Re: [PATCH 3/4] start_command: detect execvp failures early

Johannes Sixt [off-list ref] writes:

On Donnerstag, 14. Januar 2010, Junio C Hamano wrote:

quoted

Johannes Sixt [off-list ref] writes:

quoted

Previously, failures during execvp could be detected only by
finish_command. However, in some situations it is beneficial for the
parent process to know earlier that the child process will not run.

The idea to use a pipe to signal failures to the parent process and
the test case were lifted from patches by Ilari Liusvaara.

I wonder if we can do this without pipe, perhaps using "vfork, exec, then
update a variable"....

Except that some systems implement vfork(2) in terms of fork(2), I heard. 

As long as they implement it correctly, we don't care if it is implemented
in terms of fork or knife or chopstick.  The only thing we care about in
this crazy-idea was the shared address space the child can write into
until it exec or _exit while the parent is in a frozen state.

Moreover, I think that we do way too many things before the exec; isn't that 
dangerous?

Yeah, we do seem to do quite a lot more than I thought.  Scratch that
crazy idea, then.