[PATCH][1/2] [RESEND] kobject: add HOTPLUG_ENV_VAR

[Roland Dreier <roland@topspin.com>]

Add a HOTPLUG_ENV_VAR macro to <linux/kobject.h>.  There's a lot of
boilerplate code involved in setting environment variables in a
hotplug method, so we should have a convenience macro to consolidate
it (and avoid subtle bugs).


Signed-off-by: Roland Dreier <roland@topspin.com>

Index: linux-bk/include/linux/kobject.h
===================================================================
--- linux-bk.orig/include/linux/kobject.h	2004-09-12 15:17:02.000000000 -0700
+++ linux-bk/include/linux/kobject.h	2004-09-12 19:44:31.000000000 -0700
@@ -95,6 +95,20 @@
 			int num_envp, char *buffer, int buffer_size);
 };
 
+#define HOTPLUG_ENV_VAR(_buf, _size, _envp, _nenvp, _index, _fmt, _arg...) \
+	({								\
+		int len, ret = 0;					\
+		_envp[_index++] = _buf;					\
+		len = snprintf(_buf, _size, _fmt, ## _arg);		\
+		if (_size - len <= 0 || _index >= _nenvp)		\
+			ret = -ENOMEM;					\
+		else {							\
+			_buf  += len + 1;				\
+			_size -= len + 1;				\
+		}							\
+		ret;							\
+	})
+
 struct kset {
 	struct subsystem	* subsys;
 	struct kobj_type	* ktype;