From 938024c6f6b0f8ba276a3615acfeb0bbb90c25a2 Mon Sep 17 00:00:00 2001
From: Donncha O Caoimh <5656673+donnchawp@users.noreply.github.com>
Date: Tue, 26 Nov 2024 13:00:30 +0000
Subject: [PATCH 1/3] Check that there is cached content to display in browser

---
 projects/plugins/super-cache/wp-cache-phase2.php | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/projects/plugins/super-cache/wp-cache-phase2.php b/projects/plugins/super-cache/wp-cache-phase2.php
index 392d25bf258d0..5df344a759793 100644
--- a/projects/plugins/super-cache/wp-cache-phase2.php
+++ b/projects/plugins/super-cache/wp-cache-phase2.php
@@ -301,6 +301,16 @@ function wp_cache_serve_cache_file() {
 				}
 				header( 'Last-Modified: ' . $local_mod_time );
 			}
+
+			/*
+			 * On the rare occasion that the cache file is empty, maybe due to a race condition
+			 * between the file check and the file_get_contents call, we'll just regenerate the cache.
+			 */
+			if ( false === $cachefiledata ) {
+				wp_cache_debug( 'The cached file could not be read. Must generate a new one.' );
+				return false;
+			}
+
 			echo $cachefiledata;
 			exit();
 		} else {

From 792bf03c7eeac2d431a75412aef9fb09f52ae841 Mon Sep 17 00:00:00 2001
From: Donncha O Caoimh <5656673+donnchawp@users.noreply.github.com>
Date: Tue, 26 Nov 2024 13:02:33 +0000
Subject: [PATCH 2/3] changelog

---
 .../changelog/update-super-cache-cache-file-race-condition    | 4 ++++
 1 file changed, 4 insertions(+)
 create mode 100644 projects/plugins/super-cache/changelog/update-super-cache-cache-file-race-condition

diff --git a/projects/plugins/super-cache/changelog/update-super-cache-cache-file-race-condition b/projects/plugins/super-cache/changelog/update-super-cache-cache-file-race-condition
new file mode 100644
index 0000000000000..142a0ba3b9648
--- /dev/null
+++ b/projects/plugins/super-cache/changelog/update-super-cache-cache-file-race-condition
@@ -0,0 +1,4 @@
+Significance: patch
+Type: fixed
+
+Caching: make sure there is cache content to serve, even if the cache file was found

From 9749f8e8bfa3a8ef670c7761b5b592ed38e19aca Mon Sep 17 00:00:00 2001
From: Donncha O Caoimh <5656673+donnchawp@users.noreply.github.com>
Date: Tue, 26 Nov 2024 13:28:11 +0000
Subject: [PATCH 3/3] Check for cache contents earlier

---
 .../plugins/super-cache/wp-cache-phase2.php   | 39 +++++++++++++------
 1 file changed, 28 insertions(+), 11 deletions(-)

diff --git a/projects/plugins/super-cache/wp-cache-phase2.php b/projects/plugins/super-cache/wp-cache-phase2.php
index 5df344a759793..44287b4635f1e 100644
--- a/projects/plugins/super-cache/wp-cache-phase2.php
+++ b/projects/plugins/super-cache/wp-cache-phase2.php
@@ -227,18 +227,44 @@ function wp_cache_serve_cache_file() {
 				if ( $wp_cache_gzip_encoding ) {
 					if ( file_exists( $file . '.gz' ) ) {
 						$cachefiledata = file_get_contents( $file . '.gz' );
+
+						if ( false === $cachefiledata ) {
+							wp_cache_debug( 'The cached gzip file could not be read. Must generate a new one.' );
+							return false;
+						}
+
 						wp_cache_debug( "Fetched gzip static page data from supercache file using PHP. File: $file.gz" );
 					} else {
-						$cachefiledata = gzencode( file_get_contents( $file ), 6, FORCE_GZIP );
+						$cachefiledata = file_get_contents( $file ); // phpcs:ignore WordPress.WP.AlternativeFunctions.file_get_contents_file_get_contents
+
+						if ( false === $cachefiledata ) {
+							wp_cache_debug( 'The cached file could not be read. Must generate a new one.' );
+							return false;
+						}
+
+						$cachefiledata = gzencode( $cachefiledata, 6, FORCE_GZIP );
 						wp_cache_debug( "Fetched static page data from supercache file using PHP and gzipped it. File: $file" );
 					}
 				} else {
 					$cachefiledata = file_get_contents( $file );
+
+					if ( false === $cachefiledata ) {
+						wp_cache_debug( 'The cached file could not be read. Must generate a new one.' );
+						return false;
+					}
+
 					wp_cache_debug( "Fetched static page data from supercache file using PHP. File: $file" );
 				}
 			} else {
 				// get dynamic data from filtered file
-				$cachefiledata = do_cacheaction( 'wpsc_cachedata', file_get_contents( $file ) );
+				$cachefiledata = file_get_contents( $file ); // phpcs:ignore WordPress.WP.AlternativeFunctions.file_get_contents_file_get_contents
+
+				if ( false === $cachefiledata ) {
+					wp_cache_debug( 'The cached file could not be read. Must generate a new one.' );
+					return false;
+				}
+
+				$cachefiledata = do_cacheaction( 'wpsc_cachedata', $cachefiledata );
 				if ( $wp_cache_gzip_encoding ) {
 					$cachefiledata = gzencode( $cachefiledata, 6, FORCE_GZIP );
 					wp_cache_debug( "Fetched dynamic page data from supercache file using PHP and gzipped it. File: $file" );
@@ -302,15 +328,6 @@ function wp_cache_serve_cache_file() {
 				header( 'Last-Modified: ' . $local_mod_time );
 			}
 
-			/*
-			 * On the rare occasion that the cache file is empty, maybe due to a race condition
-			 * between the file check and the file_get_contents call, we'll just regenerate the cache.
-			 */
-			if ( false === $cachefiledata ) {
-				wp_cache_debug( 'The cached file could not be read. Must generate a new one.' );
-				return false;
-			}
-
 			echo $cachefiledata;
 			exit();
 		} else {