[PATCH] git-send-email: die if sendmail.* config is set

[Drew DeVault <sir@cmpwn.com>]

I've seen several people mis-configure git send-email on their first
attempt because they set the sendmail.* config options - not
sendemail.*. This patch detects this mistake and bails out with a
friendly warning.

Signed-off-by: Drew DeVault <sir@cmpwn.com>
---
 git-send-email.perl |  6 ++++++
 perl/Git.pm         | 26 ++++++++++++++++++++++++++
 2 files changed, 32 insertions(+)

diff --git a/git-send-email.perl b/git-send-email.perl
index 36c47bae1d..8e42ba00c1 100755
--- a/git-send-email.perl
+++ b/git-send-email.perl
@@ -478,6 +478,12 @@ sub read_config {
     usage();
 }
 
+if ((scalar Git::config_regexp("sendmail.*")) != 0) {
+	die __("fatal: found configuration options for 'sendmail'\n" .
+		"git-send-email is configured with the sendemail.* options - note the 'e'.\n" .
+		"Assuming this is a mistake and bailing out.\n");
+}
+
 die __("Cannot run git format-patch from outside a repository\n")
 	if $format_patch and not $repo;
 
diff --git a/perl/Git.pm b/perl/Git.pm
index 54c9ed0dde..10df990959 100644
--- a/perl/Git.pm
+++ b/perl/Git.pm
@@ -723,6 +723,32 @@ sub config_int {
 	return scalar _config_common({'kind' => '--int'}, @_);
 }
 
+=item config_regexp ( RE )
+
+Retrieve the list of configuration key names matching the regular
+expression C<RE>. The return value is a list of strings matching
+this regex.
+
+=cut
+
+sub config_regexp {
+	my ($self, $regex) = _maybe_self(@_);
+	try {
+		my @cmd = ('config', '--name-only', '--get-regexp', $regex);
+		unshift @cmd, $self if $self;
+		my @matches = command(@cmd);
+		return @matches;
+	} catch Git::Error::Command with {
+		my $E = shift;
+		if ($E->value() == 1) {
+			my @matches = ();
+			return @matches;
+		} else {
+			throw $E;
+		}
+	};
+}
+
 # Common subroutine to implement bulk of what the config* family of methods
 # do. This currently wraps command('config') so it is not so fast.
 sub _config_common {
-- 
2.27.0