Turn sssd_mem_takeover into sssd_mem_attach

The old function was not used anywhere, and this function uses better
semantics, including not using void ** which gives strict aliasing problems.

Also add a generic password destroy function

2 files changed, 51 insertions, 25 deletions

diff --git a/server/util/memory.c b/server/util/memory.c
index 87fefd2f..8ffad49a 100644
--- a/server/util/memory.c
+++ b/server/util/memory.c
@@ -1,30 +1,47 @@
 #include "talloc.h"
+#include "util/util.h"
 
 /*
- * sssd_mem_takeover
- * This function will take a non-talloc pointer and add it to a talloc
+ * sssd_mem_attach
+ * This function will take a non-talloc pointer and "attach" it to a talloc
  * memory context. It will accept a destructor for the original pointer
  * so that when the parent memory context is freed, the non-talloc
  * pointer will also be freed properly.
  */
-TALLOC_CTX *sssd_mem_takeover(TALLOC_CTX *mem_ctx,
-                              void *ptr,
-                              int (*destructor)(void **))
+
+int password_destructor(void *memctx)
+{
+    char *password = (char *)memctx;
+    int i;
+
+    /* zero out password */
+    for (i = 0; password[i]; i++) password[i] = '\0';
+
+    return 0;
+}
+
+static int mem_holder_destructor(void *ptr)
+{
+    struct mem_holder *h;
+
+    h = talloc_get_type(ptr, struct mem_holder);
+    return h->fn(h->mem);
+}
+
+void *sss_mem_attach(TALLOC_CTX *mem_ctx,
+                     void *ptr,
+                     void_destructor_fn_t *fn)
 {
-    TALLOC_CTX **handle;
+    struct mem_holder *h;
 
-    if (ptr == NULL) {
-        return NULL;
-    }
+    if (!ptr || !fn) return NULL;
 
-    handle = talloc_named_const(mem_ctx, sizeof(void *),
-                                "sssd_mem_takeover destructor handle");
-    if (handle == NULL) {
-        return NULL;
-    }
+    h = talloc(mem_ctx, struct mem_holder);
+    if (!h) return NULL;
 
-    *handle = ptr;
-    talloc_set_destructor(handle, destructor);
+    h->mem = ptr;
+    h->fn = fn;
+    talloc_set_destructor((TALLOC_CTX *)h, mem_holder_destructor);
 
-    return handle;
+    return h;
 }
diff --git a/server/util/util.h b/server/util/util.h
index 61f63fef..7acbfe61 100644
--- a/server/util/util.h
+++ b/server/util/util.h
@@ -52,11 +52,6 @@ void debug_fn(const char *format, ...);
 #define talloc_zfree(ptr) do { talloc_free(ptr); ptr = NULL; } while(0)
 #endif
 
-struct main_context {
-    struct tevent_context *event_ctx;
-    struct confdb_ctx *confdb_ctx;
-};
-
 #include "util/dlinklist.h"
 
 /* From debug.c */
@@ -64,6 +59,11 @@ void ldb_debug_messages(void *context, enum ldb_debug_level level,
                         const char *fmt, va_list ap);
 
 /* from server.c */
+struct main_context {
+    struct tevent_context *event_ctx;
+    struct confdb_ctx *confdb_ctx;
+};
+
 int server_setup(const char *name, int flags,
                  const char *conf_entry,
                  struct main_context **main_ctx);
@@ -77,9 +77,18 @@ void CatchChild(void);
 void CatchChildLeaveStatus(void);
 
 /* from memory.c */
-TALLOC_CTX *sssd_mem_takeover(TALLOC_CTX *mem_ctx,
-                              void *ptr,
-                              int (*destructor)(void **));
+typedef int (void_destructor_fn_t)(void *);
+
+struct mem_holder {
+    void *mem;
+    void_destructor_fn_t *fn;
+};
+
+void *sss_mem_attach(TALLOC_CTX *mem_ctx,
+                     void *ptr,
+                     void_destructor_fn_t *fn);
+
+int password_destructor(void *memctx);
 
 /* from usertools.c */
 char *get_username_from_uid(TALLOC_CTX *mem_ctx, uid_t uid);