PackageManager: Avoid creating encoders for appIds being written /config/sdcardfs

We know they will be ASCII, so use String.getBytes(US-ASCII) which is
much faster than creating a new ICU based CharsetEncoder for UTF-8 every time
we write one of these files (there will be a lot of them).

Test: make + manual.
Change-Id: I8eb62862ea1083e194d3f23ac68bb40aaae5efd5

1 files changed, 10 insertions, 0 deletions

diff --git a/core/java/android/os/FileUtils.java b/core/java/android/os/FileUtils.java
index 44ae6eee21d6..760df45d2b69 100644
--- a/core/java/android/os/FileUtils.java
+++ b/core/java/android/os/FileUtils.java
@@ -316,6 +316,16 @@ public class FileUtils {
         stringToFile(file.getAbsolutePath(), string);
     }
 
+    /*
+     * Writes the bytes given in {@code content} to the file whose absolute path
+     * is {@code filename}.
+     */
+    public static void bytesToFile(String filename, byte[] content) throws IOException {
+        try (FileOutputStream fos = new FileOutputStream(filename)) {
+            fos.write(content);
+        }
+    }
+
     /**
      * Writes string to file. Basically same as "echo -n $string > $filename"
      *