Re: [Qemu-devel] [PATCH 2/2] qemu-ga: Add the guest-suspend command

[Eric Blake <eblake@redhat.com>]

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On 01/16/2012 10:08 AM, Luiz Capitulino wrote:
>> Strangely enough, POSIX doesn't include strcmp() in its list of
>> async-signal-safe functions (which is what you should be restricting
>> yourself to, if qemu-ga is multi-threaded), but in practice, I think
>> that is a bug of omission in POSIX, and not something you have to change
>> in your code.
> 
> memset() ins't either... sigaction() either, which begins to get
> annoying.

sigaction() is required by POSIX to be async-signal-safe.  Where are you
looking when claiming it isn't?

memset(), strlen, strcpy, and friends in <string.h> are all in the class
of functions that I think are unintentional omissions from the list of
async-signal-safe functions (they don't read/modify anything but the
pointers passed in, so the _only_ reason I can think of why they _might_
have been omitted from the list is that there might be some machine
state that could be observably different if you were interrupted in the
middle of one of these operations, such as a processor flag bit when
using a rep prefix on x86 controlling which direction to move, but no
one has ever pointed me to a definitive answer to why they were omitted).

-- 
Eric Blake   eblake@redhat.com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


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