From 65c7427c019c1cb7c621e6be87fb298564d45f51 Mon Sep 17 00:00:00 2001
From: Akira TAGOH <akira@tagoh.org>
Date: Fri, 30 Nov 2018 07:03:54 +0000
Subject: [PATCH] Warn when constant name is used for unexpected object

This fixes the sort of weird things like `fc-match :size=rgb` done without any errors.
This might be annoyed but the error messages should helps to fix an application bug or
suggest more useful constant names to fontconfig.

Fixes https://gitlab.freedesktop.org/fontconfig/fontconfig/issues/137
---
 src/fcint.h  |  3 +++
 src/fcname.c | 30 ++++++++++++++++++++++++------
 2 files changed, 27 insertions(+), 6 deletions(-)

diff --git a/src/fcint.h b/src/fcint.h
index a9d075a..d473955 100644
--- a/src/fcint.h
+++ b/src/fcint.h
@@ -1021,6 +1021,9 @@ enum {
 #define FC_MAX_BASE_OBJECT (FC_ONE_AFTER_MAX_BASE_OBJECT - 1)
 };
 
+FcPrivate FcBool
+FcNameConstantWithObjectCheck (const FcChar8 *string, const char *object, int *result);
+
 FcPrivate FcBool
 FcNameBool (const FcChar8 *v, FcBool *result);
 
diff --git a/src/fcname.c b/src/fcname.c
index 711bb9b..041d6d6 100644
--- a/src/fcname.c
+++ b/src/fcname.c
@@ -241,6 +241,24 @@ FcNameConstant (const FcChar8 *string, int *result)
     return FcFalse;
 }
 
+FcBool
+FcNameConstantWithObjectCheck (const FcChar8 *string, const char *object, int *result)
+{
+    const FcConstant	*c;
+
+    if ((c = FcNameGetConstant(string)))
+    {
+	if (strcmp (c->object, object) != 0)
+	{
+	    fprintf (stderr, "Fontconfig error: Unexpected constant name `%s' used for object `%s': should be `%s'\n", string, object, c->object);
+	    return FcFalse;
+	}
+	*result = c->value;
+	return FcTrue;
+    }
+    return FcFalse;
+}
+
 FcBool
 FcNameBool (const FcChar8 *v, FcBool *result)
 {
@@ -287,7 +305,7 @@ FcNameBool (const FcChar8 *v, FcBool *result)
 }
 
 static FcValue
-FcNameConvert (FcType type, FcChar8 *string)
+FcNameConvert (FcType type, const char *object, FcChar8 *string)
 {
     FcValue	v;
     FcMatrix	m;
@@ -297,7 +315,7 @@ FcNameConvert (FcType type, FcChar8 *string)
     v.type = type;
     switch ((int) v.type) {
     case FcTypeInteger:
-	if (!FcNameConstant (string, &v.u.i))
+	if (!FcNameConstantWithObjectCheck (string, object, &v.u.i))
 	    v.u.i = atoi ((char *) string);
 	break;
     case FcTypeString:
@@ -338,8 +356,8 @@ FcNameConvert (FcType type, FcChar8 *string)
 	    ec = malloc (len + 1);
 	    if (sc && ec && sscanf ((char *) string, "[%s %[^]]]", sc, ec) == 2)
 	    {
-		if (FcNameConstant ((const FcChar8 *) sc, &si) &&
-		    FcNameConstant ((const FcChar8 *) ec, &ei))
+		if (FcNameConstantWithObjectCheck ((const FcChar8 *) sc, object, &si) &&
+		    FcNameConstantWithObjectCheck ((const FcChar8 *) ec, object, &ei))
 		    v.u.r =  FcRangeCreateDouble (si, ei);
 		else
 		    goto bail1;
@@ -348,7 +366,7 @@ FcNameConvert (FcType type, FcChar8 *string)
 	    {
 	    bail1:
 		v.type = FcTypeDouble;
-		if (FcNameConstant (string, &si))
+		if (FcNameConstantWithObjectCheck (string, object, &si))
 		{
 		    v.u.d = (double) si;
 		} else {
@@ -461,7 +479,7 @@ FcNameParse (const FcChar8 *name)
 		    name = FcNameFindNext (name, ":,", save, &delim);
 		    if (t)
 		    {
-			v = FcNameConvert (t->type, save);
+			v = FcNameConvert (t->type, t->object, save);
 			if (!FcPatternAdd (pat, t->object, v, FcTrue))
 			{
 			    FcValueDestroy (v);