From adb9a5e72234ca941df10e579cdaf8f1e2044dbc Mon Sep 17 00:00:00 2001
From: Andrew McCreight <continuation@gmail.com>
Date: Thu, 15 Jun 2023 14:38:03 +0000
Subject: [PATCH] Bug 1838542 - Eliminate the most common warning spam from
 nsXREDirProvider::GetFile(). r=xpcom-reviewers,jstutte

Currently, this function warns any time it fails to return something.
However, this warning happens extremely frequently in two cases:
when the property is unknown or when somebody tries to get a
profile directory in a child process.

This patch eliminates those. It also consolidates some profile
cases. Hopefully an additional 2 strcmps on common cases won't
matter.

Differential Revision: https://phabricator.services.mozilla.com/D181007
---
 toolkit/xre/nsXREDirProvider.cpp | 33 ++++++++++++++++++++++----------
 1 file changed, 23 insertions(+), 10 deletions(-)

diff --git a/toolkit/xre/nsXREDirProvider.cpp b/toolkit/xre/nsXREDirProvider.cpp
index ea1e5a80613e..41d2353fe843 100644
--- a/toolkit/xre/nsXREDirProvider.cpp
+++ b/toolkit/xre/nsXREDirProvider.cpp
@@ -327,13 +327,29 @@ nsXREDirProvider::GetFile(const char* aProperty, bool* aPersistent,
 
   nsCOMPtr<nsIFile> file;
 
-  if (!strcmp(aProperty, NS_APP_USER_PROFILE_LOCAL_50_DIR)) {
+  if (!strcmp(aProperty, NS_APP_USER_PROFILE_LOCAL_50_DIR) ||
+      !strcmp(aProperty, NS_APP_PROFILE_LOCAL_DIR_STARTUP)) {
     if (mProfileLocalDir) {
       rv = mProfileLocalDir->Clone(getter_AddRefs(file));
+    } else {
+      // Profile directories are only set up in the parent process.
+      // We don't expect every caller to check if they are in the right process,
+      // so fail immediately to avoid warning spam.
+      NS_WARNING_ASSERTION(!XRE_IsParentProcess(),
+                           "tried to get profile in parent too early");
+      return NS_ERROR_FAILURE;
     }
-  } else if (!strcmp(aProperty, NS_APP_USER_PROFILE_50_DIR)) {
+  } else if (!strcmp(aProperty, NS_APP_USER_PROFILE_50_DIR) ||
+             !strcmp(aProperty, NS_APP_PROFILE_DIR_STARTUP)) {
     if (mProfileDir) {
       rv = mProfileDir->Clone(getter_AddRefs(file));
+    } else {
+      // Profile directories are only set up in the parent process.
+      // We don't expect every caller to check if they are in the right process,
+      // so fail immediately to avoid warning spam.
+      NS_WARNING_ASSERTION(!XRE_IsParentProcess(),
+                           "tried to get profile in parent too early");
+      return NS_ERROR_FAILURE;
     }
   } else if (!strcmp(aProperty, NS_GRE_DIR)) {
     // On Android, internal files are inside the APK, a zip file, so this
@@ -388,14 +404,6 @@ nsXREDirProvider::GetFile(const char* aProperty, bool* aPersistent,
     rv = GetUserProfilesLocalDir(getter_AddRefs(file));
   } else if (!strcmp(aProperty, XRE_EXECUTABLE_FILE)) {
     rv = XRE_GetBinaryPath(getter_AddRefs(file));
-  } else if (!strcmp(aProperty, NS_APP_PROFILE_DIR_STARTUP)) {
-    if (mProfileDir) {
-      rv = mProfileDir->Clone(getter_AddRefs(file));
-    }
-  } else if (!strcmp(aProperty, NS_APP_PROFILE_LOCAL_DIR_STARTUP)) {
-    if (mProfileLocalDir) {
-      rv = mProfileLocalDir->Clone(getter_AddRefs(file));
-    }
   }
 #if defined(XP_UNIX) || defined(XP_MACOSX)
   else if (!strcmp(aProperty, XRE_SYS_LOCAL_EXTENSION_PARENT_DIR)) {
@@ -470,6 +478,11 @@ nsXREDirProvider::GetFile(const char* aProperty, bool* aPersistent,
     rv = file->AppendNative(nsLiteralCString(PREF_OVERRIDE_DIRNAME));
     NS_ENSURE_SUCCESS(rv, rv);
     rv = EnsureDirectoryExists(file);
+  } else {
+    // We don't know anything about this property. Fail without warning, because
+    // otherwise we'll get too much warning spam due to
+    // nsDirectoryService::Get() trying everything it gets with every provider.
+    return NS_ERROR_FAILURE;
   }
 
   NS_ENSURE_SUCCESS(rv, rv);