109 lines
3.9 KiB
Diff
109 lines
3.9 KiB
Diff
From 3b72a2c9d1d656c74c691a45689e1d637f669e3a Mon Sep 17 00:00:00 2001
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From: Kenneth Graunke <kenneth@whitecape.org>
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Date: Fri, 3 Jan 2014 15:08:33 -0800
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Subject: [PATCH] Force XCB event structures with 64-bit extended fields to be
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packed.
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With the advent of the Present extension, some events (such as
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PresentCompleteNotify) now use native 64-bit types on the wire.
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For XGE events, we insert an extra "uint32_t full_sequence" field
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immediately after the first 32 bytes of data. Normally, this causes
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the subsequent fields to be shifted over by 4 bytes, and the structure
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to grow in size by 4 bytes. Everything works fine.
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However, if event contains 64-bit extended fields, this may result in
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the compiler adding an extra 4 bytes of padding so that those fields
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remain aligned on 64-bit boundaries. This causes the structure to grow
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by 8 bytes, not 4. Unfortunately, XCB doesn't realize this, and
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always believes that the length only increased by 4. read_packet()
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then fails to malloc enough memory to hold the event, and the event
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processing code uses the wrong offsets.
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To fix this, mark any event structures containing 64-bit extended
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fields with __attribute__((__packed__)).
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v2: Use any(...) instead of True in (...), as suggested by
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Daniel Martin.
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v3 (Alan Coopersmith): Fix build with Solaris Studio 12.3 by moving the
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attribute to after the structure definition.
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Signed-off-by: Kenneth Graunke <kenneth@whitecape.org>
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Reviewed-by: Keith Packard <keithp@keithp.com> [v1]
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Reviewed-by: Josh Triplett <josh@joshtriplett.org> [v1]
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Reviewed-by: Daniel Martin <consume.noise@gmail.com>
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Signed-off-by: Alan Coopersmith <alan.coopersmith@oracle.com>
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---
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src/c_client.py | 12 +++++++++---
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src/xcb.h | 2 ++
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2 files changed, 11 insertions(+), 3 deletions(-)
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diff --git a/src/c_client.py b/src/c_client.py
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index 99fd307..45de544 100644
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--- a/src/c_client.py
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+++ b/src/c_client.py
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@@ -1762,7 +1762,7 @@ def c_simple(self, name):
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# Iterator
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_c_iterator(self, name)
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-def _c_complex(self):
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+def _c_complex(self, force_packed = False):
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'''
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Helper function for handling all structure types.
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Called for all structs, requests, replies, events, errors.
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@@ -1817,7 +1817,7 @@ def _c_complex(self):
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if b.type.has_name:
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_h(' } %s;', b.c_field_name)
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- _h('} %s;', self.c_type)
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+ _h('} %s%s;', 'XCB_PACKED ' if force_packed else '', self.c_type)
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def c_struct(self, name):
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'''
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@@ -2902,6 +2902,7 @@ def c_event(self, name):
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# events while generating the structure for them. Otherwise we would read
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# garbage (the internal full_sequence) when accessing normal event fields
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# there.
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+ force_packed = False
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if hasattr(self, 'is_ge_event') and self.is_ge_event and self.name == name:
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event_size = 0
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for field in self.fields:
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@@ -2911,6 +2912,11 @@ def c_event(self, name):
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full_sequence = Field(tcard32, tcard32.name, 'full_sequence', False, True, True)
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idx = self.fields.index(field)
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self.fields.insert(idx + 1, full_sequence)
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+
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+ # If the event contains any 64-bit extended fields, they need
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+ # to remain aligned on a 64-bit boundary. Adding full_sequence
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+ # would normally break that; force the struct to be packed.
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+ force_packed = any(f.type.size == 8 and f.type.is_simple for f in self.fields[(idx+1):])
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break
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_c_type_setup(self, name, ('event',))
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@@ -2920,7 +2926,7 @@ def c_event(self, name):
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if self.name == name:
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# Structure definition
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- _c_complex(self)
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+ _c_complex(self, force_packed)
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else:
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# Typedef
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_h('')
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diff --git a/src/xcb.h b/src/xcb.h
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index e62c985..73c77a3 100644
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--- a/src/xcb.h
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+++ b/src/xcb.h
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@@ -51,6 +51,8 @@ extern "C" {
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* @file xcb.h
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*/
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+#define XCB_PACKED __attribute__((__packed__))
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+
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/**
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* @defgroup XCB_Core_API XCB Core API
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* @brief Core API of the XCB library.
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--
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1.8.4.2
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