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

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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

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

-- AngelCarpintero - 26 May 2005

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

-- AngelCarpintero - 28 May 2005

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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

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This patch is released for testing in motion-3.2.2_snap9

-- KennethLavrsen - 02 Aug 2005

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