update qoi.h to latest from https://github.com/phoboslab/qoi.git

qoi.h

@@ -83,8 +83,8 @@ implementation you can define QOI_ZEROARR before including this library.
 
 -- Data Format
 
-A QOI file has a 14 byte header, followed by any number of data "chunks" and 8
-zero-bytes to mark the end of the data stream.
+A QOI file has a 14 byte header, followed by any number of data "chunks" and an
+8-byte end marker.
 
 struct qoi_header_t {
 	char     magic[4];   // magic bytes "qoif"
@@ -120,7 +120,7 @@ values encoded in these data bits have the most significant bit on the left.
 The 8-bit tags have precedence over the 2-bit tags. A decoder must check for the
 presence of an 8-bit tag first.
 
-The byte stream is padded with 8 zero-bytes at the end.
+The byte stream's end is marked with 7 0x00 bytes followed a single 0x01 byte.
 
 
 The possible chunks are:
@@ -135,6 +135,9 @@ The possible chunks are:
 2-bit tag b00
 6-bit index into the color index array: 0..63
 
+A valid encoder must not issue 7 or more consecutive QOI_OP_INDEX chunks to the
+index 0, to avoid confusion with the 8 byte end marker. 
+
 
 .- QOI_OP_DIFF -----------. 
 |         Byte[0]         |
@@ -168,8 +171,8 @@ Values are stored as unsigned integers with a bias of 2. E.g. -2 is stored as
 The green channel is used to indicate the general direction of change and is 
 encoded in 6 bits. The red and green channels (dr and db) base their diffs off
 of the green channel difference and are encoded in 4 bits. I.e.:
-  dr_dg = (last_px.r - cur_px.r) - (last_px.g - cur_px.g)
-  db_dg = (last_px.b - cur_px.b) - (last_px.g - cur_px.g)
+	dr_dg = (last_px.r - cur_px.r) - (last_px.g - cur_px.g)
+	db_dg = (last_px.b - cur_px.b) - (last_px.g - cur_px.g)
 
 The difference to the current channel values are using a wraparound operation, 
 so "10 - 13" will result in 253, while "250 + 7" will result in 1.
@@ -342,13 +345,20 @@ Implementation */
 	(((unsigned int)'q') << 24 | ((unsigned int)'o') << 16 | \
 	 ((unsigned int)'i') <<  8 | ((unsigned int)'f'))
 #define QOI_HEADER_SIZE 14
-#define QOI_PADDING 8
+
+/* 2GB is the max file size that this implementation can safely handle. We guard
+against anything larger than that, assuming the worst case with 5 bytes per 
+pixel, rounded down to a nice clean value. 400 million pixels ought to be 
+enough for anybody. */
+#define QOI_PIXELS_MAX ((unsigned int)400000000)
 
 typedef union {
 	struct { unsigned char r, g, b, a; } rgba;
 	unsigned int v;
 } qoi_rgba_t;
 
+static const unsigned char qoi_padding[8] = {0,0,0,0,0,0,0,1};
+
 void qoi_write_32(unsigned char *bytes, int *p, unsigned int v) {
 	bytes[(*p)++] = (0xff000000 & v) >> 24;
 	bytes[(*p)++] = (0x00ff0000 & v) >> 16;
@@ -376,14 +386,15 @@ void *qoi_encode(const void *data, const qoi_desc *desc, int *out_len) {
 		data == NULL || out_len == NULL || desc == NULL ||
 		desc->width == 0 || desc->height == 0 ||
 		desc->channels < 3 || desc->channels > 4 ||
-		desc->colorspace > 2
+		desc->colorspace > 1 ||
+		desc->height >= QOI_PIXELS_MAX / desc->width
 	) {
 		return NULL;
 	}
 
 	max_size = 
 		desc->width * desc->height * (desc->channels + 1) + 
-		QOI_HEADER_SIZE + QOI_PADDING;
+		QOI_HEADER_SIZE + sizeof(qoi_padding);
 
 	p = 0;
 	bytes = (unsigned char *) QOI_MALLOC(max_size);
@@ -488,8 +499,8 @@ void *qoi_encode(const void *data, const qoi_desc *desc, int *out_len) {
 		px_prev = px;
 	}
 
-	for (i = 0; i < QOI_PADDING; i++) {
-		bytes[p++] = 0;
+	for (i = 0; i < (int)sizeof(qoi_padding); i++) {
+		bytes[p++] = qoi_padding[i];
 	}
 
 	*out_len = p;
@@ -502,13 +513,13 @@ void *qoi_decode(const void *data, int size, qoi_desc *desc, int channels) {
 	unsigned char *pixels;
 	qoi_rgba_t index[64];
 	qoi_rgba_t px;
-	int px_len,  chunks_len, px_pos;
+	int px_len, chunks_len, px_pos;
 	int p = 0, run = 0;
 
 	if (
 		data == NULL || desc == NULL ||
 		(channels != 0 && channels != 3 && channels != 4) ||
-		size < QOI_HEADER_SIZE + QOI_PADDING
+		size < QOI_HEADER_SIZE + (int)sizeof(qoi_padding)
 	) {
 		return NULL;
 	}
@@ -524,8 +535,9 @@ void *qoi_decode(const void *data, int size, qoi_desc *desc, int channels) {
 	if (
 		desc->width == 0 || desc->height == 0 || 
 		desc->channels < 3 || desc->channels > 4 ||
-		desc->colorspace > 2 ||
-		header_magic != QOI_MAGIC
+		desc->colorspace > 1 ||
+		header_magic != QOI_MAGIC ||
+		desc->height >= QOI_PIXELS_MAX / desc->width
 	) {
 		return NULL;
 	}
@@ -546,7 +558,7 @@ void *qoi_decode(const void *data, int size, qoi_desc *desc, int channels) {
 	px.rgba.b = 0;
 	px.rgba.a = 255;
 
-	chunks_len = size - QOI_PADDING;
+	chunks_len = size - (int)sizeof(qoi_padding);
 	for (px_pos = 0; px_pos < px_len; px_pos += channels) {
 		if (run > 0) {
 			run--;
@@ -636,6 +648,10 @@ void *qoi_read(const char *filename, qoi_desc *desc, int channels) {
 
 	fseek(f, 0, SEEK_END);
 	size = ftell(f);
+	if (size <= 0) {
+		fclose(f);
+		return NULL;
+	}
 	fseek(f, 0, SEEK_SET);
 
 	data = QOI_MALLOC(size);