Bug 1847572 - Expand home directory paths for arbitrary users r=xpcom-reviewers,nika

Differential Revision: https://phabricator.services.mozilla.com/D185999

docshell/test/unit/test_URIFixup_info.js

@@ -803,6 +803,7 @@ if (AppConstants.platform == "win") {
   });
 } else {
   const homeDir = Services.dirsvc.get("Home", Ci.nsIFile).path;
+  const homeBase = AppConstants.platform == "macosx" ? "/Users" : "/home";
 
   testcases.push({
     input: "~",
@@ -814,6 +815,16 @@ if (AppConstants.platform == "win") {
     fixedURI: `file://${homeDir}/foo`,
     protocolChange: true,
   });
+  testcases.push({
+    input: "~foo",
+    fixedURI: `file://${homeBase}/foo`,
+    protocolChange: true,
+  });
+  testcases.push({
+    input: "~foo/bar",
+    fixedURI: `file://${homeBase}/foo/bar`,
+    protocolChange: true,
+  });
   testcases.push({
     input: "/some/file.txt",
     fixedURI: "file:///some/file.txt",

xpcom/io/nsLocalFileUnix.cpp

@@ -307,19 +307,35 @@ nsLocalFile::Clone(nsIFile** aFile) {
 
 NS_IMETHODIMP
 nsLocalFile::InitWithNativePath(const nsACString& aFilePath) {
-  if (aFilePath.EqualsLiteral("~") ||
-      Substring(aFilePath, 0, 2).EqualsLiteral("~/")) {
-    nsCOMPtr<nsIFile> homeDir;
-    nsAutoCString homePath;
-    if (NS_FAILED(
-            NS_GetSpecialDirectory(NS_OS_HOME_DIR, getter_AddRefs(homeDir))) ||
-        NS_FAILED(homeDir->GetNativePath(homePath))) {
-      return NS_ERROR_FAILURE;
-    }
+  if (!aFilePath.IsEmpty() && aFilePath.First() == '~') {
+    if (aFilePath.Length() == 1 || aFilePath.CharAt(1) == '/') {
+      // Home dir for the current user
 
-    mPath = homePath;
-    if (aFilePath.Length() > 2) {
-      mPath.Append(Substring(aFilePath, 1, aFilePath.Length() - 1));
+      nsCOMPtr<nsIFile> homeDir;
+      nsAutoCString homePath;
+      if (NS_FAILED(NS_GetSpecialDirectory(NS_OS_HOME_DIR,
+                                           getter_AddRefs(homeDir))) ||
+          NS_FAILED(homeDir->GetNativePath(homePath))) {
+        return NS_ERROR_FAILURE;
+      }
+
+      mPath = homePath;
+      if (aFilePath.Length() > 2) {
+        mPath.Append(Substring(aFilePath, 1));
+      }
+    } else {
+      // Home dir for an arbitrary user e.g. `~foo/bar` -> `/home/foo/bar`
+      // (`/Users/foo/bar` on Mac). The accurate way to get this directory
+      // is with `getpwnam`, but we would like to avoid doing blocking
+      // filesystem I/O while creating an `nsIFile`.
+
+      mPath =
+#ifdef XP_MACOSX
+          "/Users/"_ns
+#else
+          "/home/"_ns
+#endif
+          + Substring(aFilePath, 1);
     }
   } else {
     if (aFilePath.IsEmpty() || aFilePath.First() != '/') {

xpcom/tests/gtest/TestFilePreferencesUnix.cpp

@@ -160,6 +160,31 @@ TEST(TestFilePreferencesUnix, Simple)
   rv = newPath->AppendNative(".."_ns);
   ASSERT_EQ(rv, NS_ERROR_FILE_UNRECOGNIZED_PATH);
 
+#ifdef XP_UNIX
+  nsAutoCString homePath;
+  NS_GetSpecialDirectory(NS_OS_HOME_DIR, getter_AddRefs(newPath));
+  newPath->GetNativePath(homePath);
+
+  newPath->InitWithNativePath("~"_ns);
+  ASSERT_TRUE(newPath->NativePath().Equals(homePath));
+
+  newPath->InitWithNativePath("~/foo"_ns);
+  ASSERT_TRUE(newPath->NativePath().Equals(homePath + "/foo"_ns));
+
+  nsLiteralCString homeBase =
+#  ifdef XP_MACOSX
+      "/Users"_ns;
+#  else
+      "/home"_ns;
+#  endif
+
+  newPath->InitWithNativePath("~foo"_ns);
+  ASSERT_TRUE(newPath->NativePath().Equals(homeBase + "/foo"_ns));
+
+  newPath->InitWithNativePath("~foo/bar"_ns);
+  ASSERT_TRUE(newPath->NativePath().Equals(homeBase + "/foo/bar"_ns));
+#endif
+
   nsAutoCString trickyPath(tempPath);
   trickyPath.AppendLiteral("/allowed/../forbidden_dir/file");
   rv = newPath->InitWithNativePath(trickyPath);