Motion - Convert Signal To Sigaction

Convert signal to sigaction

Introduction

Replace use of signal function by sigaction.

Description of Patch

Currently, motion is using signal() function. There is two problems with this implementation - the effects of signal() call in a multi-threaded process are unspecified. - the signal handler is using printf and syslog but these functions are not safe as defined by POSIX 1003.1-2003 list

A better implementation will be to use sigaction() instead.

In multi-threaded applications using the thread library (libpthread.a), signal actions are common to all threads within the process. Any thread calling the sigaction subroutine changes the action to be taken when a specific signal is delivered to the threads process, that is, to any thread within the process. So it looks a good idea to move the signal handler initialization from motion_loop() to main() instead.

Installation of Patch

patch < filename

Change History of Patch

20050526 First version

Discussion and Comments

Christophe it seems good but needs a lot of testing.

btw SA_NOCLDWAIT should be checked because is not available in all systems, an easy ways is :


#ifdef SA_NOCLDWAIT
    act.sa_flags = SA_NOCLDWAIT;
#else
    act.sa_flags = 0;
#endif

So that will be used in main() ( motion.c ) and in httpd_run() ( webhttpd.c ).

-- AngelCarpintero - 26 May 2005

The POSIX spec only defines SA_NOCLDSTOP. Anyway, I have posted a second version of the patch to handle compilation error when SA_NOCLDSTOP or SA_RESTART is not defined

-- ChristopheGRENIER - 27 May 2005

Http control interface already include your patch in the last patch i've upload to MotionHttpControl .

-- AngelCarpintero - 26 May 2005

Updated the patch , removing the part of webhttp that is already include in a webhttpd patch.

-- AngelCarpintero - 28 May 2005

The httpd part is now in 3.2.2_snap1 sources.

When this is released we will look at the rest of the patch. I need to get some bugfixes out ASAP.

-- KennethLavrsen - 03 Jun 2005


This patch is released for testing in motion-3.2.2_snap9

-- KennethLavrsen - 02 Aug 2005


Topic revision: r12 - 13 Aug 2005, KennethLavrsen
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