commit 96ff758c6e9cd5a01443ee15afbd0df4f00c37a8
author Michael Forney <mforney@mforney.org> Tue May 25 20:55:56 2021 -0700
committer Laurent Vivier <laurent@vivier.eu> Sun Jun 20 16:41:47 2021 +0200
tree b9a4fa9a9f1bd37872a0c8b8fdee187c9837ee51
parent febf6fade63801ebca765797fa2ad9de8d9f2700

linux-user: Use public sigev_notify_thread_id member if available

_sigev_un._tid is an internal glibc field and is not available on
musl libc. The sigevent(7) man page and Linux UAPI headers both use
sigev_notify_thread_id as a public way to access this field.

musl libc supports this field since 1.2.2[0], and glibc plans to
add support as well[1][2].

If sigev_notify_thread_id is not available, fall back to _sigev_un._tid
as before.

[0] http://git.musl-libc.org/cgit/musl/commit/?id=7c71792e87691451f2a6b76348e83ad1889f1dcb
[1] https://www.openwall.com/lists/musl/2019/08/01/5
[2] https://sourceware.org/bugzilla/show_bug.cgi?id=27417

Signed-off-by: Michael Forney <mforney@mforney.org>
Reviewed-by: Laurent Vivier <laurent@vivier.eu>
Message-Id: <20210526035556.7931-1-mforney@mforney.org>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>

linux-user/syscall.c

diff --git a/linux-user/syscall.c b/linux-user/syscall.c
index 70ae888..64bbf33 100644
--- a/linux-user/syscall.c
+++ b/linux-user/syscall.c
@@ -7405,6 +7405,10 @@
 }
 #endif
 
+#ifndef HAVE_SIGEV_NOTIFY_THREAD_ID
+#define sigev_notify_thread_id _sigev_un._tid
+#endif
+
 static inline abi_long target_to_host_sigevent(struct sigevent *host_sevp,
                                                abi_ulong target_addr)
 {
@@ -7425,7 +7429,7 @@
     host_sevp->sigev_signo =
         target_to_host_signal(tswap32(target_sevp->sigev_signo));
     host_sevp->sigev_notify = tswap32(target_sevp->sigev_notify);
-    host_sevp->_sigev_un._tid = tswap32(target_sevp->_sigev_un._tid);
+    host_sevp->sigev_notify_thread_id = tswap32(target_sevp->_sigev_un._tid);
 
     unlock_user_struct(target_sevp, target_addr, 1);
     return 0;