nanosvg: Sync with upstream 3e403ec

Includes some loop condition fixes after fuzzing.

The previously identified regression (#43641) is now fixed upstream.

2 files changed, 62 insertions, 21 deletions

diff --git a/thirdparty/README.md b/thirdparty/README.md
index f590acaa0b..8cd9fc456c 100644
--- a/thirdparty/README.md
+++ b/thirdparty/README.md
@@ -435,7 +435,7 @@ Collection of single-file libraries used in Godot components.
 ## nanosvg
 
 - Upstream: https://github.com/memononen/nanosvg
-- Version: git (25241c5a8f8451d41ab1b02ab2d865b01600d949, 2019)
+- Version: git (3e403ec72a9145cbbcc6c63d94a4caf079aafec2, 2020)
 - License: zlib
 
 Files extracted from the upstream source:
diff --git a/thirdparty/nanosvg/nanosvg.h b/thirdparty/nanosvg/nanosvg.h
index e5f6900614..4c03ee5893 100644
--- a/thirdparty/nanosvg/nanosvg.h
+++ b/thirdparty/nanosvg/nanosvg.h
@@ -225,11 +225,6 @@ static int nsvg__isdigit(char c)
 	return c >= '0' && c <= '9';
 }
 
-static int nsvg__isnum(char c)
-{
-	return strchr("0123456789+-.eE", c) != 0;
-}
-
 static NSVG_INLINE float nsvg__minf(float a, float b) { return a < b ? a : b; }
 static NSVG_INLINE float nsvg__maxf(float a, float b) { return a > b ? a : b; }
 
@@ -736,9 +731,11 @@ static void nsvg__lineTo(NSVGparser* p, float x, float y)
 
 static void nsvg__cubicBezTo(NSVGparser* p, float cpx1, float cpy1, float cpx2, float cpy2, float x, float y)
 {
-	nsvg__addPoint(p, cpx1, cpy1);
-	nsvg__addPoint(p, cpx2, cpy2);
-	nsvg__addPoint(p, x, y);
+	if (p->npts > 0) {
+		nsvg__addPoint(p, cpx1, cpy1);
+		nsvg__addPoint(p, cpx2, cpy2);
+		nsvg__addPoint(p, x, y);
+	}
 }
 
 static NSVGattrib* nsvg__getAttr(NSVGparser* p)
@@ -808,7 +805,9 @@ static float nsvg__convertToPixels(NSVGparser* p, NSVGcoordinate c, float orig,
 static NSVGgradientData* nsvg__findGradientData(NSVGparser* p, const char* id)
 {
 	NSVGgradientData* grad = p->gradients;
-	while (grad) {
+	if (id == NULL || *id == '\0')
+		return NULL;
+	while (grad != NULL) {
 		if (strcmp(grad->id, id) == 0)
 			return grad;
 		grad = grad->next;
@@ -825,19 +824,26 @@ static NSVGgradient* nsvg__createGradient(NSVGparser* p, const char* id, const f
 	NSVGgradient* grad;
 	float ox, oy, sw, sh, sl;
 	int nstops = 0;
+	int refIter;
 
 	data = nsvg__findGradientData(p, id);
 	if (data == NULL) return NULL;
 
 	// TODO: use ref to fill in all unset values too.
 	ref = data;
+	refIter = 0;
 	while (ref != NULL) {
+		NSVGgradientData* nextRef = NULL;
 		if (stops == NULL && ref->stops != NULL) {
 			stops = ref->stops;
 			nstops = ref->nstops;
 			break;
 		}
-		ref = nsvg__findGradientData(p, ref->ref);
+		nextRef = nsvg__findGradientData(p, ref->ref);
+		if (nextRef == ref) break; // prevent infite loops on malformed data
+		ref = nextRef;
+		refIter++;
+		if (refIter > 32) break; // prevent infite loops on malformed data
 	}
 	if (stops == NULL) return NULL;
 
@@ -1040,6 +1046,10 @@ static void nsvg__addPath(NSVGparser* p, char closed)
 	if (closed)
 		nsvg__lineTo(p, p->pts[0], p->pts[1]);
 
+	// Expect 1 + N*3 points (N = number of cubic bezier segments).
+	if ((p->npts % 3) != 1)
+		return;
+
 	path = (NSVGpath*)malloc(sizeof(NSVGpath));
 	if (path == NULL) goto error;
 	memset(path, 0, sizeof(NSVGpath));
@@ -1458,6 +1468,15 @@ static int nsvg__parseUnits(const char* units)
 	return NSVG_UNITS_USER;
 }
 
+static int nsvg__isCoordinate(const char* s)
+{
+	// optional sign
+	if (*s == '-' || *s == '+')
+		s++;
+	// must have at least one digit, or start by a dot
+	return (nsvg__isdigit(*s) || *s == '.');
+}
+
 static NSVGcoordinate nsvg__parseCoordinateRaw(const char* str)
 {
 	NSVGcoordinate coord = {0, NSVG_UNITS_USER};
@@ -1597,25 +1616,32 @@ static int nsvg__parseRotate(float* xform, const char* str)
 static void nsvg__parseTransform(float* xform, const char* str)
 {
 	float t[6];
+	int len;
 	nsvg__xformIdentity(xform);
 	while (*str)
 	{
 		if (strncmp(str, "matrix", 6) == 0)
-			str += nsvg__parseMatrix(t, str);
+			len = nsvg__parseMatrix(t, str);
 		else if (strncmp(str, "translate", 9) == 0)
-			str += nsvg__parseTranslate(t, str);
+			len = nsvg__parseTranslate(t, str);
 		else if (strncmp(str, "scale", 5) == 0)
-			str += nsvg__parseScale(t, str);
+			len = nsvg__parseScale(t, str);
 		else if (strncmp(str, "rotate", 6) == 0)
-			str += nsvg__parseRotate(t, str);
+			len = nsvg__parseRotate(t, str);
 		else if (strncmp(str, "skewX", 5) == 0)
-			str += nsvg__parseSkewX(t, str);
+			len = nsvg__parseSkewX(t, str);
 		else if (strncmp(str, "skewY", 5) == 0)
-			str += nsvg__parseSkewY(t, str);
+			len = nsvg__parseSkewY(t, str);
 		else{
 			++str;
 			continue;
 		}
+		if (len != 0) {
+			str += len;
+		} else {
+			++str;
+			continue;
+		}
 
 		nsvg__xformPremultiply(xform, t);
 	}
@@ -1876,8 +1902,11 @@ static int nsvg__getArgsPerElement(char cmd)
 		case 'a':
 		case 'A':
 			return 7;
+		case 'z':
+		case 'Z':
+			return 0;
 	}
-	return 0;
+	return -1;
 }
 
 static void nsvg__pathMoveTo(NSVGparser* p, float* cpx, float* cpy, float* args, int rel)
@@ -2187,6 +2216,7 @@ static void nsvg__parsePath(NSVGparser* p, const char** attr)
 	float args[10];
 	int nargs;
 	int rargs = 0;
+	char initPoint;
 	float cpx, cpy, cpx2, cpy2;
 	const char* tmp[4];
 	char closedFlag;
@@ -2209,13 +2239,14 @@ static void nsvg__parsePath(NSVGparser* p, const char** attr)
 		nsvg__resetPath(p);
 		cpx = 0; cpy = 0;
 		cpx2 = 0; cpy2 = 0;
+		initPoint = 0;
 		closedFlag = 0;
 		nargs = 0;
 
 		while (*s) {
 			s = nsvg__getNextPathItem(s, item);
 			if (!*item) break;
-			if (nsvg__isnum(item[0])) {
+			if (cmd != '\0' && nsvg__isCoordinate(item)) {
 				if (nargs < 10)
 					args[nargs++] = (float)nsvg__atof(item);
 				if (nargs >= rargs) {
@@ -2228,6 +2259,7 @@ static void nsvg__parsePath(NSVGparser* p, const char** attr)
 							cmd = (cmd == 'm') ? 'l' : 'L';
 							rargs = nsvg__getArgsPerElement(cmd);
 							cpx2 = cpx; cpy2 = cpy;
+							initPoint = 1;
 							break;
 						case 'l':
 						case 'L':
@@ -2277,7 +2309,6 @@ static void nsvg__parsePath(NSVGparser* p, const char** attr)
 				}
 			} else {
 				cmd = item[0];
-				rargs = nsvg__getArgsPerElement(cmd);
 				if (cmd == 'M' || cmd == 'm') {
 					// Commit path.
 					if (p->npts > 0)
@@ -2286,7 +2317,11 @@ static void nsvg__parsePath(NSVGparser* p, const char** attr)
 					nsvg__resetPath(p);
 					closedFlag = 0;
 					nargs = 0;
-				} else if (cmd == 'Z' || cmd == 'z') {
+				} else if (initPoint == 0) {
+					// Do not allow other commands until initial point has been set (moveTo called once).
+					cmd = '\0';
+				}
+				if (cmd == 'Z' || cmd == 'z') {
 					closedFlag = 1;
 					// Commit path.
 					if (p->npts > 0) {
@@ -2302,6 +2337,12 @@ static void nsvg__parsePath(NSVGparser* p, const char** attr)
 					closedFlag = 0;
 					nargs = 0;
 				}
+				rargs = nsvg__getArgsPerElement(cmd);
+				if (rargs == -1) {
+					// Command not recognized
+					cmd = '\0';
+					rargs = 0;
+				}
 			}
 		}
 		// Commit path.