[Mesa-dev] [PATCH] trace: Correct transfer box size calculation.

[Jose Fonseca]

In particular:

1) For buffers the box expresses bytes, not pixels.

2) For textures we must not approximate the calculation with `stride *
   height`, or `slice_stride * depth`, as that can easily lead to buffer
   overflows, particularly for partial transfers.

   But this code path is not currently very relevant since the trace
   driver is only dumping data for buffers.

This should address the issue that Bruce Cherniak found and diagnosed.
---
 src/gallium/drivers/trace/tr_dump.c | 30 +++++++++++++++++-------------
 1 file changed, 17 insertions(+), 13 deletions(-)

diff --git a/src/gallium/drivers/trace/tr_dump.c b/src/gallium/drivers/trace/tr_dump.c
index 78c72492dc..aab55644f3 100644
--- a/src/gallium/drivers/trace/tr_dump.c
+++ b/src/gallium/drivers/trace/tr_dump.c
@@ -450,21 +450,25 @@ void trace_dump_box_bytes(const void *data,
 {
    size_t size;
 
-   /*
-    * Only dump buffer transfers to avoid huge files.
-    * TODO: Make this run-time configurable
-    */
-   if (resource->target != PIPE_BUFFER) {
-      size = 0;
+   if (resource->target == PIPE_BUFFER) {
+      /* For buffers the box should be in bytes, regardless of the format.
+       */
+      assert(box->height == 1);
+      assert(box->depth == 1);
+      size = box->width;
    } else {
       enum pipe_format format = resource->format;
-      if (slice_stride)
-         size = box->depth * slice_stride;
-      else if (stride)
-         size = util_format_get_nblocksy(format, box->height) * stride;
-      else {
-         size = util_format_get_nblocksx(format, box->width) * util_format_get_blocksize(format);
-      }
+      assert(box->height > 0);
+      assert(box->depth > 0);
+      size =  util_format_get_nblocksx(format, box->width )      * util_format_get_blocksize(format)
+           + (util_format_get_nblocksy(format, box->height) - 1) * stride
+           +                                  (box->depth   - 1) * slice_stride;
+
+      /*
+       * Only dump buffer transfers to avoid huge files.
+       * TODO: Make this run-time configurable
+       */
+      size = 0;
    }
 
    trace_dump_bytes(data, size);
-- 
2.11.0