turn off rewriting of X-Sendfile and X-Accel-Redirect files

install/debug.conf.template

@@ -763,6 +763,32 @@ NameVirtualHost localhost:@@APACHE_SECONDARY_PORT@@
   ModPagespeedDisableFilters remove_comments,add_instrumentation
 </VirtualHost>
 
+<VirtualHost localhost:@@APACHE_SECONDARY_PORT@@>
+  ServerName uses-sendfile.example.com
+  ModPagespeedBlockingRewriteKey psatest
+  DocumentRoot "@@APACHE_DOC_ROOT@@"
+  ModPagespeedFileCachePath "@@MOD_PAGESPEED_CACHE@@"
+  ModPagespeedEnableFilters rewrite_javascript
+  Header always set X-Sendfile blablabla
+</VirtualHost>
+
+<VirtualHost localhost:@@APACHE_SECONDARY_PORT@@>
+  ServerName uses-xaccelredirect.example.com
+  ModPagespeedBlockingRewriteKey psatest
+  DocumentRoot "@@APACHE_DOC_ROOT@@"
+  ModPagespeedFileCachePath "@@MOD_PAGESPEED_CACHE@@"
+  ModPagespeedEnableFilters rewrite_javascript
+  Header always set X-Accel-Redirect blablabla
+</VirtualHost>
+
+<VirtualHost localhost:@@APACHE_SECONDARY_PORT@@>
+  ServerName doesnt-sendfile.example.com
+  ModPagespeedBlockingRewriteKey psatest
+  DocumentRoot "@@APACHE_DOC_ROOT@@"
+  ModPagespeedFileCachePath "@@MOD_PAGESPEED_CACHE@@"
+  ModPagespeedEnableFilters rewrite_javascript
+</VirtualHost>
+
 # For testing ipro + load from file + unknown extensions.
 <VirtualHost localhost:@@APACHE_SECONDARY_PORT@@>
   ServerName lff-ipro.example.com

net/instaweb/apache/system_test.sh

@@ -517,6 +517,27 @@ start_test rewrite on Cache-control: no-transform
 URL=$TEST_ROOT/disable_no_transform/index.html?PageSpeedFilters=inline_css
 fetch_until -save -recursive $URL 'grep -c style' 2
 
+# Test that we do not rewrite resources when the X-Sendfile header is set, or
+# when the X-Accel-Redirect header is set.
+start_test check that rewriting only happens without X-Sendfile
+function verify_no_rewriting_sendfile() {
+  local sendfile_hostname=$1
+  local sendfile_header=$2
+  URL="http://${sendfile_hostname}.example.com/mod_pagespeed_test/normal.js"
+  OUT=$(http_proxy=$SECONDARY_HOSTNAME $WGET_DUMP \
+    --header 'X-PSA-Blocking-Rewrite: psatest' --save-headers $URL)
+  check_from "$OUT" grep $sendfile_header
+  check_from "$OUT" grep comment2
+}
+verify_no_rewriting_sendfile "uses-sendfile" "X-Sendfile"
+verify_no_rewriting_sendfile "uses-xaccelredirect" "X-Accel-Redirect"
+# doesnt-sendfile.example.com has identical configuration, but just does not
+# set the X-Sendfile header. Check this here to make sure that we have do
+# rewrite under other circumstances.
+URL="http://doesnt-sendfile.example.com/mod_pagespeed_test/normal.js"
+http_proxy=$SECONDARY_HOSTNAME fetch_until -save "$URL" \
+    'fgrep -c comment2' 0
+
 start_test ModPagespeedShardDomain directive in .htaccess file
 test_filter extend_cache
 fetch_until -save $TEST_ROOT/shard/shard.html 'grep -c \.pagespeed\.' 4

net/instaweb/rewriter/resource.cc

@@ -126,6 +126,9 @@ bool Resource::IsSafeToRewrite(bool rewrite_uncacheable,
              response_headers_.HasValue(HttpAttributes::kCacheControl,
                                         "no-transform")) {
     StrAppend(reason, "Cache-control: no-transform, ");
+  } else if (response_headers_.Lookup1(HttpAttributes::kXSendfile) ||
+             response_headers_.Lookup1(HttpAttributes::kXAccelRedirect)) {
+    StrAppend(reason, "Sendfile in header, unsafe to rewrite! ");
   } else if (contents().empty()) {
     // https://github.com/pagespeed/mod_pagespeed/issues/1050
     StrAppend(reason, "Resource is empty, ");

pagespeed/kernel/http/http_names.cc

@@ -116,6 +116,8 @@ const char HttpAttributes::kXSplitBelowTheFold[] = "btf";
 const char HttpAttributes::kXRequestedWith[] = "X-Requested-With";
 const char HttpAttributes::kXUACompatible[] = "X-UA-Compatible";
 const char HttpAttributes::kXPsaSplitConfig[] = "X-PSA-Split-Config";
+const char HttpAttributes::kXSendfile[] = "X-Sendfile";
+const char HttpAttributes::kXAccelRedirect[] = "X-Accel-Redirect";
 
 const char* HttpStatus::GetReasonPhrase(HttpStatus::Code rc) {
   switch (rc) {

pagespeed/kernel/http/http_names.h

@@ -149,6 +149,10 @@ struct HttpAttributes {
   // The config to be used fo the split html xpath.
   static const char kXPsaSplitConfig[];
 
+  // Sendfile type responses.
+  static const char kXSendfile[];
+  static const char kXAccelRedirect[];
+
   // Gets a sorted StringPieceVector containing all the hop-by-hop headers,
   // plus Set-Cookie and Set-Cookie2, per
   //