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

README.md

@@ -4,6 +4,8 @@ Eebie is a very small C99 library for reading and writing EBML files, namely Mat
 
 The library is meant to be embedded directly into another project.
 
+TODO: signed integer writing
+
 ## Reading example
 
     #include"eebie/reader.h"
@@ -39,7 +41,7 @@ The library is meant to be embedded directly into another project.
     }
     
     static void on_exit_element(EBMLReader *reader) {
-      // If needed, the current element ID can be found at `reader->inside.id`.
+      // If needed, the exitee element ID can be found at `reader->idStack[reader->currentDepth - 1]`.
       
       // Use accumulated buffer here.
       

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;
+		}
+	}
+}

eebie/reader.h

@@ -5,6 +5,10 @@
 
 #include"ebml.h"
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 #include<stddef.h>
 #include<stdint.h>
 
@@ -42,7 +46,16 @@ typedef struct EBMLReader {
 	void *ud;
 } EBMLReader;
 
-void ebml_reader_init(EBMLReader *this);
-int ebml_reader_feed(EBMLReader *this, const uint8_t *data, size_t length);
+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
 
 #endif

eebie/writer.c

@@ -5,7 +5,7 @@
 #include<stddef.h>
 #include<assert.h>
 
-static uint64_t VARINT_MASKS[] = {0, 0x80L, 0xC000L, 0xE00000L, 0xF0000000L, 0xF800000000L, 0xFC0000000000L, 0xFE000000000000L, 0L};
+static uint64_t VARINT_MASKS[] = {0x0UL, 0x80UL, 0x4000UL, 0x200000UL, 0x10000000UL, 0x0800000000UL, 0x040000000000UL, 0x02000000000000UL, 0x0100000000000000UL};
 
 static int byte_length(uint64_t i) {
 	if(i == 0) return 1;
@@ -15,6 +15,7 @@ static int byte_length(uint64_t i) {
 		i >>= 8;
 		n++;
 	}
+	
 	return n;
 }
 
@@ -31,7 +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) {
@@ -42,7 +44,7 @@ static void advance(EBMLWriter *this, uint64_t amount) {
 
 static void add(EBMLWriter *this, const void *data, size_t length) {
 	if(this->bufferLen + length > this->bufferCapacity) {
-		this->buffer = this->eventAlloc(this, this->buffer, (this->bufferLen + length + 1023) & ~1023);
+		this->buffer = this->eventAlloc(this, this->buffer, this->bufferCapacity = ((this->bufferLen + length + 1023) & ~1023));
 	}
 	
 	memcpy(this->buffer + this->bufferLen, data, length);
@@ -71,7 +73,7 @@ void ebml_writer_free(EBMLWriter *this) {
 void ebml_writer_push_ind(EBMLWriter *this, uint64_t id) {
 	add_varint(this, id);
 	
-	add(this, &(uint64_t) {htobe64(0x01FFFFFFFFFFFFFFL)}, sizeof(uint64_t)); // UNKNOWN-SIZED ELEMENT
+	add(this, &(uint64_t) {htobe64(0x01FFFFFFFFFFFFFFUL)}, sizeof(uint64_t)); // UNKNOWN-SIZED ELEMENT
 	
 	while(!ebml_writer_flush(this));
 }
@@ -79,7 +81,7 @@ void ebml_writer_push_ind(EBMLWriter *this, uint64_t id) {
 void ebml_writer_push(EBMLWriter *this, uint64_t id) {
 	add_varint(this, id);
 	
-	add(this, &(uint64_t) {htobe64(0x0100000000000000L)}, sizeof(uint64_t)); // LENGTH OF MAX SIZE (BECAUSE UNKNOWN)
+	add(this, &(uint64_t) {htobe64(0x0100000000000000UL)}, sizeof(uint64_t)); // LENGTH OF MAX SIZE (BECAUSE UNKNOWN)
 	
 	this->stack[this->currentDepth++] = 0;
 }
@@ -89,7 +91,7 @@ void ebml_writer_pop(EBMLWriter *this) {
 	
 	uint64_t newSize = this->stack[this->currentDepth];
 	uint64_t *s = (uint64_t*) &this->buffer[this->bufferLen - newSize - 8];
-	*s = htobe64(0x0100000000000000L | newSize);
+	*s = htobe64(0x0100000000000000UL | newSize);
 	
 	if(this->currentDepth == 0) {
 		while(!ebml_writer_flush(this));

eebie/writer.h

@@ -6,6 +6,10 @@
 #include<stddef.h>
 #include<stdbool.h>
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 #define EBML_WRITE_MAXIMUM_DEPTH 128
 
 struct EBMLWriter;
@@ -27,15 +31,19 @@ typedef struct EBMLWriter {
 	void *ud;
 } EBMLWriter;
 
-void ebml_writer_init(EBMLWriter *this);
-void ebml_writer_free(EBMLWriter *this);
+void ebml_writer_init(EBMLWriter*);
+void ebml_writer_free(EBMLWriter*);
 
-void ebml_writer_push_ind(EBMLWriter *this, uint64_t id);
-void ebml_writer_push(EBMLWriter *this, uint64_t id);
-void ebml_writer_pop(EBMLWriter *this);
+void ebml_writer_push_ind(EBMLWriter*, uint64_t id);
+void ebml_writer_push(EBMLWriter*, uint64_t id);
+void ebml_writer_pop(EBMLWriter*);
 
-bool ebml_writer_flush(EBMLWriter *this);
+bool ebml_writer_flush(EBMLWriter*);
 
-void ebml_writer_put(EBMLWriter *this, uint64_t id, EBMLElementType type, EBMLPrimitive primitive);
+void ebml_writer_put(EBMLWriter*, uint64_t id, EBMLElementType type, EBMLPrimitive primitive);
+
+#ifdef __cplusplus
+}
+#endif
 
 #endif