[RFC,5/6] msqid: Provide internal copy of struct __msqid64_ds
Commit Message
After the commit SHA1: 3283f711132eaadc4f04bd8c1d84c910c29ba
"sysv: linux: Add 64-bit time_t variant for msgctl"
The glibc internal, 64 bit supporting version of struct __msqid64_ds has
been exported.
This approach has issue when one would like to add Y2038 support to glibc.
The problem is that both struct msqid_ds and __msqid64_ds rely on exported
implementation of the msg.h header (./sysvipc/sys/msg.h) which
unconditionally includes ./sysdeps/unix/sysv/linux/bits/msq.h which in
turn includes ./sysdeps/unix/sysv/linux/bits/types/struct_msqid_ds.h
As a result the externally exported struct msqid_ds.h is used internally
by glibc. Problem starts when one wants to extend this struct with 64 bit
time support:
| In file included from ../sysdeps/unix/sysv/linux/bits/msq.h:28,
| from ../sysvipc/sys/msg.h:30,
| from ../sysdeps/unix/sysv/linux/include/sys/msg.h:2,
| from ../include/sys/msg.h:1,
| from ../sysdeps/unix/sysv/linux/msgctl.c:19:
| ../sysdeps/unix/sysv/linux/bits/types/struct_msqid_ds.h:31:6: error:
"__USE_TIME_BITS64" is not defined, evaluates to 0 [-Werror=undef]
| # if __USE_TIME_BITS64
| ^~~~~~~~~~~~~~~~~
To fix this issue - the internal,for glibc, copy of struct __msqid64_ds
has been re-introduced. This will allow clear separation between exported
and internal glibc types.
Moreover, the __TIMESIZE based alias shall be internal to glibc.
Build tests:
./src/scripts/build-many-glibcs.py glibcs
---
include/bits/types/struct_msqid64_ds.h | 36 +++++++++++++++++++
.../sysv/linux/bits/types/struct_msqid64_ds.h | 4 ---
2 files changed, 36 insertions(+), 4 deletions(-)
create mode 100644 include/bits/types/struct_msqid64_ds.h
Comments
Hi Adhemerval,
> After the commit SHA1: 3283f711132eaadc4f04bd8c1d84c910c29ba
> "sysv: linux: Add 64-bit time_t variant for msgctl"
>
> The glibc internal, 64 bit supporting version of struct __msqid64_ds
> has been exported.
>
> This approach has issue when one would like to add Y2038 support to
> glibc. The problem is that both struct msqid_ds and __msqid64_ds rely
> on exported implementation of the msg.h header (./sysvipc/sys/msg.h)
> which unconditionally includes ./sysdeps/unix/sysv/linux/bits/msq.h
> which in turn includes
> ./sysdeps/unix/sysv/linux/bits/types/struct_msqid_ds.h
>
> As a result the externally exported struct msqid_ds.h is used
> internally by glibc. Problem starts when one wants to extend this
> struct with 64 bit time support:
>
> | In file included from ../sysdeps/unix/sysv/linux/bits/msq.h:28,
> | from ../sysvipc/sys/msg.h:30,
> | from
> ../sysdeps/unix/sysv/linux/include/sys/msg.h:2, |
> from ../include/sys/msg.h:1, | from
> ../sysdeps/unix/sysv/linux/msgctl.c:19: |
> ../sysdeps/unix/sysv/linux/bits/types/struct_msqid_ds.h:31:6: error:
> "__USE_TIME_BITS64" is not defined, evaluates to 0 [-Werror=undef] |
> # if __USE_TIME_BITS64 | ^~~~~~~~~~~~~~~~~
>
>
> To fix this issue - the internal,for glibc, copy of struct
> __msqid64_ds has been re-introduced. This will allow clear separation
> between exported and internal glibc types.
>
> Moreover, the __TIMESIZE based alias shall be internal to glibc.
>
> Build tests:
> ./src/scripts/build-many-glibcs.py glibcs
We had a discussion regarding this patch some time ago [1].
The conclusion was that we would need to duplicate this structure to
have a copy of msqid_ds structure as adding new members to exported
(and POSIX standardized) headers causes POSIX naming pollution.
Can we have a final agreement on this patch?
This also would require discussion about related patch -
"msg: provide glibc local copy of struct msqid_ds" [2]
Links:
[1] - https://marc.info/?t=160383682700004&r=1&w=2
[2] - https://marc.info/?t=160383682700003&r=1&w=2
> ---
> include/bits/types/struct_msqid64_ds.h | 36
> +++++++++++++++++++ .../sysv/linux/bits/types/struct_msqid64_ds.h |
> 4 --- 2 files changed, 36 insertions(+), 4 deletions(-)
> create mode 100644 include/bits/types/struct_msqid64_ds.h
>
> diff --git a/include/bits/types/struct_msqid64_ds.h
> b/include/bits/types/struct_msqid64_ds.h new file mode 100644
> index 0000000000..8c39a2a872
> --- /dev/null
> +++ b/include/bits/types/struct_msqid64_ds.h
> @@ -0,0 +1,36 @@
> +/* Internal for glibc implementation of the SysV message struct
> msqid64_ds.
> + Copyright (C) 2020 Free Software Foundation, Inc.
> + This file is part of the GNU C Library.
> +
> + The GNU C Library is free software; you can redistribute it and/or
> + modify it under the terms of the GNU Lesser General Public
> + License as published by the Free Software Foundation; either
> + version 2.1 of the License, or (at your option) any later version.
> +
> + The GNU C Library is distributed in the hope that it will be
> useful,
> + but WITHOUT ANY WARRANTY; without even the implied warranty of
> + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
> + Lesser General Public License for more details.
> +
> + You should have received a copy of the GNU Lesser General Public
> + License along with the GNU C Library; if not, see
> + <https://www.gnu.org/licenses/>. */
> +
> +#include <time.h>
> +
> +#if __TIMESIZE == 64
> +# define __msqid64_ds msqid_ds
> +#else
> +struct __msqid64_ds
> +{
> + struct ipc_perm msg_perm; /* structure describing operation
> permission */
> + __time64_t msg_stime; /* time of last msgsnd
> command */
> + __time64_t msg_rtime; /* time of last msgsnd
> command */
> + __time64_t msg_ctime; /* time of last change */
> + __syscall_ulong_t __msg_cbytes; /* current number of bytes on
> queue */
> + msgqnum_t msg_qnum; /* number of messages currently
> on queue */
> + msglen_t msg_qbytes; /* max number of bytes allowed
> on queue */
> + __pid_t msg_lspid; /* pid of last msgsnd() */
> + __pid_t msg_lrpid; /* pid of last msgrcv() */
> +};
> +#endif
> diff --git a/sysdeps/unix/sysv/linux/bits/types/struct_msqid64_ds.h
> b/sysdeps/unix/sysv/linux/bits/types/struct_msqid64_ds.h index
> 3536c8ea62..07cc1036ab 100644 ---
> a/sysdeps/unix/sysv/linux/bits/types/struct_msqid64_ds.h +++
> b/sysdeps/unix/sysv/linux/bits/types/struct_msqid64_ds.h @@ -20,9
> +20,6 @@ # error "Never use <bits/msq.h> directly; include
> <sys/msg.h> instead." #endif
>
> -#if __TIMESIZE == 64
> -# define __msqid64_ds msqid_ds
> -#else
> struct __msqid64_ds
> {
> struct ipc_perm msg_perm; /* structure describing operation
> permission */ @@ -35,4 +32,3 @@ struct __msqid64_ds
> __pid_t msg_lspid; /* pid of last msgsnd() */
> __pid_t msg_lrpid; /* pid of last msgrcv() */
> };
> -#endif
Best regards,
Lukasz Majewski
--
DENX Software Engineering GmbH, Managing Director: Wolfgang Denk
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
Phone: (+49)-8142-66989-59 Fax: (+49)-8142-66989-80 Email: lukma@denx.de
new file mode 100644
@@ -0,0 +1,36 @@
+/* Internal for glibc implementation of the SysV message struct msqid64_ds.
+ Copyright (C) 2020 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ The GNU C Library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library; if not, see
+ <https://www.gnu.org/licenses/>. */
+
+#include <time.h>
+
+#if __TIMESIZE == 64
+# define __msqid64_ds msqid_ds
+#else
+struct __msqid64_ds
+{
+ struct ipc_perm msg_perm; /* structure describing operation permission */
+ __time64_t msg_stime; /* time of last msgsnd command */
+ __time64_t msg_rtime; /* time of last msgsnd command */
+ __time64_t msg_ctime; /* time of last change */
+ __syscall_ulong_t __msg_cbytes; /* current number of bytes on queue */
+ msgqnum_t msg_qnum; /* number of messages currently on queue */
+ msglen_t msg_qbytes; /* max number of bytes allowed on queue */
+ __pid_t msg_lspid; /* pid of last msgsnd() */
+ __pid_t msg_lrpid; /* pid of last msgrcv() */
+};
+#endif
@@ -20,9 +20,6 @@
# error "Never use <bits/msq.h> directly; include <sys/msg.h> instead."
#endif
-#if __TIMESIZE == 64
-# define __msqid64_ds msqid_ds
-#else
struct __msqid64_ds
{
struct ipc_perm msg_perm; /* structure describing operation permission */
@@ -35,4 +32,3 @@ struct __msqid64_ds
__pid_t msg_lspid; /* pid of last msgsnd() */
__pid_t msg_lrpid; /* pid of last msgrcv() */
};
-#endif