Bug fix: Fix X pixmap leakage in shadow_paint

- Fix X pixmap leakage in shadow_paint.

- Add the skeleton of a X resource leakage checker.

src/xrescheck.h

@@ -0,0 +1,70 @@
+#ifndef COMPTON_XRESCHECK_H
+#define COMPTON_XRESCHECK_H
+
+#include "common.h"
+#include <uthash.h>
+
+typedef struct {
+  XID xid;
+  const char *type;
+  const char *file;
+  const char *func;
+  int line;
+  UT_hash_handle hh;
+} xrc_xid_record_t;
+
+#define M_POS_DATA_PARAMS const char *file, int line, const char *func
+#define M_POS_DATA_PASSTHROUGH file, line, func
+#define M_POS_DATA __FILE__, __LINE__, __func__
+
+void
+xrc_add_xid_(XID xid, const char *type, M_POS_DATA_PARAMS);
+
+#define xrc_add_xid(xid, type) xrc_add_xid_(xid, type, M_POS_DATA)
+
+void
+xrc_delete_xid_(XID xid, M_POS_DATA_PARAMS);
+
+#define xrc_delete_xid(xid) xrc_delete_xid_(xid, M_POS_DATA)
+
+void
+xrc_report_xid(void);
+
+void
+xrc_clear_xid(void);
+
+// Pixmap
+
+static inline Pixmap
+XCreatePixmap_(Display *dpy, Drawable drawable,
+    unsigned int width, unsigned int height, unsigned int depth,
+    M_POS_DATA_PARAMS) {
+  Pixmap ret = XCreatePixmap(dpy, drawable, width, height, depth);
+  if (ret)
+    xrc_add_xid_(ret, "Pixmap", M_POS_DATA_PASSTHROUGH);
+  return ret;
+}
+
+#define XCreatePixmap(dpy, drawable, width, height, depth) \
+  XCreatePixmap_(dpy, drawable, width, height, depth, M_POS_DATA)
+
+static inline Pixmap
+XCompositeNameWindowPixmap_(Display *dpy, Window window, M_POS_DATA_PARAMS) {
+  Pixmap ret = XCompositeNameWindowPixmap(dpy, window);
+  if (ret)
+    xrc_add_xid_(ret, "PixmapC", M_POS_DATA_PASSTHROUGH);
+  return ret;
+}
+
+#define XCompositeNameWindowPixmap(dpy, window) \
+  XCompositeNameWindowPixmap_(dpy, window, M_POS_DATA)
+
+static inline void
+XFreePixmap_(Display *dpy, Pixmap pixmap, M_POS_DATA_PARAMS) {
+  XFreePixmap(dpy, pixmap);
+  xrc_delete_xid_(pixmap, M_POS_DATA_PASSTHROUGH);
+}
+
+#define XFreePixmap(dpy, pixmap) XFreePixmap_(dpy, pixmap, M_POS_DATA);
+
+#endif