[Libguestfs] [PATCH libguestfs] launch: Implement a safer getumask.
Eric Blake
eblake at redhat.com
Wed Apr 13 21:58:52 UTC 2016
On 04/13/2016 03:53 PM, Eric Blake wrote:
>> + mask = umask (0);
>> + if (mask == -1) {
>> + perror ("umask");
>
> perror() is NOT async-safe (it manipulates stdio, and could permanently
> wedgelock the child if you happened to fork() while some other thread
> was also using stdio). Safe error reporting in a fork()d child is
> basically impossible; the best you can do is write() something back to
> the parent and let the parent do the error reporting. :(
The official list is at:
http://pubs.opengroup.org/onlinepubs/9699919799/functions/V2_chap02.html#tag_15_04
at the end of subheading 2.4.3
although you'll want to also consult
http://austingroupbugs.net/view.php?id=692
for several functions (like strlen()) that were accidentally omitted
from the list and will appear when POSIX 2008 TC 2 comes out later this
year.
--
Eric Blake eblake redhat com +1-919-301-3266
Libvirt virtualization library http://libvirt.org
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