an [abandoned] attempt to slice out the docker/docker/pkg package
fe45bb6d4d
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]
|
||
|---|---|---|
| ansiescape | ||
| archive | ||
| broadcastwriter | ||
| chrootarchive | ||
| devicemapper | ||
| directory | ||
| fileutils | ||
| graphdb | ||
| homedir | ||
| httputils | ||
| ioutils | ||
| jsonlog | ||
| jsonmessage | ||
| listenbuffer | ||
| mflag | ||
| mount | ||
| namesgenerator | ||
| nat | ||
| parsers | ||
| pidfile | ||
| plugins | ||
| pools | ||
| progressreader | ||
| promise | ||
| proxy | ||
| pubsub | ||
| random | ||
| reexec | ||
| signal | ||
| sockets | ||
| stdcopy | ||
| streamformatter | ||
| stringid | ||
| stringutils | ||
| symlink | ||
| sysinfo | ||
| system | ||
| systemd | ||
| tailfile | ||
| tarsum | ||
| term | ||
| timeoutconn | ||
| timeutils | ||
| tlsconfig | ||
| truncindex | ||
| ulimit | ||
| units | ||
| urlutil | ||
| useragent | ||
| version | ||
| README.md | ||
pkg/ is a collection of utility packages used by the Docker project without being specific to its internals.
Utility packages are kept separate from the docker core codebase to keep it as small and concise as possible. If some utilities grow larger and their APIs stabilize, they may be moved to their own repository under the Docker organization, to facilitate re-use by other projects. However that is not the priority.
The directory pkg is named after the same directory in the camlistore project. Since Brad is a core
Go maintainer, we thought it made sense to copy his methods for organizing Go code :) Thanks Brad!
Because utility packages are small and neatly separated from the rest of the codebase, they are a good place to start for aspiring maintainers and contributors. Get in touch if you want to help maintain them!