Fix memory leak in FindFontSet

Valgrind results before:

  definitely lost: 800 bytes in 23 blocks
  indirectly lost: 872 bytes in 6 blocks
    possibly lost: 0 bytes in 0 blocks
  still reachable: 991,316 bytes in 1,795 blocks
       suppressed: 0 bytes in 0 blocks

Valgrind results after:

  definitely lost: 200 bytes in 17 blocks
  indirectly lost: 0 bytes in 0 blocks
    possibly lost: 0 bytes in 0 blocks
  still reachable: 918,812 bytes in 994 blocks
       suppressed: 0 bytes in 0 blocks

Signed-off-by: Tim Wiederhake <twied@gmx.net>
Part-of: <https://gitlab.freedesktop.org/xorg/app/twm/-/merge_requests/29>

3 files changed, 40 insertions, 0 deletions

diff --git a/src/twm.c b/src/twm.c
index 1221bf8..d383873 100644
--- a/src/twm.c
+++ b/src/twm.c
@@ -813,6 +813,25 @@ CreateFonts(void)
     Scr->HaveFonts = TRUE;
 }
 
+static void
+DestroyFonts(void)
+{
+    for (int i = 0; i < NumScreens; ++i) {
+        ScreenInfo *scr = ScreenList[i];
+
+        if (!scr) {
+            continue;
+        }
+
+        DestroyFont(&scr->TitleBarFont);
+        DestroyFont(&scr->MenuFont);
+        DestroyFont(&scr->IconFont);
+        DestroyFont(&scr->SizeFont);
+        DestroyFont(&scr->IconManagerFont);
+        DestroyFont(&scr->DefaultFont);
+    }
+}
+
 void
 RestoreWithdrawnLocation(TwmWindow *tmp)
 {
@@ -903,6 +922,7 @@ Done(XtPointer client_data _X_UNUSED, XtSignalId *si2 _X_UNUSED)
 {
     if (dpy) {
         Reborder(CurrentTime);
+        DestroyFonts();
         XCloseDisplay(dpy);
     }
 
diff --git a/src/util.c b/src/util.c
index 9a04ac1..52f6148 100644
--- a/src/util.c
+++ b/src/util.c
@@ -607,6 +607,7 @@ FindFontSet(MyFont *font, const char *fontname)
                 twmVerbose("font for charset %s is lacking.",
                            missing_charset_list_return[i]);
             }
+            XFreeStringList(missing_charset_list_return);
         }
 
         font_extents = XExtentsOfFontSet(font->fontset);
@@ -672,6 +673,24 @@ GetFont(MyFont *font)
     }
 }
 
+void
+DestroyFont(MyFont *font)
+{
+    if (!font) {
+        return;
+    }
+
+    if (font->fontset) {
+        XFreeFontSet(dpy, font->fontset);
+        font->fontset = NULL;
+    }
+
+    if (font->font) {
+        XFreeFont(dpy, font->font);
+        font->font = NULL;
+    }
+}
+
 int
 MyFont_TextWidth(MyFont *font, const char *string, int len)
 {
diff --git a/src/util.h b/src/util.h
index 6adeed9..a7ded89 100644
--- a/src/util.h
+++ b/src/util.h
@@ -77,6 +77,7 @@ extern void LocateStandardColormaps(void);
 extern void GetColor(int kind, Pixel *what, const char *name);
 extern void GetColorValue(int kind, XColor *what, const char *name);
 extern void GetFont(MyFont *font);
+extern void DestroyFont(MyFont *font);
 extern int MyFont_TextWidth(MyFont *font, const char *string, int len);
 extern void MyFont_DrawImageString(Display *dpy, Drawable d, MyFont *font,
                                    GC gc, int x, int y, const char *string,