Kir Kolyshkin 516010e92d Simplify/fix MkdirAll usage ... This subtle bug keeps lurking in because error checking for `Mkdir()` and `MkdirAll()` is slightly different wrt to `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. Mostly, this commit just removes ignoring the IsExist error, as it should not be ignored. Also, there are a couple of cases then IsExist is handled as "directory already exist" which is wrong. As a result, some code that never worked as intended is now removed. NOTE that `idtools.MkdirAndChown()` behaves like `os.MkdirAll()` rather than `os.Mkdir()` -- so its description is amended accordingly, and its usage is handled as such (i.e. IsExist error is not ignored). For more details, a quote from my runc commit 6f82d4b (July 2015): 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 Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>		2017-11-27 17:32:12 -08:00
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local.go
local_test.go
local_unix.go
local_windows.go