[Libguestfs] [PATCH libnbd v2 1/2] lib: Don't use perror after fork in nbd_connect_callback.

[Eric Blake]

On 9/30/19 4:27 PM, Eric Blake wrote:
> On 9/30/19 11:32 AM, Richard W.M. Jones wrote:
>> perror is not fork-safe and so could deadlock.  Instead open code a
>> fork-safe version of perror.  While this fixes the current behaviour,
>> in the long term we'd like to capture the error message into the usual
>> error mechanism, so this is not the full and final fix for this issue.
>>
>> Also this fixes the exit code to be 126/127 instead of 1.
>>

>> +  write (2, s, strlen (s));
> 
> Surprisingly, strlen() is not listed in current POSIX' list of 
> async-signal-safe functions.  But I have an open bug to remedy that, and 
> don't see any problem in using it.

Correction - I forgot my own history.  POSIX 2008 had indeed omitted it, 
but my bug was accepted, and strlen() _is_ async-signal-safe in POSIX 
2017, per http://austingroupbugs.net/view.php?id=692

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3226
Virtualization:  qemu.org | libvirt.org