Unfriendly IT, or how to get Perforce diffs e-mailed to you

Work for a big corporation can be very challenging sometimes. This touches me especially when I have to request something, and IT department doesn’t agree for providing me this functionality. Sometimes things are very simple, sometimes are more complex.

In this particular case, I tried to provide myself a way to review Perforce commits other person working with me was doing. Solution, which we all know to be pretty darn good, is to have diffs e-mailed to you, just like we do on:

FreeBSD mailing lists

But, as you already know, getting this functionality isn’t always that easy if you have The Big Brother. Most often than not, I end up crafting myself yet-another-tiny-script, that helps me a lot.

Here it is:

#!/bin/sh
# vim: set tw=1000:

#
# You must do p4 changes > ~/.p4_diff/prev before starting
# to use this script.
#

p4=/home/wojciec/bin/p4

dir=/home/wojciec/.p4_diff/

mkdir -p $dir

curr=$dir/curr
prev=$dir/prev

$p4 changes > $curr

diff $prev $curr 2>&1 > /dev/null
if [ $? -eq 0 ]; then
	# no new commits.
	echo "P4DIFF: no commits";
	exit 0;
fi

#Fool-proof stuff
DIFF_NUM=`diff -u $prev $curr | wc -l | cut -d " " -f 1`
if [ $DIFF_NUM -gt 25 ]; then
	echo "P4DIFF: something is wrong with metadata: > 25 commits in 5 mins?";
	exit;
fi

diff -u $prev $curr | grep '^+C' | while read DIFF_LINE; do
	CHANGE_NUM=`echo $DIFF_LINE | cut -d " " -f 2`
	SUBJECT="P4DIFF `echo $DIFF_LINE | sed 's/^+//' | cut -d " " -f 2,6-`"

	echo "DIFF_LINE      : $DIFF_LINE"
	echo "SUBJECT:       : $SUBJECT";
	echo "CHANGE_NUM     : $CHANGE_NUM";

	$p4 describe -du $CHANGE_NUM | mail -s "$SUBJECT" wojciec
done
cp $curr $prev

I purposefully didn’t fix it, so that you understand what you’re doing (hint: read the comment). Cron job with this script will produce some junk on the output and will get e-mailed to you. I prefer that – I have a e-mail filter dumping these e-mails to a separate e-mail folders under CRON/ directory, so that I can inspect things going wrong.

PS: This post doesn’t solve “How to keep your Perforce session opened”, but I’m not brave enough to show it to you, so this is that part you have to figure out by yourself.

Script turned out to be pretty useful. I can see from Perforce what sort of problems hardware group is solving!