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  1. Jun 03, 2020
  2. Nov 11, 2019
  3. Nov 04, 2019
  4. Oct 09, 2019
  5. Nov 30, 2018
    • Owen W. Taylor's avatar
      Fix docs for glnx_file_replace_contents() · c2dbe181
      Owen W. Taylor authored
      The docs for `glnx_file_replace_contents[_with_perms]` say that the default mode
      is 0666 - umask, but it's actually 0644. Because there's no thread-safe way of
      finding out the current umask without grubbing around in /proc/self/status,
      simply make the docs reflect reality.
      c2dbe181
  6. Oct 24, 2017
  7. Oct 16, 2017
  8. Oct 05, 2017
  9. Oct 02, 2017
  10. Sep 25, 2017
    • Colin Walters's avatar
      fdio: Open target dirname for glnx_file_copy_at() · 5ee2f1be
      Colin Walters authored
      Particularly if `AT_FDCWD` is used, we need to open
      in the target dir, otherwise we can get `EXDEV` when trying
      to do the final link.
      
      (Theoretically we can cross a mountpoint even with fd-relative
       though this is a lot less likely)
      5ee2f1be
  11. Sep 13, 2017
  12. Sep 12, 2017
    • Colin Walters's avatar
    • Colin Walters's avatar
      fdio: Use O_TMPFILE + rename-overwrite for regfile copies · 673f48f6
      Colin Walters authored
      I was working on rpm-ostree unified core, and hit the fact that
      `glnx_file_copy_at()` had the same bug with `fsetxattr()` and files whose mode
      is <= `0400` (e.g. `000` in the case of `/etc/shadow`) that libostree did a
      while ago.  Basically, Linux currently allows `write()` on non-writable open files
      but not `fsetxattr()`.  This situation is masked for privileged (i.e.
      `CAP_DAC_OVERRIDE`) code.
      
      Looking at this, I think it's cleaner to convert to `O_TMPFILE` here,
      since that code already handles setting the tmpfile to mode `0600`.  Now,
      this *is* a behavior change in the corner case of existing files which
      are symbolic links.  Previously we'd do an `open(O_TRUNC)` which would follow
      the link.
      
      But in the big picture, I think the use cases for `open(O_TRUNC)` are really
      rare - I audited all callers of this in ostree/rpm-ostree/flatpak, and all of
      them will be fine with this behavior change. For example, the ostree `/etc`
      merge code already explicitly unlinks the target beforehand. Other cases like
      supporting `repo/pubring.gpg` in an ostree repo being a symlink...eh, just no.
      
      Making this change allows us to convert to new style, and brings all of the
      general benefits of using `O_TMPFILE` too.
      673f48f6
    • Colin Walters's avatar
      fdio: Support taking ownership of tmpfile fd · 9d995a36
      Colin Walters authored
      While reading a strace I noticed a double close in the tests; this was because
      we were missing an assignment to `-1` in the tests. However, let's make
      supporting this clearer by explicitly supporting the fd being `-1` while still
      setting the `initialized` variable to `FALSE`. We also add the `EBADF` assertion
      checking.
      9d995a36
    • Colin Walters's avatar
      fdio: Use O_EXCL for anonymous tmpfiles · 806bb46e
      Colin Walters authored
      I noticed while reading the manpage for `linkat()` that `O_TMPFILE`
      supports `O_EXCL` to mean exactly what we're doing with the anonymous
      tmpfile API.
      
      Change the code to start using it; this required refactoring the internals since
      we had a check to be sure the caller wasn't passing `O_EXCL` for the
      non-anonymous path which we want to keep.
      
      Presumably the storage system could do smarter things if it knows a file will
      always be anonymous, e.g. it doesn't need to journal its data.
      806bb46e
  13. Aug 09, 2017
    • Colin Walters's avatar
      fdio: Merge systemd code to use copy_file_range(), use FICLONE · d18f026e
      Colin Walters authored
      FICLONE is the new alias for the formerly btrfs-specific ioctl; XFS
      has experimental patches to support it.
      
      Further, we should use copy_file_range() for the case where we're only doing a
      limited copy. Both NFS and XFS (with reflink enabled) understand it.
      
      Part of the reason I'm doing this is so that ostree's `/etc` merge will start
      using XFS reflinks. But another major reason is to take the next step after and
      copy this code into GLib as well, so that all of the general GLib users will
      benefit; e.g. Nautilus will transparently do server copy offloads with NFS home
      directories.
      
      See also this coreutils thread about `copy_file_range()`:
      <https://debbugs.gnu.org/cgi/bugreport.cgi?bug=24399>. I don't care about file
      holes for our use cases, so it's fine.
      
      Other changes while I'm here:
       - Tweak the sendfile() case to match the newly inlined logic for cfr
       - Add a TEMP_FAILURE_RETRY() around the read()
      d18f026e
  14. Jul 19, 2017
    • Colin Walters's avatar
      fdio: Introduce glnx_openat_read() · 268ae488
      Colin Walters authored
      This is kind of long overdue. Reasons are the same as the other wrappers. I
      debated adding `O_NOFOLLOW` support but the use cases for that are pretty
      obscure, callers who want that can just use the syscall directly for now.
      268ae488
  15. Jul 17, 2017
    • Colin Walters's avatar
      Remove glnx_stream_fstat() · 8b75c8e3
      Colin Walters authored
      There are only two users of this in ostree, and one of them is
      fairly bogus; we can just use `fstat()`.
      8b75c8e3
    • Colin Walters's avatar
      fdio: Add cleanup+flush API for FILE* · e30a773f
      Colin Walters authored
      Mostly in ostree/rpm-ostree, we work in either raw `int fd`, or
      `G{Input,Output}Stream`.  One exception is the rpm-ostree `/etc/passwd`
      handling, which uses `FILE*` since that's what glibc exposes.
      
      And in general, there are use cases for `FILE*`; the raw `GUnixOutputStream` for
      example isn't buffered, and doing so via e.g. `GBufferedOutputStream` means
      allocating *two* GObjects and even worse going through multiple vfuncs for every
      write.
      
      `FILE*` is used heavily in systemd, and provides buffering. It is a bit cheaper
      than gobjects, but has its own trap; by default every operation locks a mutex.
      For more information on that, see `unlocked_stdio(3)`. However, callers can
      avoid that by using e.g. `fwrite_unlocked`, which I plan to do for most users of
      `FILE*` that aren't writing to one of the standard streams like `stdout` etc.
      e30a773f
  16. Jul 10, 2017
  17. Jun 28, 2017
  18. Jun 26, 2017
  19. Jun 14, 2017
    • Colin Walters's avatar
      Add G_IN_SET, patch our internal users via spatch · 9a1b77ef
      Colin Walters authored
      I originally tried to get this into GLib:
      https://bugzilla.gnome.org/show_bug.cgi?id=783751
      
      But that looks like it's going to fail due to MSVC. Let's add it here at least
      so I can start using it tomorrow and not wait for the MSVC team to catch up.
      
      I renamed `glnx-alloca.h` to `glnx-macros.h` as a more natural collective
      home for things from systemd's `macro.h`.
      
      Finally, I used a Coccinelle spatch similar to the one referenced
      in the above BZ to patch our uses.
      9a1b77ef
  20. Jun 13, 2017
  21. May 19, 2017
  22. May 17, 2017
  23. May 15, 2017
    • Colin Walters's avatar
      fdio: Redo tmpfile API with GLnxTmpfile struct · 9929adcd
      Colin Walters authored
      The core problem with the previous tmpfile code
      is we don't have an autocleanup that calls `unlinkat`
      in the non-`O_TMPFILE` case.  And even if we did, it'd
      be awkward still since the `glnx_link_tmpfile_at()` call
      *consumes* the tmpfile.
      
      Fix this by introducing a struct with a cleanup macro. This simplifies a number
      of the callers in libostree - a notable case is where we had two arrays, one of
      fds, one of paths. It makes other places in libostree a bit more complex, but
      that's because some of the commit code paths want to deal with temporary
      *symlinks* too.
      
      Most callers are better though - in libglnx itself, `glnx_file_copy_at()` now
      correctly unlinks on failure for example.
      9929adcd
  24. Apr 28, 2017
    • Colin Walters's avatar
      fdio: Expose glnx_regfile_copy_bytes(), rewrite: GNU style, POSIX errno · 3a4d0f46
      Colin Walters authored
      NOTE: This changes the error handling API of `glnx_loop_write()` to be
      "old school POSIX" instead of "systemd".
      
      In ostree in a few places we use `g_output_stream_splice()`.  I
      thought this would use `splice()`, but actually it doesn't today.
      
      They also, if a cancellable is provided, end up dropping into `poll()` for every
      read and write. (In addition to copying data to/from userspace).
      
      My opinion on this is - for *local files* that's dumb. In the big picture, you
      really only need cancellation when copying gigabytes. Down the line, we could
      perhaps add a `glnx_copy_bytes_cancellable()` that only did that check e.g.
      every gigabyte of copied data. And when we do that we should use
      `g_cancellable_set_error_if_cancelled()` rather than a `poll()` with the regular
      file FD, since regular files are *always* readable and writable.
      
      For my use case with rpm-ostree though, we don't have gigabyte sized files, and
      seeing all of the `poll()` calls in strace is annoying. So let's have the
      non-cancellable file copying API that's modern and uses both reflink and
      `sendfile()` if available, in that order.
      
      My plan at some point once this is tested more is to migrate this code
      into GLib.
      
      Note that in order to keep our APIs consistent, I switched the systemd-imported
      code to "old school POSIX" error conventions. Otherwise we'd have *3* (POSIX,
      systemd, and GError) and particularly given the first two are easily confused,
      it'd be a recipe for bugs.
      3a4d0f46
  25. Apr 25, 2017
    • Colin Walters's avatar
      fdio: Mostly port to new code style · dc1956b2
      Colin Walters authored
      There's one function that did `unlinkat()` in the cleanup section,
      not doing that yet.
      
      Note I uncovered a few bugs in a few places where we didn't preserve errno
      before doing an `unlinkat()` in error paths in a few cases.
      
      I also tried to prefix a few more error cases with the system call name.
      dc1956b2
  26. Mar 23, 2017
    • Jonathan Lebon's avatar
      glnx-errors.h: add glnx_null_throw[_*] variants · 0c52d85e
      Jonathan Lebon authored
      These are equivalent to the non-null throw, except that the returned
      value is a NULL pointer. They can be used in functions where one wants
      to return a pointer. E.g.:
      
      	GKeyFile *foo(GError **error) {
      		return glnx_null_throw (error, "foobar");
      	}
      
      The function call redirections are wrapped around a compound statement
      expression[1] so that they represent a single top-level expression. This
      allows us to avoid -Wunused-value warnings vs using a comma operator if
      the return value isn't used.
      
      I made the 'args...' absorb the fmt argument as well so that callers can
      still use it without always having to specify at least one additional
      variadic argument. I had to check to be sure that the expansion is all
      done by the preprocessor, so we don't need to worry about stack
      intricacies.
      
      [1] https://gcc.gnu.org/onlinedocs/gcc/Statement-Exprs.html
      0c52d85e
  27. Mar 02, 2017
  28. Oct 05, 2016
  29. Aug 04, 2016
  30. Aug 03, 2016
  31. Jul 08, 2016
    • Colin Walters's avatar
      fdio: Add unlinkat() in error paths for tmpfiles · d2e588d9
      Colin Walters authored
      This is kind of an ABI change but it's for the better I think; on
      error we consistently clean up the temp file.
      
      This is obviously necessary without `O_TMPFILE`.  With it, we still
      need an error cleanup in the case where we're trying to replace an
      existing file.  I noticed this in ostree's `tests/test-refs.sh` which
      intentionally tries to rename a file over a directory path.
      d2e588d9
    • Colin Walters's avatar
      fdio: Use correct dfd with O_TMPFILE in rename case · 78ae7877
      Colin Walters authored
      While auditing this code to figure out why ostree's
      `tests/test-refs.sh` was failing, while the bug turned out to be
      different, I noticed that in the case where `dfd != target_dfd`, we
      failed to do the right `renameat()`.  (No code I'm aware of does this
      now).
      78ae7877
  32. Jul 01, 2016
    • Colin Walters's avatar
      fdio: Add open_tmpfile_linkable() and link_tmpfile_at() · 113c770d
      Colin Walters authored
      We had a bug previously where we failed to clean up a temporary file
      in an error path.  This is a classic case where the new `O_TMPFILE`
      API in Linux is nicer.
      
      To implement this, as usual we start with some original bits from
      systemd.  But in this case I ended up having to heavily modify it
      because systemd doesn't support "link into place and overwrite".  They
      don't actually use their tempfile code much at all in fact - as far as
      I can tell, just in the coredump code.
      
      Whereas in many apps, ostree included, a very common use case is
      atomically updating an existing file, which is
      `glnx_file_replace_contents_at()`, including subtleties like doing an
      `fdatasync()` if the file already existed.
      
      Implementing this then is slightly weird since we need to link() the
      file into place, then rename() after.
      
      It's still better though because if we e.g. hit `ENOSPC` halfway
      through, we'll clean up the file automatically.
      
      We still do keep the mode where we error out if the file exists.
      Finally, the ostree core though does have a more unusual case where we
      want to ignore EEXIST (allow concurrent object writers), so add
      support for that now.
      
      Note: One really confusing bug I had here was that `O_TMPFILE` ignores
      the provided mode, and this caused ostree to write refs that weren't
      world readable.
      
      Rework things so we always call `fchmod()`, but as a consequence we're
      no longer honoring umask in the default case.  I doubt anyone will
      care, and if they do we should probably fix ostree to consistently use
      a mode inherited from the repo or something.
      113c770d
  33. Jun 16, 2016
    • Yu Qi Zhang's avatar
      fdio: Delete .tmp file on failure · a6d08657
      Yu Qi Zhang authored
      We noticed the temp files being left over in ostree when (mistakenly)
      trying to replace the contents of a subpath that wasn't a directory.
      
      In the future we should look at the systemd code using `O_TMPFILE`
      here.
      a6d08657
  34. May 03, 2016
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