Don't recursively list directories in realCasePath() (#641)

We only need to list the path's immediate parent directory in order to
find its real case.

Closes #636

CHANGELOG.md

@@ -1,5 +1,8 @@
 ## 1.17.5
 
+* Avoid recursively listing directories when finding the canonical name of a
+  file on case-insensitive filesystems.
+
 * Fix importing files relative to `package:`-imported files.
 
 * Don't claim that "package:" URLs aren't supported when they actually are.

lib/src/executable/options.dart

@@ -356,7 +356,7 @@ class ExecutableOptions {
   /// [destination] directories.
   Map<String, String> _listSourceDirectory(String source, String destination) {
     var map = <String, String>{};
-    for (var path in listDir(source)) {
+    for (var path in listDir(source, recursive: true)) {
       var basename = p.basename(path);
       if (basename.startsWith("_")) continue;
 

lib/src/io/interface.dart

@@ -79,9 +79,11 @@ bool dirExists(String path) => null;
 /// necessary.
 void ensureDir(String path) => null;
 
-/// Recursively lists the files (not sub-directories) of the directory at
-/// [path].
-Iterable<String> listDir(String path) => null;
+/// Lists the files (not sub-directories) in the directory at [path].
+///
+/// If [recursive] is `true`, this lists files in directories transitively
+/// beneath [path] as well.
+Iterable<String> listDir(String path, {bool recursive = false}) => null;
 
 /// Returns the modification time of the file at [path].
 DateTime modificationTime(String path) => null;

lib/src/io/node.dart

@@ -191,14 +191,23 @@ void ensureDir(String path) {
   });
 }
 
-Iterable<String> listDir(String path) {
-  Iterable<String> list(String parent) =>
-      _fs.readdirSync(parent).expand((child) {
-        var path = p.join(parent, child as String);
-        return dirExists(path) ? listDir(path) : [path];
-      });
+Iterable<String> listDir(String path, {bool recursive = false}) {
+  return _systemErrorToFileSystemException(() {
+    if (!recursive) {
+      return _fs
+          .readdirSync(path)
+          .map((child) => p.join(path, child as String))
+          .where((child) => !dirExists(child));
+    } else {
+      Iterable<String> list(String parent) =>
+          _fs.readdirSync(parent).expand((child) {
+            var path = p.join(parent, child as String);
+            return dirExists(path) ? list(path) : [path];
+          });
 
-  return _systemErrorToFileSystemException(() => list(path));
+      return list(path);
+    }
+  });
 }
 
 DateTime modificationTime(String path) =>

lib/src/io/vm.dart

@@ -71,10 +71,11 @@ bool dirExists(String path) => io.Directory(path).existsSync();
 
 void ensureDir(String path) => io.Directory(path).createSync(recursive: true);
 
-Iterable<String> listDir(String path) => io.Directory(path)
-    .listSync(recursive: true)
-    .where((entity) => entity is io.File)
-    .map((entity) => entity.path);
+Iterable<String> listDir(String path, {bool recursive = false}) =>
+    io.Directory(path)
+        .listSync(recursive: recursive)
+        .where((entity) => entity is io.File)
+        .map((entity) => entity.path);
 
 DateTime modificationTime(String path) {
   var stat = io.FileStat.statSync(path);