Handle indefinite elements

Makefile

@@ -0,0 +1,7 @@
+libeebie.so:
+	$(CC) -shared -g -O2 -o libeebie.so eebie/reader.c eebie/writer.c
+
+install:
+	install -d /usr/local/include/eebie
+	install eebie/*.h /usr/local/include/eebie
+	install libeebie.so /usr/local/lib

eebie/reader.c

@@ -9,6 +9,8 @@
 
 #include"reader.h"
 
+#define is_max(u) ((u) == 0xFFFFFFFFFFFFFFFFUL)
+
 void ebml_reader_init(EBMLReader *this) {
 	memset(this, 0, sizeof(*this));
 	this->state = EBMLRS_WAITING_FOR_ELEMENT_ID;
@@ -89,6 +91,10 @@ static int get_varint(const uint8_t *data, size_t length, uint64_t *result) {
 	
 	if(ret >= 0) {
 		*result &= ~VARINT_MASKS[ret];
+		
+		if(*result == (1UL << (ret * 7)) - 1) {
+			*result = 0xFFFFFFFFFFFFFFFFUL;
+		}
 	}
 	
 	return ret;
@@ -137,7 +143,7 @@ int ebml_reader_feed(EBMLReader *this, const uint8_t *data, size_t length) {
 		}
 		
 		this->idStack[this->currentDepth] = this->inside.id;
-		this->stack[this->currentDepth] = elLength + status;
+		this->stack[this->currentDepth] = is_max(elLength) ? elLength : elLength + status;
 		
 		this->currentDepth++;
 		
@@ -156,8 +162,10 @@ int ebml_reader_feed(EBMLReader *this, const uint8_t *data, size_t length) {
 	}
 	
 	for(int i = 0; i < this->currentDepth; i++) {
+		if(!is_max(this->stack[i])) {
 			this->stack[i] -= eaten;
 		}
+	}
 	
 	while(this->currentDepth > 0 && this->stack[this->currentDepth - 1] == 0) {
 		
@@ -173,3 +181,12 @@ int ebml_reader_feed(EBMLReader *this, const uint8_t *data, size_t length) {
 	
 	return eaten;
 }
+
+void ebml_reader_leave(EBMLReader *this, uint64_t id) {
+	for(int i = 0; i < this->currentDepth; i++) {
+		if(this->idStack[i] == id) {
+			this->currentDepth = i;
+			return;
+		}
+	}
+}

eebie/reader.h

@@ -49,6 +49,11 @@ typedef struct EBMLReader {
 void ebml_reader_init(EBMLReader*);
 int ebml_reader_feed(EBMLReader*, const uint8_t *data, size_t length);
 
+// Because Eebie is schemaless, it must be told when we have left an
+// indefinite element, otherwise the stack may grow indefinitely and
+// even overflow. The user may call this from eventEnterElement.
+void ebml_reader_leave(EBMLReader*, uint64_t id);
+
 #ifdef __cplusplus
 }
 #endif

eebie/writer.c

@@ -32,7 +32,8 @@ static int bit_length(uint64_t i) {
 }
 
 static uint64_t encode_int(uint64_t i) {
-	return i | VARINT_MASKS[(bit_length(i) + 6) / 7];
+	// bit_length(i + 1) over bit_length(i) because 0xFF... lengths are interpreted as indefinite
+	return i | VARINT_MASKS[(bit_length(i + 1) + 6) / 7];
 }
 
 static void advance(EBMLWriter *this, uint64_t amount) {