linux-kernel - Re: [RFC / musing] Scoped exception handling in Linux userspace?

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Message-ID: <CALCETrXnVBPNGGTQQoXnpEmjXHxbhiWx+4RuMVQLRG5sfMpofA@mail.gmail.com>
Date:	Thu, 18 Jul 2013 17:50:19 -0700
From:	Andy Lutomirski <luto@...capital.net>
To:	David Daney <ddaney.cavm@...il.com>
Cc:	linux-kernel@...r.kernel.org, gcc@....gnu.org
Subject: Re: [RFC / musing] Scoped exception handling in Linux userspace?

On Thu, Jul 18, 2013 at 5:40 PM, David Daney <ddaney.cavm@...il.com> wrote:
> On 07/18/2013 05:26 PM, Andy Lutomirski wrote:
>>
>> Windows has a feature that I've wanted on Linux forever: stack-based
>> (i.e. scoped) exception handling.  The upshot is that you can do,
>> roughly, this (pseudocode):
>>
>> int callback(...)
>> {
>>    /* Called if code_that_may_fault faults.  May return "unwind to
>> landing pad", "propagate the fault", or "fixup and retry" */
>> }
>>
>> void my_function()
>> {
>>    __hideous_try_thing(callback) {
>>      code_that_may_fault();
>>    } blahblahblah {
>>      landing_pad_code();
>>    }
>> }
>
>
> How is this different than throwing exceptions from a signal handler?

Two ways.  First, exceptions thrown from a signal handler can't be
retries.  Second, and more importantly, installing a signal handler in
a library is a terrible idea.

--Andy
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