From e0716abc81b0590b1ef5094445f790e728595c00 Mon Sep 17 00:00:00 2001
From: Mid <>
Date: Tue, 7 Oct 2025 12:27:21 +0300
Subject: [PATCH] Handle indefinite elements

---
 eebie/reader.c | 21 +++++++++++++++++++--
 eebie/reader.h |  5 +++++
 2 files changed, 24 insertions(+), 2 deletions(-)

diff --git a/eebie/reader.c b/eebie/reader.c
index 45c14f5..1482903 100644
--- a/eebie/reader.c
+++ b/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++;
 		
@@ -156,7 +162,9 @@ int ebml_reader_feed(EBMLReader *this, const uint8_t *data, size_t length) {
 	}
 	
 	for(int i = 0; i < this->currentDepth; i++) {
-		this->stack[i] -= eaten;
+		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;
+		}
+	}
+}
diff --git a/eebie/reader.h b/eebie/reader.h
index 6330f2b..61af8b6 100644
--- a/eebie/reader.h
+++ b/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