From fe45bb6d4d85bee2d057c65bc65171c462bbbd65 Mon Sep 17 00:00:00 2001 From: Kir Kolyshkin Date: Wed, 29 Jul 2015 16:49:05 -0700 Subject: [PATCH] Simplify and fix os.MkdirAll() usage 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. [v2: a separate aufs commit is merged into this one] [1] https://github.com/golang/go/blob/f9ed2f75/src/os/path.go Signed-off-by: Kir Kolyshkin --- archive/archive.go | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/archive/archive.go b/archive/archive.go index 11a707d..362e07c 100644 --- a/archive/archive.go +++ b/archive/archive.go @@ -714,7 +714,7 @@ func (archiver *Archiver) CopyWithTar(src, dst string) error { } // Create dst, copy src's content into it logrus.Debugf("Creating dest directory: %s", dst) - if err := system.MkdirAll(dst, 0755); err != nil && !os.IsExist(err) { + if err := system.MkdirAll(dst, 0755); err != nil { return err } logrus.Debugf("Calling TarUntar(%s, %s)", src, dst) @@ -746,7 +746,7 @@ func (archiver *Archiver) CopyFileWithTar(src, dst string) (err error) { dst = filepath.Join(dst, filepath.Base(src)) } // Create the holding directory if necessary - if err := system.MkdirAll(filepath.Dir(dst), 0700); err != nil && !os.IsExist(err) { + if err := system.MkdirAll(filepath.Dir(dst), 0700); err != nil { return err }