gnu: git: Apply patch adding the --header-cmd feature.

In preparation to fix <https://issues.guix.gnu.org/58813>.

* gnu/packages/patches/git-header-cmd.patch: New file.
* gnu/local.mk (dist_patch_DATA): Register it.
* gnu/packages/version-control.scm (git) [source]: Apply patch.

3 files changed, 290 insertions, 1 deletions

diff --git a/gnu/local.mk b/gnu/local.mk
index b4f5453dda..4976b5c740 100644
--- a/gnu/local.mk
+++ b/gnu/local.mk
@@ -1211,6 +1211,7 @@ dist_patch_DATA =						\
   %D%/packages/patches/genimage-mke2fs-test.patch		\
   %D%/packages/patches/geoclue-config.patch			\
   %D%/packages/patches/gettext-libunicode-update.patch		\
+  %D%/packages/patches/git-header-cmd.patch			\
   %D%/packages/patches/ghc-8.0-fall-back-to-madv_dontneed.patch	\
   %D%/packages/patches/ghc-9.2-glibc-2.33-link-order.patch \
   %D%/packages/patches/ghc-9.2-grep-warnings.patch \
diff --git a/gnu/packages/patches/git-header-cmd.patch b/gnu/packages/patches/git-header-cmd.patch
new file mode 100644
index 0000000000..a8964ab174
--- /dev/null
+++ b/gnu/packages/patches/git-header-cmd.patch
@@ -0,0 +1,287 @@
+Add a '--header-cmd' to git send-email.
+
+Upstream status can be tracked at:
+https://lore.kernel.org/git/20230423122744.4865-1-maxim.cournoyer@gmail.com/T/#t
+
+diff --git a/Documentation/config/sendemail.txt b/Documentation/config/sendemail.txt
+index 51da7088a8..92a9ebe98c 100644
+--- a/Documentation/config/sendemail.txt
++++ b/Documentation/config/sendemail.txt
+@@ -61,6 +61,7 @@ sendemail.ccCmd::
+ sendemail.chainReplyTo::
+ sendemail.envelopeSender::
+ sendemail.from::
++sendemail.headerCmd::
+ sendemail.signedoffbycc::
+ sendemail.smtpPass::
+ sendemail.suppresscc::
+diff --git a/Documentation/git-send-email.txt b/Documentation/git-send-email.txt
+index b0f438ec99..4d2ae061f9 100644
+--- a/Documentation/git-send-email.txt
++++ b/Documentation/git-send-email.txt
+@@ -320,6 +320,17 @@ Automating
+ 	Output of this command must be single email address per line.
+ 	Default is the value of `sendemail.ccCmd` configuration value.
+ 
++--header-cmd=<command>::
++	Specify a command that is executed once per outgoing message
++	and output RFC 2822 style header lines to be inserted into
++	them. When the `sendemail.headerCmd` configuration variable is
++	set, its value is always used. When --header-cmd is provided
++	at the command line, its value takes precedence over the
++	`sendemail.headerCmd` configuration variable.
++
++--no-header-cmd::
++	Disable any header command in use.
++
+ --[no-]chain-reply-to::
+ 	If this is set, each email will be sent as a reply to the previous
+ 	email sent.  If disabled with "--no-chain-reply-to", all emails after
+diff --git a/git-send-email.perl b/git-send-email.perl
+index 66c9171109..22a64e608f 100755
+--- a/git-send-email.perl
++++ b/git-send-email.perl
+@@ -87,8 +87,10 @@ sub usage {
+ 
+   Automating:
+     --identity              <str>  * Use the sendemail.<id> options.
+-    --to-cmd                <str>  * Email To: via `<str> \$patch_path`
+-    --cc-cmd                <str>  * Email Cc: via `<str> \$patch_path`
++    --to-cmd                <str>  * Email To: via `<str> \$patch_path`.
++    --cc-cmd                <str>  * Email Cc: via `<str> \$patch_path`.
++    --header-cmd            <str>  * Add headers via `<str> \$patch_path`.
++    --no-header-cmd                * Disable any header command in use.
+     --suppress-cc           <str>  * author, self, sob, cc, cccmd, body, bodycc, misc-by, all.
+     --[no-]cc-cover                * Email Cc: addresses in the cover letter.
+     --[no-]to-cover                * Email To: addresses in the cover letter.
+@@ -202,7 +204,7 @@ sub format_2822_time {
+ 	$author,$sender,$smtp_authpass,$annotate,$compose,$time);
+ # Things we either get from config, *or* are overridden on the
+ # command-line.
+-my ($no_cc, $no_to, $no_bcc, $no_identity);
++my ($no_cc, $no_to, $no_bcc, $no_identity, $no_header_cmd);
+ my (@config_to, @getopt_to);
+ my (@config_cc, @getopt_cc);
+ my (@config_bcc, @getopt_bcc);
+@@ -269,7 +271,7 @@ sub do_edit {
+ # Variables with corresponding config settings
+ my ($suppress_from, $signed_off_by_cc);
+ my ($cover_cc, $cover_to);
+-my ($to_cmd, $cc_cmd);
++my ($to_cmd, $cc_cmd, $header_cmd);
+ my ($smtp_server, $smtp_server_port, @smtp_server_options);
+ my ($smtp_authuser, $smtp_encryption, $smtp_ssl_cert_path);
+ my ($batch_size, $relogin_delay);
+@@ -318,6 +320,7 @@ sub do_edit {
+     "tocmd" => \$to_cmd,
+     "cc" => \@config_cc,
+     "cccmd" => \$cc_cmd,
++    "headercmd" => \$header_cmd,
+     "aliasfiletype" => \$aliasfiletype,
+     "bcc" => \@config_bcc,
+     "suppresscc" => \@suppress_cc,
+@@ -519,6 +522,8 @@ sub config_regexp {
+ 		    "compose" => \$compose,
+ 		    "quiet" => \$quiet,
+ 		    "cc-cmd=s" => \$cc_cmd,
++		    "header-cmd=s" => \$header_cmd,
++		    "no-header-cmd" => \$no_header_cmd,
+ 		    "suppress-from!" => \$suppress_from,
+ 		    "no-suppress-from" => sub {$suppress_from = 0},
+ 		    "suppress-cc=s" => \@suppress_cc,
+@@ -1780,16 +1785,16 @@ sub process_file {
+ 	$subject = $initial_subject;
+ 	$message = "";
+ 	$message_num++;
+-	# First unfold multiline header fields
++	# Retrieve and unfold header fields.
++	my @header_lines = ();
+ 	while(<$fh>) {
+ 		last if /^\s*$/;
+-		if (/^\s+\S/ and @header) {
+-			chomp($header[$#header]);
+-			s/^\s+/ /;
+-			$header[$#header] .= $_;
+-	    } else {
+-			push(@header, $_);
+-		}
++		push(@header_lines, $_);
++	}
++	@header = unfold_headers(@header_lines);
++	# Add computed headers, if applicable.
++	unless ($no_header_cmd || ! $header_cmd) {
++		push @header, invoke_header_cmd($header_cmd, $t);
+ 	}
+ 	# Now parse the header
+ 	foreach(@header) {
+@@ -2021,15 +2026,63 @@ sub process_file {
+ 	}
+ }
+ 
++# Execute a command and return its output lines as an array.  Blank
++# lines which do not appear at the end of the output are reported as
++# errors.
++sub execute_cmd {
++	my ($prefix, $cmd, $file) = @_;
++	my @lines = ();
++	my $seen_blank_line = 0;
++	open my $fh, "-|", "$cmd \Q$file\E"
++		or die sprintf(__("(%s) Could not execute '%s'"), $prefix, $cmd);
++	while (my $line = <$fh>) {
++		die sprintf(__("(%s) Malformed output from '%s'"), $prefix, $cmd)
++		    if $seen_blank_line;
++		if ($line =~ /^$/) {
++			$seen_blank_line = $line =~ /^$/;
++			next;
++		}
++		push @lines, $line;
++	}
++	close $fh
++	    or die sprintf(__("(%s) failed to close pipe to '%s'"), $prefix, $cmd);
++	return @lines;
++}
++
++# Process headers lines, unfolding multiline headers as defined by RFC
++# 2822.
++sub unfold_headers {
++	my @headers;
++	foreach(@_) {
++		last if /^\s*$/;
++		if (/^\s+\S/ and @headers) {
++			chomp($headers[$#headers]);
++			s/^\s+/ /;
++			$headers[$#headers] .= $_;
++		} else {
++			push(@headers, $_);
++		}
++	}
++	return @headers;
++}
++
++# Invoke the provided CMD with FILE as an argument, which should
++# output RFC 2822 email headers. Fold multiline headers and return the
++# headers as an array.
++sub invoke_header_cmd {
++	my ($cmd, $file) = @_;
++	my @lines = execute_cmd("header-cmd", $header_cmd, $file);
++	return unfold_headers(@lines);
++}
++
+ # Execute a command (e.g. $to_cmd) to get a list of email addresses
+ # and return a results array
+ sub recipients_cmd {
+ 	my ($prefix, $what, $cmd, $file) = @_;
+-
++	my @lines = ();
+ 	my @addresses = ();
+-	open my $fh, "-|", "$cmd \Q$file\E"
+-	    or die sprintf(__("(%s) Could not execute '%s'"), $prefix, $cmd);
+-	while (my $address = <$fh>) {
++	@lines = execute_cmd($prefix, $cmd, $file);
++	for my $address (@lines) {
+ 		$address =~ s/^\s*//g;
+ 		$address =~ s/\s*$//g;
+ 		$address = sanitize_address($address);
+@@ -2038,8 +2091,6 @@ sub recipients_cmd {
+ 		printf(__("(%s) Adding %s: %s from: '%s'\n"),
+ 		       $prefix, $what, $address, $cmd) unless $quiet;
+ 		}
+-	close $fh
+-	    or die sprintf(__("(%s) failed to close pipe to '%s'"), $prefix, $cmd);
+ 	return @addresses;
+ }
+ 
+diff --git a/t/t9001-send-email.sh b/t/t9001-send-email.sh
+index 6520346246..6519eea1ed 100755
+--- a/t/t9001-send-email.sh
++++ b/t/t9001-send-email.sh
+@@ -374,13 +374,16 @@ test_expect_success $PREREQ,!AUTOIDENT 'broken implicit ident aborts send-email'
+ 	)
+ '
+ 
+-test_expect_success $PREREQ 'setup tocmd and cccmd scripts' '
++test_expect_success $PREREQ 'setup cmd scripts' '
+ 	write_script tocmd-sed <<-\EOF &&
+ 	sed -n -e "s/^tocmd--//p" "$1"
+ 	EOF
+-	write_script cccmd-sed <<-\EOF
++	write_script cccmd-sed <<-\EOF &&
+ 	sed -n -e "s/^cccmd--//p" "$1"
+ 	EOF
++	write_script headercmd-sed <<-\EOF
++	sed -n -e "s/^headercmd--//p" "$1"
++	EOF
+ '
+ 
+ test_expect_success $PREREQ 'tocmd works' '
+@@ -410,6 +413,70 @@ test_expect_success $PREREQ 'cccmd works' '
+ 	grep "^	cccmd@example.com" msgtxt1
+ '
+ 
++test_expect_success $PREREQ 'headercmd works' '
++	clean_fake_sendmail &&
++	cp $patches headercmd.patch &&
++	echo "headercmd--X-Debbugs-CC: dummy@example.com" >>headercmd.patch &&
++	git send-email \
++		--from="Example <nobody@example.com>" \
++		--to=nobody@example.com \
++		--header-cmd=./headercmd-sed \
++		--smtp-server="$(pwd)/fake.sendmail" \
++		headercmd.patch \
++		&&
++	grep "^X-Debbugs-CC: dummy@example.com" msgtxt1
++'
++
++test_expect_success $PREREQ '--no-header-cmd works' '
++	clean_fake_sendmail &&
++	cp $patches headercmd.patch &&
++	echo "headercmd--X-Debbugs-CC: dummy@example.com" >>headercmd.patch &&
++	git send-email \
++		--from="Example <nobody@example.com>" \
++		--to=nobody@example.com \
++		--header-cmd=./headercmd-sed \
++                --no-header-cmd \
++		--smtp-server="$(pwd)/fake.sendmail" \
++		headercmd.patch \
++		&&
++	! grep "^X-Debbugs-CC: dummy@example.com" msgtxt1
++'
++
++test_expect_success $PREREQ 'multiline fields are correctly unfolded' '
++	clean_fake_sendmail &&
++	cp $patches headercmd.patch &&
++	write_script headercmd-multiline <<-\EOF &&
++	echo "X-Debbugs-CC: someone@example.com
++FoldedField: This is a tale
++ best told using
++ multiple lines."
++	EOF
++	git send-email \
++		--from="Example <nobody@example.com>" \
++		--to=nobody@example.com \
++		--header-cmd=./headercmd-multiline \
++		--smtp-server="$(pwd)/fake.sendmail" \
++		headercmd.patch &&
++	grep "^FoldedField: This is a tale best told using multiple lines.$" msgtxt1
++'
++
++# Blank lines in the middle of the output of a command are invalid.
++test_expect_success $PREREQ 'malform output reported on blank lines in command output' '
++	clean_fake_sendmail &&
++	cp $patches headercmd.patch &&
++	write_script headercmd-malformed-output <<-\EOF &&
++	echo "X-Debbugs-CC: someone@example.com
++
++SomeOtherField: someone-else@example.com"
++	EOF
++	! git send-email \
++		--from="Example <nobody@example.com>" \
++		--to=nobody@example.com \
++		--header-cmd=./headercmd-malformed-output \
++		--smtp-server="$(pwd)/fake.sendmail" \
++		headercmd.patch
++'
++
+ test_expect_success $PREREQ 'reject long lines' '
+ 	z8=zzzzzzzz &&
+ 	z64=$z8$z8$z8$z8$z8$z8$z8$z8 &&
diff --git a/gnu/packages/version-control.scm b/gnu/packages/version-control.scm
index c2ec490383..4fbf3b4d05 100644
--- a/gnu/packages/version-control.scm
+++ b/gnu/packages/version-control.scm
@@ -234,7 +234,8 @@ Python 3.3 and later, rather than on Python 2.")
                                 version ".tar.xz"))
             (sha256
              (base32
-              "1mpjvhyw8mv2q941xny4d0gw3mb6b4bqaqbh73jd8b1v6zqpaps7"))))
+              "1mpjvhyw8mv2q941xny4d0gw3mb6b4bqaqbh73jd8b1v6zqpaps7"))
+            (patches (search-patches "git-header-cmd.patch"))))
    (build-system gnu-build-system)
    (native-inputs
     `(("native-perl" ,perl)