Note ABI of XResQueryClientIds

XResQueryClientIds is now documented to return an array of 32-bit
values, not an array of longs. The previous implementation allocated
space for 32-bit values but read longs into that, overflowing the
array. Applications using this were expecting 32-bit values.

This "worked" on little endian 64-bit systems because only one value
was typically provided and the low 32-bits got stuck in the right
place, although the allocation was overrun at the end. That might
cause trouble if the allocator is checking carefully.

Signed-off-by: Keith Packard <keithp@keithp.com>

2 files changed, 2 insertions, 0 deletions

diff --git a/include/X11/extensions/XRes.h b/include/X11/extensions/XRes.h
index 1c81616..bedf625 100644
--- a/include/X11/extensions/XRes.h
+++ b/include/X11/extensions/XRes.h
@@ -98,6 +98,7 @@ Status XResQueryClientPixmapBytes (
 
 /* v1.2 */
 
+/* Returns an array of uint32_t values, not an array of long */
 Status XResQueryClientIds (
    Display            *dpy,
    long                num_specs,
diff --git a/src/XRes.c b/src/XRes.c
index 90e72c9..10f166e 100644
--- a/src/XRes.c
+++ b/src/XRes.c
@@ -261,6 +261,7 @@ static Bool ReadClientValues(
     return True;
 }
 
+/* Returns an array of uint32_t values, not an array of long */
 Status XResQueryClientIds (
    Display            *dpy,
    long                num_specs,