PluginXBM: use regex in Load() as standard-compliant and safe text parser

Source/Plugins/PluginXBM.cpp

@@ -29,7 +29,11 @@
 // Internal functions
 // ==========================================================
 
-#define MAX_LINE	512
+#define MAX_LINE 512
+#define LINE_FORMAT_WIDTH_OR_HEIGHT  "#define %" FI_QUOTE(MAX_LINE) "s %d"
+#define LINE_FORMAT_BITS_V10 "static short %" FI_QUOTE(MAX_LINE) "s = {"
+#define LINE_FORMAT_BITS_V11_OPT1 "static char %" FI_QUOTE(MAX_LINE) "s = {"
+#define LINE_FORMAT_BITS_V11_OPT2 "static unsigned char %" FI_QUOTE(MAX_LINE) "s = {"
 
 static const char *ERR_XBM_SYNTAX	= "Syntax error";
 static const char *ERR_XBM_LINE		= "Line too long";
@@ -87,76 +91,79 @@ Read an XBM file into a buffer
 */
 static const char* 
 readXBMFile(FreeImageIO *io, fi_handle handle, int *widthP, int *heightP, std::unique_ptr<void, decltype(&free)> &dataP) {
-	char line[MAX_LINE], name_and_type[MAX_LINE];
-    char *ptr{};
-    char *t{};
+	std::string line(MAX_LINE, '\0'), name(MAX_LINE + 1, '\0');
+	char *ptr{};
 	int version = 0;
 	size_t bytes, bytes_per_line, raster_length;
-	int v, padding;
 	int c1, c2, value1, value2;
 	int hex_table[256];
-    bool found_declaration{}; // haven't found it yet; haven't even looked
+	bool found_declaration{}; // haven't found it yet; haven't even looked
 	/* in scanning through the bitmap file, we have found the first
-	 line of the C declaration of the array (the "static char ..."
-	 or whatever line)
+	 line of the C declaration of the array (the "static char ..." or whatever line)
 	 */
-    bool eof{};	// we've encountered end of file while searching file
 
 	*widthP = *heightP = -1;
 
-	while (!found_declaration && !eof) {
+	for (;;) {
+		if (!readLine(line.data(), MAX_LINE, io, handle)) {
+			break;
+		}
 
-		if (!readLine(line, MAX_LINE, io, handle)) {
-			eof = true;
+		if (strlen(line.c_str()) >= MAX_LINE - 1) {
+			return ERR_XBM_LINE;
 		}
-		else {
-			if (strlen(line) == MAX_LINE - 1)
-				return( ERR_XBM_LINE );
-			if (sscanf_s(line, "#define %s %d", name_and_type, MAX_LINE, &v) == 2) {
-				if ((t = strrchr(name_and_type, '_')) == nullptr)
-					t = name_and_type;
-				else
-					t++;
-				if (!strcmp("width", t))
-					*widthP = v;
-				else if (!strcmp("height", t))
-					*heightP = v;
-				continue;
-			}
 
-			if (sscanf_s(line, "static short %s = {", name_and_type, MAX_LINE) == 1) {
-				version = 10;
-				found_declaration = true;
-			}
-			else if (sscanf_s(line, "static char %s = {", name_and_type, MAX_LINE) == 1) {
-				version = 11;
-				found_declaration = true;
-			}
-			else if (sscanf_s(line, "static unsigned char %s = {", name_and_type, MAX_LINE) == 1) {
-				version = 11;
-				found_declaration = true;
+		int val{};
+		if (2 == std::sscanf(line.c_str(), LINE_FORMAT_WIDTH_OR_HEIGHT, name.data(), &val)) {
+			if (const auto suffix = std::strrchr(name.c_str(), '_')) {
+				if (0 == std::strcmp("_width", suffix)) {
+					*widthP = val;
+					continue;
+				}
+				if (0 == std::strcmp("_height", suffix)) {
+					*heightP = val;
+					continue;
+				}
 			}
 		}
+
+		if (1 == std::sscanf(line.c_str(), LINE_FORMAT_BITS_V10, name.data())) {
+			version = 10;
+			found_declaration = true;
+			break;
+		}
+
+		if (1 == std::sscanf(line.c_str(), LINE_FORMAT_BITS_V11_OPT1, name.data()) || 
+				 1 == std::sscanf(line.c_str(), LINE_FORMAT_BITS_V11_OPT2, name.data())) {
+			version = 11;
+			found_declaration = true;
+			break;
+		}
 	}
 
-	if (!found_declaration)
-		return( ERR_XBM_DECL );
+	if (!found_declaration) {
+		return ERR_XBM_DECL;
+	}
 
-	if (*widthP == -1)
-		return( ERR_XBM_WIDTH );
-	if (*heightP == -1)
-		return( ERR_XBM_HEIGHT );
+	if (*widthP <= 0) {
+		return ERR_XBM_WIDTH;
+	}
+	if (*heightP <= 0) {
+		return ERR_XBM_HEIGHT;
+	}
 
-	padding = 0;
-	if ( ((*widthP % 16) >= 1) && ((*widthP % 16) <= 8) && (version == 10) )
+	int padding = 0;
+	if (((*widthP % 16) >= 1) && ((*widthP % 16) <= 8) && (version == 10)) {
 		padding = 1;
+	}
 
 	bytes_per_line = (*widthP + 7) / 8 + padding;
 
 	raster_length =  bytes_per_line * *heightP;
 	dataP.reset(malloc(raster_length));
-	if (!dataP)
-		return( ERR_XBM_MEMORY );
+	if (!dataP) {
+		return ERR_XBM_MEMORY;
+	}
 
 	// initialize hex_table
 	for ( c1 = 0; c1 < 256; c1++ ) {