fcntl-linux.h: add F_OFD_*32 constants
Commit Message
The original assumption with OFD lock support was that userland would
always pass in a struct flock that has been set up for large file
support (LFS). It's possible however for someone to build a 32-bit
program without large file support, and still try to use OFD locks. If
that happens then it will send a non-LFS struct flock to the kernel,
which will then try to interpret it as a LFS one, which can cause
unexpected results.
My original idea was to just ensure that the build would fail in this
case by not defining the F_OFD_* constants when LFS support was not
enabled.
Instead though, it's probably better long-term to just go ahead and
support OFD locks with non-LFS struct flock. To do that without breaking
programs that are already working, we add a set of F_OFD_*32 constants,
and add the plumbing to the kernel to make those do the right thing.
This patch adds the same constants to glibc, and has it redefine the
"normal" F_OFD_* constants to their *32 equvalents when LFS support is
not in use.
Signed-off-by: Jeff Layton <jlayton@redhat.com>
---
ChangeLog | 4 ++++
sysdeps/unix/sysv/linux/bits/fcntl-linux.h | 17 +++++++++++++----
2 files changed, 17 insertions(+), 4 deletions(-)
Comments
On 18 Aug 2016 08:03, Jeff Layton wrote:
> +2016-08-18 Jeff Layton <jlayton@redhat.com>
> + * sysdeps/unix/sysv/linux/bits/fcntl-linux.h:
> + Add F_OFD_GETLK32, F_OFD_SETLK32, F_OFD_SETLKW32
Should be a blank line after the first one. look at all the other
entries in this file as an example.
> --- a/sysdeps/unix/sysv/linux/bits/fcntl-linux.h
> +++ b/sysdeps/unix/sysv/linux/bits/fcntl-linux.h
> @@ -127,11 +127,20 @@
> This means that they are inherited across fork or clone with CLONE_FILES
> like BSD (flock) locks, and they are only released automatically when the
> last reference to the the file description against which they were acquired
> - is put. */
> + is put. */
> #ifdef __USE_GNU
> -# define F_OFD_GETLK 36
> -# define F_OFD_SETLK 37
> -# define F_OFD_SETLKW 38
> +# if __OFF_T_MATCHES_OFF64_T || defined __USE_FILE_OFFSET64
> +# define F_OFD_GETLK 36
> +# define F_OFD_SETLK 37
> +# define F_OFD_SETLKW 38
> +# else
> +# define F_OFD_GETLK32 39
> +# define F_OFD_SETLK32 40
> +# define F_OFD_SETLKW32 41
> +# define F_OFD_GETLK F_OFD_GETLK32
> +# define F_OFD_SETLK F_OFD_SETLK32
> +# define F_OFD_SETLKW F_OFD_SETLKW32
> +# endif
> #endif
i think we should define *64 and *32 variants all the time, and
then route the F_OFD_GETLK/etc... to them based on compile mode.
-mike
On Thu, 2016-08-18 at 06:04 -0700, Mike Frysinger wrote:
> On 18 Aug 2016 08:03, Jeff Layton wrote:
> >
> > > > +2016-08-18 Jeff Layton <jlayton@redhat.com>
> > > > + * sysdeps/unix/sysv/linux/bits/fcntl-linux.h:
> > > > + Add F_OFD_GETLK32, F_OFD_SETLK32, F_OFD_SETLKW32
>
> Should be a blank line after the first one. look at all the other
> entries in this file as an example.
>
Ok, will fix...
> >
> > --- a/sysdeps/unix/sysv/linux/bits/fcntl-linux.h
> > +++ b/sysdeps/unix/sysv/linux/bits/fcntl-linux.h
> > @@ -127,11 +127,20 @@
> > This means that they are inherited across fork or clone with CLONE_FILES
> > like BSD (flock) locks, and they are only released automatically when the
> > last reference to the the file description against which they were acquired
> > - is put. */
> > + is put. */
> > #ifdef __USE_GNU
> > > > -# define F_OFD_GETLK 36
> > > > -# define F_OFD_SETLK 37
> > > > -# define F_OFD_SETLKW 38
> > +# if __OFF_T_MATCHES_OFF64_T || defined __USE_FILE_OFFSET64
> > > > +# define F_OFD_GETLK 36
> > > > +# define F_OFD_SETLK 37
> > > > +# define F_OFD_SETLKW 38
> > +# else
> > > > +# define F_OFD_GETLK32 39
> > > > +# define F_OFD_SETLK32 40
> > > > +# define F_OFD_SETLKW32 41
> > > > +# define F_OFD_GETLK F_OFD_GETLK32
> > > > +# define F_OFD_SETLK F_OFD_SETLK32
> > > > +# define F_OFD_SETLKW F_OFD_SETLKW32
> > +# endif
> > #endif
>
> i think we should define *64 and *32 variants all the time, and
> then route the F_OFD_GETLK/etc... to them based on compile mode.
> -mike
Sorry, I don't quite understand here. The whole point is that the
existing F_OFD_* constants are already implicitly 64-bit. Why do we
need separate constants postfixed with "64" that no one will ever use?
On 18 Aug 2016 09:49, Jeff Layton wrote:
> On Thu, 2016-08-18 at 06:04 -0700, Mike Frysinger wrote:
> > On 18 Aug 2016 08:03, Jeff Layton wrote:
> > > --- a/sysdeps/unix/sysv/linux/bits/fcntl-linux.h
> > > +++ b/sysdeps/unix/sysv/linux/bits/fcntl-linux.h
> > > @@ -127,11 +127,20 @@
> > > This means that they are inherited across fork or clone with CLONE_FILES
> > > like BSD (flock) locks, and they are only released automatically when the
> > > last reference to the the file description against which they were acquired
> > > - is put. */
> > > + is put. */
> > > #ifdef __USE_GNU
> > > > > -# define F_OFD_GETLK 36
> > > > > -# define F_OFD_SETLK 37
> > > > > -# define F_OFD_SETLKW 38
> > > +# if __OFF_T_MATCHES_OFF64_T || defined __USE_FILE_OFFSET64
> > > > > +# define F_OFD_GETLK 36
> > > > > +# define F_OFD_SETLK 37
> > > > > +# define F_OFD_SETLKW 38
> > > +# else
> > > > > +# define F_OFD_GETLK32 39
> > > > > +# define F_OFD_SETLK32 40
> > > > > +# define F_OFD_SETLKW32 41
> > > > > +# define F_OFD_GETLK F_OFD_GETLK32
> > > > > +# define F_OFD_SETLK F_OFD_SETLK32
> > > > > +# define F_OFD_SETLKW F_OFD_SETLKW32
> > > +# endif
> > > #endif
> >
> > i think we should define *64 and *32 variants all the time, and
> > then route the F_OFD_GETLK/etc... to them based on compile mode.
>
> Sorry, I don't quite understand here. The whole point is that the
> existing F_OFD_* constants are already implicitly 64-bit. Why do we
> need separate constants postfixed with "64" that no one will ever use?
you're making them not explicitly 64-bit when off_t!=off64_t.
all the other commands in this file have used the convention:
<cmd>: automatically 32-bit or 64-bit
<cmd>64: always 64-bit
so the header would do:
#define F_OFD_GETLK64 36
#define F_OFD_SETLK64 37
#define F_OFD_SETLKW64 38
#if __OFF_T_MATCHES_OFF64_T || defined __USE_FILE_OFFSET64
# define F_OFD_GETLK F_OFD_GETLK64
# define F_OFD_SETLK F_OFD_SETLK64
# define F_OFD_SETLKW F_OFD_SETLKW64
#else
# define F_OFD_GETLK 39
# define F_OFD_SETLK 40
# define F_OFD_SETLKW 41
#endif
the defines deviate a bit from the names used on the kernel side,
but we've already done that, and you're proposed patch does too.
-mike
@@ -1,3 +1,7 @@
+2016-08-18 Jeff Layton <jlayton@redhat.com>
+ * sysdeps/unix/sysv/linux/bits/fcntl-linux.h:
+ Add F_OFD_GETLK32, F_OFD_SETLK32, F_OFD_SETLKW32
+
2016-08-18 Stefan Liebler <stli@linux.vnet.ibm.com>
* sysdeps/ieee754/dbl-64/k_rem_pio2.c (__kernel_rem_pio2):
@@ -127,11 +127,20 @@
This means that they are inherited across fork or clone with CLONE_FILES
like BSD (flock) locks, and they are only released automatically when the
last reference to the the file description against which they were acquired
- is put. */
+ is put. */
#ifdef __USE_GNU
-# define F_OFD_GETLK 36
-# define F_OFD_SETLK 37
-# define F_OFD_SETLKW 38
+# if __OFF_T_MATCHES_OFF64_T || defined __USE_FILE_OFFSET64
+# define F_OFD_GETLK 36
+# define F_OFD_SETLK 37
+# define F_OFD_SETLKW 38
+# else
+# define F_OFD_GETLK32 39
+# define F_OFD_SETLK32 40
+# define F_OFD_SETLKW32 41
+# define F_OFD_GETLK F_OFD_GETLK32
+# define F_OFD_SETLK F_OFD_SETLK32
+# define F_OFD_SETLKW F_OFD_SETLKW32
+# endif
#endif
#ifdef __USE_LARGEFILE64