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Fix MkdirAll* and its usage #629
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LGTM |
@kolyshkin Needs a rebase |
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LGTM
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LGTM. but this needs rebase
LGTM |
os.MkdirAll() function returns "not a directory" error in case a directory to be created already exists but is not a directory (e.g. a file). MkdirAllNewAs function do not replicate the behavior. This is a bug since it is expected to ensure the required directory exists and is indeed a directory, and return an error otherwise. Signed-off-by: Kir Kolyshkin <[email protected]>
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. For more details, a quote from my opencontainers/runc#162 (July 2015): -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: If a directory to be created already exists, no error is returned. 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. In practice, though, current MkdirAll implementation [1] returns ENOTDIR in most of cases described in containers#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 containers#1, IsExist check after MkdirAll is not needed. Because of containers#2 and containers#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 <[email protected]>
rebased |
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LGTM
A couple of fixes; similar to moby/moby#35618
1. idtools/mkdirAs: error out if dir exists as file
os.MkdirAll()
function returns "not a directory" error in case adirectory to be created already exists but is not a directory
(e.g. a file). MkdirAllNewAs function do not replicate the behavior.
This is a bug since it is expected to ensure the required directory
exists and is indeed a directory, and return an error otherwise.
2. fix MkdirAll usage
This subtle bug keeps lurking in because error checking for
Mkdir()
and
MkdirAll()
is slightly different wrtEEXIST
/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.
For more details, a quote from my opencontainers/runc#162 (July 2005):
TL;DR: check for IsExist(err) after a failed MkdirAll() is both
redundant and wrong -- so two reasons to remove it.
Quoting MkdirAll documentation:
This means two things:
If a directory to be created already exists, no error is
returned.
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.
ENOTDIR in most of cases described in Add a configuration file #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.