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8a7ecd774c
If a wl_array has size zero, wl_array_for_each computes NULL + 0 to get to the end pointer. This should be fine, and indeed it would be fine in C++. But the C specification has a mistake here and it is actually undefined behavior. See https://davidben.net/2024/01/15/empty-slices.html Clang's -fsanitize=undefined flags this. I ran into this in Chromium's build with wayland-scanner on one of our XML files. ../../third_party/wayland/src/src/scanner.c:1853:2: runtime error: applying zero offset to null pointer #0 0x55c979b8e02c in emit_code third_party/wayland/src/src/scanner.c:1853:2 #1 0x55c979b89323 in main third_party/wayland/src/src/scanner.c #2 0x7f8dfdb8c6c9 in __libc_start_call_main csu/../sysdeps/nptl/libc_start_call_main.h:58:16 #3 0x7f8dfdb8c784 in __libc_start_main csu/../csu/libc-start.c:360:3 #4 0x55c979b70f39 in _start (...) An empty XML file is sufficient to hit this case, so I've added it as a test. To reproduce, undo the fix and include only the test, then build with: CC=clang CFLAGS="-fno-sanitize-recover=undefined" meson build/ -Db_sanitize=undefined -Db_lundef=false ninja -C build test Signed-off-by: David Benjamin <davidben@google.com>
58 lines
917 B
C
58 lines
917 B
C
/* SCANNER TEST */
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#ifndef EMPTY_SERVER_PROTOCOL_H
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#define EMPTY_SERVER_PROTOCOL_H
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#include <stdint.h>
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#include <stddef.h>
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#include "wayland-server.h"
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#ifdef __cplusplus
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extern "C" {
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#endif
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struct wl_client;
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struct wl_resource;
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/**
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* @page page_empty The empty protocol
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* @section page_ifaces_empty Interfaces
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* - @subpage page_iface_empty -
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*/
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struct empty;
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#ifndef EMPTY_INTERFACE
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#define EMPTY_INTERFACE
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/**
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* @page page_iface_empty empty
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* @section page_iface_empty_api API
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* See @ref iface_empty.
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*/
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/**
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* @defgroup iface_empty The empty interface
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*/
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extern const struct wl_interface empty_interface;
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#endif
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/**
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* @ingroup iface_empty
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* @struct empty_interface
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*/
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struct empty_interface {
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/**
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*/
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void (*empty)(struct wl_client *client,
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struct wl_resource *resource);
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};
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/**
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* @ingroup iface_empty
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*/
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#define EMPTY_EMPTY_SINCE_VERSION 1
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#ifdef __cplusplus
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}
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#endif
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#endif
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