send-email: Don't leak To: headers between patches

If the first patch in a series has a To: header in the file and the
second patch in the series doesn't the address from the first patch will
be part of the To: addresses in the second patch. Fix this by treating the
to list like the cc list. Have an initial to list come from the command
line, user input and config options. Then build up a to list from each
patch and concatenate the two together before sending the patch. Finally,
reset the list after sending each patch so the To: headers from a patch
don't get used for the next one.

Reported-by: Viresh Kumar <viresh.kumar@st.com>
Signed-off-by: Stephen Boyd <bebarino@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

git-send-email.perl

@@ -138,7 +138,7 @@ sub format_2822_time {
 sub cleanup_compose_files();
 
 # Variables we fill in automatically, or via prompting:
-my (@to,$no_to,@cc,$no_cc,@initial_cc,@bcclist,$no_bcc,@xh,
+my (@to,$no_to,@initial_to,@cc,$no_cc,@initial_cc,@bcclist,$no_bcc,@xh,
 	$initial_reply_to,$initial_subject,@files,
 	$author,$sender,$smtp_authpass,$annotate,$compose,$time);
 
@@ -213,7 +213,7 @@ sub do_edit {
     "smtpuser" => \$smtp_authuser,
     "smtppass" => \$smtp_authpass,
 	"smtpdomain" => \$smtp_domain,
-    "to" => \@to,
+    "to" => \@initial_to,
     "cc" => \@initial_cc,
     "cccmd" => \$cc_cmd,
     "aliasfiletype" => \$aliasfiletype,
@@ -271,7 +271,7 @@ sub signal_handler {
 my $rc = GetOptions("sender|from=s" => \$sender,
                     "in-reply-to=s" => \$initial_reply_to,
 		    "subject=s" => \$initial_subject,
-		    "to=s" => \@to,
+		    "to=s" => \@initial_to,
 		    "no-to" => \$no_to,
 		    "cc=s" => \@initial_cc,
 		    "no-cc" => \$no_cc,
@@ -409,7 +409,7 @@ sub read_config {
 
 # Verify the user input
 
-foreach my $entry (@to) {
+foreach my $entry (@initial_to) {
 	die "Comma in --to entry: $entry'\n" unless $entry !~ m/,/;
 }
 
@@ -711,9 +711,9 @@ ($)
 	$prompting++;
 }
 
-if (!@to) {
+if (!@initial_to) {
 	my $to = ask("Who should the emails be sent to? ");
-	push @to, parse_address_line($to) if defined $to; # sanitized/validated later
+	push @initial_to, parse_address_line($to) if defined $to; # sanitized/validated later
 	$prompting++;
 }
 
@@ -731,8 +731,8 @@ sub expand_one_alias {
 	return $aliases{$alias} ? expand_aliases(@{$aliases{$alias}}) : $alias;
 }
 
-@to = expand_aliases(@to);
-@to = (map { sanitize_address($_) } @to);
+@initial_to = expand_aliases(@initial_to);
+@initial_to = (map { sanitize_address($_) } @initial_to);
 @initial_cc = expand_aliases(@initial_cc);
 @bcclist = expand_aliases(@bcclist);
 
@@ -1136,6 +1136,7 @@ sub send_message {
 	my $author_encoding;
 	my $has_content_type;
 	my $body_encoding;
+	@to = ();
 	@cc = ();
 	@xh = ();
 	my $input_format = undef;
@@ -1300,6 +1301,7 @@ sub send_message {
 		($confirm =~ /^(?:auto|compose)$/ && $compose && $message_num == 1));
 	$needs_confirm = "inform" if ($needs_confirm && $confirm_unconfigured && @cc);
 
+	@to = (@initial_to, @to);
 	@cc = (@initial_cc, @cc);
 
 	my $message_was_sent = send_message();

t/t9001-send-email.sh

@@ -971,6 +971,21 @@ test_expect_success $PREREQ 'patches To headers are appended to' '
 	grep "RCPT TO:<nobody@example.com>" stdout
 '
 
+test_expect_success $PREREQ 'To headers from files reset each patch' '
+	patch1=`git format-patch -1 --to="bodies@example.com"` &&
+	patch2=`git format-patch -1 --to="other@example.com" HEAD~` &&
+	test_when_finished "rm $patch1 && rm $patch2" &&
+	git send-email \
+		--dry-run \
+		--from="Example <nobody@example.com>" \
+		--to="nobody@example.com" \
+		--smtp-server relay.example.com \
+		$patch1 $patch2 >stdout &&
+	test $(grep -c "RCPT TO:<bodies@example.com>" stdout) = 1 &&
+	test $(grep -c "RCPT TO:<nobody@example.com>" stdout) = 2 &&
+	test $(grep -c "RCPT TO:<other@example.com>" stdout) = 1
+'
+
 test_expect_success $PREREQ 'setup expect' '
 cat >email-using-8bit <<EOF
 From fe6ecc66ece37198fe5db91fa2fc41d9f4fe5cc4 Mon Sep 17 00:00:00 2001