From 6408c1cbc87f03fc9e92471165886ddbe7cdbeae Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bj=C3=B8rn=20Erik=20Pedersen?=
 <bjorn.erik.pedersen@gmail.com>
Date: Tue, 16 Jun 2020 10:42:41 +0200
Subject: [PATCH] Fix server data race/nil pointer in withMaps

Fixes #7392
---
 hugolib/content_map_page.go |  1 -
 hugolib/hugo_sites.go       | 18 +++++++++++++-----
 hugolib/hugo_sites_build.go |  2 +-
 hugolib/site.go             |  4 +---
 4 files changed, 15 insertions(+), 10 deletions(-)

diff --git a/hugolib/content_map_page.go b/hugolib/content_map_page.go
index 8c7ecc341..b5165b2a5 100644
--- a/hugolib/content_map_page.go
+++ b/hugolib/content_map_page.go
@@ -47,7 +47,6 @@ func newPageMaps(h *HugoSites) *pageMaps {
 		workers: para.New(h.numWorkers),
 		pmaps:   mps,
 	}
-
 }
 
 type pageMap struct {
diff --git a/hugolib/hugo_sites.go b/hugolib/hugo_sites.go
index 3183242b7..16de27b0d 100644
--- a/hugolib/hugo_sites.go
+++ b/hugolib/hugo_sites.go
@@ -78,7 +78,8 @@ type HugoSites struct {
 	// As loaded from the /data dirs
 	data map[string]interface{}
 
-	content *pageMaps
+	contentInit sync.Once
+	content     *pageMaps
 
 	// Keeps track of bundle directories and symlinks to enable partial rebuilding.
 	ContentChanges *contentChangeMap
@@ -92,6 +93,13 @@ type HugoSites struct {
 	*testCounters
 }
 
+func (h *HugoSites) getContentMaps() *pageMaps {
+	h.contentInit.Do(func() {
+		h.content = newPageMaps(h)
+	})
+	return h.content
+}
+
 // Only used in tests.
 type testCounters struct {
 	contentRenderCounter uint64
@@ -253,7 +261,7 @@ func (h *HugoSites) PrintProcessingStats(w io.Writer) {
 func (h *HugoSites) GetContentPage(filename string) page.Page {
 	var p page.Page
 
-	h.content.walkBundles(func(b *contentNode) bool {
+	h.getContentMaps().walkBundles(func(b *contentNode) bool {
 		if b.p == nil || b.fi == nil {
 			return false
 		}
@@ -706,7 +714,7 @@ func (h *HugoSites) renderCrossSitesArtifacts() error {
 }
 
 func (h *HugoSites) removePageByFilename(filename string) {
-	h.content.withMaps(func(m *pageMap) error {
+	h.getContentMaps().withMaps(func(m *pageMap) error {
 		m.deleteBundleMatching(func(b *contentNode) bool {
 			if b.p == nil {
 				return false
@@ -897,7 +905,7 @@ func (h *HugoSites) findPagesByKindIn(kind string, inPages page.Pages) page.Page
 }
 
 func (h *HugoSites) resetPageState() {
-	h.content.walkBundles(func(n *contentNode) bool {
+	h.getContentMaps().walkBundles(func(n *contentNode) bool {
 		if n.p == nil {
 			return false
 		}
@@ -914,7 +922,7 @@ func (h *HugoSites) resetPageState() {
 }
 
 func (h *HugoSites) resetPageStateFromEvents(idset identity.Identities) {
-	h.content.walkBundles(func(n *contentNode) bool {
+	h.getContentMaps().walkBundles(func(n *contentNode) bool {
 		if n.p == nil {
 			return false
 		}
diff --git a/hugolib/hugo_sites_build.go b/hugolib/hugo_sites_build.go
index fac20e883..f39e7a7e5 100644
--- a/hugolib/hugo_sites_build.go
+++ b/hugolib/hugo_sites_build.go
@@ -263,7 +263,7 @@ func (h *HugoSites) assemble(bcfg *BuildCfg) error {
 		return nil
 	}
 
-	if err := h.content.AssemblePages(); err != nil {
+	if err := h.getContentMaps().AssemblePages(); err != nil {
 		return err
 	}
 
diff --git a/hugolib/site.go b/hugolib/site.go
index d544cb095..a0390780a 100644
--- a/hugolib/site.go
+++ b/hugolib/site.go
@@ -1296,14 +1296,12 @@ func (s *Site) readAndProcessContent(filenames ...string) error {
 
 	proc := newPagesProcessor(s.h, sourceSpec)
 
-	c := newPagesCollector(sourceSpec, s.h.content, s.Log, s.h.ContentChanges, proc, filenames...)
+	c := newPagesCollector(sourceSpec, s.h.getContentMaps(), s.Log, s.h.ContentChanges, proc, filenames...)
 
 	if err := c.Collect(); err != nil {
 		return err
 	}
 
-	s.h.content = newPageMaps(s.h)
-
 	return nil
 }