GL alias model meshes are now doubly protected from corruption and model

mismatch. First, the md4 checksum is stored in the mesh, and the md4 checksum
of the mesh and the model checksum are also stored. If, on loading, either
checksum fails, the model is re-meshed.

include/mdfour.h:
	Add define for MDFOUR_DIGEST_BYTES
source/.gdbinit
	setrom _windowed_mouse 0 so mods don't make debugging difficult
source/model_alias.c:
	pass original model data and size to GL_MakeAliasModelDisplayLists
source/sw_model_alias.c:
	GL_MakeAliasModelDisplayLists take (but ignore) new params
source/gl_mesh.c:
	do md4 checksums on the model and mesh

include/mdfour.h

@@ -32,6 +32,8 @@
 
 #include	"uint32.h"
 
+#define MDFOUR_DIGEST_BYTES 16
+
 struct mdfour {
 	uint32 A, B, C, D;
 	uint32 totalN;

source/.gdbinit

@@ -1 +1 @@
-set args -nocdaudio +set _windowed_mouse 0 +set gl_sky_clip 1 +set show_fps 1
+set args -nocdaudio +setrom _windowed_mouse 0 +set gl_sky_clip 1 +set show_fps 1

source/gl_mesh.c

@@ -39,6 +39,7 @@
 #include <stdio.h>
 
 #include "console.h"
+#include "mdfour.h"
 #include "model.h"
 #include "quakefs.h"
 
@@ -301,17 +302,22 @@ GL_MakeAliasModelDisplayLists
 ================
 */
 void
-GL_MakeAliasModelDisplayLists (model_t *m, aliashdr_t *hdr)
+GL_MakeAliasModelDisplayLists (model_t *m, aliashdr_t *hdr, void *_m, int _s)
 {
 	int         i, j;
 	int        *cmds;
 	trivertx_t *verts;
 	char        cache[MAX_QPATH], fullpath[MAX_OSPATH];
 	QFile      *f;
+	unsigned char model_digest[MDFOUR_DIGEST_BYTES];
+	unsigned char mesh_digest[MDFOUR_DIGEST_BYTES];
+	qboolean    remesh = true;
 
 	aliasmodel = m;
 	paliashdr = hdr;					// (aliashdr_t *)Mod_Extradata (m);
 
+	mdfour (model_digest, (unsigned char*)_m, _s);
+
 	// 
 	// look for a cached version
 	// 
@@ -322,12 +328,37 @@ GL_MakeAliasModelDisplayLists (model_t *m, aliashdr_t *hdr)
 
 	COM_FOpenFile (cache, &f);
 	if (f) {
-		Qread (f, &numcommands, 4);
+		unsigned char d1[MDFOUR_DIGEST_BYTES];
-		Qread (f, &numorder, 4);
+		unsigned char d2[MDFOUR_DIGEST_BYTES];
-		Qread (f, &commands, numcommands * sizeof (commands[0]));
+		struct mdfour md;
-		Qread (f, &vertexorder, numorder * sizeof (vertexorder[0]));
+		int nc;
+		int no;
+
+		memset (d1, 0, sizeof (d1));
+		memset (d2, 0, sizeof (d2));
+		Qread (f, &nc, 4);
+		Qread (f, &no, 4);
+		Qread (f, &commands, nc * sizeof (commands[0]));
+		Qread (f, &vertexorder, no * sizeof (vertexorder[0]));
+		Qread (f, d1, MDFOUR_DIGEST_BYTES);
+		Qread (f, d2, MDFOUR_DIGEST_BYTES);
 		Qclose (f);
-	} else {
+
+		mdfour_begin (&md);
+		mdfour_update (&md, (unsigned char*)&nc, 4);
+		mdfour_update (&md, (unsigned char*)&no, 4);
+		mdfour_update (&md, (unsigned char*)&commands, nc * sizeof (commands[0]));
+		mdfour_update (&md, (unsigned char*)&vertexorder, no * sizeof (vertexorder[0]));
+		mdfour_update (&md, d1, MDFOUR_DIGEST_BYTES);
+		mdfour_result (&md, mesh_digest);
+
+		if (memcmp (d2, mesh_digest, MDFOUR_DIGEST_BYTES) == 0 && memcmp (d1, model_digest, MDFOUR_DIGEST_BYTES) == 0) {
+			remesh = false;
+			numcommands = nc;
+			numorder = no;
+		}
+	}
+	if (remesh) {
 		// 
 		// build it from scratch
 		// 
@@ -346,10 +377,23 @@ GL_MakeAliasModelDisplayLists (model_t *m, aliashdr_t *hdr)
 		}
 
 		if (f) {
+			struct mdfour md;
+
+			mdfour_begin (&md);
+			mdfour_update (&md, (unsigned char*)&numcommands, 4);
+			mdfour_update (&md, (unsigned char*)&numorder, 4);
+			mdfour_update (&md, (unsigned char*)&commands, numcommands * sizeof (commands[0]));
+			mdfour_update (&md, (unsigned char*)&vertexorder,
+						   numorder * sizeof (vertexorder[0]));
+			mdfour_update (&md, model_digest, MDFOUR_DIGEST_BYTES);
+			mdfour_result (&md, mesh_digest);
+
 			Qwrite (f, &numcommands, 4);
 			Qwrite (f, &numorder, 4);
 			Qwrite (f, &commands, numcommands * sizeof (commands[0]));
 			Qwrite (f, &vertexorder, numorder * sizeof (vertexorder[0]));
+			Qwrite (f, model_digest, MDFOUR_DIGEST_BYTES);
+			Qwrite (f, mesh_digest, MDFOUR_DIGEST_BYTES);
 			Qclose (f);
 		}
 	}

source/model_alias.c

@@ -57,7 +57,7 @@ extern model_t *loadmodel;
 void       *Mod_LoadAllSkins (int numskins, daliasskintype_t *pskintype,
 
 							  int *pskinindex);
-void        GL_MakeAliasModelDisplayLists (model_t *m, aliashdr_t *hdr);
+void        GL_MakeAliasModelDisplayLists (model_t *m, aliashdr_t *hdr, void *model, int size);
 
 /*
 ==============================================================================
@@ -254,7 +254,7 @@ Mod_LoadAliasModel (model_t *mod, void *buffer)
 	// 
 	// build the draw lists
 	// 
-	GL_MakeAliasModelDisplayLists (mod, pheader);
+	GL_MakeAliasModelDisplayLists (mod, pheader, buffer, com_filesize);
 
 //
 // move the complete, relocatable alias model to the cache

source/sw_model_alias.c

@@ -169,7 +169,7 @@ Mod_LoadAllSkins (int numskins, daliasskintype_t *pskintype, int *pskinindex)
 }
 
 void
-GL_MakeAliasModelDisplayLists (model_t *m, aliashdr_t *hdr)
+GL_MakeAliasModelDisplayLists (model_t *m, aliashdr_t *hdr, void *_m, int _s)
 {
 	int         i, j;
 	stvert_t   *pstverts;