From ff262e488c280c809f3ddc40ae3efd65fd350801 Mon Sep 17 00:00:00 2001
From: Bryce Kwon <bryce@brycekwon.com>
Date: Sun, 19 Jul 2026 16:22:09 -1000
Subject: Stat oversized diffs instead of inlining them

---
 source/ui-diff.c | 48 ++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 48 insertions(+)

(limited to 'source/ui-diff.c')

diff --git a/source/ui-diff.c b/source/ui-diff.c
index baaa1f8..b34f7b3 100644
--- a/source/ui-diff.c
+++ b/source/ui-diff.c
@@ -40,6 +40,11 @@ static int use_ssdiff = 0;
 static struct diff_filepair *current_filepair;
 static const char *current_prefix;
 
+/* Caps apply only to whole-commit views. A single-file diff page must
+ * always render fully, since it is where the capped views link to. */
+static int cap_diffs;
+static int item_idx;
+
 struct diff_filespec *cgit_get_current_old_file(void)
 {
 	return current_filepair->one;
@@ -299,11 +304,13 @@ static void filepair_cb(struct diff_filepair *pair)
 	unsigned long old_size = 0;
 	unsigned long new_size = 0;
 	int binary = 0;
+	int idx;
 	linediff_fn print_line_fn = print_line;
 
 	if (!show_filepair(pair))
 		return;
 
+	idx = item_idx++;
 	current_filepair = pair;
 	if (use_ssdiff) {
 		cgit_ssdiff_header_begin();
@@ -313,6 +320,29 @@ static void filepair_cb(struct diff_filepair *pair)
 	       &pair->two->oid, pair->two->path, pair->two->mode);
 	if (use_ssdiff)
 		cgit_ssdiff_header_end();
+
+	/* The diffstat pass counted this file's lines. Over the budget,
+	 * print the header and hand off to the single-file diff page
+	 * instead of rendering the whole thing inline. */
+	if (cap_diffs && ctx.cfg.max_diff_lines > 0 && idx < files &&
+	    !items[idx].binary && items[idx].added + items[idx].removed >
+				  (unsigned int)ctx.cfg.max_diff_lines) {
+		if (use_ssdiff)
+			html("<tr><td colspan='4' class='truncated'>");
+		else
+			html("<div class='truncated'>");
+		html("This diff is too large to be rendered inline. ");
+		cgit_diff_link("View it on its own page", NULL, NULL,
+			       ctx.qry.head, ctx.qry.oid, ctx.qry.oid2,
+			       items[idx].new_path);
+		html(".");
+		if (use_ssdiff) {
+			html("</td></tr>");
+			cgit_ssdiff_footer();
+		} else
+			html("</div>");
+		return;
+	}
 	if (S_ISGITLINK(pair->one->mode) || S_ISGITLINK(pair->two->mode)) {
 		if (S_ISGITLINK(pair->one->mode)) {
 			char *l = fmt("-Subproject %s", oid_to_hex(&pair->one->oid));
@@ -406,6 +436,8 @@ void cgit_print_diff(const char *new_rev, const char *old_rev,
 		current_prefix = NULL;
 	}
 
+	cap_diffs = !prefix && !current_prefix;
+
 	if (!new_rev)
 		new_rev = ctx.qry.head;
 	if (repo_get_oid(the_repository, new_rev, new_rev_oid)) {
@@ -493,12 +525,28 @@ void cgit_print_diff(const char *new_rev, const char *old_rev,
 		return;
 	}
 
+	/* A commit touching more files than max-diff-files stops at the
+	 * stat above, where every file links to its own diff page. */
+	if (cap_diffs && ctx.cfg.max_diff_files > 0 &&
+	    files > ctx.cfg.max_diff_files) {
+		html("<div class='truncated'>");
+		html("This diff is too large to be rendered inline. "
+		     "Follow a file above, or the ");
+		cgit_patch_link("patch", NULL, NULL, NULL, ctx.qry.oid, NULL);
+		html(" link for the whole commit.");
+		html("</div>");
+		if (show_ctrls)
+			cgit_print_layout_end();
+		return;
+	}
+
 	if (use_ssdiff) {
 		html("<table summary='ssdiff' class='ssdiff'>");
 	} else {
 		html("<table summary='diff' class='diff'>");
 		html("<tr><td>");
 	}
+	item_idx = 0;
 	cgit_diff_tree(old_rev_oid, new_rev_oid, filepair_cb, prefix,
 		       ctx.qry.ignorews);
 	if (!use_ssdiff)
-- 
cgit v2.8.0