[PATCH v7 2/2] send-email: expose header information to git-send-email's sendemail-validate hook

["Strawbridge, Michael" <Michael.Strawbridge@amd.com>]

To allow further flexibility in the Git hook, the SMTP header
information of the email which git-send-email intends to send, is now
passed as the 2nd argument to the sendemail-validate hook.

As an example, this can be useful for acting upon keywords in the
subject or specific email addresses.

Cc: Luben Tuikov <luben.tuikov@amd.com>
Cc: Junio C Hamano <gitster@pobox.com>
Signed-off-by: Michael Strawbridge <michael.strawbridge@amd.com>
---
 Documentation/githooks.txt | 28 +++++++++++++++++++++++----
 git-send-email.perl        | 31 ++++++++++++++++++++----------
 t/t9001-send-email.sh      | 39 ++++++++++++++++++++++++++++++++++++--
 3 files changed, 82 insertions(+), 16 deletions(-)

diff --git a/Documentation/githooks.txt b/Documentation/githooks.txt
index a16e62bc8c..978d599be5 100644
--- a/Documentation/githooks.txt
+++ b/Documentation/githooks.txt
@@ -583,10 +583,30 @@ processed by rebase.
 sendemail-validate
 ~~~~~~~~~~~~~~~~~~
 
-This hook is invoked by linkgit:git-send-email[1].  It takes a single parameter,
-the name of the file that holds the e-mail to be sent.  Exiting with a
-non-zero status causes `git send-email` to abort before sending any
-e-mails.
+This hook is invoked by linkgit:git-send-email[1].
+
+It takes these command line arguments. They are,
+1. the name of the file which holds the contents of the email to be sent.
+2. The name of the file which holds the SMTP envelope and headers of the email.
+
+The SMTP envelope and headers are passed in the exact same way as they
+are passed to the user's Mail Transport Agent (MTA). In effect, the email
+given to the user's MTA, is the contents of $2 followed by the contents
+of $1.
+
+Below is an example for a few common headers. Take notice of the
+capitalization and multi-line tab structure.
+
+  From: Example <from@example.com>
+  To: to@example.com
+  Cc: cc@example.com,
+	  A <author@example.com>,
+	  One <one@example.com>,
+	  two@example.com
+  Subject: PATCH-STRING
+
+Exiting with a non-zero status causes `git send-email` to abort
+before sending any e-mails.
 
 fsmonitor-watchman
 ~~~~~~~~~~~~~~~~~~
diff --git a/git-send-email.perl b/git-send-email.perl
index 42f135a266..4f2039284e 100755
--- a/git-send-email.perl
+++ b/git-send-email.perl
@@ -787,14 +787,6 @@ sub is_format_patch_arg {
 
 @files = handle_backup_files(@files);
 
-if ($validate) {
-	foreach my $f (@files) {
-		unless (-p $f) {
-			validate_patch($f, $target_xfer_encoding);
-		}
-	}
-}
-
 if (@files) {
 	unless ($quiet) {
 		print $_,"\n" for (@files);
@@ -1738,6 +1730,16 @@ sub send_message {
 	return 1;
 }
 
+if ($validate) {
+	foreach my $f (@files) {
+		unless (-p $f) {
+		        pre_process_file($f, 1);
+
+			validate_patch($f, $target_xfer_encoding);
+		}
+	}
+}
+
 $in_reply_to = $initial_in_reply_to;
 $references = $initial_in_reply_to || '';
 $message_num = 0;
@@ -2101,11 +2103,20 @@ sub validate_patch {
 			chdir($repo->wc_path() or $repo->repo_path())
 				or die("chdir: $!");
 			local $ENV{"GIT_DIR"} = $repo->repo_path();
+
+			my ($recipients_ref, $to, $date, $gitversion, $cc, $ccline, $header) = gen_header();
+
+			require File::Temp;
+			my ($header_filehandle, $header_filename) = File::Temp::tempfile(
+                            ".gitsendemail.header.XXXXXX", DIR => $repo->repo_path());
+			print $header_filehandle $header;
+
 			my @cmd = ("git", "hook", "run", "--ignore-missing",
 				    $hook_name, "--");
-			my @cmd_msg = (@cmd, "<patch>");
-			my @cmd_run = (@cmd, $target);
+			my @cmd_msg = (@cmd, "<patch>", "<header>");
+			my @cmd_run = (@cmd, $target, $header_filename);
 			$hook_error = system_or_msg(\@cmd_run, undef, "@cmd_msg");
+			unlink($header_filehandle);
 			chdir($cwd_save) or die("chdir: $!");
 		}
 		if ($hook_error) {
diff --git a/t/t9001-send-email.sh b/t/t9001-send-email.sh
index 1130ef21b3..c0fcbacdaa 100755
--- a/t/t9001-send-email.sh
+++ b/t/t9001-send-email.sh
@@ -540,7 +540,7 @@ test_expect_success $PREREQ "--validate respects relative core.hooksPath path" '
 	test_path_is_file my-hooks.ran &&
 	cat >expect <<-EOF &&
 	fatal: longline.patch: rejected by sendemail-validate hook
-	fatal: command '"'"'git hook run --ignore-missing sendemail-validate -- <patch>'"'"' died with exit code 1
+	fatal: command '"'"'git hook run --ignore-missing sendemail-validate -- <patch> <header>'"'"' died with exit code 1
 	warning: no patches were sent
 	EOF
 	test_cmp expect actual
@@ -559,12 +559,47 @@ test_expect_success $PREREQ "--validate respects absolute core.hooksPath path" '
 	test_path_is_file my-hooks.ran &&
 	cat >expect <<-EOF &&
 	fatal: longline.patch: rejected by sendemail-validate hook
-	fatal: command '"'"'git hook run --ignore-missing sendemail-validate -- <patch>'"'"' died with exit code 1
+	fatal: command '"'"'git hook run --ignore-missing sendemail-validate -- <patch> <header>'"'"' died with exit code 1
 	warning: no patches were sent
 	EOF
 	test_cmp expect actual
 '
 
+test_expect_success $PREREQ 'setup expect' "
+cat >expected-headers <<\EOF
+From: Example <from@example.com>
+To: to@example.com
+Cc: cc@example.com,
+	A <author@example.com>,
+	One <one@example.com>,
+	two@example.com
+Subject: [PATCH 1/1] Second.
+Date: DATE-STRING
+Message-Id: MESSAGE-ID-STRING
+X-Mailer: X-MAILER-STRING
+Reply-To: Reply <reply@example.com>
+MIME-Version: 1.0
+Content-Transfer-Encoding: quoted-printable
+EOF
+"
+
+test_expect_success $PREREQ "--validate hook supports header argument" '
+	write_script my-hooks/sendemail-validate <<-\EOF &&
+	grep "X-test-header: v1.0" "$2"
+	EOF
+	test_config core.hooksPath "my-hooks" &&
+	rm -fr outdir &&
+	git format-patch \
+		--add-header="X-test-header: v1.0" \
+		-n HEAD^1 -o outdir &&
+	git send-email \
+		--dry-run \
+		--to=nobody@example.com \
+		--smtp-server="$(pwd)/fake.sendmail" \
+		--validate \
+		outdir/000?-*.patch
+'
+
 for enc in 7bit 8bit quoted-printable base64
 do
 	test_expect_success $PREREQ "--transfer-encoding=$enc produces correct header" '
-- 
2.34.1