From: Martin Mares <mj@ucw.cz>
Date: Tue, 19 Apr 2011 12:44:46 +0000 (+0200)
Subject: Resources: Allow res_free(NULL) and res_detach(NULL)
X-Git-Tag: v5.0~74^2~13
X-Git-Url: http://mj.ucw.cz/gitweb/?a=commitdiff_plain;h=0f88062c8973258611a8cba9a0e9668d1c688030;p=libucw.git

Resources: Allow res_free(NULL) and res_detach(NULL)
---

diff --git a/ucw/respool.c b/ucw/respool.c
index a4978fdf..09b8953f 100644
--- a/ucw/respool.c
+++ b/ucw/respool.c
@@ -121,6 +121,8 @@ res_drop(struct resource *r)
 void
 res_detach(struct resource *r)
 {
+  if (!r)
+    return;
   if (r->rclass->detach)
     r->rclass->detach(r);
   res_drop(r);
@@ -129,6 +131,8 @@ res_detach(struct resource *r)
 void
 res_free(struct resource *r)
 {
+  if (!r)
+    return;
   if (r->rclass->free)
     r->rclass->free(r);
   res_drop(r);
diff --git a/ucw/respool.h b/ucw/respool.h
index 55f17bee..56955707 100644
--- a/ucw/respool.h
+++ b/ucw/respool.h
@@ -77,7 +77,18 @@ static inline struct respool *rp_switch(struct respool *rp)
 struct resource *res_alloc(const struct res_class *rc) LIKE_MALLOC;	// Returns NULL if there is no pool active
 
 void res_dump(struct resource *r, uns indent);		/** Prints out a debugging dump of the resource to stdout. **/
-void res_free(struct resource *r);			/** Frees a resource, unlinking it from its pool. **/
+
+/**
+ * Frees a resource, unlinking it from its pool.
+ * When called with a NULL pointer, it does nothing, but safely.
+ **/
+void res_free(struct resource *r);
+
+/**
+ * Unlinks a resource from a pool and releases its meta-data. However, the resource itself is kept.
+ * When called with a NULL pointer, it does nothing, but safely.
+ **/
+void res_detach(struct resource *r);
 
 /** Marks a resource as temporary (sets @RES_FLAG_TEMP). **/
 static inline void res_temporary(struct resource *r)
@@ -119,12 +130,10 @@ struct res_class {
   uns res_size;						// Size of the resource structure (0=default)
 };
 
-/** Unlinks a resource from a pool and releases its meta-data. However, the resource itself is kept. **/
-void res_detach(struct resource *r);
-
 /**
  * Unlinks a resource from a pool and releases its meta-data. Unlike @res_detach(),
- * it does not invoke any callbacks.
+ * it does not invoke any callbacks. The caller must make sure that no references to
+ * the meta-data remain, so this is generally safe only inside resource class code.
  **/
 void res_drop(struct resource *r);