From 8c6d796da7e050bb5defd863170828a1db7146c9 Mon Sep 17 00:00:00 2001
From: Adrian Cochrane <adrian@openwork.nz>
Date: Tue, 13 Dec 2022 14:56:17 +1300
Subject: [PATCH] Fix remaining segfaults.

---
 Graphics/Text/Font/Choose/FontSet.hs | 16 ++++++++++------
 cbits/pattern.c                      |  9 +++++++--
 2 files changed, 17 insertions(+), 8 deletions(-)

diff --git a/Graphics/Text/Font/Choose/FontSet.hs b/Graphics/Text/Font/Choose/FontSet.hs
index 37a1daf..ece57e6 100644
--- a/Graphics/Text/Font/Choose/FontSet.hs
+++ b/Graphics/Text/Font/Choose/FontSet.hs
@@ -52,15 +52,19 @@ withFontSets' (fonts:fontss) i fontss' cb = withFontSet fonts $ \fonts' -> do
 
 thawFontSet :: FontSet_ -> IO FontSet
 thawFontSet fonts' = do
+    -- Very hacky, but these debug statements must be in here to avoid segfaults.
+    -- FIXME: Is there an alternative?
+    print "a"
     n <- get_fontSet_nfont fonts'
-    array <- get_fontSet_fonts fonts'
-    if n == 0 || array == nullPtr
-    then return []
+    print "b"
+    if n == 0 then return []
     else do
-        list <- peekArray n array
-        forM list (thawPattern_ . pure)
+        print "c"
+        ret <- forM [0..pred n] (thawPattern_ . get_fontSet_font fonts')
+        print "d"
+        return ret
 foreign import ccall "get_fontSet_nfont" get_fontSet_nfont :: FontSet_ -> IO Int
-foreign import ccall "get_fontSet_fonts" get_fontSet_fonts :: FontSet_ -> IO (Ptr Pattern_)
+foreign import ccall "get_fontSet_font" get_fontSet_font :: FontSet_ -> Int -> IO Pattern_
 
 thawFontSet_ :: IO FontSet_ -> IO FontSet
 thawFontSet_ cb = bracket (throwNull <$> cb) fcFontSetDestroy thawFontSet
diff --git a/cbits/pattern.c b/cbits/pattern.c
index c947988..0eb7512 100644
--- a/cbits/pattern.c
+++ b/cbits/pattern.c
@@ -1,4 +1,5 @@
 #include <fontconfig/fontconfig.h>
+#include <stddef.h>
 
 int my_FcCHARSET_MAP_SIZE() {
     return FC_CHARSET_MAP_SIZE;
@@ -31,6 +32,10 @@ int get_fontSet_nfont(FcFontSet *fonts) {
     return fonts->nfont;
 }
 
-FcPattern **get_fontSet_fonts(FcFontSet *fonts) {
-    return fonts->fonts;
+FcPattern *get_fontSet_font(FcFontSet *fonts, int i) {
+    if (i < 0) return NULL;
+    if (i >= fonts->nfont) return NULL;
+    if (i >= fonts->sfont) return NULL;
+    if (fonts->fonts == NULL) return NULL;
+    return fonts->fonts[i];
 }
-- 
2.30.2