Re: [gentoo-portage-dev] [PATCH] file_copy: fix lseek offset after EINTR (bug 618086)

[Zac Medico]

On Sun, May 14, 2017 at 6:31 AM, Brian Dolbec <dolsen@g.o> wrote:

> On Tue,  9 May 2017 23:59:34 -0700
> Zac Medico <zmedico@g.o> wrote:
>
> > Fix the lseek offset for the plain read/write loop to account
> > for buffered data that has not been written to to the output
> > file yet (due to previous interruption by EINTR). This code
> > only affects Linux 2.6.32 and earlier (newer kernels use
> > copy_file_range or sendfile).
> >
> > X-Gentoo-bug: 618086
> > X-Gentoo-bug-url: https://bugs.gentoo.org/show_bug.cgi?id=618086
> > ---
> >  src/portage_util_file_copy_reflink_linux.c | 13 ++++++++-----
> >  1 file changed, 8 insertions(+), 5 deletions(-)
> >
> > diff --git a/src/portage_util_file_copy_reflink_linux.c
> > b/src/portage_util_file_copy_reflink_linux.c index 2fb17a0..4be9e05
> > 100644 --- a/src/portage_util_file_copy_reflink_linux.c
> > +++ b/src/portage_util_file_copy_reflink_linux.c
> > @@ -323,12 +323,14 @@ _reflink_linux_file_copy(PyObject *self,
> > PyObject *args) if (buf == NULL) {
> >                      error = errno;
> >
> > -                /* For the read call, the fd_in file offset must be
> > -                 * exactly equal to offset_out. Use lseek to ensure
> > -                 * correct state, in case an EINTR retry caused it to
> > -                 * get out of sync somewhow.
> > +                /* For the read call, the fd_in file offset must be
> > exactly
> > +                 * equal to offset_out + buf_bytes, where buf_bytes
> > is the
> > +                 * amount of buffered data that has not been written
> > to
> > +                 * to the output file yet. Use lseek to ensure
> > correct state,
> > +                 * in case an EINTR retry caused it to get out of
> > sync
> > +                 * somewhow.
> >                   */
> > -                } else if (lseek(fd_in, offset_out, SEEK_SET) < 0) {
> > +                } else if (lseek(fd_in, offset_out + buf_bytes,
> > SEEK_SET) < 0) { error = errno;
> >                  } else {
> >                      while (1) {
> > @@ -345,6 +347,7 @@ _reflink_linux_file_copy(PyObject *self, PyObject
> > *args)
> >                              } else if (buf_bytes < 0) {
> >                                  error = errno;
> > +                                buf_bytes = 0;
> >                                  break;
> >                              }
> >                          }
>
> looks fine :)
>

Thanks, merged:

https://gitweb.gentoo.org/proj/portage.git/commit/?id=a3c87da25dc1944e6b7720e304318ae5474dff95
-- 
Thanks,
Zac