[PATCH igt] lib: Assert that the internal gem_create interface matches the ioctl

From: Chris Wilson <chris@chris-wilson.co.uk>
To: intel-gfx@lists.freedesktop.org
Subject: [PATCH igt] lib: Assert that the internal gem_create interface matches the ioctl
Date: Tue,  3 Oct 2017 15:05:18 +0100	[thread overview]
Message-ID: <20171003140518.29004-1-chris@chris-wilson.co.uk> (raw)

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
---
 lib/igt_core.h       | 14 ++++++++++++++
 lib/ioctl_wrappers.c |  4 ++++
 2 files changed, 18 insertions(+)

diff --git a/lib/igt_core.h b/lib/igt_core.h
index f8543d65..f5f65984 100644
--- a/lib/igt_core.h
+++ b/lib/igt_core.h
@@ -932,4 +932,18 @@ int igt_system_quiet(const char *command);
 		free(buf); \
 	} while (0)
 
+/**
+ * igt_typecheck:
+ * @type: The intended type we expect the variable to be
+ * @x: The variable we wish to check
+ *
+ * Performs a *compile-time* check that a variable is of a particular type.
+ */
+#define igt_typecheck(type, x) ({ \
+	type __dummy; \
+        typeof(x) __dummy2; \
+        (void)(&__dummy == &__dummy2); \
+        1; \
+})
+
 #endif /* IGT_CORE_H */
diff --git a/lib/ioctl_wrappers.c b/lib/ioctl_wrappers.c
index 87511fc6..0b523fac 100644
--- a/lib/ioctl_wrappers.c
+++ b/lib/ioctl_wrappers.c
@@ -558,6 +558,10 @@ int __gem_create(int fd, uint64_t size, uint32_t *handle)
 	};
 	int err = 0;
 
+	/* Ensure that our internal interface matches the kernel's */
+	igt_typecheck(typeof(create.size), size);
+	igt_typecheck(typeof(create.handle), *handle);
+
 	if (igt_ioctl(fd, DRM_IOCTL_I915_GEM_CREATE, &create) == 0)
 		*handle = create.handle;
 	else
-- 
2.14.2

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