Process::spawn

[Ian Gough]

I was taking another look at Process::spawn and I think it might have some implementation issues.

 

1) wait4 has an option value of 0. This prevents it from detecting that the process on which it waits has been terminated by a signal such as SIGSTOP. I noticed that spawn did not exit when I killed the spawned process with 'kill'. Perhaps the option value should be WUNTRACED.

 

From the man page on wait4 on Mac OS X:

"If the WUNTRACED option is set, children of the current process that are stopped due to a

SIGTTIN, SIGTTOU, SIGTSTP, or SIGSTOP signal also have their status reported."

 

 

3) The vfork child calls execvp and then exit. It should probably check for an exec error and call _exit().  From the man page:

 

Vfork() can normally be used just like fork.  It does not work, however,
     to return while running in the childs context from the procedure that
     called vfork() since the eventual return from vfork() would then return
     to a no longer existent stack frame.  Be careful, also, to call _exit
     rather than exit if you can't execve, since exit will flush and close
     standard I/O channels, and thereby mess up the parent processes standard
     I/O data structures.  (Even with fork it is wrong to call exit since
     buffered data would then be flushed twice.)