Re: [PATCH] daemon: send stderr of service programs to the syslog

Johannes Sixt [off-list ref] wrote:

If git-daemon is run with --detach or --inetd, then stderr is explicitly
redirected to /dev/null. But notice that the service programs were spawned
via execl_git_cmd(), in particular, the stderr channel is inherited from
the daemon. This means that errors that the programs wrote to stderr (for
example, via die()), went to /dev/null.

This patch arranges that the daemon does not merely exec the service
program, but forks it and monitors stderr of the child; it writes the
errors that it produces to the daemons log via logerror().

A consequence is that the daemon process remains in memory for the full
duration of the service program, but this cannot be avoided.

Signed-off-by: Johannes Sixt <redacted>
---
 I don't know whether service programs like upload-archive or upload-pack
 write progress report to stderr or not, for example, if a client does not
 support side-bands. In this case this patch is probably not enough since
 this would fill the log with unneeded progress information. Any hints
 are appreciated.

They could, if they were broken.  :-)

IIRC only upload-pack produces progress (from pack-objects).
It does so by using a pipe on fd 2, and either copying it down
to the client via side-band, or discarding it.  So progress data
shouldn't ever appear on upload-pack's own fd 2, which means you
won't get it in this syslog thing.

But I have to wonder, why are we doing this?  Why can't we teach the
individual server program to record its error to the syslog before
it aborts?  Are we looking for SIGSEGV or something?  Its only the
daemon program staying around in memory, but that's a lot of little
daemons doing nothing waiting for their children to terminate.
Seems like a waste to me.
 
-- 
Shawn.