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@nalind nalind commented Aug 10, 2020

When we're omitting timestamps, set timestamps on entries in new layers that we're adding to the Unix epoch as well.

rhatdan and others added 2 commits August 6, 2020 12:19
Currently you can only do deterministic builds with commit command
this change will cause the metadata in the container image to be
epoch 0.

Next step is to save the data in the tar balls as 0.

Signed-off-by: Daniel J Walsh <dwalsh@redhat.com>
When we're omitting timestamps, set timestamps on entries in new layers
that we're adding to the Unix epoch as well.

Signed-off-by: Nalin Dahyabhai <nalin@redhat.com>
@rhatdan rhatdan force-pushed the omit branch 2 times, most recently from dda822c to 8bb100b Compare August 11, 2020 09:28
rhatdan added a commit that referenced this pull request Oct 31, 2020
This subtle bug keeps lurking in because error checking for `Mkdir()`
and `MkdirAll()` is slightly different wrt `EEXIST`/`IsExist`:

 - for `Mkdir()`, `IsExist` error should (usually) be ignored
   (unless you want to make sure directory was not there before)
   as it means "the destination directory was already there";

 - for `MkdirAll()`, `IsExist` error should NEVER be ignored.

This commit removes ignoring the IsExist error, as it should not
be ignored.

[v2: skip patching (*Builder).Run]

For more details, a quote from opencontainers/runc PR containers#162:

-quote-

TL;DR: check for IsExist(err) after a failed MkdirAll() is both
redundant and wrong -- so two reasons to remove it.

Quoting MkdirAll documentation:

> MkdirAll creates a directory named path, along with any necessary
> parents, and returns nil, or else returns an error. If path
> is already a directory, MkdirAll does nothing and returns nil.

This means two things:

1. If a directory to be created already exists, no error is
returned.

2. If the error returned is IsExist (EEXIST), it means there exists
a non-directory with the same name as MkdirAll need to use for
directory. Example: we want to MkdirAll("a/b"), but file "a"
(or "a/b") already exists, so MkdirAll fails.

The above is a theory, based on quoted documentation and my UNIX
knowledge.

3. In practice, though, current MkdirAll implementation [1] returns
ENOTDIR in most of cases described in #2, with the exception when
there is a race between MkdirAll and someone else creating the
last component of MkdirAll argument as a file. In this very case
MkdirAll() will indeed return EEXIST.

Because of #1, IsExist check after MkdirAll is not needed.

Because of #2 and #3, ignoring IsExist error is just plain wrong,
as directory we require is not created. It's cleaner to report
the error now.

Note this error is all over the tree, I guess due to copy-paste,
or trying to follow the same usage pattern as for Mkdir(),
or some not quite correct examples on the Internet.

> [1] https://github.com/golang/go/blob/f9ed2f75/src/os/path.go

-end-quote-

Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>
Signed-off-by: Daniel J Walsh <dwalsh@redhat.com>
rhatdan added a commit that referenced this pull request Nov 3, 2020
This subtle bug keeps lurking in because error checking for `Mkdir()`
and `MkdirAll()` is slightly different wrt `EEXIST`/`IsExist`:

 - for `Mkdir()`, `IsExist` error should (usually) be ignored
   (unless you want to make sure directory was not there before)
   as it means "the destination directory was already there";

 - for `MkdirAll()`, `IsExist` error should NEVER be ignored.

This commit removes ignoring the IsExist error, as it should not
be ignored.

[v2: skip patching (*Builder).Run]

For more details, a quote from opencontainers/runc PR containers#162:

-quote-

TL;DR: check for IsExist(err) after a failed MkdirAll() is both
redundant and wrong -- so two reasons to remove it.

Quoting MkdirAll documentation:

> MkdirAll creates a directory named path, along with any necessary
> parents, and returns nil, or else returns an error. If path
> is already a directory, MkdirAll does nothing and returns nil.

This means two things:

1. If a directory to be created already exists, no error is
returned.

2. If the error returned is IsExist (EEXIST), it means there exists
a non-directory with the same name as MkdirAll need to use for
directory. Example: we want to MkdirAll("a/b"), but file "a"
(or "a/b") already exists, so MkdirAll fails.

The above is a theory, based on quoted documentation and my UNIX
knowledge.

3. In practice, though, current MkdirAll implementation [1] returns
ENOTDIR in most of cases described in #2, with the exception when
there is a race between MkdirAll and someone else creating the
last component of MkdirAll argument as a file. In this very case
MkdirAll() will indeed return EEXIST.

Because of #1, IsExist check after MkdirAll is not needed.

Because of #2 and #3, ignoring IsExist error is just plain wrong,
as directory we require is not created. It's cleaner to report
the error now.

Note this error is all over the tree, I guess due to copy-paste,
or trying to follow the same usage pattern as for Mkdir(),
or some not quite correct examples on the Internet.

> [1] https://github.com/golang/go/blob/f9ed2f75/src/os/path.go

-end-quote-

Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>
Signed-off-by: Daniel J Walsh <dwalsh@redhat.com>
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A friendly reminder that this PR had no activity for 30 days.

@rhatdan rhatdan closed this Mar 7, 2021
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2 participants