Redact ISOBMFF boxes with 'free'
Test: atest MediaStore_Video_MediaTest android.os.RedactingFileDescriptorTest
Bug: 135499138
Change-Id: Idaa8ad30300d5427f91bb2543be3152881018cf6
(cherry picked from commit 4ec5fda3d6edd9b9b8858e6961ba53f31a8c03fc)
diff --git a/core/java/android/os/RedactingFileDescriptor.java b/core/java/android/os/RedactingFileDescriptor.java
index 4e5eaac..a1ed214 100644
--- a/core/java/android/os/RedactingFileDescriptor.java
+++ b/core/java/android/os/RedactingFileDescriptor.java
@@ -35,7 +35,7 @@
/**
* Variant of {@link FileDescriptor} that allows its creator to specify regions
- * that should be redacted (appearing as zeros to the reader).
+ * that should be redacted.
*
* @hide
*/
@@ -44,13 +44,16 @@
private static final boolean DEBUG = true;
private volatile long[] mRedactRanges;
+ private volatile long[] mFreeOffsets;
private FileDescriptor mInner = null;
private ParcelFileDescriptor mOuter = null;
- private RedactingFileDescriptor(Context context, File file, int mode, long[] redactRanges)
+ private RedactingFileDescriptor(
+ Context context, File file, int mode, long[] redactRanges, long[] freeOffsets)
throws IOException {
mRedactRanges = checkRangesArgument(redactRanges);
+ mFreeOffsets = freeOffsets;
try {
try {
@@ -88,13 +91,17 @@
*
* @param file The underlying file to open.
* @param mode The {@link ParcelFileDescriptor} mode to open with.
- * @param redactRanges List of file offsets that should be redacted, stored
+ * @param redactRanges List of file ranges that should be redacted, stored
* as {@code [start1, end1, start2, end2, ...]}. Start values are
* inclusive and end values are exclusive.
+ * @param freePositions List of file offsets at which the four byte value 'free' should be
+ * written instead of zeros within parts of the file covered by {@code redactRanges}.
+ * Non-redacted bytes will not be modified even if covered by a 'free'. This is
+ * useful for overwriting boxes in ISOBMFF files with padding data.
*/
public static ParcelFileDescriptor open(Context context, File file, int mode,
- long[] redactRanges) throws IOException {
- return new RedactingFileDescriptor(context, file, mode, redactRanges).mOuter;
+ long[] redactRanges, long[] freePositions) throws IOException {
+ return new RedactingFileDescriptor(context, file, mode, redactRanges, freePositions).mOuter;
}
/**
@@ -169,6 +176,15 @@
for (long j = start; j < end; j++) {
data[(int) (j - offset)] = 0;
}
+ // Overwrite data at 'free' offsets within the redaction ranges.
+ for (long freeOffset : mFreeOffsets) {
+ final long freeEnd = freeOffset + 4;
+ final long redactFreeStart = Math.max(freeOffset, start);
+ final long redactFreeEnd = Math.min(freeEnd, end);
+ for (long j = redactFreeStart; j < redactFreeEnd; j++) {
+ data[(int) (j - offset)] = (byte) "free".charAt((int) (j - freeOffset));
+ }
+ }
}
return n;
}
diff --git a/core/tests/coretests/src/android/os/RedactingFileDescriptorTest.java b/core/tests/coretests/src/android/os/RedactingFileDescriptorTest.java
index d5163e1..eff4826 100644
--- a/core/tests/coretests/src/android/os/RedactingFileDescriptorTest.java
+++ b/core/tests/coretests/src/android/os/RedactingFileDescriptorTest.java
@@ -64,7 +64,7 @@
@Test
public void testSingleByte() throws Exception {
final FileDescriptor fd = RedactingFileDescriptor.open(mContext, mFile, MODE_READ_ONLY,
- new long[] { 10, 11 }).getFileDescriptor();
+ new long[] { 10, 11 }, new long[] {}).getFileDescriptor();
final byte[] buf = new byte[1_000];
assertEquals(buf.length, Os.read(fd, buf, 0, buf.length));
@@ -80,7 +80,7 @@
@Test
public void testRanges() throws Exception {
final FileDescriptor fd = RedactingFileDescriptor.open(mContext, mFile, MODE_READ_ONLY,
- new long[] { 100, 200, 300, 400 }).getFileDescriptor();
+ new long[] { 100, 200, 300, 400 }, new long[] {}).getFileDescriptor();
final byte[] buf = new byte[10];
assertEquals(buf.length, Os.pread(fd, buf, 0, 10, 90));
@@ -102,7 +102,7 @@
@Test
public void testEntireFile() throws Exception {
final FileDescriptor fd = RedactingFileDescriptor.open(mContext, mFile, MODE_READ_ONLY,
- new long[] { 0, 5_000_000 }).getFileDescriptor();
+ new long[] { 0, 5_000_000 }, new long[] {}).getFileDescriptor();
try (FileInputStream in = new FileInputStream(fd)) {
int val;
@@ -115,7 +115,7 @@
@Test
public void testReadWrite() throws Exception {
final FileDescriptor fd = RedactingFileDescriptor.open(mContext, mFile, MODE_READ_WRITE,
- new long[] { 100, 200, 300, 400 }).getFileDescriptor();
+ new long[] { 100, 200, 300, 400 }, new long[] {}).getFileDescriptor();
// Redacted at first
final byte[] buf = new byte[10];
@@ -168,4 +168,76 @@
assertArrayEquals(new long[] { 100, 200 },
removeRange(new long[] { 100, 200 }, 150, 150));
}
+
+ @Test
+ public void testFreeAtStart() throws Exception {
+ final FileDescriptor fd = RedactingFileDescriptor.open(mContext, mFile, MODE_READ_WRITE,
+ new long[] { 1, 10 }, new long[] {1}).getFileDescriptor();
+
+ final byte[] buf = new byte[10];
+ assertEquals(buf.length, Os.pread(fd, buf, 0, 10, 0));
+ assertArrayEquals(
+ new byte[] { 64, (byte) 'f', (byte) 'r', (byte) 'e', (byte) 'e', 0, 0, 0, 0, 0 },
+ buf);
+ }
+
+ @Test
+ public void testFreeAtOffset() throws Exception {
+ final FileDescriptor fd = RedactingFileDescriptor.open(mContext, mFile, MODE_READ_WRITE,
+ new long[] { 1, 10 }, new long[] {3}).getFileDescriptor();
+
+ final byte[] buf = new byte[10];
+ assertEquals(buf.length, Os.pread(fd, buf, 0, 10, 0));
+ assertArrayEquals(
+ new byte[] { 64, 0, 0, (byte) 'f', (byte) 'r', (byte) 'e', (byte) 'e', 0, 0, 0 },
+ buf);
+ }
+
+ @Test
+ public void testFreeAcrossRedactionStart() throws Exception {
+ final FileDescriptor fd = RedactingFileDescriptor.open(mContext, mFile, MODE_READ_WRITE,
+ new long[] { 1, 10 }, new long[] {0}).getFileDescriptor();
+
+ final byte[] buf = new byte[10];
+ assertEquals(buf.length, Os.pread(fd, buf, 0, 10, 0));
+ assertArrayEquals(
+ new byte[] { 64, (byte) 'r', (byte) 'e', (byte) 'e', 0, 0, 0, 0, 0, 0 },
+ buf);
+ }
+
+ @Test
+ public void testFreeAcrossRedactionEnd() throws Exception {
+ final FileDescriptor fd = RedactingFileDescriptor.open(mContext, mFile, MODE_READ_WRITE,
+ new long[] { 1, 3 }, new long[] {2}).getFileDescriptor();
+
+ final byte[] buf = new byte[10];
+ assertEquals(buf.length, Os.pread(fd, buf, 0, 10, 0));
+ assertArrayEquals(
+ new byte[] { 64, 0, (byte) 'f', 64, 64, 64, 64, 64, 64, 64 },
+ buf);
+ }
+
+ @Test
+ public void testFreeOutsideRedaction() throws Exception {
+ final FileDescriptor fd = RedactingFileDescriptor.open(mContext, mFile, MODE_READ_WRITE,
+ new long[] { 1, 8 }, new long[] { 8 }).getFileDescriptor();
+
+ final byte[] buf = new byte[10];
+ assertEquals(buf.length, Os.pread(fd, buf, 0, 10, 0));
+ assertArrayEquals(
+ new byte[] { 64, 0, 0, 0, 0, 0, 0, 0, 64, 64 },
+ buf);
+ }
+
+ @Test
+ public void testFreeMultipleRedactions() throws Exception {
+ final FileDescriptor fd = RedactingFileDescriptor.open(mContext, mFile, MODE_READ_WRITE,
+ new long[] { 1, 2, 3, 4 }, new long[] { 0 }).getFileDescriptor();
+
+ final byte[] buf = new byte[10];
+ assertEquals(buf.length, Os.pread(fd, buf, 0, 10, 0));
+ assertArrayEquals(
+ new byte[] { 64, (byte) 'r', 64, (byte) 'e', 64, 64, 64, 64, 64, 64 },
+ buf);
+ }
}
