ -25,10 +25,14 @@ typedef	__sigset_t	sigset_t;
  * Select uses bit masks of file descriptors in longs.
  * These macros manipulate such bit fields (the filesystem macros use chars).
  * FD_SETSIZE may be defined by the user, but the default here
- * should be >= NOFILE (param.h).
+ * should be enough for most uses.
  */
-#ifndef	FD_SETSIZE
-#define	FD_SETSIZE	64
+#ifndef FD_SETSIZE
+# ifdef __CYGWIN__
+#  define FD_SETSIZE	1024
+# else
+#  define FD_SETSIZE	64
+# endif
 #endif
 
 typedef unsigned long	__fd_mask;
diff --git a/winsup/cygwin/include/cygwin/version.h b/winsup/cygwin/include/cygwin/version.h
index 6f65a1299..a5d38f37a 100644
--- a/winsup/cygwin/include/cygwin/version.h
+++ b/winsup/cygwin/include/cygwin/version.h
@@ -517,12 +517,13 @@ details. */
        pthread_rwlock_clockrdlock, pthread_rwlock_clockwrlock,
        sem_clockwait, sig2str, str2sig.
   342: Remove cleanup_glue.
+  343: Change FD_SETSIZE and NOFILE.
 
   Note that we forgot to bump the api for ualarm, strtoll, strtoull,
   sigaltstack, sethostname. */
 
 #define CYGWIN_VERSION_API_MAJOR 0
-#define CYGWIN_VERSION_API_MINOR 342
+#define CYGWIN_VERSION_API_MINOR 343
 
 /* There is also a compatibity version number associated with the shared memory
    regions.  It is incremented when incompatible changes are made to the shared
diff --git a/winsup/cygwin/include/sys/param.h b/winsup/cygwin/include/sys/param.h
index 63de726e6..742599b8b 100644
--- a/winsup/cygwin/include/sys/param.h
+++ b/winsup/cygwin/include/sys/param.h
@@ -17,7 +17,9 @@
 /* Max number of open files.  The Posix version is OPEN_MAX.  */
 /* Number of fds is virtually unlimited in cygwin, but we must provide
    some reasonable value for Posix conformance */
-#define NOFILE		8192
+#if !defined NOFILE && defined OPEN_MAX
+# define NOFILE         OPEN_MAX
+#endif
 
 /* Max number of groups; must keep in sync with NGROUPS_MAX in limits.h */
 #define NGROUPS		NGROUPS_MAX
diff --git a/winsup/cygwin/release/3.4.0 b/winsup/cygwin/release/3.4.0
index f310912c9..08d28d510 100644
--- a/winsup/cygwin/release/3.4.0
+++ b/winsup/cygwin/release/3.4.0
@@ -25,6 +25,10 @@ What changed:
   the current directory as Linux does.
   Addresses: https://cygwin.com/pipermail/cygwin/2022-June/251730.html
 
+- The default values of FD_SETSIZE and NOFILE are now 1024 and 3200,
+  respectively.
+  Addresses: https://cygwin.com/pipermail/cygwin/2022-July/251839.html
+
 
 Bug Fixes
 ---------
diff --git a/winsup/doc/new-features.xml b/winsup/doc/new-features.xml
index 0149a027a..46dc028f1 100644
--- a/winsup/doc/new-features.xml
+++ b/winsup/doc/new-features.xml
@@ -33,6 +33,11 @@ Handle UDP_SEGMENT and UDP_GRO socket options.
 The stdio input functions no longer try again to read after EOF.
 </para></listitem>
 
+<listitem><para>
+The default values of FD_SETSIZE and NOFILE are now 1024 and 3200,
+respectively.
+</para></listitem>
+
 </itemizedlist>
 
 </sect2>
-- 
2.36.1



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