[PATCH resend] dix: Reinstate GetImage window size check

[Aaron Plattner]

Commit 587c3a2d1961834558193e8e14e8e381a077a253 fixed DoGetImage to
check windows against their backing drawables, rather than against the
screen dimensions, to prevent reading outside the bounds of redirected
windows' backing pixmaps (see bug #22804).  Unfortunately, while
making that change I also removed the check that the rectangle is
contained within the bounds of the source window, which is a violation
of the specification:

    If the drawable is a window, the window must be viewable, and it
    must be the case that, if there were no inferiors or overlapping
    windows, the specified rectangle of the window would be fully
    visible on the screen *and wholly contained within the outside
    edges of the window* (or a Match error results). Note that the
    borders of the window can be included and read with this request.

    (emphasis mine)

Reinstate the window dimension check, to return BadMatch if the
GetImage request falls outside the bounds of the window.

Fixes X Test Suite test XGetImage-15:

    400|0 15 1 11:05:41|IC Start
    200|0 15 11:05:41|TP Start
    520|0 15 00005146 1 1|VSW5TESTSUITE PURPOSE 15
    520|0 15 00005146 1 2|Assertion XGetImage-15.(A)
    520|0 15 00005146 1 3|When the drawable is a window and the window is viewable
    520|0 15 00005146 1 4|and it is not the case that given there were no inferiors or
    520|0 15 00005146 1 5|overlapping windows the specified rectangle of the window
    520|0 15 00005146 1 6|would be fully visible on the screen and wholly contained
    520|0 15 00005146 1 7|within the outside edges of the window, then a BadMatch
    520|0 15 00005146 1 8|error occurs.
    520|0 15 00005146 1 9|METH: Create window which is not fully visible on the screen.
    520|0 15 00005146 1 10|METH: Call XMapWindow to make sure the window is viewable.
    520|0 15 00005146 1 11|METH: Call XGetImage with rectangle extending beyond edge of screen.
    520|0 15 00005146 1 12|METH: Verify XGetImage return value is null.
    520|0 15 00005146 1 13|METH: Verify that BadMatch error occurred.
    520|0 15 00005146 1 14|METH: Create window which is fully visible on the screen.
    520|0 15 00005146 1 15|METH: Call XMapWindow to make sure the window is viewable.
    520|0 15 00005146 1 16|METH: Call XGetImage with rectangle extending beyond edge of window.
    520|0 15 00005146 1 17|METH: Verify XGetImage return value is null.
    520|0 15 00005146 1 18|METH: Verify that BadMatch error occurred.
    520|0 15 00005146 1 19|REPORT: Got Success, Expecting BadMatch
    520|0 15 00005146 1 20|REPORT: Null image not returned.
    220|0 15 1 11:05:41|FAIL

Signed-off-by: Aaron Plattner <aplattner at nvidia.com>
---
This change has been sitting on my queue for a while.  It should be pretty easy
to review.

 dix/dispatch.c |    8 ++++++++
 1 files changed, 8 insertions(+), 0 deletions(-)

diff --git a/dix/dispatch.c b/dix/dispatch.c
index 43cb4d1..2b6cb82 100644
--- a/dix/dispatch.c
+++ b/dix/dispatch.c
@@ -2029,6 +2029,14 @@ DoGetImage(ClientPtr client, int format, Drawable drawable,
 	if (!pWin->viewable)
 	    return BadMatch;
 
+	/* If the drawable is a window, the rectangle must be contained within
+	 * its bounds (including the border). */
+	if (x < -wBorderWidth(pWin) ||
+	    x + width > wBorderWidth(pWin) + (int)pDraw->width ||
+	    y < -wBorderWidth(pWin) ||
+	    y + height > wBorderWidth(pWin) + (int)pDraw->height)
+	    return BadMatch;
+
 	relx += pDraw->x;
 	rely += pDraw->y;
 
-- 
1.7.5.4