[DragonFlyBSD - Bug #2910] (Closed) Rethinking __printflike in the context of drm's __printf

[bugtracker-admin at leaf.dragonflybsd.org]

Issue #2910 has been updated by swildner.

Status changed from New to Closed

Closing this issue.

Whoever brings in Linux code that may pass NULL to a function which itself is decorated with __printf, could change the macro to __printf0like().


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Bug #2910: Rethinking __printflike in the context of drm's __printf
http://bugs.dragonflybsd.org/issues/2910#change-12915

* Author: davshao
* Status: Closed
* Priority: Normal
* Assignee: 
* Category: 
* Target version: 
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Currently DragonFly drm defines __printf to be __printflike.  It seems likely to me that Linux drm actually expects behavior __printf0like, without the __nonnull__(fmtarg) attribute.  

For example, more recent versions of Linux drm want to define a function like this:

extern __printf(6, 7)
int drm_crtc_init_with_planes(struct drm_device *dev,
			      struct drm_crtc *crtc,
			      struct drm_plane *primary,
			      struct drm_plane *cursor,
			      const struct drm_crtc_funcs *funcs,
			      const char *name, ...);

and call it sometimes (well strangely enough, so far all of the time) with name == NULL.
Then inside the newer versions of the function is something like this:

	if (name) {
		__va_list ap;

		__va_start(ap, name);
		crtc->name = kvasprintf(GFP_KERNEL, name, ap);
		__va_end(ap);
	} else {
		crtc->name = kasprintf(GFP_KERNEL, "crtc-%d",
				       drm_num_crtcs(dev));
	}

The obvious fix is in sys/dev/drm/include/linux/compiler.h
to redefine __printf as __printf0like.

For curiosity's sake, given the gcc 4+ series of compilers now used for DragonFly in 2015
as opposed to 2004 when the __printflike and __printf0like distinction was made, is it
still necessary to have both __printflike and printf0like?



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