From: notcancername <notcancername@protomail.com>
Date: Mon, 31 Jul 2023 20:21:56 +0000 (+0200)
Subject: Fix yet more UB. Provide explanatory comments.
X-Git-Url: https://git.rm.cloudns.org/?a=commitdiff_plain;h=1c963f0c1ebdf86d7cda9f3f2138e24b64154176;p=xonotic%2Fdarkplaces.git

Fix yet more UB. Provide explanatory comments.

Signed-off-by: notcancername <notcancername@protomail.com>
---

diff --git a/cl_main.c b/cl_main.c
index fe1840af..4794081c 100644
--- a/cl_main.c
+++ b/cl_main.c
@@ -3112,7 +3112,8 @@ void CL_Init (void)
 
 		// for QW connections
 		Cvar_RegisterVariable(&qport);
-		Cvar_SetValueQuick(&qport, (rand() * RAND_MAX + rand()) & 0xffff);
+		// multiplying by RAND_MAX necessary for Windows, for which RAND_MAX is only 32767.
+		Cvar_SetValueQuick(&qport, ((unsigned int)rand() * RAND_MAX + (unsigned int)rand()) & 0xffff);
 
 		Cmd_AddCommand(CF_CLIENT, "timerefresh", CL_TimeRefresh_f, "turn quickly and print rendering statistcs");
 
diff --git a/com_msg.c b/com_msg.c
index 1da366af..80503b62 100644
--- a/com_msg.c
+++ b/com_msg.c
@@ -30,6 +30,9 @@ Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 ============================================================================
 */
 
+/* Casting to unsigned when shifting by 24 bits here is necessary to prevent UB
+ * caused by shifting outside the range of int on platforms where int is 32 bits.
+ */
 
 float BuffBigFloat (const unsigned char *buffer)
 {
@@ -287,7 +290,7 @@ int MSG_ReadLittleLong (sizebuf_t *sb)
 		return -1;
 	}
 	sb->readcount += 4;
-	return sb->data[sb->readcount-4] | (sb->data[sb->readcount-3]<<8) | (sb->data[sb->readcount-2]<<16) | (sb->data[sb->readcount-1]<<24);
+	return sb->data[sb->readcount-4] | (sb->data[sb->readcount-3]<<8) | (sb->data[sb->readcount-2]<<16) | ((unsigned)sb->data[sb->readcount-1]<<24);
 }
 
 int MSG_ReadBigLong (sizebuf_t *sb)
@@ -298,7 +301,7 @@ int MSG_ReadBigLong (sizebuf_t *sb)
 		return -1;
 	}
 	sb->readcount += 4;
-	return (sb->data[sb->readcount-4]<<24) + (sb->data[sb->readcount-3]<<16) + (sb->data[sb->readcount-2]<<8) + sb->data[sb->readcount-1];
+	return ((unsigned)sb->data[sb->readcount-4]<<24) + (sb->data[sb->readcount-3]<<16) + (sb->data[sb->readcount-2]<<8) + sb->data[sb->readcount-1];
 }
 
 float MSG_ReadLittleFloat (sizebuf_t *sb)
@@ -314,7 +317,7 @@ float MSG_ReadLittleFloat (sizebuf_t *sb)
 		return -1;
 	}
 	sb->readcount += 4;
-	dat.l = sb->data[sb->readcount-4] | (sb->data[sb->readcount-3]<<8) | (sb->data[sb->readcount-2]<<16) | (sb->data[sb->readcount-1]<<24);
+	dat.l = sb->data[sb->readcount-4] | (sb->data[sb->readcount-3]<<8) | (sb->data[sb->readcount-2]<<16) | ((unsigned)sb->data[sb->readcount-1]<<24);
 	return dat.f;
 }
 
@@ -331,7 +334,7 @@ float MSG_ReadBigFloat (sizebuf_t *sb)
 		return -1;
 	}
 	sb->readcount += 4;
-	dat.l = (sb->data[sb->readcount-4]<<24) | (sb->data[sb->readcount-3]<<16) | (sb->data[sb->readcount-2]<<8) | sb->data[sb->readcount-1];
+	dat.l = ((unsigned)sb->data[sb->readcount-4]<<24) | (sb->data[sb->readcount-3]<<16) | (sb->data[sb->readcount-2]<<8) | sb->data[sb->readcount-1];
 	return dat.f;
 }
 
diff --git a/r_shadow.c b/r_shadow.c
index 3f77792d..c80f0d7d 100644
--- a/r_shadow.c
+++ b/r_shadow.c
@@ -1226,7 +1226,7 @@ static unsigned int R_Shadow_MakeTextures_SamplePoint(float x, float y, float z)
 	float dist = sqrt(x*x+y*y+z*z);
 	float intensity = dist < 1 ? ((1.0f - dist) * r_shadow_lightattenuationlinearscale.value / (r_shadow_lightattenuationdividebias.value + dist*dist)) : 0;
 	// note this code could suffer byte order issues except that it is multiplying by an integer that reads the same both ways
-	return ((unsigned int)bound(0, intensity * 256.0f, 255)) * 0x01010101U;
+	return bound(0, (unsigned int)(intensity * 256.0f), 255) * 0x01010101U;
 }
 
 static void R_Shadow_MakeTextures(void)