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feat: decoder hardening with proper errors #1

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Merged
Fyzu merged 1 commit into from
Jun 2, 2026
Merged

feat: decoder hardening with proper errors #1

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1 change: 1 addition & 0 deletions buff-json-protoc-plugin/CLAUDE.md
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Original file line number Diff line number Diff line change
Expand Up @@ -77,6 +77,7 @@ For each non-WKT, non-map-entry message type:
- **Cross-file nested encoder calls** — `protoToEncoderClass` only contains messages from `filesToGenerate`. If a nested message is defined in a non-generated file, the fallback to `writer.writeMessage(jsonWriter, nested)` is used (which still finds the encoder at runtime via `instanceof BuffJsonCodecHolder`)
- **Insertion point file paths** — for `java_multiple_files = true`, message insertion points target `package/MessageName.java`; for `false`, they target `package/OuterClassName.java`. The `outer_class_scope` insertion point always targets the outer class file
- **Block comments** (`/** */`) — the `*` prefix on each line is stripped by `CommentGenerator.stripLines()`, producing clean multiline text
- **Generated decoders route fallible parses through `FieldReader`** — `DecoderGenerator` emits `FieldReader.readBytes(reader)` for bytes, `FieldReader.enumNumber(reader, EnumClass.getDescriptor(), name)` for enum names, and `FieldReader.parseIntKey`/`parseUnsignedIntKey`/`parseLongKey`/`parseUnsignedLongKey(reader, keyStr)` for numeric map keys — never inline `BASE64.decode`/`Enum.valueOf`/`Long.parseLong`. This gives generated code the same `JSONException`-for-bad-input contract as the runtime path (see buff-json `Error Contract`); the helpers are `public` because generated code lives in the user's package

## Build

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26 changes: 14 additions & 12 deletions buff-json-protoc-plugin/src/main/java/io/suboptimal/buffjson/protoc/DecoderGenerator.java
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Expand Up @@ -157,8 +157,9 @@ private static void generateMapFieldRead(StringBuilder sb, FieldDescriptor fd, M
String valuePutter = putter + "Value(" + keyExpr + ", ";
String enumClass = protoToJavaClass.get(valueFd.getEnumType().getFullName());
sb.append(indent).append(" if (reader.isString()) {\n");
sb.append(indent).append(" ").append(valuePutter).append(enumClass)
.append(".valueOf(reader.readString()).getNumber());\n");
sb.append(indent).append(" ").append(valuePutter)
.append("io.suboptimal.buffjson.internal.FieldReader.enumNumber(reader, ").append(enumClass)
.append(".getDescriptor(), reader.readString()));\n");
sb.append(indent).append(" } else {\n");
sb.append(indent).append(" ").append(valuePutter).append("reader.readInt32Value());\n");
sb.append(indent).append(" }\n");
Expand Down Expand Up @@ -223,17 +224,18 @@ private static void emitValueRead(StringBuilder sb, FieldDescriptor fd, String p
sb.append(indent).append(prefix).append("(reader.readBoolValue()").append(closeSuffix).append(");\n");
case STRING ->
sb.append(indent).append(prefix).append("(reader.readString()").append(closeSuffix).append(");\n");
case BYTE_STRING -> sb.append(indent).append(prefix).append(
"(com.google.protobuf.ByteString.copyFrom(io.suboptimal.buffjson.internal.FieldReader.BASE64.decode(reader.readString()))")
.append(closeSuffix).append(");\n");
case BYTE_STRING -> sb.append(indent).append(prefix)
.append("(io.suboptimal.buffjson.internal.FieldReader.readBytes(reader)").append(closeSuffix)
.append(");\n");
case ENUM -> {
// Enum fields use the Value variant: setFoo -> setFooValue, addFoo ->
// addFooValue
String valueName = prefix + "Value";
String enumClass = protoToJavaClass.get(fd.getEnumType().getFullName());
sb.append(indent).append("if (reader.isString()) {\n");
sb.append(indent).append(" ").append(valueName).append("(").append(enumClass)
.append(".valueOf(reader.readString()).getNumber()").append(closeSuffix).append(");\n");
sb.append(indent).append(" ").append(valueName)
.append("(io.suboptimal.buffjson.internal.FieldReader.enumNumber(reader, ").append(enumClass)
.append(".getDescriptor(), reader.readString())").append(closeSuffix).append(");\n");
sb.append(indent).append("} else {\n");
sb.append(indent).append(" ").append(valueName).append("(reader.readInt32Value()")
.append(closeSuffix).append(");\n");
Expand Down Expand Up @@ -301,16 +303,16 @@ private static String mapKeyExpr(FieldDescriptor keyFd) {
case INT -> {
var type = keyFd.getType();
if (type == FieldDescriptor.Type.UINT32 || type == FieldDescriptor.Type.FIXED32)
yield "(int) Long.parseLong(keyStr)";
yield "Integer.parseInt(keyStr)";
yield "io.suboptimal.buffjson.internal.FieldReader.parseUnsignedIntKey(reader, keyStr)";
yield "io.suboptimal.buffjson.internal.FieldReader.parseIntKey(reader, keyStr)";
}
case LONG -> {
var type = keyFd.getType();
if (type == FieldDescriptor.Type.UINT64 || type == FieldDescriptor.Type.FIXED64)
yield "Long.parseUnsignedLong(keyStr)";
yield "Long.parseLong(keyStr)";
yield "io.suboptimal.buffjson.internal.FieldReader.parseUnsignedLongKey(reader, keyStr)";
yield "io.suboptimal.buffjson.internal.FieldReader.parseLongKey(reader, keyStr)";
}
case BOOLEAN -> "Boolean.parseBoolean(keyStr)";
case BOOLEAN -> "io.suboptimal.buffjson.internal.FieldReader.parseBoolKey(reader, keyStr)";
default -> throw new IllegalArgumentException("Unsupported map key type: " + keyFd.getJavaType());
};
}
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