Allow for missing or disabled compat_output

When the compat output is missing (I don't think this is actually
possible), or is disabled (and hence has no crtc), we would like to
avoid dereferencing NULL pointers. This patch creates inline functions
to extract the current compat output, crtc or associated RandR crtc
structure, carefully checking for NULL pointers everywhere.

Reviewed-by: Adam Jackson <ajax@redhat.com>
Signed-off-by: Keith Packard <keithp@keithp.com>

1 files changed, 26 insertions, 0 deletions

diff --git a/hw/xfree86/modes/xf86Crtc.h b/hw/xfree86/modes/xf86Crtc.h
index 9baa956a3..68a968cc2 100644
--- a/hw/xfree86/modes/xf86Crtc.h
+++ b/hw/xfree86/modes/xf86Crtc.h
@@ -689,6 +689,32 @@ extern _X_EXPORT int xf86CrtcConfigPrivateIndex;
 
 #define XF86_CRTC_CONFIG_PTR(p)	((xf86CrtcConfigPtr) ((p)->privates[xf86CrtcConfigPrivateIndex].ptr))
 
+static _X_INLINE xf86OutputPtr
+xf86CompatOutput(ScrnInfoPtr pScrn)
+{
+    xf86CrtcConfigPtr config = XF86_CRTC_CONFIG_PTR(pScrn);
+    return config->output[config->compat_output];
+}
+
+static _X_INLINE xf86CrtcPtr
+xf86CompatCrtc(ScrnInfoPtr pScrn)
+{
+    xf86OutputPtr compat_output = xf86CompatOutput(pScrn);
+    if (!compat_output)
+	return NULL;
+    return compat_output->crtc;
+}
+
+static _X_INLINE RRCrtcPtr
+xf86CompatRRCrtc(ScrnInfoPtr pScrn)
+{
+    xf86CrtcPtr	compat_crtc = xf86CompatCrtc(pScrn);
+    if (!compat_crtc)
+	return NULL;
+    return compat_crtc->randr_crtc;
+}
+
+
 /*
  * Initialize xf86CrtcConfig structure
  */