Implement git refs API for listing references (branches, tags and other) (#5354)

* Inital routes to git refs api

* Git refs API implementation

* Update swagger

* Fix copyright

* Make swagger happy add basic test

* Fix test

* Fix test again :)

9 files changed, 1302 insertions, 0 deletions

diff --git a/vendor/gopkg.in/src-d/go-billy.v4/LICENSE b/vendor/gopkg.in/src-d/go-billy.v4/LICENSE
new file mode 100644
index 0000000000..9d60756894
--- /dev/null
+++ b/vendor/gopkg.in/src-d/go-billy.v4/LICENSE
@@ -0,0 +1,201 @@
+                                 Apache License
+                           Version 2.0, January 2004
+                        http://www.apache.org/licenses/
+
+   TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION
+
+   1. Definitions.
+
+      "License" shall mean the terms and conditions for use, reproduction,
+      and distribution as defined by Sections 1 through 9 of this document.
+
+      "Licensor" shall mean the copyright owner or entity authorized by
+      the copyright owner that is granting the License.
+
+      "Legal Entity" shall mean the union of the acting entity and all
+      other entities that control, are controlled by, or are under common
+      control with that entity. For the purposes of this definition,
+      "control" means (i) the power, direct or indirect, to cause the
+      direction or management of such entity, whether by contract or
+      otherwise, or (ii) ownership of fifty percent (50%) or more of the
+      outstanding shares, or (iii) beneficial ownership of such entity.
+
+      "You" (or "Your") shall mean an individual or Legal Entity
+      exercising permissions granted by this License.
+
+      "Source" form shall mean the preferred form for making modifications,
+      including but not limited to software source code, documentation
+      source, and configuration files.
+
+      "Object" form shall mean any form resulting from mechanical
+      transformation or translation of a Source form, including but
+      not limited to compiled object code, generated documentation,
+      and conversions to other media types.
+
+      "Work" shall mean the work of authorship, whether in Source or
+      Object form, made available under the License, as indicated by a
+      copyright notice that is included in or attached to the work
+      (an example is provided in the Appendix below).
+
+      "Derivative Works" shall mean any work, whether in Source or Object
+      form, that is based on (or derived from) the Work and for which the
+      editorial revisions, annotations, elaborations, or other modifications
+      represent, as a whole, an original work of authorship. For the purposes
+      of this License, Derivative Works shall not include works that remain
+      separable from, or merely link (or bind by name) to the interfaces of,
+      the Work and Derivative Works thereof.
+
+      "Contribution" shall mean any work of authorship, including
+      the original version of the Work and any modifications or additions
+      to that Work or Derivative Works thereof, that is intentionally
+      submitted to Licensor for inclusion in the Work by the copyright owner
+      or by an individual or Legal Entity authorized to submit on behalf of
+      the copyright owner. For the purposes of this definition, "submitted"
+      means any form of electronic, verbal, or written communication sent
+      to the Licensor or its representatives, including but not limited to
+      communication on electronic mailing lists, source code control systems,
+      and issue tracking systems that are managed by, or on behalf of, the
+      Licensor for the purpose of discussing and improving the Work, but
+      excluding communication that is conspicuously marked or otherwise
+      designated in writing by the copyright owner as "Not a Contribution."
+
+      "Contributor" shall mean Licensor and any individual or Legal Entity
+      on behalf of whom a Contribution has been received by Licensor and
+      subsequently incorporated within the Work.
+
+   2. Grant of Copyright License. Subject to the terms and conditions of
+      this License, each Contributor hereby grants to You a perpetual,
+      worldwide, non-exclusive, no-charge, royalty-free, irrevocable
+      copyright license to reproduce, prepare Derivative Works of,
+      publicly display, publicly perform, sublicense, and distribute the
+      Work and such Derivative Works in Source or Object form.
+
+   3. Grant of Patent License. Subject to the terms and conditions of
+      this License, each Contributor hereby grants to You a perpetual,
+      worldwide, non-exclusive, no-charge, royalty-free, irrevocable
+      (except as stated in this section) patent license to make, have made,
+      use, offer to sell, sell, import, and otherwise transfer the Work,
+      where such license applies only to those patent claims licensable
+      by such Contributor that are necessarily infringed by their
+      Contribution(s) alone or by combination of their Contribution(s)
+      with the Work to which such Contribution(s) was submitted. If You
+      institute patent litigation against any entity (including a
+      cross-claim or counterclaim in a lawsuit) alleging that the Work
+      or a Contribution incorporated within the Work constitutes direct
+      or contributory patent infringement, then any patent licenses
+      granted to You under this License for that Work shall terminate
+      as of the date such litigation is filed.
+
+   4. Redistribution. You may reproduce and distribute copies of the
+      Work or Derivative Works thereof in any medium, with or without
+      modifications, and in Source or Object form, provided that You
+      meet the following conditions:
+
+      (a) You must give any other recipients of the Work or
+          Derivative Works a copy of this License; and
+
+      (b) You must cause any modified files to carry prominent notices
+          stating that You changed the files; and
+
+      (c) You must retain, in the Source form of any Derivative Works
+          that You distribute, all copyright, patent, trademark, and
+          attribution notices from the Source form of the Work,
+          excluding those notices that do not pertain to any part of
+          the Derivative Works; and
+
+      (d) If the Work includes a "NOTICE" text file as part of its
+          distribution, then any Derivative Works that You distribute must
+          include a readable copy of the attribution notices contained
+          within such NOTICE file, excluding those notices that do not
+          pertain to any part of the Derivative Works, in at least one
+          of the following places: within a NOTICE text file distributed
+          as part of the Derivative Works; within the Source form or
+          documentation, if provided along with the Derivative Works; or,
+          within a display generated by the Derivative Works, if and
+          wherever such third-party notices normally appear. The contents
+          of the NOTICE file are for informational purposes only and
+          do not modify the License. You may add Your own attribution
+          notices within Derivative Works that You distribute, alongside
+          or as an addendum to the NOTICE text from the Work, provided
+          that such additional attribution notices cannot be construed
+          as modifying the License.
+
+      You may add Your own copyright statement to Your modifications and
+      may provide additional or different license terms and conditions
+      for use, reproduction, or distribution of Your modifications, or
+      for any such Derivative Works as a whole, provided Your use,
+      reproduction, and distribution of the Work otherwise complies with
+      the conditions stated in this License.
+
+   5. Submission of Contributions. Unless You explicitly state otherwise,
+      any Contribution intentionally submitted for inclusion in the Work
+      by You to the Licensor shall be under the terms and conditions of
+      this License, without any additional terms or conditions.
+      Notwithstanding the above, nothing herein shall supersede or modify
+      the terms of any separate license agreement you may have executed
+      with Licensor regarding such Contributions.
+
+   6. Trademarks. This License does not grant permission to use the trade
+      names, trademarks, service marks, or product names of the Licensor,
+      except as required for reasonable and customary use in describing the
+      origin of the Work and reproducing the content of the NOTICE file.
+
+   7. Disclaimer of Warranty. Unless required by applicable law or
+      agreed to in writing, Licensor provides the Work (and each
+      Contributor provides its Contributions) on an "AS IS" BASIS,
+      WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
+      implied, including, without limitation, any warranties or conditions
+      of TITLE, NON-INFRINGEMENT, MERCHANTABILITY, or FITNESS FOR A
+      PARTICULAR PURPOSE. You are solely responsible for determining the
+      appropriateness of using or redistributing the Work and assume any
+      risks associated with Your exercise of permissions under this License.
+
+   8. Limitation of Liability. In no event and under no legal theory,
+      whether in tort (including negligence), contract, or otherwise,
+      unless required by applicable law (such as deliberate and grossly
+      negligent acts) or agreed to in writing, shall any Contributor be
+      liable to You for damages, including any direct, indirect, special,
+      incidental, or consequential damages of any character arising as a
+      result of this License or out of the use or inability to use the
+      Work (including but not limited to damages for loss of goodwill,
+      work stoppage, computer failure or malfunction, or any and all
+      other commercial damages or losses), even if such Contributor
+      has been advised of the possibility of such damages.
+
+   9. Accepting Warranty or Additional Liability. While redistributing
+      the Work or Derivative Works thereof, You may choose to offer,
+      and charge a fee for, acceptance of support, warranty, indemnity,
+      or other liability obligations and/or rights consistent with this
+      License. However, in accepting such obligations, You may act only
+      on Your own behalf and on Your sole responsibility, not on behalf
+      of any other Contributor, and only if You agree to indemnify,
+      defend, and hold each Contributor harmless for any liability
+      incurred by, or claims asserted against, such Contributor by reason
+      of your accepting any such warranty or additional liability.
+
+   END OF TERMS AND CONDITIONS
+
+   APPENDIX: How to apply the Apache License to your work.
+
+      To apply the Apache License to your work, attach the following
+      boilerplate notice, with the fields enclosed by brackets "{}"
+      replaced with your own identifying information. (Don't include
+      the brackets!)  The text should be enclosed in the appropriate
+      comment syntax for the file format. We also recommend that a
+      file or class name and description of purpose be included on the
+      same "printed page" as the copyright notice for easier
+      identification within third-party archives.
+
+   Copyright 2017 Sourced Technologies S.L.
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
diff --git a/vendor/gopkg.in/src-d/go-billy.v4/fs.go b/vendor/gopkg.in/src-d/go-billy.v4/fs.go
new file mode 100644
index 0000000000..a9efccdeb2
--- /dev/null
+++ b/vendor/gopkg.in/src-d/go-billy.v4/fs.go
@@ -0,0 +1,202 @@
+package billy
+
+import (
+	"errors"
+	"io"
+	"os"
+	"time"
+)
+
+var (
+	ErrReadOnly        = errors.New("read-only filesystem")
+	ErrNotSupported    = errors.New("feature not supported")
+	ErrCrossedBoundary = errors.New("chroot boundary crossed")
+)
+
+// Capability holds the supported features of a billy filesystem. This does
+// not mean that the capability has to be supported by the underlying storage.
+// For example, a billy filesystem may support WriteCapability but the
+// storage be mounted in read only mode.
+type Capability uint64
+
+const (
+	// WriteCapability means that the fs is writable.
+	WriteCapability Capability = 1 << iota
+	// ReadCapability means that the fs is readable.
+	ReadCapability
+	// ReadAndWriteCapability is the ability to open a file in read and write mode.
+	ReadAndWriteCapability
+	// SeekCapability means it is able to move position inside the file.
+	SeekCapability
+	// TruncateCapability means that a file can be truncated.
+	TruncateCapability
+	// LockCapability is the ability to lock a file.
+	LockCapability
+
+	// DefaultCapabilities lists all capable features supported by filesystems
+	// without Capability interface. This list should not be changed until a
+	// major version is released.
+	DefaultCapabilities Capability = WriteCapability | ReadCapability |
+		ReadAndWriteCapability | SeekCapability | TruncateCapability |
+		LockCapability
+
+	// AllCapabilities lists all capable features.
+	AllCapabilities Capability = WriteCapability | ReadCapability |
+		ReadAndWriteCapability | SeekCapability | TruncateCapability |
+		LockCapability
+)
+
+// Filesystem abstract the operations in a storage-agnostic interface.
+// Each method implementation mimics the behavior of the equivalent functions
+// at the os package from the standard library.
+type Filesystem interface {
+	Basic
+	TempFile
+	Dir
+	Symlink
+	Chroot
+}
+
+// Basic abstract the basic operations in a storage-agnostic interface as
+// an extension to the Basic interface.
+type Basic interface {
+	// Create creates the named file with mode 0666 (before umask), truncating
+	// it if it already exists. If successful, methods on the returned File can
+	// be used for I/O; the associated file descriptor has mode O_RDWR.
+	Create(filename string) (File, error)
+	// Open opens the named file for reading. If successful, methods on the
+	// returned file can be used for reading; the associated file descriptor has
+	// mode O_RDONLY.
+	Open(filename string) (File, error)
+	// OpenFile is the generalized open call; most users will use Open or Create
+	// instead. It opens the named file with specified flag (O_RDONLY etc.) and
+	// perm, (0666 etc.) if applicable. If successful, methods on the returned
+	// File can be used for I/O.
+	OpenFile(filename string, flag int, perm os.FileMode) (File, error)
+	// Stat returns a FileInfo describing the named file.
+	Stat(filename string) (os.FileInfo, error)
+	// Rename renames (moves) oldpath to newpath. If newpath already exists and
+	// is not a directory, Rename replaces it. OS-specific restrictions may
+	// apply when oldpath and newpath are in different directories.
+	Rename(oldpath, newpath string) error
+	// Remove removes the named file or directory.
+	Remove(filename string) error
+	// Join joins any number of path elements into a single path, adding a
+	// Separator if necessary. Join calls filepath.Clean on the result; in
+	// particular, all empty strings are ignored. On Windows, the result is a
+	// UNC path if and only if the first path element is a UNC path.
+	Join(elem ...string) string
+}
+
+type TempFile interface {
+	// TempFile creates a new temporary file in the directory dir with a name
+	// beginning with prefix, opens the file for reading and writing, and
+	// returns the resulting *os.File. If dir is the empty string, TempFile
+	// uses the default directory for temporary files (see os.TempDir).
+	// Multiple programs calling TempFile simultaneously will not choose the
+	// same file. The caller can use f.Name() to find the pathname of the file.
+	// It is the caller's responsibility to remove the file when no longer
+	// needed.
+	TempFile(dir, prefix string) (File, error)
+}
+
+// Dir abstract the dir related operations in a storage-agnostic interface as
+// an extension to the Basic interface.
+type Dir interface {
+	// ReadDir reads the directory named by dirname and returns a list of
+	// directory entries sorted by filename.
+	ReadDir(path string) ([]os.FileInfo, error)
+	// MkdirAll creates a directory named path, along with any necessary
+	// parents, and returns nil, or else returns an error. The permission bits
+	// perm are used for all directories that MkdirAll creates. If path is/
+	// already a directory, MkdirAll does nothing and returns nil.
+	MkdirAll(filename string, perm os.FileMode) error
+}
+
+// Symlink abstract the symlink related operations in a storage-agnostic
+// interface as an extension to the Basic interface.
+type Symlink interface {
+	// Lstat returns a FileInfo describing the named file. If the file is a
+	// symbolic link, the returned FileInfo describes the symbolic link. Lstat
+	// makes no attempt to follow the link.
+	Lstat(filename string) (os.FileInfo, error)
+	// Symlink creates a symbolic-link from link to target. target may be an
+	// absolute or relative path, and need not refer to an existing node.
+	// Parent directories of link are created as necessary.
+	Symlink(target, link string) error
+	// Readlink returns the target path of link.
+	Readlink(link string) (string, error)
+}
+
+// Change abstract the FileInfo change related operations in a storage-agnostic
+// interface as an extension to the Basic interface
+type Change interface {
+	// Chmod changes the mode of the named file to mode. If the file is a
+	// symbolic link, it changes the mode of the link's target.
+	Chmod(name string, mode os.FileMode) error
+	// Lchown changes the numeric uid and gid of the named file. If the file is
+	// a symbolic link, it changes the uid and gid of the link itself.
+	Lchown(name string, uid, gid int) error
+	// Chown changes the numeric uid and gid of the named file. If the file is a
+	// symbolic link, it changes the uid and gid of the link's target.
+	Chown(name string, uid, gid int) error
+	// Chtimes changes the access and modification times of the named file,
+	// similar to the Unix utime() or utimes() functions.
+	//
+	// The underlying filesystem may truncate or round the values to a less
+	// precise time unit.
+	Chtimes(name string, atime time.Time, mtime time.Time) error
+}
+
+// Chroot abstract the chroot related operations in a storage-agnostic interface
+// as an extension to the Basic interface.
+type Chroot interface {
+	// Chroot returns a new filesystem from the same type where the new root is
+	// the given path. Files outside of the designated directory tree cannot be
+	// accessed.
+	Chroot(path string) (Filesystem, error)
+	// Root returns the root path of the filesystem.
+	Root() string
+}
+
+// File represent a file, being a subset of the os.File
+type File interface {
+	// Name returns the name of the file as presented to Open.
+	Name() string
+	io.Writer
+	io.Reader
+	io.ReaderAt
+	io.Seeker
+	io.Closer
+	// Lock locks the file like e.g. flock. It protects against access from
+	// other processes.
+	Lock() error
+	// Unlock unlocks the file.
+	Unlock() error
+	// Truncate the file.
+	Truncate(size int64) error
+}
+
+// Capable interface can return the available features of a filesystem.
+type Capable interface {
+	// Capabilities returns the capabilities of a filesystem in bit flags.
+	Capabilities() Capability
+}
+
+// Capabilities returns the features supported by a filesystem. If the FS
+// does not implement Capable interface it returns all features.
+func Capabilities(fs Basic) Capability {
+	capable, ok := fs.(Capable)
+	if !ok {
+		return DefaultCapabilities
+	}
+
+	return capable.Capabilities()
+}
+
+// CapabilityCheck tests the filesystem for the provided capabilities and
+// returns true in case it supports all of them.
+func CapabilityCheck(fs Basic, capabilities Capability) bool {
+	fsCaps := Capabilities(fs)
+	return fsCaps&capabilities == capabilities
+}
diff --git a/vendor/gopkg.in/src-d/go-billy.v4/helper/chroot/chroot.go b/vendor/gopkg.in/src-d/go-billy.v4/helper/chroot/chroot.go
new file mode 100644
index 0000000000..44ddb3db53
--- /dev/null
+++ b/vendor/gopkg.in/src-d/go-billy.v4/helper/chroot/chroot.go
@@ -0,0 +1,242 @@
+package chroot
+
+import (
+	"os"
+	"path/filepath"
+	"strings"
+
+	"gopkg.in/src-d/go-billy.v4"
+	"gopkg.in/src-d/go-billy.v4/helper/polyfill"
+)
+
+// ChrootHelper is a helper to implement billy.Chroot.
+type ChrootHelper struct {
+	underlying billy.Filesystem
+	base       string
+}
+
+// New creates a new filesystem wrapping up the given 'fs'.
+// The created filesystem has its base in the given ChrootHelperectory of the
+// underlying filesystem.
+func New(fs billy.Basic, base string) billy.Filesystem {
+	return &ChrootHelper{
+		underlying: polyfill.New(fs),
+		base:       base,
+	}
+}
+
+func (fs *ChrootHelper) underlyingPath(filename string) (string, error) {
+	if isCrossBoundaries(filename) {
+		return "", billy.ErrCrossedBoundary
+	}
+
+	return fs.Join(fs.Root(), filename), nil
+}
+
+func isCrossBoundaries(path string) bool {
+	path = filepath.ToSlash(path)
+	path = filepath.Clean(path)
+
+	return strings.HasPrefix(path, ".."+string(filepath.Separator))
+}
+
+func (fs *ChrootHelper) Create(filename string) (billy.File, error) {
+	fullpath, err := fs.underlyingPath(filename)
+	if err != nil {
+		return nil, err
+	}
+
+	f, err := fs.underlying.Create(fullpath)
+	if err != nil {
+		return nil, err
+	}
+
+	return newFile(fs, f, filename), nil
+}
+
+func (fs *ChrootHelper) Open(filename string) (billy.File, error) {
+	fullpath, err := fs.underlyingPath(filename)
+	if err != nil {
+		return nil, err
+	}
+
+	f, err := fs.underlying.Open(fullpath)
+	if err != nil {
+		return nil, err
+	}
+
+	return newFile(fs, f, filename), nil
+}
+
+func (fs *ChrootHelper) OpenFile(filename string, flag int, mode os.FileMode) (billy.File, error) {
+	fullpath, err := fs.underlyingPath(filename)
+	if err != nil {
+		return nil, err
+	}
+
+	f, err := fs.underlying.OpenFile(fullpath, flag, mode)
+	if err != nil {
+		return nil, err
+	}
+
+	return newFile(fs, f, filename), nil
+}
+
+func (fs *ChrootHelper) Stat(filename string) (os.FileInfo, error) {
+	fullpath, err := fs.underlyingPath(filename)
+	if err != nil {
+		return nil, err
+	}
+
+	return fs.underlying.Stat(fullpath)
+}
+
+func (fs *ChrootHelper) Rename(from, to string) error {
+	var err error
+	from, err = fs.underlyingPath(from)
+	if err != nil {
+		return err
+	}
+
+	to, err = fs.underlyingPath(to)
+	if err != nil {
+		return err
+	}
+
+	return fs.underlying.Rename(from, to)
+}
+
+func (fs *ChrootHelper) Remove(path string) error {
+	fullpath, err := fs.underlyingPath(path)
+	if err != nil {
+		return err
+	}
+
+	return fs.underlying.Remove(fullpath)
+}
+
+func (fs *ChrootHelper) Join(elem ...string) string {
+	return fs.underlying.Join(elem...)
+}
+
+func (fs *ChrootHelper) TempFile(dir, prefix string) (billy.File, error) {
+	fullpath, err := fs.underlyingPath(dir)
+	if err != nil {
+		return nil, err
+	}
+
+	f, err := fs.underlying.(billy.TempFile).TempFile(fullpath, prefix)
+	if err != nil {
+		return nil, err
+	}
+
+	return newFile(fs, f, fs.Join(dir, filepath.Base(f.Name()))), nil
+}
+
+func (fs *ChrootHelper) ReadDir(path string) ([]os.FileInfo, error) {
+	fullpath, err := fs.underlyingPath(path)
+	if err != nil {
+		return nil, err
+	}
+
+	return fs.underlying.(billy.Dir).ReadDir(fullpath)
+}
+
+func (fs *ChrootHelper) MkdirAll(filename string, perm os.FileMode) error {
+	fullpath, err := fs.underlyingPath(filename)
+	if err != nil {
+		return err
+	}
+
+	return fs.underlying.(billy.Dir).MkdirAll(fullpath, perm)
+}
+
+func (fs *ChrootHelper) Lstat(filename string) (os.FileInfo, error) {
+	fullpath, err := fs.underlyingPath(filename)
+	if err != nil {
+		return nil, err
+	}
+
+	return fs.underlying.(billy.Symlink).Lstat(fullpath)
+}
+
+func (fs *ChrootHelper) Symlink(target, link string) error {
+	target = filepath.FromSlash(target)
+
+	// only rewrite target if it's already absolute
+	if filepath.IsAbs(target) || strings.HasPrefix(target, string(filepath.Separator)) {
+		target = fs.Join(fs.Root(), target)
+		target = filepath.Clean(filepath.FromSlash(target))
+	}
+
+	link, err := fs.underlyingPath(link)
+	if err != nil {
+		return err
+	}
+
+	return fs.underlying.(billy.Symlink).Symlink(target, link)
+}
+
+func (fs *ChrootHelper) Readlink(link string) (string, error) {
+	fullpath, err := fs.underlyingPath(link)
+	if err != nil {
+		return "", err
+	}
+
+	target, err := fs.underlying.(billy.Symlink).Readlink(fullpath)
+	if err != nil {
+		return "", err
+	}
+
+	if !filepath.IsAbs(target) && !strings.HasPrefix(target, string(filepath.Separator)) {
+		return target, nil
+	}
+
+	target, err = filepath.Rel(fs.base, target)
+	if err != nil {
+		return "", err
+	}
+
+	return string(os.PathSeparator) + target, nil
+}
+
+func (fs *ChrootHelper) Chroot(path string) (billy.Filesystem, error) {
+	fullpath, err := fs.underlyingPath(path)
+	if err != nil {
+		return nil, err
+	}
+
+	return New(fs.underlying, fullpath), nil
+}
+
+func (fs *ChrootHelper) Root() string {
+	return fs.base
+}
+
+func (fs *ChrootHelper) Underlying() billy.Basic {
+	return fs.underlying
+}
+
+// Capabilities implements the Capable interface.
+func (fs *ChrootHelper) Capabilities() billy.Capability {
+	return billy.Capabilities(fs.underlying)
+}
+
+type file struct {
+	billy.File
+	name string
+}
+
+func newFile(fs billy.Filesystem, f billy.File, filename string) billy.File {
+	filename = fs.Join(fs.Root(), filename)
+	filename, _ = filepath.Rel(fs.Root(), filename)
+
+	return &file{
+		File: f,
+		name: filename,
+	}
+}
+
+func (f *file) Name() string {
+	return f.name
+}
diff --git a/vendor/gopkg.in/src-d/go-billy.v4/helper/polyfill/polyfill.go b/vendor/gopkg.in/src-d/go-billy.v4/helper/polyfill/polyfill.go
new file mode 100644
index 0000000000..f613c255d9
--- /dev/null
+++ b/vendor/gopkg.in/src-d/go-billy.v4/helper/polyfill/polyfill.go
@@ -0,0 +1,105 @@
+package polyfill
+
+import (
+	"os"
+	"path/filepath"
+
+	"gopkg.in/src-d/go-billy.v4"
+)
+
+// Polyfill is a helper that implements all missing method from billy.Filesystem.
+type Polyfill struct {
+	billy.Basic
+	c capabilities
+}
+
+type capabilities struct{ tempfile, dir, symlink, chroot bool }
+
+// New creates a new filesystem wrapping up 'fs' the intercepts all the calls
+// made and errors if fs doesn't implement any of the billy interfaces.
+func New(fs billy.Basic) billy.Filesystem {
+	if original, ok := fs.(billy.Filesystem); ok {
+		return original
+	}
+
+	h := &Polyfill{Basic: fs}
+
+	_, h.c.tempfile = h.Basic.(billy.TempFile)
+	_, h.c.dir = h.Basic.(billy.Dir)
+	_, h.c.symlink = h.Basic.(billy.Symlink)
+	_, h.c.chroot = h.Basic.(billy.Chroot)
+	return h
+}
+
+func (h *Polyfill) TempFile(dir, prefix string) (billy.File, error) {
+	if !h.c.tempfile {
+		return nil, billy.ErrNotSupported
+	}
+
+	return h.Basic.(billy.TempFile).TempFile(dir, prefix)
+}
+
+func (h *Polyfill) ReadDir(path string) ([]os.FileInfo, error) {
+	if !h.c.dir {
+		return nil, billy.ErrNotSupported
+	}
+
+	return h.Basic.(billy.Dir).ReadDir(path)
+}
+
+func (h *Polyfill) MkdirAll(filename string, perm os.FileMode) error {
+	if !h.c.dir {
+		return billy.ErrNotSupported
+	}
+
+	return h.Basic.(billy.Dir).MkdirAll(filename, perm)
+}
+
+func (h *Polyfill) Symlink(target, link string) error {
+	if !h.c.symlink {
+		return billy.ErrNotSupported
+	}
+
+	return h.Basic.(billy.Symlink).Symlink(target, link)
+}
+
+func (h *Polyfill) Readlink(link string) (string, error) {
+	if !h.c.symlink {
+		return "", billy.ErrNotSupported
+	}
+
+	return h.Basic.(billy.Symlink).Readlink(link)
+}
+
+func (h *Polyfill) Lstat(path string) (os.FileInfo, error) {
+	if !h.c.symlink {
+		return nil, billy.ErrNotSupported
+	}
+
+	return h.Basic.(billy.Symlink).Lstat(path)
+}
+
+func (h *Polyfill) Chroot(path string) (billy.Filesystem, error) {
+	if !h.c.chroot {
+		return nil, billy.ErrNotSupported
+	}
+
+	return h.Basic.(billy.Chroot).Chroot(path)
+}
+
+func (h *Polyfill) Root() string {
+	if !h.c.chroot {
+		return string(filepath.Separator)
+	}
+
+	return h.Basic.(billy.Chroot).Root()
+}
+
+func (h *Polyfill) Underlying() billy.Basic {
+	return h.Basic
+}
+
+// Capabilities implements the Capable interface.
+func (h *Polyfill) Capabilities() billy.Capability {
+	return billy.Capabilities(h.Basic)
+}
diff --git a/vendor/gopkg.in/src-d/go-billy.v4/osfs/os.go b/vendor/gopkg.in/src-d/go-billy.v4/osfs/os.go
new file mode 100644
index 0000000000..ff35a3ba96
--- /dev/null
+++ b/vendor/gopkg.in/src-d/go-billy.v4/osfs/os.go
@@ -0,0 +1,139 @@
+// Package osfs provides a billy filesystem for the OS.
+package osfs // import "gopkg.in/src-d/go-billy.v4/osfs"
+
+import (
+	"io/ioutil"
+	"os"
+	"path/filepath"
+	"sync"
+
+	"gopkg.in/src-d/go-billy.v4"
+	"gopkg.in/src-d/go-billy.v4/helper/chroot"
+)
+
+const (
+	defaultDirectoryMode = 0755
+	defaultCreateMode    = 0666
+)
+
+// OS is a filesystem based on the os filesystem.
+type OS struct{}
+
+// New returns a new OS filesystem.
+func New(baseDir string) billy.Filesystem {
+	return chroot.New(&OS{}, baseDir)
+}
+
+func (fs *OS) Create(filename string) (billy.File, error) {
+	return fs.OpenFile(filename, os.O_RDWR|os.O_CREATE|os.O_TRUNC, defaultCreateMode)
+}
+
+func (fs *OS) OpenFile(filename string, flag int, perm os.FileMode) (billy.File, error) {
+	if flag&os.O_CREATE != 0 {
+		if err := fs.createDir(filename); err != nil {
+			return nil, err
+		}
+	}
+
+	f, err := os.OpenFile(filename, flag, perm)
+	if err != nil {
+		return nil, err
+	}
+	return &file{File: f}, err
+}
+
+func (fs *OS) createDir(fullpath string) error {
+	dir := filepath.Dir(fullpath)
+	if dir != "." {
+		if err := os.MkdirAll(dir, defaultDirectoryMode); err != nil {
+			return err
+		}
+	}
+
+	return nil
+}
+
+func (fs *OS) ReadDir(path string) ([]os.FileInfo, error) {
+	l, err := ioutil.ReadDir(path)
+	if err != nil {
+		return nil, err
+	}
+
+	var s = make([]os.FileInfo, len(l))
+	for i, f := range l {
+		s[i] = f
+	}
+
+	return s, nil
+}
+
+func (fs *OS) Rename(from, to string) error {
+	if err := fs.createDir(to); err != nil {
+		return err
+	}
+
+	return os.Rename(from, to)
+}
+
+func (fs *OS) MkdirAll(path string, perm os.FileMode) error {
+	return os.MkdirAll(path, defaultDirectoryMode)
+}
+
+func (fs *OS) Open(filename string) (billy.File, error) {
+	return fs.OpenFile(filename, os.O_RDONLY, 0)
+}
+
+func (fs *OS) Stat(filename string) (os.FileInfo, error) {
+	return os.Stat(filename)
+}
+
+func (fs *OS) Remove(filename string) error {
+	return os.Remove(filename)
+}
+
+func (fs *OS) TempFile(dir, prefix string) (billy.File, error) {
+	if err := fs.createDir(dir + string(os.PathSeparator)); err != nil {
+		return nil, err
+	}
+
+	f, err := ioutil.TempFile(dir, prefix)
+	if err != nil {
+		return nil, err
+	}
+	return &file{File: f}, nil
+}
+
+func (fs *OS) Join(elem ...string) string {
+	return filepath.Join(elem...)
+}
+
+func (fs *OS) RemoveAll(path string) error {
+	return os.RemoveAll(filepath.Clean(path))
+}
+
+func (fs *OS) Lstat(filename string) (os.FileInfo, error) {
+	return os.Lstat(filepath.Clean(filename))
+}
+
+func (fs *OS) Symlink(target, link string) error {
+	if err := fs.createDir(link); err != nil {
+		return err
+	}
+
+	return os.Symlink(target, link)
+}
+
+func (fs *OS) Readlink(link string) (string, error) {
+	return os.Readlink(link)
+}
+
+// Capabilities implements the Capable interface.
+func (fs *OS) Capabilities() billy.Capability {
+	return billy.DefaultCapabilities
+}
+
+// file is a wrapper for an os.File which adds support for file locking.
+type file struct {
+	*os.File
+	m sync.Mutex
+}
diff --git a/vendor/gopkg.in/src-d/go-billy.v4/osfs/os_posix.go b/vendor/gopkg.in/src-d/go-billy.v4/osfs/os_posix.go
new file mode 100644
index 0000000000..0eda3bd300
--- /dev/null
+++ b/vendor/gopkg.in/src-d/go-billy.v4/osfs/os_posix.go
@@ -0,0 +1,21 @@
+// +build !windows
+
+package osfs
+
+import (
+	"syscall"
+)
+
+func (f *file) Lock() error {
+	f.m.Lock()
+	defer f.m.Unlock()
+
+	return syscall.Flock(int(f.File.Fd()), syscall.LOCK_EX)
+}
+
+func (f *file) Unlock() error {
+	f.m.Lock()
+	defer f.m.Unlock()
+
+	return syscall.Flock(int(f.File.Fd()), syscall.LOCK_UN)
+}
diff --git a/vendor/gopkg.in/src-d/go-billy.v4/osfs/os_windows.go b/vendor/gopkg.in/src-d/go-billy.v4/osfs/os_windows.go
new file mode 100644
index 0000000000..5eb98829d0
--- /dev/null
+++ b/vendor/gopkg.in/src-d/go-billy.v4/osfs/os_windows.go
@@ -0,0 +1,57 @@
+// +build windows
+
+package osfs
+
+import (
+	"os"
+	"runtime"
+	"unsafe"
+
+	"golang.org/x/sys/windows"
+)
+
+type fileInfo struct {
+	os.FileInfo
+	name string
+}
+
+func (fi *fileInfo) Name() string {
+	return fi.name
+}
+
+var (
+	kernel32DLL    = windows.NewLazySystemDLL("kernel32.dll")
+	lockFileExProc = kernel32DLL.NewProc("LockFileEx")
+	unlockFileProc = kernel32DLL.NewProc("UnlockFile")
+)
+
+const (
+	lockfileExclusiveLock = 0x2
+)
+
+func (f *file) Lock() error {
+	f.m.Lock()
+	defer f.m.Unlock()
+
+	var overlapped windows.Overlapped
+	// err is always non-nil as per sys/windows semantics.
+	ret, _, err := lockFileExProc.Call(f.File.Fd(), lockfileExclusiveLock, 0, 0xFFFFFFFF, 0,
+		uintptr(unsafe.Pointer(&overlapped)))
+	runtime.KeepAlive(&overlapped)
+	if ret == 0 {
+		return err
+	}
+	return nil
+}
+
+func (f *file) Unlock() error {
+	f.m.Lock()
+	defer f.m.Unlock()
+
+	// err is always non-nil as per sys/windows semantics.
+	ret, _, err := unlockFileProc.Call(f.File.Fd(), 0, 0, 0xFFFFFFFF, 0)
+	if ret == 0 {
+		return err
+	}
+	return nil
+}
diff --git a/vendor/gopkg.in/src-d/go-billy.v4/util/glob.go b/vendor/gopkg.in/src-d/go-billy.v4/util/glob.go
new file mode 100644
index 0000000000..fdcb3e5f0a
--- /dev/null
+++ b/vendor/gopkg.in/src-d/go-billy.v4/util/glob.go
@@ -0,0 +1,111 @@
+package util
+
+import (
+	"path/filepath"
+	"sort"
+	"strings"
+
+	"gopkg.in/src-d/go-billy.v4"
+)
+
+// Glob returns the names of all files matching pattern or nil
+// if there is no matching file. The syntax of patterns is the same
+// as in Match. The pattern may describe hierarchical names such as
+// /usr/*/bin/ed (assuming the Separator is '/').
+//
+// Glob ignores file system errors such as I/O errors reading directories.
+// The only possible returned error is ErrBadPattern, when pattern
+// is malformed.
+//
+// Function originally from https://golang.org/src/path/filepath/match_test.go
+func Glob(fs billy.Filesystem, pattern string) (matches []string, err error) {
+	if !hasMeta(pattern) {
+		if _, err = fs.Lstat(pattern); err != nil {
+			return nil, nil
+		}
+		return []string{pattern}, nil
+	}
+
+	dir, file := filepath.Split(pattern)
+	// Prevent infinite recursion. See issue 15879.
+	if dir == pattern {
+		return nil, filepath.ErrBadPattern
+	}
+
+	var m []string
+	m, err = Glob(fs, cleanGlobPath(dir))
+	if err != nil {
+		return
+	}
+	for _, d := range m {
+		matches, err = glob(fs, d, file, matches)
+		if err != nil {
+			return
+		}
+	}
+	return
+}
+
+// cleanGlobPath prepares path for glob matching.
+func cleanGlobPath(path string) string {
+	switch path {
+	case "":
+		return "."
+	case string(filepath.Separator):
+		// do nothing to the path
+		return path
+	default:
+		return path[0 : len(path)-1] // chop off trailing separator
+	}
+}
+
+// glob searches for files matching pattern in the directory dir
+// and appends them to matches. If the directory cannot be
+// opened, it returns the existing matches. New matches are
+// added in lexicographical order.
+func glob(fs billy.Filesystem, dir, pattern string, matches []string) (m []string, e error) {
+	m = matches
+	fi, err := fs.Stat(dir)
+	if err != nil {
+		return
+	}
+
+	if !fi.IsDir() {
+		return
+	}
+
+	names, _ := readdirnames(fs, dir)
+	sort.Strings(names)
+
+	for _, n := range names {
+		matched, err := filepath.Match(pattern, n)
+		if err != nil {
+			return m, err
+		}
+		if matched {
+			m = append(m, filepath.Join(dir, n))
+		}
+	}
+	return
+}
+
+// hasMeta reports whether path contains any of the magic characters
+// recognized by Match.
+func hasMeta(path string) bool {
+	// TODO(niemeyer): Should other magic characters be added here?
+	return strings.ContainsAny(path, "*?[")
+}
+
+func readdirnames(fs billy.Filesystem, dir string) ([]string, error) {
+	files, err := fs.ReadDir(dir)
+	if err != nil {
+		return nil, err
+	}
+
+	var names []string
+	for _, file := range files {
+		names = append(names, file.Name())
+	}
+
+	return names, nil
+}
diff --git a/vendor/gopkg.in/src-d/go-billy.v4/util/util.go b/vendor/gopkg.in/src-d/go-billy.v4/util/util.go
new file mode 100644
index 0000000000..cf7fb57f75
--- /dev/null
+++ b/vendor/gopkg.in/src-d/go-billy.v4/util/util.go
@@ -0,0 +1,224 @@
+package util
+
+import (
+	"io"
+	"os"
+	"path/filepath"
+	"strconv"
+	"sync"
+	"time"
+
+	"gopkg.in/src-d/go-billy.v4"
+)
+
+// RemoveAll removes path and any children it contains. It removes everything it
+// can but returns the first error it encounters. If the path does not exist,
+// RemoveAll returns nil (no error).
+func RemoveAll(fs billy.Basic, path string) error {
+	fs, path = getUnderlyingAndPath(fs, path)
+
+	if r, ok := fs.(removerAll); ok {
+		return r.RemoveAll(path)
+	}
+
+	return removeAll(fs, path)
+}
+
+type removerAll interface {
+	RemoveAll(string) error
+}
+
+func removeAll(fs billy.Basic, path string) error {
+	// This implementation is adapted from os.RemoveAll.
+
+	// Simple case: if Remove works, we're done.
+	err := fs.Remove(path)
+	if err == nil || os.IsNotExist(err) {
+		return nil
+	}
+
+	// Otherwise, is this a directory we need to recurse into?
+	dir, serr := fs.Stat(path)
+	if serr != nil {
+		if os.IsNotExist(serr) {
+			return nil
+		}
+
+		return serr
+	}
+
+	if !dir.IsDir() {
+		// Not a directory; return the error from Remove.
+		return err
+	}
+
+	dirfs, ok := fs.(billy.Dir)
+	if !ok {
+		return billy.ErrNotSupported
+	}
+
+	// Directory.
+	fis, err := dirfs.ReadDir(path)
+	if err != nil {
+		if os.IsNotExist(err) {
+			// Race. It was deleted between the Lstat and Open.
+			// Return nil per RemoveAll's docs.
+			return nil
+		}
+
+		return err
+	}
+
+	// Remove contents & return first error.
+	err = nil
+	for _, fi := range fis {
+		cpath := fs.Join(path, fi.Name())
+		err1 := removeAll(fs, cpath)
+		if err == nil {
+			err = err1
+		}
+	}
+
+	// Remove directory.
+	err1 := fs.Remove(path)
+	if err1 == nil || os.IsNotExist(err1) {
+		return nil
+	}
+
+	if err == nil {
+		err = err1
+	}
+
+	return err
+
+}
+
+// WriteFile writes data to a file named by filename in the given filesystem.
+// If the file does not exist, WriteFile creates it with permissions perm;
+// otherwise WriteFile truncates it before writing.
+func WriteFile(fs billy.Basic, filename string, data []byte, perm os.FileMode) error {
+	f, err := fs.OpenFile(filename, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, perm)
+	if err != nil {
+		return err
+	}
+
+	n, err := f.Write(data)
+	if err == nil && n < len(data) {
+		err = io.ErrShortWrite
+	}
+
+	if err1 := f.Close(); err == nil {
+		err = err1
+	}
+
+	return err
+}
+
+// Random number state.
+// We generate random temporary file names so that there's a good
+// chance the file doesn't exist yet - keeps the number of tries in
+// TempFile to a minimum.
+var rand uint32
+var randmu sync.Mutex
+
+func reseed() uint32 {
+	return uint32(time.Now().UnixNano() + int64(os.Getpid()))
+}
+
+func nextSuffix() string {
+	randmu.Lock()
+	r := rand
+	if r == 0 {
+		r = reseed()
+	}
+	r = r*1664525 + 1013904223 // constants from Numerical Recipes
+	rand = r
+	randmu.Unlock()
+	return strconv.Itoa(int(1e9 + r%1e9))[1:]
+}
+
+// TempFile creates a new temporary file in the directory dir with a name
+// beginning with prefix, opens the file for reading and writing, and returns
+// the resulting *os.File. If dir is the empty string, TempFile uses the default
+// directory for temporary files (see os.TempDir). Multiple programs calling
+// TempFile simultaneously will not choose the same file. The caller can use
+// f.Name() to find the pathname of the file. It is the caller's responsibility
+// to remove the file when no longer needed.
+func TempFile(fs billy.Basic, dir, prefix string) (f billy.File, err error) {
+	// This implementation is based on stdlib ioutil.TempFile.
+
+	if dir == "" {
+		dir = os.TempDir()
+	}
+
+	nconflict := 0
+	for i := 0; i < 10000; i++ {
+		name := filepath.Join(dir, prefix+nextSuffix())
+		f, err = fs.OpenFile(name, os.O_RDWR|os.O_CREATE|os.O_EXCL, 0600)
+		if os.IsExist(err) {
+			if nconflict++; nconflict > 10 {
+				randmu.Lock()
+				rand = reseed()
+				randmu.Unlock()
+			}
+			continue
+		}
+		break
+	}
+	return
+}
+
+// TempDir creates a new temporary directory in the directory dir
+// with a name beginning with prefix and returns the path of the
+// new directory. If dir is the empty string, TempDir uses the
+// default directory for temporary files (see os.TempDir).
+// Multiple programs calling TempDir simultaneously
+// will not choose the same directory. It is the caller's responsibility
+// to remove the directory when no longer needed.
+func TempDir(fs billy.Dir, dir, prefix string) (name string, err error) {
+	// This implementation is based on stdlib ioutil.TempDir
+
+	if dir == "" {
+		dir = os.TempDir()
+	}
+
+	nconflict := 0
+	for i := 0; i < 10000; i++ {
+		try := filepath.Join(dir, prefix+nextSuffix())
+		err = fs.MkdirAll(try, 0700)
+		if os.IsExist(err) {
+			if nconflict++; nconflict > 10 {
+				randmu.Lock()
+				rand = reseed()
+				randmu.Unlock()
+			}
+			continue
+		}
+		if os.IsNotExist(err) {
+			if _, err := os.Stat(dir); os.IsNotExist(err) {
+				return "", err
+			}
+		}
+		if err == nil {
+			name = try
+		}
+		break
+	}
+	return
+}
+
+type underlying interface {
+	Underlying() billy.Basic
+}
+
+func getUnderlyingAndPath(fs billy.Basic, path string) (billy.Basic, string) {
+	u, ok := fs.(underlying)
+	if !ok {
+		return fs, path
+	}
+	if ch, ok := fs.(billy.Chroot); ok {
+		path = fs.Join(ch.Root(), path)
+	}
+
+	return u.Underlying(), path
+}