Adds support to open local repositories and to use file-based object storage (#55)v3.1.0

* remove some comments

* idx writer/reader

* Shut up ssh tests, they are annoying

* Add file scheme test to clients

* Add dummy file client

* Add test fot file client

* Make tests use fixture endpoint

* add parser for packed-refs format

* add parser for packed-refs format

* WIP adding dir.Refs() tests

* Add test for fixture refs

* refs parser for the refs directory

* Documentation

* Add Capabilities to file client

* tgz.Exatract now accpets a path instead of a Reader

* fix bug in idxfile fanout calculation

* remove dead code

* packfile documentation

* clean packfile parser code

* add core.Object.Content() and returns errors for core.ObjectStorage.Iter()

* add seekable storage

* add dir repos to NewRepository

* clean prints

* Add dir client documentation to README

* Organize the README

* README

* Clean tgz package

* Clean temp dirs after tgz tests

* Gometalinter on gitdir

* Clean pattern function

* metalinter tgz

* metalinter gitdir

* gitdir coverage and remove seekable packfile filedescriptor leak

* gitdir Idxfile tests and remove file descriptor leak

* gitdir Idxfile tests when no idx is found

* clean storage/seekable/internal/index and some formats/idxfile API issues

* clean storage/seekable

* clean formats/idx

* turn packfile/doc.go into packfile/doc.txt

* move formats/packfile/reader to decoder

* fix packfile decoder error names

* improve documentation

* comment packfile decoder errors

* comment public API (format/packfile)

* remve duplicated code in packfile decoder test

* move tracking_reader into an internal package and clean it

* use iota for packfile format

* rename packfile parse.go to packfile object_at.go

* clean packfile deltas

* fix delta header size bug

* improve delta documentation

* clean packfile deltas

* clean packfiles deltas

* clean repository.go

* Remove go 1.5 from Travis CI

Because go 1.5 does not suport internal packages.

* change local repo scheme to local://

* change "local://" to "file://" as the local scheme

* fix broken indentation

* shortens names of variables in short scopes

* more shortening of variable names

* more shortening of variable names

* Rename git dir client to "file", as the scheme used for it

* Fix file format ctor name, now that the package name has change

* Sortcut local repo constructor to not use remotes

The object storage is build directly in the repository ctor, instead
of creating a remote and waiting for the user to pull it.

* update README and fix some errors in it

* remove file scheme client

* Local respositories has now a new ctor

This is, they are no longer identified by the scheme of the URL, but are
created different from inception.

* remove unused URL field form Repository

* move all git dir logic to seekable sotrage ctor

* fix documentation

* Make formats/file/dir an internal package to storage/seekable

* change package storage/seekable to storage/fs

* clean storage/fs

* overall storage/fs clean

* more cleaning

* some metalinter fixes

* upgrade cshared to last changes

* remove dead code

* fix test error info

* remove file scheme check from clients

* fix test error message

* fix test error message

* fix error messages

* style changes

* fix comments everywhere

* style changes

* style changes

* scaffolding and tests for local packfiles without ifx files

* outsource index building from packfile to the packfile decoder

* refactor packfile header reading into a new function

* move code to generate index from packfile back to index package

* add header parsing

* fix documentation errata

* add undeltified and OFS delta support for index building from the packfile

* add tests for packfile with ref-deltas

* support for packfiles with ref-deltas and no idx

* refactor packfile format parser to reuse code

* refactor packfile format parser to reuse code

* refactor packfile format parser to reuse code

* refactor packfile format parser to reuse code

* refactor packfile format parser to reuse code

* WIP refactor packfile format parser to reuse code

* refactor packfile format parser to reuse code

* remove prints from tests

* remove prints from tests

* refactor packfile.core into packfile.parser

* rename packfile reader to something that shows it is a recaller

* rename cannot recall error

* rename packfile.Reader to packfile.ReadRecaller and document

* speed up test by using StreamReader instead of SeekableReader when possible

* clean packfile StreamReader

* stream_reader tests

* refactor packfile.StreamReader into packfile.StreamReadRecaller

* refactor packfile.SeekableReader into packfile.SeekableReadRecaller and document it

* generalize packfile.StreamReadRecaller test to all packfile.ReadRecaller implementations

* speed up storage/fs tests

* speed up tests in . by loading packfiles in memory

* speed up repository tests by using and smaller fixture

* restore doc.go files

* rename packfile.ReadRecaller implementations to shorter names

* update comments to type changes

* packfile.Parser test (WIP)

* packfile.Parser tests and add ForgetAll() to packfile.ReadRecaller

* add test for packfile.ReadRecaller.ForgetAll()

* clarify seekable being able to recallByOffset forgetted objects

* use better names for internal maps

* metalinter packfile package

* speed up some tests

* documentation fixes

* change storage.fs package name to storage.proxy to avoid confusion with new filesystem support

* New fs package and os transparent implementation

Now NewRepositoryFromFS receives a fs and a path and tests are
modified accordingly, but it is still not using for anything.

* add fs to gitdir and proxy.store

* reduce fs interface for easier implementation

* remove garbage dirs from tgz tests

* change file name gitdir/dir.go to gitdir/gitdir.go

* fs.OS tests

* metalinter utils/fs

* add NewRepositoryFromFS documentation to README

* Readability fixes to README

* move tgz to an external dependency

* move filesystem impl. example to example dir

* rename proxy/store.go to proxy/storage.go for coherence with memory/storage.go

* rename proxy package to seekable

1 files changed, 152 insertions, 0 deletions

diff --git a/storage/seekable/storage.go b/storage/seekable/storage.go
new file mode 100644
index 0000000..8d75700
--- /dev/null
+++ b/storage/seekable/storage.go
@@ -0,0 +1,152 @@
+package seekable
+
+import (
+	"fmt"
+	"os"
+
+	"gopkg.in/src-d/go-git.v3/core"
+	"gopkg.in/src-d/go-git.v3/formats/packfile"
+	"gopkg.in/src-d/go-git.v3/storage/seekable/internal/gitdir"
+	"gopkg.in/src-d/go-git.v3/storage/seekable/internal/index"
+	"gopkg.in/src-d/go-git.v3/utils/fs"
+)
+
+// ObjectStorage is an implementation of core.ObjectStorage that stores
+// data on disk in the standard git format (this is, the .git directory).
+//
+// Zero values of this type are not safe to use, see the New function below.
+//
+// Currently only reads are supported, no writting.
+//
+// Also values from this type are not yet able to track changes on disk, this is,
+// Gitdir values will get outdated as soon as repositories change on disk.
+type ObjectStorage struct {
+	dir   *gitdir.GitDir
+	index index.Index
+}
+
+// New returns a new ObjectStorage for the git directory at the specified path.
+func New(fs fs.FS, path string) (*ObjectStorage, error) {
+	s := &ObjectStorage{}
+
+	var err error
+	s.dir, err = gitdir.New(fs, path)
+	if err != nil {
+		return nil, err
+	}
+
+	s.index, err = buildIndex(s.dir)
+
+	return s, err
+}
+
+func buildIndex(dir *gitdir.GitDir) (index.Index, error) {
+	fs, idxfile, err := dir.Idxfile()
+	if err != nil {
+		if err == gitdir.ErrIdxNotFound {
+			return buildIndexFromPackfile(dir)
+		}
+		return nil, err
+	}
+
+	return buildIndexFromIdxfile(fs, idxfile)
+}
+
+func buildIndexFromPackfile(dir *gitdir.GitDir) (index.Index, error) {
+	fs, packfile, err := dir.Packfile()
+	if err != nil {
+		return nil, err
+	}
+
+	f, err := fs.Open(packfile)
+	if err != nil {
+		return nil, err
+	}
+
+	defer func() {
+		errClose := f.Close()
+		if err == nil {
+			err = errClose
+		}
+	}()
+
+	return index.NewFromPackfile(f)
+}
+
+func buildIndexFromIdxfile(fs fs.FS, path string) (index.Index, error) {
+	f, err := fs.Open(path)
+	if err != nil {
+		return nil, err
+	}
+
+	defer func() {
+		errClose := f.Close()
+		if err == nil {
+			err = errClose
+		}
+	}()
+
+	return index.NewFromIdx(f)
+}
+
+// Set adds a new object to the storage. As this functionality is not
+// yet supported, this method always returns a "not implemented yet"
+// error an zero hash.
+func (s *ObjectStorage) Set(core.Object) (core.Hash, error) {
+	return core.ZeroHash, fmt.Errorf("not implemented yet")
+}
+
+// Get returns the object with the given hash, by searching for it in
+// the packfile.
+func (s *ObjectStorage) Get(h core.Hash) (core.Object, error) {
+	offset, err := s.index.Get(h)
+	if err != nil {
+		return nil, err
+	}
+
+	fs, path, err := s.dir.Packfile()
+	if err != nil {
+		return nil, err
+	}
+
+	f, err := fs.Open(path)
+	if err != nil {
+		return nil, err
+	}
+
+	defer func() {
+		errClose := f.Close()
+		if err == nil {
+			err = errClose
+		}
+	}()
+
+	_, err = f.Seek(offset, os.SEEK_SET)
+	if err != nil {
+		return nil, err
+	}
+
+	r := packfile.NewSeekable(f)
+	r.HashToOffset = map[core.Hash]int64(s.index)
+	p := packfile.NewParser(r)
+
+	return p.ReadObject()
+}
+
+// Iter returns an iterator for all the objects in the packfile with the
+// given type.
+func (s *ObjectStorage) Iter(t core.ObjectType) (core.ObjectIter, error) {
+	var objects []core.Object
+
+	for hash := range s.index {
+		object, err := s.Get(hash)
+		if err != nil {
+			return nil, err
+		}
+		if object.Type() == t {
+			objects = append(objects, object)
+		}
+	}
+
+	return core.NewObjectSliceIter(objects), nil
+}