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, 167 insertions, 164 deletions

diff --git a/formats/packfile/doc.go b/formats/packfile/doc.go
index cb3f542..c79c180 100644
--- a/formats/packfile/doc.go
+++ b/formats/packfile/doc.go
@@ -1,165 +1,168 @@
-package packfile
+// Package packfile documentation:
+/*
+
+GIT pack format
+===============
+
+== pack-*.pack files have the following format:
+
+   - A header appears at the beginning and consists of the following:
+
+     4-byte signature:
+         The signature is: {'P', 'A', 'C', 'K'}
+
+     4-byte version number (network byte order):
+         GIT currently accepts version number 2 or 3 but
+         generates version 2 only.
+
+     4-byte number of objects contained in the pack (network byte order)
+
+     Observation: we cannot have more than 4G versions ;-) and
+     more than 4G objects in a pack.
+
+   - The header is followed by number of object entries, each of
+     which looks like this:
+
+     (undeltified representation)
+     n-byte type and length (3-bit type, (n-1)*7+4-bit length)
+     compressed data
+
+     (deltified representation)
+     n-byte type and length (3-bit type, (n-1)*7+4-bit length)
+     20-byte base object name
+     compressed delta data
+
+     Observation: length of each object is encoded in a variable
+     length format and is not constrained to 32-bit or anything.
+
+  - The trailer records 20-byte SHA1 checksum of all of the above.
+
+== Original (version 1) pack-*.idx files have the following format:
+
+  - The header consists of 256 4-byte network byte order
+    integers.  N-th entry of this table records the number of
+    objects in the corresponding pack, the first byte of whose
+    object name is less than or equal to N.  This is called the
+    'first-level fan-out' table.
+
+  - The header is followed by sorted 24-byte entries, one entry
+    per object in the pack.  Each entry is:
+
+    4-byte network byte order integer, recording where the
+    object is stored in the packfile as the offset from the
+    beginning.
+
+    20-byte object name.
+
+  - The file is concluded with a trailer:
+
+    A copy of the 20-byte SHA1 checksum at the end of
+    corresponding packfile.
 
-// GIT pack format
-// ===============
-//
-// == pack-*.pack files have the following format:
-//
-//    - A header appears at the beginning and consists of the following:
-//
-//      4-byte signature:
-//          The signature is: {'P', 'A', 'C', 'K'}
-//
-//      4-byte version number (network byte order):
-//          GIT currently accepts version number 2 or 3 but
-//          generates version 2 only.
-//
-//      4-byte number of objects contained in the pack (network byte order)
-//
-//      Observation: we cannot have more than 4G versions ;-) and
-//      more than 4G objects in a pack.
-//
-//    - The header is followed by number of object entries, each of
-//      which looks like this:
-//
-//      (undeltified representation)
-//      n-byte type and length (3-bit type, (n-1)*7+4-bit length)
-//      compressed data
-//
-//      (deltified representation)
-//      n-byte type and length (3-bit type, (n-1)*7+4-bit length)
-//      20-byte base object name
-//      compressed delta data
-//
-//      Observation: length of each object is encoded in a variable
-//      length format and is not constrained to 32-bit or anything.
-//
-//   - The trailer records 20-byte SHA1 checksum of all of the above.
-//
-// == Original (version 1) pack-*.idx files have the following format:
-//
-//   - The header consists of 256 4-byte network byte order
-//     integers.  N-th entry of this table records the number of
-//     objects in the corresponding pack, the first byte of whose
-//     object name is less than or equal to N.  This is called the
-//     'first-level fan-out' table.
-//
-//   - The header is followed by sorted 24-byte entries, one entry
-//     per object in the pack.  Each entry is:
-//
-//     4-byte network byte order integer, recording where the
-//     object is stored in the packfile as the offset from the
-//     beginning.
-//
-//     20-byte object name.
-//
-//   - The file is concluded with a trailer:
-//
-//     A copy of the 20-byte SHA1 checksum at the end of
-//     corresponding packfile.
-//
-//     20-byte SHA1-checksum of all of the above.
-//
-// Pack Idx file:
-//
-//     --  +--------------------------------+
-// fanout  | fanout[0] = 2 (for example)    |-.
-// table   +--------------------------------+ |
-//         | fanout[1]                      | |
-//         +--------------------------------+ |
-//         | fanout[2]                      | |
-//         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ |
-//         | fanout[255] = total objects    |---.
-//     --  +--------------------------------+ | |
-// main        | offset                         | | |
-// index       | object name 00XXXXXXXXXXXXXXXX | | |
-// table       +--------------------------------+ | |
-//         | offset                         | | |
-//         | object name 00XXXXXXXXXXXXXXXX | | |
-//         +--------------------------------+<+ |
-//       .-| offset                         |   |
-//       | | object name 01XXXXXXXXXXXXXXXX |   |
-//       | +--------------------------------+   |
-//       | | offset                         |   |
-//       | | object name 01XXXXXXXXXXXXXXXX |   |
-//       | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~   |
-//       | | offset                         |   |
-//       | | object name FFXXXXXXXXXXXXXXXX |   |
-//     --| +--------------------------------+<--+
-// trailer   | | packfile checksum              |
-//       | +--------------------------------+
-//       | | idxfile checksum               |
-//       | +--------------------------------+
-//           .-------.
-//                   |
-// Pack file entry: <+
-//
-//      packed object header:
-//     1-byte size extension bit (MSB)
-//            type (next 3 bit)
-//            size0 (lower 4-bit)
-//         n-byte sizeN (as long as MSB is set, each 7-bit)
-//         size0..sizeN form 4+7+7+..+7 bit integer, size0
-//         is the least significant part, and sizeN is the
-//         most significant part.
-//      packed object data:
-//         If it is not DELTA, then deflated bytes (the size above
-//         is the size before compression).
-//     If it is REF_DELTA, then
-//       20-byte base object name SHA1 (the size above is the
-//         size of the delta data that follows).
-//           delta data, deflated.
-//     If it is OFS_DELTA, then
-//       n-byte offset (see below) interpreted as a negative
-//         offset from the type-byte of the header of the
-//         ofs-delta entry (the size above is the size of
-//         the delta data that follows).
-//       delta data, deflated.
-//
-//      offset encoding:
-//       n bytes with MSB set in all but the last one.
-//       The offset is then the number constructed by
-//       concatenating the lower 7 bit of each byte, and
-//       for n >= 2 adding 2^7 + 2^14 + ... + 2^(7*(n-1))
-//       to the result.
-//
-//
-//
-// == Version 2 pack-*.idx files support packs larger than 4 GiB, and
-//    have some other reorganizations.  They have the format:
-//
-//   - A 4-byte magic number '\377tOc' which is an unreasonable
-//     fanout[0] value.
-//
-//   - A 4-byte version number (= 2)
-//
-//   - A 256-entry fan-out table just like v1.
-//
-//   - A table of sorted 20-byte SHA1 object names.  These are
-//     packed together without offset values to reduce the cache
-//     footprint of the binary search for a specific object name.
-//
-//   - A table of 4-byte CRC32 values of the packed object data.
-//     This is new in v2 so compressed data can be copied directly
-//     from pack to pack during repacking without undetected
-//     data corruption.
-//
-//   - A table of 4-byte offset values (in network byte order).
-//     These are usually 31-bit pack file offsets, but large
-//     offsets are encoded as an index into the next table with
-//     the msbit set.
-//
-//   - A table of 8-byte offset entries (empty for pack files less
-//     than 2 GiB).  Pack files are organized with heavily used
-//     objects toward the front, so most object references should
-//     not need to refer to this table.
-//
-//   - The same trailer as a v1 pack file:
-//
-//     A copy of the 20-byte SHA1 checksum at the end of
-//     corresponding packfile.
-//
-//     20-byte SHA1-checksum of all of the above.
-//
-// From:
-// https://www.kernel.org/pub/software/scm/git/docs/v1.7.5/technical/pack-protocol.txt
+    20-byte SHA1-checksum of all of the above.
+
+Pack Idx file:
+
+    --  +--------------------------------+
+fanout  | fanout[0] = 2 (for example)    |-.
+table   +--------------------------------+ |
+        | fanout[1]                      | |
+        +--------------------------------+ |
+        | fanout[2]                      | |
+        ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ |
+        | fanout[255] = total objects    |---.
+    --  +--------------------------------+ | |
+main        | offset                         | | |
+index       | object name 00XXXXXXXXXXXXXXXX | | |
+table       +--------------------------------+ | |
+        | offset                         | | |
+        | object name 00XXXXXXXXXXXXXXXX | | |
+        +--------------------------------+<+ |
+      .-| offset                         |   |
+      | | object name 01XXXXXXXXXXXXXXXX |   |
+      | +--------------------------------+   |
+      | | offset                         |   |
+      | | object name 01XXXXXXXXXXXXXXXX |   |
+      | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~   |
+      | | offset                         |   |
+      | | object name FFXXXXXXXXXXXXXXXX |   |
+    --| +--------------------------------+<--+
+trailer   | | packfile checksum              |
+      | +--------------------------------+
+      | | idxfile checksum               |
+      | +--------------------------------+
+          .-------.
+                  |
+Pack file entry: <+
+
+     packed object header:
+    1-byte size extension bit (MSB)
+           type (next 3 bit)
+           size0 (lower 4-bit)
+        n-byte sizeN (as long as MSB is set, each 7-bit)
+        size0..sizeN form 4+7+7+..+7 bit integer, size0
+        is the least significant part, and sizeN is the
+        most significant part.
+     packed object data:
+        If it is not DELTA, then deflated bytes (the size above
+        is the size before compression).
+    If it is REF_DELTA, then
+      20-byte base object name SHA1 (the size above is the
+        size of the delta data that follows).
+          delta data, deflated.
+    If it is OFS_DELTA, then
+      n-byte offset (see below) interpreted as a negative
+        offset from the type-byte of the header of the
+        ofs-delta entry (the size above is the size of
+        the delta data that follows).
+      delta data, deflated.
+
+     offset encoding:
+      n bytes with MSB set in all but the last one.
+      The offset is then the number constructed by
+      concatenating the lower 7 bit of each byte, and
+      for n >= 2 adding 2^7 + 2^14 + ... + 2^(7*(n-1))
+      to the result.
+
+
+
+== Version 2 pack-*.idx files support packs larger than 4 GiB, and
+   have some other reorganizations.  They have the format:
+
+  - A 4-byte magic number '\377tOc' which is an unreasonable
+    fanout[0] value.
+
+  - A 4-byte version number (= 2)
+
+  - A 256-entry fan-out table just like v1.
+
+  - A table of sorted 20-byte SHA1 object names.  These are
+    packed together without offset values to reduce the cache
+    footprint of the binary search for a specific object name.
+
+  - A table of 4-byte CRC32 values of the packed object data.
+    This is new in v2 so compressed data can be copied directly
+    from pack to pack during repacking without undetected
+    data corruption.
+
+  - A table of 4-byte offset values (in network byte order).
+    These are usually 31-bit pack file offsets, but large
+    offsets are encoded as an index into the next table with
+    the msbit set.
+
+  - A table of 8-byte offset entries (empty for pack files less
+    than 2 GiB).  Pack files are organized with heavily used
+    objects toward the front, so most object references should
+    not need to refer to this table.
+
+  - The same trailer as a v1 pack file:
+
+    A copy of the 20-byte SHA1 checksum at the end of
+    corresponding packfile.
+
+    20-byte SHA1-checksum of all of the above.
+
+From:
+https://www.kernel.org/pub/software/scm/git/docs/v1.7.5/technical/pack-protocol.txt
+*/
+package packfile