[PATCH 2/3] open_noatime: add flags arg, only add O_LARGEFILE

[Rob Browning]

Add a flags argument to the python function, and stop adding any flags
other than O_NOATIME and O_LARGEFILE. This is in preparation for
reintroduction on the python side, and the addition of a parallel
openat_noatime for use from a file descriptor based drecurse that
doesn't chdir.

Migrating away from our open_noatime on the python side was a mistake
because Linux (at least) disallows O_NOATIME in various situations,
which we handled in our helper. Adjust the previous comment to
reflect the fact that this isn't a long lost behavior.

Signed-off-by: Rob Browning <r...@defaultvalue.org>
Tested-by: Rob Browning <r...@defaultvalue.org>
---
lib/bup/_helpers.c | 37 +++++++++++++++----------------------
1 file changed, 15 insertions(+), 22 deletions(-)

diff --git a/lib/bup/_helpers.c b/lib/bup/_helpers.c
index ce6b6e9f..b7922ec9 100644
--- a/lib/bup/_helpers.c
+++ b/lib/bup/_helpers.c
@@ -960,29 +960,22 @@ static PyObject *random_sha(PyObject *self, PyObject *args)
}


-static int _open_noatime(const char *filename, int attrs)
+static int _open_noatime(const char *path, int flags)
{
- int attrs_noatime, fd;
- attrs |= O_RDONLY;
-#ifdef O_NOFOLLOW
- attrs |= O_NOFOLLOW;
-#endif
#ifdef O_LARGEFILE
- attrs |= O_LARGEFILE;
+ flags |= O_LARGEFILE;
#endif
- attrs_noatime = attrs;
#ifdef O_NOATIME
- attrs_noatime |= O_NOATIME;
+ const int flags_noatime = flags | O_NOATIME;
+#else
+ const int flags_noatime = flags;
#endif
- fd = open(filename, attrs_noatime);
+ int fd = open(path, flags_noatime);
if (fd < 0 && errno == EPERM)
{
- // older Linux kernels would return EPERM if you used O_NOATIME
- // and weren't the file's owner. This pointless restriction was
- // relaxed eventually, but we have to handle it anyway.
- // (VERY old kernels didn't recognized O_NOATIME, but they would
- // just harmlessly ignore it, so this branch won't trigger)
- fd = open(filename, attrs);
+ // If nothing else, Linux kernels may return EPERM for
+ // O_NOATIME when you're not the file's owner.
+ fd = open(path, flags);
}
return fd;
}
@@ -990,13 +983,13 @@ static int _open_noatime(const char *filename, int attrs)

static PyObject *open_noatime(PyObject *self, PyObject *args)
{
- char *filename = NULL;
- int fd;
- if (!PyArg_ParseTuple(args, cstr_argf, &filename))
+ char *path;
+ int flags;
+ if (!PyArg_ParseTuple(args, "yi", &path, &flags))
return NULL;
- fd = _open_noatime(filename, 0);
+ int fd = _open_noatime(path, flags);
if (fd < 0)
- return PyErr_SetFromErrnoWithFilename(PyExc_OSError, filename);
+ return PyErr_SetFromErrnoWithFilename(PyExc_OSError, path);
return Py_BuildValue("i", fd);
}

@@ -1022,7 +1015,7 @@ static PyObject *bup_get_linux_file_attr(PyObject *self, PyObject *args)
if (!PyArg_ParseTuple(args, cstr_argf, &path))
return NULL;

- fd = _open_noatime(path, O_NONBLOCK);
+ fd = _open_noatime(path, O_RDONLY | O_NOFOLLOW | O_NONBLOCK);
if (fd == -1)
return PyErr_SetFromErrnoWithFilename(PyExc_OSError, path);

--
2.47.3