Re: [PATCH v9 2/2] send-email: expose header information to git-send-email's sendemail-validate hook

> 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>
> Cc: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
> Acked-by: Luben Tuikov <luben.tuikov@amd.com>
> Signed-off-by: Michael Strawbridge <michael.strawbridge@amd.com>
> ---
>  Documentation/githooks.txt | 27 ++++++++++++++++++----
>  git-send-email.perl        | 46 ++++++++++++++++++++++----------------
>  t/t9001-send-email.sh      | 27 ++++++++++++++++++++--
>  3 files changed, 75 insertions(+), 25 deletions(-)
> 
> diff --git a/Documentation/githooks.txt b/Documentation/githooks.txt
> index a16e62bc8c..0decbfc92d 100644
> --- a/Documentation/githooks.txt
> +++ b/Documentation/githooks.txt
> @@ -583,10 +583,29 @@ 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 headers of the email.
> +
> +The SMTP 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..0e595d6ac5 100755
> --- a/git-send-email.perl
> +++ b/git-send-email.perl
> @@ -785,16 +785,31 @@ sub is_format_patch_arg {
>  	push @files, $repo->command('format-patch', '-o', File::Temp::tempdir(CLEANUP => 1), @rev_list_opts);
>  }
>  
> -@files = handle_backup_files(@files);
> +if (defined $sender) {
> +	$sender =~ s/^\s+|\s+$//g;
> +	($sender) = expand_aliases($sender);
> +} else {
> +	$sender = $repoauthor->() || $repocommitter->() || '';
> +}
> +
> +# $sender could be an already sanitized address
> +# (e.g. sendemail.from could be manually sanitized by user).
> +# But it's a no-op to run sanitize_address on an already sanitized address.
> +$sender = sanitize_address($sender);
> +
> +$time = time - scalar $#files;
>  
>  if ($validate) {
>  	foreach my $f (@files) {
>  		unless (-p $f) {
> +		        pre_process_file($f, 1);
>  			validate_patch($f, $target_xfer_encoding);
>  		}
>  	}
>  }
>  
> +@files = handle_backup_files(@files);
> +
>  if (@files) {
>  	unless ($quiet) {
>  		print $_,"\n" for (@files);
> @@ -1043,18 +1058,6 @@ sub file_declares_8bit_cte {
>  	}
>  }
>  
> -if (defined $sender) {
> -	$sender =~ s/^\s+|\s+$//g;
> -	($sender) = expand_aliases($sender);
> -} else {
> -	$sender = $repoauthor->() || $repocommitter->() || '';
> -}
> -
> -# $sender could be an already sanitized address
> -# (e.g. sendemail.from could be manually sanitized by user).
> -# But it's a no-op to run sanitize_address on an already sanitized address.
> -$sender = sanitize_address($sender);
> -
>  my $to_whom = __("To whom should the emails be sent (if anyone)?");
>  my $prompting = 0;
>  if (!@initial_to && !defined $to_cmd) {
> @@ -1214,10 +1217,6 @@ sub make_message_id {
>  	#print "new message id = $message_id\n"; # Was useful for debugging
>  }
>  
> -
> -
> -$time = time - scalar $#files;
> -
>  sub unquote_rfc2047 {
>  	local ($_) = @_;
>  	my $charset;
> @@ -2101,11 +2100,20 @@ sub validate_patch {
>  			chdir($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..8a5c111a24 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 +559,35 @@ 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 $PREREQ "--validate hook supports header argument" '
> +	write_script my-hooks/sendemail-validate <<-\EOF &&
> +        if test "$#" -ge 2
> +	then