[PATCH] post-receive-email: do not call sendmail if no mail was generated

[Lars Noschinski <lars@public.noschinski.de>]

contrib/hooks/post-receive-email used to call the send_mail function
(and thus, /usr/sbin/sendmail), even if generate_mail returned an error.
This is problematic, as the sendmail binary provided by exim4 generates
an error mail if provided with an empty input.

Therefore, this commit changes post-receive-email to only call sendmail
if generate_mail returned without error.

Signed-off-by: Lars Noschinski <lars@public.noschinski.de>
---
 contrib/hooks/post-receive-email |    5 ++++-
 1 files changed, 4 insertions(+), 1 deletions(-)

Obvious drawback of this solution is that the mails are kept in memory as a
whole. But the mails should be small enough, so that this does not hurt.

I'm not sure how to write a test for this bug, as the hook (correctly) uses an
absolute path to call sendmail.

diff --git a/contrib/hooks/post-receive-email b/contrib/hooks/post-receive-email
index 2a66063..818a270 100755
--- a/contrib/hooks/post-receive-email
+++ b/contrib/hooks/post-receive-email
@@ -684,6 +684,9 @@ if [ -n "$1" -a -n "$2" -a -n "$3" ]; then
 else
 	while read oldrev newrev refname
 	do
-		generate_email $oldrev $newrev $refname | send_mail
+		mail="$(generate_email $oldrev $newrev $refname)"
+		if [ $? -eq 0 ]; then
+			printf '%s' "$mail" | send_mail
+		fi
 	done
 fi
-- 
1.6.3.3