Split trailers out of the commit message

author: Bryce Kwon <bryce@brycekwon.com> 2026-09-12 17:22:15 -1000
committer: Bryce Kwon <bryce@brycekwon.com> 2026-09-12 17:22:15 -1000
commit: 1ff9942ed311c6c0faf3d129bb543d33bb9aded7 (patch)
parent: fb68e26829b4ad3b34e4df9a39b22107c20f2b5d (diff)
tree: 042204c1b66a6e0e3054ca2dc3d4a2e2b05370e0 /source
download: cgit-1ff9942ed311c6c0faf3d129bb543d33bb9aded7.tar.gz
cgit-1ff9942ed311c6c0faf3d129bb543d33bb9aded7.zip
6 files changed, 149 insertions, 6 deletions
diff --git a/source/cgit.c b/source/cgit.c
index e6e8613..ae91dd2 100644
--- a/source/cgit.c
+++ b/source/cgit.c
@@ -247,6 +247,8 @@ static void print_repo(FILE *f, struct cgit_repo *repo)
 		cgit_fprintf_filter(repo->source_filter, f, "repo.source-filter=");
 	if (repo->email_filter && repo->email_filter != ctx.cfg.email_filter)
 		cgit_fprintf_filter(repo->email_filter, f, "repo.email-filter=");
+	if (repo->trailer_filter && repo->trailer_filter != ctx.cfg.trailer_filter)
+		cgit_fprintf_filter(repo->trailer_filter, f, "repo.trailer-filter=");
 	if (repo->snapshots != ctx.cfg.snapshots) {
 		char *formats = build_snapshot_setting(repo->snapshots);
 		fprintf(f, "repo.snapshots=%s\n", formats ? formats : "");
@@ -262,6 +264,7 @@ static void print_repo(FILE *f, struct cgit_repo *repo)
 		fprintf(f, "repo.logo-link=%s\n", repo->logo_link);
 	fprintf(f, "repo.enable-remote-branches=%d\n", repo->enable_remote_branches);
 	fprintf(f, "repo.enable-subject-links=%d\n", repo->enable_subject_links);
+	fprintf(f, "repo.enable-trailers=%d\n", repo->enable_trailers);
 	fprintf(f, "repo.enable-html-serving=%d\n", repo->enable_html_serving);
 	if (repo->branch_sort == 1)
 		fprintf(f, "repo.branch-sort=age\n");
@@ -560,6 +563,8 @@ static void apply_config(const char *name, const char *value)
 		ctx.cfg.enable_remote_branches = atoi(value);
 	else if (!strcmp(name, "enable-subject-links"))
 		ctx.cfg.enable_subject_links = atoi(value);
+	else if (!strcmp(name, "enable-trailers"))
+		ctx.cfg.enable_trailers = atoi(value);
 	else if (!strcmp(name, "enable-html-serving"))
 		ctx.cfg.enable_html_serving = atoi(value);
 	else if (!strcmp(name, "enable-tree-linenumbers"))
@@ -598,6 +603,8 @@ static void apply_config(const char *name, const char *value)
 		ctx.cfg.commit_filter = cgit_new_filter(value, COMMIT);
 	else if (!strcmp(name, "email-filter"))
 		ctx.cfg.email_filter = cgit_new_filter(value, EMAIL);
+	else if (!strcmp(name, "trailer-filter"))
+		ctx.cfg.trailer_filter = cgit_new_filter(value, TRAILER);
 	else if (!strcmp(name, "auth-filter"))
 		ctx.cfg.auth_filter = cgit_new_filter(value, AUTH);
 	else if (!strcmp(name, "embedded"))
@@ -1165,6 +1172,8 @@ void cgit_repo_config(struct cgit_repo *repo, const char *name, const char *valu
 		repo->enable_remote_branches = atoi(value);
 	else if (!strcmp(name, "enable-subject-links"))
 		repo->enable_subject_links = atoi(value);
+	else if (!strcmp(name, "enable-trailers"))
+		repo->enable_trailers = atoi(value);
 	else if (!strcmp(name, "enable-html-serving"))
 		repo->enable_html_serving = atoi(value);
 	else if (!strcmp(name, "branch-sort")) {
@@ -1204,7 +1213,8 @@ void cgit_repo_config(struct cgit_repo *repo, const char *name, const char *valu
 		!strcmp(name, "about-filter")	||
 		!strcmp(name, "commit-filter")	||
 		!strcmp(name, "source-filter")	||
-		!strcmp(name, "email-filter")
+		!strcmp(name, "email-filter")	||
+		!strcmp(name, "trailer-filter")
 	) {
 		if (!ctx.cfg.enable_filter_overrides)
 			fprintf(stderr, "[cgit] Ignoring repo %s: enable-filter-overrides is not set\n", name);
@@ -1214,8 +1224,10 @@ void cgit_repo_config(struct cgit_repo *repo, const char *name, const char *valu
 			repo->commit_filter = cgit_new_filter(value, COMMIT);
 		else if (!strcmp(name, "source-filter"))
 			repo->source_filter = cgit_new_filter(value, SOURCE);
-		else
+		else if (!strcmp(name, "email-filter"))
 			repo->email_filter = cgit_new_filter(value, EMAIL);
+		else
+			repo->trailer_filter = cgit_new_filter(value, TRAILER);
 	} else
 		fprintf(stderr, "[cgit] Unknown repo config key: %s\n", name);
 }
diff --git a/source/cgit.h b/source/cgit.h
index cc4ac02..d976906 100644
--- a/source/cgit.h
+++ b/source/cgit.h
@@ -90,6 +90,7 @@ struct cgit_repo {
 	int enable_log_linecount;
 	int enable_remote_branches;
 	int enable_subject_links;
+	int enable_trailers;
 	int enable_html_serving;
 	int max_stats;
 	int branch_sort;
@@ -99,6 +100,7 @@ struct cgit_repo {
 	struct cgit_filter *commit_filter;
 	struct cgit_filter *source_filter;
 	struct cgit_filter *email_filter;
+	struct cgit_filter *trailer_filter;
 	struct string_list submodules;
 	int hide;
 	int ignore;
@@ -228,6 +230,7 @@ struct cgit_config {
 	int enable_relative_dates;
 	int enable_remote_branches;
 	int enable_subject_links;
+	int enable_trailers;
 	int enable_html_serving;
 	int enable_tree_linenumbers;
 	int enable_tree_group_dirs;
@@ -263,6 +266,7 @@ struct cgit_config {
 	struct cgit_filter *commit_filter;
 	struct cgit_filter *source_filter;
 	struct cgit_filter *email_filter;
+	struct cgit_filter *trailer_filter;
 	struct cgit_filter *auth_filter;
 };
 
diff --git a/source/filter.c b/source/filter.c
index 2731d58..81c4681 100644
--- a/source/filter.c
+++ b/source/filter.c
@@ -395,12 +395,14 @@ void cgit_cleanup_filters(void)
 	cleanup_filter(ctx.cfg.commit_filter);
 	cleanup_filter(ctx.cfg.source_filter);
 	cleanup_filter(ctx.cfg.email_filter);
+	cleanup_filter(ctx.cfg.trailer_filter);
 	cleanup_filter(ctx.cfg.auth_filter);
 	for (i = 0; i < cgit_repolist.count; ++i) {
 		cleanup_filter(cgit_repolist.repos[i].about_filter);
 		cleanup_filter(cgit_repolist.repos[i].commit_filter);
 		cleanup_filter(cgit_repolist.repos[i].source_filter);
 		cleanup_filter(cgit_repolist.repos[i].email_filter);
+		cleanup_filter(cgit_repolist.repos[i].trailer_filter);
 	}
 }
 
@@ -438,6 +440,7 @@ struct cgit_filter *cgit_new_filter(const char *cmd, filter_type filtertype)
 		argument_count = 12;
 		break;
 	case EMAIL:
+	case TRAILER:
 		argument_count = 2;
 		break;
 	case SOURCE:
diff --git a/source/filter.h b/source/filter.h
index 861578c..fa43416 100644
--- a/source/filter.h
+++ b/source/filter.h
@@ -13,7 +13,7 @@
 #include <stdio.h>
 
 typedef enum {
-	ABOUT, COMMIT, SOURCE, EMAIL, AUTH
+	ABOUT, COMMIT, SOURCE, EMAIL, TRAILER, AUTH
 } filter_type;
 
 struct cgit_filter {
diff --git a/source/shared.c b/source/shared.c
index beda48b..59712ce 100644
--- a/source/shared.c
+++ b/source/shared.c
@@ -215,6 +215,7 @@ struct cgit_repo *cgit_add_repo(const char *url)
 	repo->enable_log_linecount = ctx.cfg.enable_log_linecount;
 	repo->enable_remote_branches = ctx.cfg.enable_remote_branches;
 	repo->enable_subject_links = ctx.cfg.enable_subject_links;
+	repo->enable_trailers = ctx.cfg.enable_trailers;
 	repo->enable_html_serving = ctx.cfg.enable_html_serving;
 	repo->max_stats = ctx.cfg.max_stats;
 	repo->branch_sort = ctx.cfg.branch_sort;
@@ -226,6 +227,7 @@ struct cgit_repo *cgit_add_repo(const char *url)
 	repo->commit_filter = ctx.cfg.commit_filter;
 	repo->source_filter = ctx.cfg.source_filter;
 	repo->email_filter = ctx.cfg.email_filter;
+	repo->trailer_filter = ctx.cfg.trailer_filter;
 	repo->clone_url = ctx.cfg.clone_url;
 	repo->submodules.strdup_strings = 1;
 	repo->hide = repo->ignore = 0;
diff --git a/source/ui-commit.c b/source/ui-commit.c
index 6055509..b67f5db 100644
--- a/source/ui-commit.c
+++ b/source/ui-commit.c
@@ -18,6 +18,9 @@
 #include "ui-log.h"
 #include "ui-shared.h"
 
+#include <list.h>
+#include <trailer.h>
+
 // The diff below the message is always taken against the first parent alone,
 // which says little about a merge of many branches, so a commit with this
 // many parents or more is shown without a diff at all.
@@ -76,6 +79,127 @@ static void print_filtered_text(const char *text)
 	cgit_close_filter(ctx.repo->commit_filter);
 }
 
+/*
+ * A value shaped like an ident is written the way the author row is, through
+ * the email filter. Anything else goes through the trailer filter when one is
+ * set, and otherwise through the commit filter, so the links a site already
+ * draws in message text keep appearing on trailer lines.
+ */
+static void print_trailer_value(const char *key, const char *value)
+{
+	struct ident_split ident;
+	struct strbuf name = STRBUF_INIT, email = STRBUF_INIT;
+
+	if (!split_ident_line(&ident, value, strlen(value)) &&
+		memchr(ident.mail_begin, '@', ident.mail_end - ident.mail_begin)) {
+		strbuf_add(&name, ident.name_begin, ident.name_end - ident.name_begin);
+		strbuf_addch(&email, '<');
+		strbuf_add(&email, ident.mail_begin, ident.mail_end - ident.mail_begin);
+		strbuf_addch(&email, '>');
+		cgit_open_filter(ctx.repo->email_filter, email.buf, "commit");
+		html_txt(name.buf);
+		if (ctx.cfg.enable_plain_email) {
+			html(" ");
+			html_txt(email.buf);
+		}
+		cgit_close_filter(ctx.repo->email_filter);
+		strbuf_release(&name);
+		strbuf_release(&email);
+	} else if (ctx.repo->trailer_filter) {
+		cgit_open_filter(ctx.repo->trailer_filter, key, "commit");
+		html_txt(value);
+		cgit_close_filter(ctx.repo->trailer_filter);
+	} else
+		print_filtered_text(value);
+}
+
+/*
+ * One row per trailer, except that a run of trailers sharing a key becomes a
+ * single row listing every value. A line git kept in the block without being
+ * able to split it, such as a cherry-pick note, gets a row of its own.
+ */
+static void print_trailers(const char *msg)
+{
+	struct trailer_iterator iter;
+	struct strbuf key = STRBUF_INIT;
+	int open = 0;
+
+	html("<table class='commit-trailers'>\n");
+	trailer_iterator_init(&iter, msg);
+	while (trailer_iterator_advance(&iter)) {
+		if (!iter.val.len) {
+			if (open)
+				html("</td></tr>\n");
+			open = 0;
+			html("<tr><td colspan='2'>");
+			print_filtered_text(iter.key.buf);
+			html("</td></tr>\n");
+			continue;
+		}
+		if (open && !strcasecmp(key.buf, iter.key.buf))
+			html("<br>");
+		else {
+			if (open)
+				html("</td></tr>\n");
+			strbuf_reset(&key);
+			strbuf_addbuf(&key, &iter.key);
+			html("<tr><th>");
+			html_txt(key.buf);
+			html("</th><td>");
+			open = 1;
+		}
+		print_trailer_value(key.buf, iter.val.buf);
+	}
+	if (open)
+		html("</td></tr>\n");
+	html("</table>\n");
+	trailer_iterator_release(&iter);
+	strbuf_release(&key);
+}
+
+/*
+ * Git finds the trailer block by looking at the whole message, title included,
+ * so the subject goes back in front of the body before asking, and the offsets
+ * that come back are shifted by that prefix. The blank line that separated the
+ * body from its block is dropped along with the block.
+ */
+static void print_message(struct commitinfo *info)
+{
+	struct strbuf full = STRBUF_INIT;
+	struct process_trailer_options opts = PROCESS_TRAILER_OPTIONS_INIT;
+	struct trailer_block *block;
+	LIST_HEAD(items);
+	size_t prefix, start, end;
+	char *body = NULL;
+
+	if (ctx.repo->enable_trailers) {
+		strbuf_addf(&full, "%s\n\n%s", info->subject, info->msg);
+		prefix = full.len - strlen(info->msg);
+		opts.no_divider = 1;
+		block = parse_trailers(&opts, full.buf, &items);
+		start = trailer_block_start(block);
+		end = trailer_block_end(block);
+		free_trailers(&items);
+		trailer_block_release(block);
+		if (start >= prefix && start < end) {
+			size_t len = start - prefix;
+
+			while (len > 0 && info->msg[len - 1] == '\n')
+				len--;
+			body = xmemdupz(info->msg, len);
+		}
+	}
+
+	html("<div class='commit-msg'>");
+	print_filtered_text(body ? body : info->msg);
+	html("</div>\n");
+	if (body)
+		print_trailers(full.buf);
+
+	free(body);
+	strbuf_release(&full);
+}
+
 void cgit_print_commit(char *hex, const char *prefix)
 {
 	struct commit *commit;
@@ -145,9 +269,7 @@ void cgit_print_commit(char *hex, const char *prefix)
 	print_filtered_text(info->subject);
 	cgit_print_commit_decorations(commit);
 	html("</div>\n");
-	html("<div class='commit-msg'>");
-	print_filtered_text(info->msg);
-	html("</div>\n");
+	print_message(info);
 	if (notes.len != 0) {
 		html("<div class='notes-header'>Notes</div>\n");
 		html("<div class='notes'>");
author	Bryce Kwon <bryce@brycekwon.com>	2026-09-12 17:22:15 -1000
committer	Bryce Kwon <bryce@brycekwon.com>	2026-09-12 17:22:15 -1000
commit	1ff9942ed311c6c0faf3d129bb543d33bb9aded7 (patch)
parent	fb68e26829b4ad3b34e4df9a39b22107c20f2b5d (diff)
tree	042204c1b66a6e0e3054ca2dc3d4a2e2b05370e0 /source
download	cgit-1ff9942ed311c6c0faf3d129bb543d33bb9aded7.tar.gz cgit-1ff9942ed311c6c0faf3d129bb543d33bb9aded7.zip
-rw-r--r--	source/cgit.c	16
-rw-r--r--	source/cgit.h	4
-rw-r--r--	source/filter.c	3
-rw-r--r--	source/filter.h	2
-rw-r--r--	source/shared.c	2
-rw-r--r--	source/ui-commit.c	128