add unpack + test against a temporary git repo

common/pack.js

@@ -0,0 +1,10 @@
+module.exports.getType = function(typeStr) {
+  return {
+    "001":"commit",
+    "010":"tree",
+    "011":"blob",
+    "100":"tag",
+    "110":"ofs_delta",
+    "111":"ref_delta"
+    }[typeStr]
+}

lib/pack/object.js

@@ -0,0 +1,24 @@
+var PackObject = function(type, buffer, offset) {
+  this.type = type;
+  this.buffer = buffer;
+  this.offset = offset;
+}
+
+PackObject.prototype.type = null;
+
+
+// createPackObject
+module.exports.createPackObject = function(type, buffer, offset) {
+  return new PackObject(type, buffer, offset);
+};
+
+module.exports.OBJ_BAD = -1,
+module.exports.OBJ_NONE = 0,
+module.exports.OBJ_COMMIT = 1,
+module.exports.OBJ_TREE = 2,
+module.exports.OBJ_BLOB = 3,
+module.exports.OBJ_TAG = 4,
+module.exports.OBJ_OFS_DELTA = 6,
+module.exports.OBJ_REF_DELTA = 7,
+module.exports.OBJ_ANY,
+module.exports.OBJ_MAX

lib/unpack.js

@@ -0,0 +1,102 @@
+
+// Unpack a git pack file
+// see: http://www.kernel.org/pub/software/scm/git/docs/technical/pack-format.txt
+
+var Buffer = require('buffer').Buffer,
+    packObject = require('./pack/object'),
+    getType = require('../common/pack').getType,
+    rawInflate = require('../common/rawinflate'),
+    Git = require('../git');;
+
+    // TODO: I really want to use this, but there is no way to get the
+    //       number of bytes it consumed
+    //zlib = require('zlib').createInflate();
+
+git = new Git();
+
+module.exports = function unpack(buffer, fn) {
+
+  var obj = {
+    version: null,
+    count: null,
+    objects : []
+  },
+  where = 0,
+  fwd = function(amount) {
+    where += amount;
+    return where;
+  };
+
+  if (!Buffer.isBuffer(buffer)) {
+    return fn(new Error('Unpack expects a buffer'));
+  }
+
+  if (buffer.length < 4 || buffer.slice(0, 4).toString('ascii') !== 'PACK') {
+    return fn(new Error('Invalid signature'));
+  }
+
+  if (buffer.length < 8) {
+    return fn(new Error('Invalid version length'));
+  }
+
+  obj.version = buffer.readUInt32BE(4);
+  if (obj.version !== 2) {
+    return fn(new Error('Invalid version (expected 2)'));
+  }
+
+  if (buffer.length < 12) {
+    return fn(new Error('Invalid object count'));
+  }
+
+  obj.count = buffer.readUInt32BE(8);
+
+  if (obj.count > 0 && buffer.length === 12) {
+    return fn(new Error('Invalid object entry section'), obj)
+  }
+
+  var where = 12, objectIndex = 0;
+  var readObject = function(buffer) {
+    if (objectIndex < obj.count) {
+
+      // Read the type
+      var c = buffer.readUInt8(where);
+
+      var type = (c >> 4) & 7;
+      var length = (c & 15);
+      var shift = 4;
+      var offset = where;
+
+      fwd(1);
+      while (c & 0x80) {
+        c = buffer.readUInt8(where);
+        length += (c & 0x7f) << shift;
+        shift += 7;
+        fwd(1);
+      }
+
+      var inflated = rawInflate(git.bytesToString(buffer.slice(fwd(2))));
+      // TODO: WARNING!! the compressed length returned by this function is incorrect
+
+      // TODO: collect the sha
+      if (type === packObject.OBJ_OFS_DELTA || type === packObject.OBJ_REF_DELTA) {
+        fwd(20);
+      }
+
+      fwd(inflated.compressedLength + 4);
+
+      obj.objects.push(packObject.createPackObject(type, inflated.toString() , offset));
+
+      process.nextTick(function() {
+        objectIndex++;
+        readObject(buffer);
+      });
+
+    } else {
+      console.log(obj);
+      process.exit();
+      fn(null, obj);
+    }
+  };
+
+  readObject(buffer);
+};

package.json

@@ -3,12 +3,13 @@
   "description": "A subset of git features implemented in nodejs with streams",
   "version": "0.0.1",
   "dependencies": {
-    "request": "*",
-    "rimraf": "~2.0.2",
-    "glob": "~3.1.14"
+    "request": "*"
   },
   "devDependencies": {
-    "tap": "*"
+    "tap": "*",
+    "rimraf": "~2.0.2",
+    "glob": "~3.1.14",
+    "cpr": "0.0.6"
   },
   "contributors": [
     {

test/fixtures/repo-pack/readme.md

@@ -1 +1 @@
-read this
+hello world

test/fixtures/repo.js

@@ -1,33 +1,45 @@
 var fs = require('fs'),
     exec = require('child_process').exec,
     glob = require('glob'),
-    rimraf = require('rimraf');
+    rimraf = require('rimraf'),
+    cpr = require('cpr').cpr;
 
-var packFile = __dirname + '/repo/.git/objects/pack/pack-82308c01d9ad8886e8c0003ddf5a83de8a60815f.pack';
-var packRepoPath =  __dirname + '/repo-pack/';
+
+var packRepoPath =  __dirname + '/tmp/repo-pack/';
 var packRepoOpts = { cwd : packRepoPath };
 
 module.exports.getPackFile = function(fn) {
 
-  exec('git init . && git add . && git commit -m "add readme" && git repack', packRepoOpts, function() {
-    exec('git count-objects -v', packRepoOpts, function(err, stdout) {
-      if (err) throw err;
+  cpr(__dirname + '/repo-pack/', packRepoPath, { deleteFirst: true }, function() {
 
-      var count = parseInt(stdout.split('\n').shift().split(' ').pop(), 10);
+    exec('git init . && git add . && git commit -m "add readme"', packRepoOpts, function() {
 
-      glob(packRepoPath + '/.git/objects/pack/*.pack', function(err, files) {
-        if (err) throw err;
 
-        var packFile = files[0];
+      fs.writeFileSync(packRepoPath + 'readme.md', "hello again");
 
-        fs.readFile(packFile, function(err, buffer) {
+      exec('git commit -am "change readme" && git repack && git verify-pack -v .git/objects/pack/pack-*.idx', packRepoOpts, function(e, out) {
+console.log(out);
+        exec('git count-objects -v', packRepoOpts, function(err, stdout) {
           if (err) throw err;
 
-          rimraf(packRepoPath + '/.git', function() {
-             fn(null, {
-               totalObjects: count,
-               buffer: buffer
-             });
+          var count = parseInt(stdout.split('\n').shift().split(' ').pop(), 10);
+
+          glob(packRepoPath + '/.git/objects/pack/*.pack', function(err, files) {
+            if (err) throw err;
+
+            var packFile = files[0];
+
+            fs.readFile(packFile, function(err, buffer) {
+              if (err) throw err;
+
+              // cleanup
+              //rimraf(packRepoPath, function() {
+                 fn(null, {
+                   totalObjects: count,
+                   buffer: buffer
+                 });
+              //});
+            });
           });
         });
       });