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[Java][FlexBuffers] Deprecate typed vector strings due to design flaw (#5722)

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* [Java][FlexBuffers] Deprecate typed vector strings due to design flaw

It will still be possible to read buffers with this type, but the
elements will be treated as FBT_KEY and will be read as null-terminated
string.

Trying to build a vector of strings as typed will throw an exception.

More information on https://github.com/google/flatbuffers/issues/5627

Also, fix another bug on strings, where long strings were not properly
aligned.

* [Java][FlexBuffers] Make FBT_VECTOR_STRING_DEPRECATED considered typed.

The logic for FlexBuffers.isVectorType() was changed
to not consider FBT_VECTOR_STRING_DEPRECATED a typed
vector, but that can lead to missinterpretation for
existing serialized data. So we are reverting.
This commit is contained in:
Paulo Pinheiro
2020-01-24 18:58:15 +01:00
committed by Wouter van Oortmerssen
parent a593a11e59
commit 3f677f2414
3 changed files with 106 additions and 26 deletions
Download Patch File Download Diff File Expand all files Collapse all files

18
java/com/google/flatbuffers/FlexBuffers.java
View File

@@ -77,7 +77,9 @@ public class FlexBuffers {
/** Represent a vector of keys type */
public static final int FBT_VECTOR_KEY = 14;
/** Represent a vector of strings type */
public static final int FBT_VECTOR_STRING = 15;
// DEPRECATED, use FBT_VECTOR or FBT_VECTOR_KEY instead.
// more info on thttps://github.com/google/flatbuffers/issues/5627.
public static final int FBT_VECTOR_STRING_DEPRECATED = 15;
/// @cond FLATBUFFERS_INTERNAL
public static final int FBT_VECTOR_INT2 = 16; // Typed tuple = no type table; no size field).
@@ -107,7 +109,7 @@ public class FlexBuffers {
* @return true if typed vector
*/
static boolean isTypedVector(int type) {
return (type >= FBT_VECTOR_INT && type <= FBT_VECTOR_STRING) || type == FBT_VECTOR_BOOL;
return (type >= FBT_VECTOR_INT && type <= FBT_VECTOR_STRING_DEPRECATED) || type == FBT_VECTOR_BOOL;
}
/**
@@ -145,7 +147,7 @@ public class FlexBuffers {
}
static boolean isTypedVectorElementType(int type) {
return (type >= FBT_INT && type <= FBT_STRING) || type == FBT_BOOL;
return (type >= FBT_INT && type <= FBT_KEY) || type == FBT_BOOL;
}
// return position of the element that the offset is pointing to
@@ -322,8 +324,7 @@ public class FlexBuffers {
* @return true if a typed vector type
*/
public boolean isTypedVector() {
return (type >= FBT_VECTOR_INT && type <= FBT_VECTOR_STRING) ||
type == FBT_VECTOR_BOOL;
return FlexBuffers.isTypedVector(type);
}
/**
@@ -482,7 +483,7 @@ public class FlexBuffers {
public String asString() {
if (isString()) {
int start = indirect(bb, end, parentWidth);
int size = readInt(bb, start - byteWidth, byteWidth);
int size = (int) readUInt(bb, start - byteWidth, byteWidth);
return Utf8.getDefault().decodeUtf8(bb, start, size);
}
else if (isKey()){
@@ -516,6 +517,9 @@ public class FlexBuffers {
public Vector asVector() {
if (isVector()) {
return new Vector(bb, indirect(bb, end, parentWidth), byteWidth);
} else if(type == FlexBuffers.FBT_VECTOR_STRING_DEPRECATED) {
// deprecated. Should be treated as key vector
return new TypedVector(bb, indirect(bb, end, parentWidth), byteWidth, FlexBuffers.FBT_KEY);
} else if (FlexBuffers.isTypedVector(type)) {
return new TypedVector(bb, indirect(bb, end, parentWidth), byteWidth, FlexBuffers.toTypedVectorElementType(type));
} else {
@@ -590,7 +594,7 @@ public class FlexBuffers {
case FBT_VECTOR_UINT:
case FBT_VECTOR_FLOAT:
case FBT_VECTOR_KEY:
case FBT_VECTOR_STRING:
case FBT_VECTOR_STRING_DEPRECATED:
case FBT_VECTOR_BOOL:
return sb.append(asVector());
case FBT_VECTOR_INT2:

17
java/com/google/flatbuffers/FlexBuffersBuilder.java
View File

@@ -358,24 +358,24 @@ public class FlexBuffersBuilder {
}
private Value writeString(int key, String s) {
return writeBlob(key, s.getBytes(StandardCharsets.UTF_8), FBT_STRING);
return writeBlob(key, s.getBytes(StandardCharsets.UTF_8), FBT_STRING, true);
}
// in bits to fit a unsigned int
private static int widthUInBits(long len) {
static int widthUInBits(long len) {
if (len <= byteToUnsignedInt((byte)0xff)) return WIDTH_8;
if (len <= shortToUnsignedInt((short)0xffff)) return WIDTH_16;
if (len <= intToUnsignedLong(0xffff_ffff)) return WIDTH_32;
return WIDTH_64;
}
private Value writeBlob(int key, byte[] blob, int type) {
private Value writeBlob(int key, byte[] blob, int type, boolean trailing) {
int bitWidth = widthUInBits(blob.length);
int byteWidth = align(bitWidth);
writeInt(blob.length, byteWidth);
int sloc = bb.position();
bb.put(blob);
if (type == FBT_STRING) {
if (trailing) {
bb.put((byte) 0);
}
return Value.blob(key, sloc, type, bitWidth);
@@ -384,7 +384,7 @@ public class FlexBuffersBuilder {
// Align to prepare for writing a scalar with a certain size.
private int align(int alignment) {
int byteWidth = 1 << alignment;
int padBytes = Value.paddingBytes(bb.capacity(), byteWidth);
int padBytes = Value.paddingBytes(bb.position(), byteWidth);
while (padBytes-- != 0) {
bb.put((byte) 0);
}
@@ -417,7 +417,7 @@ public class FlexBuffersBuilder {
*/
public int putBlob(String key, byte[] val) {
int iKey = putKey(key);
Value value = writeBlob(iKey, val, FBT_BLOB);
Value value = writeBlob(iKey, val, FBT_BLOB, false);
stack.add(value);
return (int) value.iValue;
}
@@ -504,6 +504,9 @@ public class FlexBuffersBuilder {
if (typed) {
if (i == start) {
vectorType = stack.get(i).type;
if (!FlexBuffers.isTypedVectorElementType(vectorType)) {
throw new FlexBufferException("TypedVector does not support this element type");
}
} else {
// If you get this assert, you are writing a typed vector with
// elements that are not all the same type.
@@ -659,7 +662,7 @@ public class FlexBuffersBuilder {
}
static Value blob(int key, int position, int type, int bitWidth) {
return new Value(key, type, WIDTH_8, position);
return new Value(key, type, bitWidth, position);
}
static Value int8(int key, int value) {