From 3dcfc072bbc984df6bad53a19fadfaa4a5af7812 Mon Sep 17 00:00:00 2001
From: Andrew Thornton <art27@cantab.net>
Date: Sat, 3 Jul 2021 21:28:40 +0100
Subject: [PATCH 1/2] Fix relative links in postprocessed images

If a pre-post-processed file contains relative img tags these need to be updated
and joined correctly with the prefix. Finally, the node attributes need to be updated.

Fix #16308

Signed-off-by: Andrew Thornton <art27@cantab.net>
---
 modules/markup/html.go      |  3 ++-
 modules/markup/html_test.go | 32 ++++++++++++++++++++++++++++++++
 2 files changed, 34 insertions(+), 1 deletion(-)

diff --git a/modules/markup/html.go b/modules/markup/html.go
index 1e55629ab5dd7..7afd8114c1b32 100644
--- a/modules/markup/html.go
+++ b/modules/markup/html.go
@@ -364,7 +364,7 @@ func visitNode(ctx *RenderContext, procs []processor, node *html.Node, visitText
 		}
 	case html.ElementNode:
 		if node.Data == "img" {
-			for _, attr := range node.Attr {
+			for i, attr := range node.Attr {
 				if attr.Key != "src" {
 					continue
 				}
@@ -377,6 +377,7 @@ func visitNode(ctx *RenderContext, procs []processor, node *html.Node, visitText
 
 					attr.Val = util.URLJoin(prefix, attr.Val)
 				}
+				node.Attr[i] = attr
 			}
 		} else if node.Data == "a" {
 			visitText = false
diff --git a/modules/markup/html_test.go b/modules/markup/html_test.go
index 85418892ef7f1..969c01af6f278 100644
--- a/modules/markup/html_test.go
+++ b/modules/markup/html_test.go
@@ -425,6 +425,38 @@ func TestRender_ShortLinks(t *testing.T) {
 		`<p><a href="https://example.org" rel="nofollow">[[foobar]]</a></p>`)
 }
 
+func TestRender_RelativeImages(t *testing.T) {
+	setting.AppURL = AppURL
+	setting.AppSubURL = AppSubURL
+	tree := util.URLJoin(AppSubURL, "src", "master")
+
+	test := func(input, expected, expectedWiki string) {
+		buffer, err := markdown.RenderString(&RenderContext{
+			URLPrefix: tree,
+		}, input)
+		assert.NoError(t, err)
+		assert.Equal(t, strings.TrimSpace(expected), strings.TrimSpace(buffer))
+		buffer, err = markdown.RenderString(&RenderContext{
+			URLPrefix: setting.AppSubURL,
+			Metas:     localMetas,
+			IsWiki:    true,
+		}, input)
+		assert.NoError(t, err)
+		assert.Equal(t, strings.TrimSpace(expectedWiki), strings.TrimSpace(buffer))
+	}
+
+	mediatree := util.URLJoin(AppSubURL, "media", "master")
+
+	url := util.URLJoin(mediatree, "Link")
+	urlWiki := util.URLJoin(AppSubURL, "wiki", "raw", "Link")
+
+	test(
+		`<img src="Link">`,
+		`<img src="`+url+`"/>`,
+		`<img src="`+urlWiki+`"/>`)
+
+}
+
 func Test_ParseClusterFuzz(t *testing.T) {
 	setting.AppURL = AppURL
 	setting.AppSubURL = AppSubURL

From 7517ee6940cc3594b17320813faa9aaed527a3a9 Mon Sep 17 00:00:00 2001
From: 6543 <6543@obermui.de>
Date: Sun, 4 Jul 2021 01:09:30 +0200
Subject: [PATCH 2/2] extend test

---
 modules/markup/html_test.go | 13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)

diff --git a/modules/markup/html_test.go b/modules/markup/html_test.go
index 969c01af6f278..a494c5bd1831b 100644
--- a/modules/markup/html_test.go
+++ b/modules/markup/html_test.go
@@ -433,6 +433,7 @@ func TestRender_RelativeImages(t *testing.T) {
 	test := func(input, expected, expectedWiki string) {
 		buffer, err := markdown.RenderString(&RenderContext{
 			URLPrefix: tree,
+			Metas:     localMetas,
 		}, input)
 		assert.NoError(t, err)
 		assert.Equal(t, strings.TrimSpace(expected), strings.TrimSpace(buffer))
@@ -445,16 +446,18 @@ func TestRender_RelativeImages(t *testing.T) {
 		assert.Equal(t, strings.TrimSpace(expectedWiki), strings.TrimSpace(buffer))
 	}
 
+	rawwiki := util.URLJoin(AppSubURL, "wiki", "raw")
 	mediatree := util.URLJoin(AppSubURL, "media", "master")
 
-	url := util.URLJoin(mediatree, "Link")
-	urlWiki := util.URLJoin(AppSubURL, "wiki", "raw", "Link")
-
 	test(
 		`<img src="Link">`,
-		`<img src="`+url+`"/>`,
-		`<img src="`+urlWiki+`"/>`)
+		`<img src="`+util.URLJoin(mediatree, "Link")+`"/>`,
+		`<img src="`+util.URLJoin(rawwiki, "Link")+`"/>`)
 
+	test(
+		`<img src="./icon.png">`,
+		`<img src="`+util.URLJoin(mediatree, "icon.png")+`"/>`,
+		`<img src="`+util.URLJoin(rawwiki, "icon.png")+`"/>`)
 }
 
 func Test_ParseClusterFuzz(t *testing.T) {