Merge branch 'macro_free_v2_squashed'

1 files changed, 24 insertions, 1 deletions

diff --git a/src/common/util.h b/src/common/util.h
index 6bc853da26..8dc64ce9fa 100644
--- a/src/common/util.h
+++ b/src/common/util.h
@@ -80,12 +80,22 @@ extern int dmalloc_free(const char *file, const int line, void *pnt,
  * This is a macro.  If you need a function pointer to release memory from
  * tor_malloc(), use tor_free_().
  */
+#ifdef __GNUC__
+#define tor_free(p) STMT_BEGIN                                 \
+    typeof(&(p)) tor_free__tmpvar = &(p);                      \
+    if (PREDICT_LIKELY((*tor_free__tmpvar)!=NULL)) {           \
+      raw_free(*tor_free__tmpvar);                             \
+      *tor_free__tmpvar=NULL;                                  \
+    }                                                          \
+  STMT_END
+#else
 #define tor_free(p) STMT_BEGIN                                 \
     if (PREDICT_LIKELY((p)!=NULL)) {                           \
       raw_free(p);                                             \
       (p)=NULL;                                                \
     }                                                          \
   STMT_END
+#endif
 #endif /* defined(USE_DMALLOC) */
 
 #define tor_malloc(size)       tor_malloc_(size DMALLOC_ARGS)
@@ -109,6 +119,17 @@ extern int dmalloc_free(const char *file, const int line, void *pnt,
 
 void tor_log_mallinfo(int severity);
 
+/* Helper macro: free a variable of type 'typename' using freefn, and
+ * set the variable to NULL.
+ */
+#define FREE_AND_NULL(typename, freefn, var)                            \
+  do {                                                                  \
+    /* only evaluate (var) once. */                                     \
+    typename **tmp__free__ptr ## freefn = &(var);                       \
+    freefn(*tmp__free__ptr ## freefn);                                  \
+    (*tmp__free__ptr ## freefn) = NULL;                                 \
+  } while (0)
+
 /** Macro: yield a pointer to the field at position <b>off</b> within the
  * structure <b>st</b>.  Example:
  * <pre>
@@ -423,7 +444,9 @@ struct process_environment_t {
 };
 
 process_environment_t *process_environment_make(struct smartlist_t *env_vars);
-void process_environment_free(process_environment_t *env);
+void process_environment_free_(process_environment_t *env);
+#define process_environment_free(env) \
+  FREE_AND_NULL(process_environment_t, process_environment_free_, (env))
 
 struct smartlist_t *get_current_process_environment_variables(void);