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

4 files changed, 32 insertions, 15 deletions

diff --git a/clients/common.go b/clients/common.go
index 55b3b4b..b6da656 100644
--- a/clients/common.go
+++ b/clients/common.go
@@ -55,10 +55,10 @@ func NewGitUploadPackService(repoURL string) (common.GitUploadPackService, error
 	if err != nil {
 		return nil, fmt.Errorf("invalid url %q", repoURL)
 	}
-	service, ok := KnownProtocols[u.Scheme]
+	s, ok := KnownProtocols[u.Scheme]
 	if !ok {
 		return nil, fmt.Errorf("unsupported scheme %q", u.Scheme)
 	}
 
-	return service, nil
+	return s, nil
 }
diff --git a/clients/common/common.go b/clients/common/common.go
index 5aa6269..7280450 100644
--- a/clients/common/common.go
+++ b/clients/common/common.go
@@ -236,11 +236,7 @@ func (r *GitUploadPackInfo) decodeHeaderLine(line string) {
 }
 
 func (r *GitUploadPackInfo) isValidLine(line string) bool {
-	if line[0] == '#' {
-		return false
-	}
-
-	return true
+	return line[0] != '#'
 }
 
 func (r *GitUploadPackInfo) readLine(line string) {
diff --git a/clients/common_test.go b/clients/common_test.go
index 88f66ab..c571f04 100644
--- a/clients/common_test.go
+++ b/clients/common_test.go
@@ -3,23 +3,41 @@ package clients
 import (
 	"fmt"
 	"io"
+	"os"
 	"testing"
 
-	. "gopkg.in/check.v1"
 	"gopkg.in/src-d/go-git.v3/clients/common"
+
+	"github.com/alcortesm/tgz"
+	. "gopkg.in/check.v1"
 )
 
 func Test(t *testing.T) { TestingT(t) }
 
-type SuiteCommon struct{}
+type SuiteCommon struct {
+	dirFixturePath string
+}
 
 var _ = Suite(&SuiteCommon{})
 
+const fixtureTGZ = "../storage/seekable/internal/gitdir/fixtures/spinnaker-gc.tgz"
+
+func (s *SuiteCommon) SetUpSuite(c *C) {
+	var err error
+	s.dirFixturePath, err = tgz.Extract(fixtureTGZ)
+	c.Assert(err, IsNil)
+}
+
+func (s *SuiteCommon) TearDownSuite(c *C) {
+	err := os.RemoveAll(s.dirFixturePath)
+	c.Assert(err, IsNil)
+}
+
 func (s *SuiteCommon) TestNewGitUploadPackService(c *C) {
 	var tests = [...]struct {
-		input    string
-		err      bool
-		expected string
+		input string
+		err   bool
+		exp   string
 	}{
 		{"://example.com", true, "<nil>"},
 		{"badscheme://github.com/src-d/go-git", true, "<nil>"},
@@ -30,8 +48,10 @@ func (s *SuiteCommon) TestNewGitUploadPackService(c *C) {
 
 	for i, t := range tests {
 		output, err := NewGitUploadPackService(t.input)
-		c.Assert(err != nil, Equals, t.err, Commentf("%d) %q: wrong error value", i, t.input))
-		c.Assert(typeAsString(output), Equals, t.expected, Commentf("%d) %q: wrong type", i, t.input))
+		c.Assert(err != nil, Equals, t.err,
+			Commentf("%d) %q: wrong error value (was: %s)", i, t.input, err))
+		c.Assert(typeAsString(output), Equals, t.exp,
+			Commentf("%d) %q: wrong type", i, t.input))
 	}
 }
 
@@ -70,7 +90,6 @@ func (s *SuiteCommon) TestInstallProtocol(c *C) {
 
 	for i, t := range tests {
 		if t.panic {
-			fmt.Println(t.service == nil)
 			c.Assert(func() { InstallProtocol(t.scheme, t.service) }, PanicMatches, `nil service`)
 			continue
 		}
diff --git a/clients/ssh/git_upload_pack_test.go b/clients/ssh/git_upload_pack_test.go
index 4b50c4c..07aa816 100644
--- a/clients/ssh/git_upload_pack_test.go
+++ b/clients/ssh/git_upload_pack_test.go
@@ -1,3 +1,5 @@
+// +build ssh
+
 package ssh
 
 import (