Merge branch 'jk/format-patch-from'

"git format-patch" learned "--from[=whom]" option, which sets the
"From: " header to the specified person (or the person who runs the
command, if "=whom" part is missing) and move the original author
information to an in-body From: header as necessary.

* jk/format-patch-from:
  teach format-patch to place other authors into in-body "From"
  pretty.c: drop const-ness from pretty_print_context

Documentation/git-format-patch.txt

@@ -187,6 +187,21 @@ will want to ensure that threading is disabled for `git send-email`.
 	The negated form `--no-cc` discards all `Cc:` headers added so
 	far (from config or command line).
 
+--from::
+--from=<ident>::
+	Use `ident` in the `From:` header of each commit email. If the
+	author ident of the commit is not textually identical to the
+	provided `ident`, place a `From:` header in the body of the
+	message with the original author. If no `ident` is given, use
+	the committer ident.
++
+Note that this option is only useful if you are actually sending the
+emails and want to identify yourself as the sender, but retain the
+original author (and `git am` will correctly pick up the in-body
+header). Note also that `git send-email` already handles this
+transformation for you, and this option should not be used if you are
+feeding the result to `git send-email`.
+
 --add-header=<header>::
 	Add an arbitrary header to the email headers.  This is in addition
 	to any configured headers, and may be used multiple times.

builtin/log.c

@@ -1112,6 +1112,21 @@ static int cc_callback(const struct option *opt, const char *arg, int unset)
 	return 0;
 }
 
+static int from_callback(const struct option *opt, const char *arg, int unset)
+{
+	char **from = opt->value;
+
+	free(*from);
+
+	if (unset)
+		*from = NULL;
+	else if (arg)
+		*from = xstrdup(arg);
+	else
+		*from = xstrdup(git_committer_info(IDENT_NO_DATE));
+	return 0;
+}
+
 int cmd_format_patch(int argc, const char **argv, const char *prefix)
 {
 	struct commit *commit;
@@ -1134,6 +1149,7 @@ int cmd_format_patch(int argc, const char **argv, const char *prefix)
 	int quiet = 0;
 	int reroll_count = -1;
 	char *branch_name = NULL;
+	char *from = NULL;
 	const struct option builtin_format_patch_options[] = {
 		{ OPTION_CALLBACK, 'n', "numbered", &numbered, NULL,
 			    N_("use [PATCH n/m] even with a single patch"),
@@ -1177,6 +1193,9 @@ int cmd_format_patch(int argc, const char **argv, const char *prefix)
 			    0, to_callback },
 		{ OPTION_CALLBACK, 0, "cc", NULL, N_("email"), N_("add Cc: header"),
 			    0, cc_callback },
+		{ OPTION_CALLBACK, 0, "from", &from, N_("ident"),
+			    N_("set From address to <ident> (or committer ident if absent)"),
+			    PARSE_OPT_OPTARG, from_callback },
 		OPT_STRING(0, "in-reply-to", &in_reply_to, N_("message-id"),
 			    N_("make first mail a reply to <message-id>")),
 		{ OPTION_CALLBACK, 0, "attach", &rev, N_("boundary"),
@@ -1264,6 +1283,11 @@ int cmd_format_patch(int argc, const char **argv, const char *prefix)
 
 	rev.extra_headers = strbuf_detach(&buf, NULL);
 
+	if (from) {
+		if (split_ident_line(&rev.from_ident, from, strlen(from)))
+			die(_("invalid ident line: %s"), from);
+	}
+
 	if (start_number < 0)
 		start_number = 1;
 

commit.h

@@ -6,6 +6,7 @@
 #include "strbuf.h"
 #include "decorate.h"
 #include "gpg-interface.h"
+#include "string-list.h"
 
 struct commit_list {
 	struct commit *item;
@@ -79,6 +80,9 @@ enum cmit_fmt {
 };
 
 struct pretty_print_context {
+	/*
+	 * Callers should tweak these to change the behavior of pp_* functions.
+	 */
 	enum cmit_fmt fmt;
 	int abbrev;
 	const char *subject;
@@ -92,6 +96,15 @@ struct pretty_print_context {
 	const char *output_encoding;
 	struct string_list *mailmap;
 	int color;
+	struct ident_split *from_ident;
+
+	/*
+	 * Fields below here are manipulated internally by pp_* functions and
+	 * should not be counted on by callers.
+	 */
+
+	/* Manipulated by the pp_* functions internally. */
+	struct string_list in_body_headers;
 };
 
 struct userformat_want {
@@ -111,20 +124,20 @@ extern void userformat_find_requirements(const char *fmt, struct userformat_want
 extern void format_commit_message(const struct commit *commit,
 				  const char *format, struct strbuf *sb,
 				  const struct pretty_print_context *context);
-extern void pretty_print_commit(const struct pretty_print_context *pp,
+extern void pretty_print_commit(struct pretty_print_context *pp,
 				const struct commit *commit,
 				struct strbuf *sb);
 extern void pp_commit_easy(enum cmit_fmt fmt, const struct commit *commit,
 			   struct strbuf *sb);
-void pp_user_info(const struct pretty_print_context *pp,
+void pp_user_info(struct pretty_print_context *pp,
 		  const char *what, struct strbuf *sb,
 		  const char *line, const char *encoding);
-void pp_title_line(const struct pretty_print_context *pp,
+void pp_title_line(struct pretty_print_context *pp,
 		   const char **msg_p,
 		   struct strbuf *sb,
 		   const char *encoding,
 		   int need_8bit_cte);
-void pp_remainder(const struct pretty_print_context *pp,
+void pp_remainder(struct pretty_print_context *pp,
 		  const char **msg_p,
 		  struct strbuf *sb,
 		  int indent);

log-tree.c

@@ -618,6 +618,8 @@ void show_log(struct rev_info *opt)
 	ctx.mailmap = opt->mailmap;
 	ctx.color = opt->diffopt.use_color;
 	ctx.output_encoding = get_log_output_encoding();
+	if (opt->from_ident.mail_begin && opt->from_ident.name_begin)
+		ctx.from_ident = &opt->from_ident;
 	pretty_print_commit(&ctx, commit, &msgbuf);
 
 	if (opt->add_signoff)

pretty.c

@@ -406,7 +406,7 @@ static const char *show_ident_date(const struct ident_split *ident,
 	return show_date(date, tz, mode);
 }
 
-void pp_user_info(const struct pretty_print_context *pp,
+void pp_user_info(struct pretty_print_context *pp,
 		  const char *what, struct strbuf *sb,
 		  const char *line, const char *encoding)
 {
@@ -432,6 +432,23 @@ void pp_user_info(const struct pretty_print_context *pp,
 		map_user(pp->mailmap, &mailbuf, &maillen, &namebuf, &namelen);
 
 	if (pp->fmt == CMIT_FMT_EMAIL) {
+		if (pp->from_ident) {
+			struct strbuf buf = STRBUF_INIT;
+
+			strbuf_addstr(&buf, "From: ");
+			strbuf_add(&buf, namebuf, namelen);
+			strbuf_addstr(&buf, " <");
+			strbuf_add(&buf, mailbuf, maillen);
+			strbuf_addstr(&buf, ">\n");
+			string_list_append(&pp->in_body_headers,
+					   strbuf_detach(&buf, NULL));
+
+			mailbuf = pp->from_ident->mail_begin;
+			maillen = pp->from_ident->mail_end - mailbuf;
+			namebuf = pp->from_ident->name_begin;
+			namelen = pp->from_ident->name_end - namebuf;
+		}
+
 		strbuf_addstr(sb, "From: ");
 		if (needs_rfc2047_encoding(namebuf, namelen, RFC2047_ADDRESS)) {
 			add_rfc2047(sb, namebuf, namelen,
@@ -1514,7 +1531,7 @@ void format_commit_message(const struct commit *commit,
 	free(context.signature_check.signer);
 }
 
-static void pp_header(const struct pretty_print_context *pp,
+static void pp_header(struct pretty_print_context *pp,
 		      const char *encoding,
 		      const struct commit *commit,
 		      const char **msg_p,
@@ -1575,7 +1592,7 @@ static void pp_header(const struct pretty_print_context *pp,
 	}
 }
 
-void pp_title_line(const struct pretty_print_context *pp,
+void pp_title_line(struct pretty_print_context *pp,
 		   const char **msg_p,
 		   struct strbuf *sb,
 		   const char *encoding,
@@ -1602,6 +1619,16 @@ void pp_title_line(const struct pretty_print_context *pp,
 	}
 	strbuf_addch(sb, '\n');
 
+	if (need_8bit_cte == 0) {
+		int i;
+		for (i = 0; i < pp->in_body_headers.nr; i++) {
+			if (has_non_ascii(pp->in_body_headers.items[i].string)) {
+				need_8bit_cte = 1;
+				break;
+			}
+		}
+	}
+
 	if (need_8bit_cte > 0) {
 		const char *header_fmt =
 			"MIME-Version: 1.0\n"
@@ -1615,10 +1642,21 @@ void pp_title_line(const struct pretty_print_context *pp,
 	if (pp->fmt == CMIT_FMT_EMAIL) {
 		strbuf_addch(sb, '\n');
 	}
+
+	if (pp->in_body_headers.nr) {
+		int i;
+		for (i = 0; i < pp->in_body_headers.nr; i++) {
+			strbuf_addstr(sb, pp->in_body_headers.items[i].string);
+			free(pp->in_body_headers.items[i].string);
+		}
+		string_list_clear(&pp->in_body_headers, 0);
+		strbuf_addch(sb, '\n');
+	}
+
 	strbuf_release(&title);
 }
 
-void pp_remainder(const struct pretty_print_context *pp,
+void pp_remainder(struct pretty_print_context *pp,
 		  const char **msg_p,
 		  struct strbuf *sb,
 		  int indent)
@@ -1650,7 +1688,7 @@ void pp_remainder(const struct pretty_print_context *pp,
 	}
 }
 
-void pretty_print_commit(const struct pretty_print_context *pp,
+void pretty_print_commit(struct pretty_print_context *pp,
 			 const struct commit *commit,
 			 struct strbuf *sb)
 {

revision.h

@@ -144,6 +144,7 @@ struct rev_info {
 	int		numbered_files;
 	int		reroll_count;
 	char		*message_id;
+	struct ident_split from_ident;
 	struct string_list *ref_message_ids;
 	int		add_signoff;
 	const char	*extra_headers;

t/t4014-format-patch.sh

@@ -972,6 +972,49 @@ test_expect_success 'empty subject prefix does not have extra space' '
 	test_cmp expect actual
 '
 
+test_expect_success '--from=ident notices bogus ident' '
+	test_must_fail git format-patch -1 --stdout --from=foo >patch
+'
+
+test_expect_success '--from=ident replaces author' '
+	git format-patch -1 --stdout --from="Me <me@example.com>" >patch &&
+	cat >expect <<-\EOF &&
+	From: Me <me@example.com>
+
+	From: A U Thor <author@example.com>
+
+	EOF
+	sed -ne "/^From:/p; /^$/p; /^---$/q" <patch >patch.head &&
+	test_cmp expect patch.head
+'
+
+test_expect_success '--from uses committer ident' '
+	git format-patch -1 --stdout --from >patch &&
+	cat >expect <<-\EOF &&
+	From: C O Mitter <committer@example.com>
+
+	From: A U Thor <author@example.com>
+
+	EOF
+	sed -ne "/^From:/p; /^$/p; /^---$/q" <patch >patch.head &&
+	test_cmp expect patch.head
+'
+
+test_expect_success 'in-body headers trigger content encoding' '
+	GIT_AUTHOR_NAME="éxötìc" test_commit exotic &&
+	test_when_finished "git reset --hard HEAD^" &&
+	git format-patch -1 --stdout --from >patch &&
+	cat >expect <<-\EOF &&
+	From: C O Mitter <committer@example.com>
+	Content-Type: text/plain; charset=UTF-8
+
+	From: éxötìc <author@example.com>
+
+	EOF
+	sed -ne "/^From:/p; /^$/p; /^Content-Type/p; /^---$/q" <patch >patch.head &&
+	test_cmp expect patch.head
+'
+
 append_signoff()
 {
 	C=$(git commit-tree HEAD^^{tree} -p HEAD) &&