Fixed up realloc() to zero extra memory on GTK+. Thanks to Rena (irc.badnik.net) and hyphenated (irc.freenode.net/#go-nuts) for confirming my memset() and spotting errors.

unix/alloc.c

@@ -1,27 +1,55 @@
 // 7 april 2015
-#include <stdio.h>
+#include <string.h>
 #include "uipriv_unix.h"
 
+static GHashTable *allocsizes;			// map[*void]*size_t
+
+void initAlloc(void)
+{
+	allocsizes = g_hash_table_new(g_direct_hash, g_direct_equal);
+}
+
 void *uiAlloc(size_t size)
 {
 	void *out;
+	size_t *s;
 
 	out = g_malloc0(size);
+	if (g_hash_table_lookup(allocsizes, out) != NULL)
+		complain("already have a size for %p in uiAlloc()", out);
+	s = g_new0(size_t, 1);
+	*s = size;
+	g_hash_table_insert(allocsizes, out, s);
 	return out;
 }
 
-void *uiRealloc(void *p, size_t size)
+void *uiRealloc(void *p, size_t new)
 {
 	void *out;
+	size_t *s;
 
 	if (p == NULL)
-		return uiAlloc(size);
-	// TODO fill with 0s
-	out = g_realloc(p, size);
+		return uiAlloc(new);
+	out = g_realloc(p, new);
+	s = (size_t *) g_hash_table_lookup(allocsizes, p);
+	if (s == NULL)
+		complain("no size found for %p in uiRealloc()", p);
+	if (new <= *s)
+		memset(((uint8_t *) out) + *s, 0, new - *s);
+	*s = new;
+	g_hash_table_remove(allocsizes, p);
+	g_hash_table_insert(allocsizes, out, s);
 	return out;
 }
 
 void uiFree(void *p)
 {
+	size_t *s;
+
 	g_free(p);
+	s = (size_t *) g_hash_table_lookup(allocsizes, p);
+	if (s == NULL)
+		complain("no size found for %p in uiFree()", p);
+	g_hash_table_remove(allocsizes, p);
+	g_free(s);
 }

unix/main.c

@@ -14,6 +14,7 @@ const char *uiInit(uiInitOptions *o)
 		g_error_free(err);
 		return msg;
 	}
+	initAlloc();
 	return NULL;
 }
 

unix/uipriv_unix.h

@@ -14,3 +14,6 @@
 // menu.c
 extern GtkWidget *makeMenubar(uiWindow *);
 extern void freeMenubar(GtkWidget *);
+
+// alloc.c
+extern void initAlloc(void);