Read font info files incrementally

The previous text-mode reading had a problem where the extractable character count of a file opened in non-binary (text) mode is subject to the actual contents of the file due to newline translation and EOF characters, and can only be determined by actually scanning over the content.

GetLen yields the binary size of the file and thus tends to overallocate the buffer, leading to the actual read attempting to read more data than can actually be extracted. This puts the code at the mercy of what garbage the target string contains from the allocator and how much data could actually be read.

Author: zao

engine/render/r_font.cpp

@@ -6,19 +6,22 @@
 
 #include "r_local.h"
 
+#include <fstream>
+#include <string>
+
 // =======
 // Classes
 // =======
 
 // Glyph parameters
 struct f_glyph_s {
-	double	tcLeft;
-	double	tcRight;
-	double	tcTop;
-	double	tcBottom;
-	int		width;
-	int		spLeft;
-	int		spRight;
+	double	tcLeft = 0.0;
+	double	tcRight = 0.0;
+	double	tcTop = 0.0;
+	double	tcBottom = 0.0;
+	int		width = 0;
+	int		spLeft = 0;
+	int		spRight = 0;
 };
 
 // Font height info
@@ -45,27 +48,20 @@ r_font_c::r_font_c(r_renderer_c* renderer, const char* fontName)
 	// Open info file
 	char tgfName[260];
 	sprintf_s(tgfName, 260, "%s.tgf", fileNameBase);
-	fileInputStream_c tgf;
-	if (tgf.FileOpen(tgfName, false)) {
+	std::ifstream tgf(tgfName);
+	if (!tgf) {
 		renderer->sys->con->Warning("font \"%s\" not found", fontName);
 		return;
 	}
 
-	// Read contents of info file
-	size_t tgfLen = tgf.GetLen();
-	char* tgfDat = AllocStringLen(tgfLen);
-	tgf.Read(tgfDat, tgfLen);
-	tgf.FileClose();
-
 	maxHeight = 0;
 	f_fontHeight_s* fh = NULL;
 
 	// Parse info file
-	char* tk_context;
-	char* sub = strtok_s(tgfDat, "\n", &tk_context);
-	do {
+	std::string sub;
+	while (std::getline(tgf, sub)) {
 		int h, x, y, w, sl, sr;
-		if (sscanf_s(sub, "HEIGHT %u;", &h) == 1) {
+		if (sscanf_s(sub.c_str(), "HEIGHT %u;", &h) == 1) {
 			// New height
 			fh = new f_fontHeight_s;
 			fontHeights[numFontHeight++] = fh;
@@ -77,7 +73,7 @@ r_font_c::r_font_c(r_renderer_c* renderer, const char* fontName)
 				maxHeight = h;
 			}
 			fh->numGlyph = 0;
-		} else if (fh && sscanf_s(sub, "GLYPH %u %u %u %d %d;", &x, &y, &w, &sl, &sr) == 5) {
+		} else if (fh && sscanf_s(sub.c_str(), "GLYPH %u %u %u %d %d;", &x, &y, &w, &sl, &sr) == 5) {
 			// Add glyph
 			if (fh->numGlyph >= 128) continue;
 			f_glyph_s* glyph = &fh->glyphs[fh->numGlyph++];
@@ -89,9 +85,7 @@ r_font_c::r_font_c(r_renderer_c* renderer, const char* fontName)
 			glyph->spLeft = sl;
 			glyph->spRight = sr;
 		}
-	} while (sub = strtok_s(NULL, "\n", &tk_context));
-
-	FreeString(tgfDat);
+	}
 
 	// Generate mapping of text height to font height
 	fontHeightMap = new int[maxHeight + 1];