Merge "use BufferedInputStream in readTextFile" into jb-mr1-dev

Author: guang-google

core/java/android/os/FileUtils.java

@@ -16,6 +16,7 @@
 
 package android.os;
 
+import java.io.BufferedInputStream;
 import java.io.ByteArrayOutputStream;
 import java.io.File;
 import java.io.FileInputStream;
@@ -91,7 +92,7 @@ public static boolean copyFile(File srcFile, File destFile) {
         }
         return result;
     }
-    
+
     /**
      * Copy data from a source stream to destFile.
      * Return true if succeed, return false if failed.
@@ -143,12 +144,16 @@ public static boolean isFilenameSafe(File file) {
      */
     public static String readTextFile(File file, int max, String ellipsis) throws IOException {
         InputStream input = new FileInputStream(file);
+        // wrapping a BufferedInputStream around it because when reading /proc with unbuffered
+        // input stream, bytes read not equal to buffer size is not necessarily the correct
+        // indication for EOF; but it is true for BufferedInputStream due to its implementation.
+        BufferedInputStream bis = new BufferedInputStream(input);
         try {
             long size = file.length();
             if (max > 0 || (size > 0 && max == 0)) {  // "head" mode: read the first N bytes
                 if (size > 0 && (max == 0 || size < max)) max = (int) size;
                 byte[] data = new byte[max + 1];
-                int length = input.read(data);
+                int length = bis.read(data);
                 if (length <= 0) return "";
                 if (length <= max) return new String(data, 0, length);
                 if (ellipsis == null) return new String(data, 0, max);
@@ -161,7 +166,7 @@ public static String readTextFile(File file, int max, String ellipsis) throws IO
                     if (last != null) rolled = true;
                     byte[] tmp = last; last = data; data = tmp;
                     if (data == null) data = new byte[-max];
-                    len = input.read(data);
+                    len = bis.read(data);
                 } while (len == data.length);
 
                 if (last == null && len <= 0) return "";
@@ -178,12 +183,13 @@ public static String readTextFile(File file, int max, String ellipsis) throws IO
                 int len;
                 byte[] data = new byte[1024];
                 do {
-                    len = input.read(data);
+                    len = bis.read(data);
                     if (len > 0) contents.write(data, 0, len);
                 } while (len == data.length);
                 return contents.toString();
             }
         } finally {
+            bis.close();
             input.close();
         }
     }