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TEST RELEASE: Cygwin 2.1.0-0.1
- From: Corinna Vinschen <corinna-cygwin at cygwin dot com>
- To: cygwin-announce at cygwin dot com
- Date: Sat, 20 Jun 2015 22:55:12 +0200
- Subject: TEST RELEASE: Cygwin 2.1.0-0.1
- Authentication-results: sourceware.org; auth=none
- Reply-to: The Cygwin Mailing List <cygwin at cygwin dot com>
Hi Cygwin friends and users,
I released a TEST version of Cygwin. The version number is 2.1.0-0.1.
This test release is mostly for interested *developers*.
The important news which needs some testing is the implementation of
sigaltstack(2) and the underlying implementation of running a signal
handler on the alternate signal stack.
- The alternate signal stack installed via sigaltstack is only valid
for the current thread. Each thread must call its own sigaltstack.
On pthread_create, the alternate signal stack setting of the calling
thread is *not* propagated to the newly created thread. This follows
current Linux semantics.
- The alternate signal stack is a minimal stack. Certain datastructures
used by Cygwin (_cygtls area) and Windows (on 32 bit: exception records)
are not copied over to the alternate signal stack. The stack settings
in the Thread Environment Block (TEB) are not reflecting the current
alternate stack while running the signal handler. The TEB will still
point to the original thread stack. This seems to work nicely in my
testing, but there may be Windows functions which stop working in this
- The 32 bit version stores the original stack register content at the
base of the alternate stack. If you screw this up while running
the signal handler, your thread is doomed on return to the caller.
- The 64 bit version stores the information in callee-saved registers
r12 and r13 per MS-ABI.
I'd be grateful if curious developers would give this new sigaltstack
implementation a whirl and report back if it's working for them as
desired/expected. And if not, simple reproducers in plain C are most
welcome in this case. Discussing aspects of this implementation may be
best handled on the cygwin-developers mailing list or the
#cygwin-developers IRC channel on Freenode.
All changes in this release so far:
- First cut of an implementation to allow signal handlers running on an
alternate signal stack.
- New API sigaltstack, plus definitions for SA_ONSTACK, SS_ONSTACK, SS_DISABLE,
- New API: sethostname.
- Enable non-SA_RESTART behaviour on threads other than main thread.
- Try to handle concurrent close on socket more gracefully
To install 32-bit Cygwin use https://cygwin.com/setup-x86.exe
To install 64 bit Cygwin use https://cygwin.com/setup-x86_64.exe
Corinna Vinschen Please, send mails regarding Cygwin to
Cygwin Maintainer cygwin AT cygwin DOT com