authenticate using ssh agent

pygit2/credentials.py

@@ -85,3 +85,8 @@ class Keypair(object):
 
     def __call__(self, _url, _username, _allowed):
         return self
+
+
+class KeypairFromAgent(Keypair):
+    def __init__(self, username):
+        super(KeypairFromAgent, self).__init__(username, None, None, None)

pygit2/decl.h

@@ -204,6 +204,9 @@ int git_cred_ssh_key_new(
 	const char *publickey,
 	const char *privatekey,
 	const char *passphrase);
+int git_cred_ssh_key_from_agent(
+    git_cred **out,
+    const char *username);
 
 /*
  * git_diff

pygit2/remote.py

@@ -32,6 +32,7 @@ from __future__ import absolute_import
 from _pygit2 import Oid
 from .errors import check_error, GitError
 from .ffi import ffi, C
+from .credentials import KeypairFromAgent
 from .refspec import Refspec
 from .utils import to_bytes, strarray_to_strings, strings_to_strarray
 
@@ -455,10 +456,14 @@ def get_credentials(fn, url, username, allowed):
                                                 to_bytes(passwd))
 
     elif cred_type == C.GIT_CREDTYPE_SSH_KEY:
-        name, pubkey, privkey, passphrase = creds.credential_tuple
+        if isinstance(creds, KeypairFromAgent):
-        err = C.git_cred_ssh_key_new(ccred, to_bytes(name), to_bytes(pubkey),
+            username = creds.credential_tuple[0]
-                                     to_bytes(privkey), to_bytes(passphrase))
+            err = C.git_cred_ssh_key_from_agent(ccred, to_bytes(username))
-
+        else:
+            name, pubkey, privkey, passphrase = creds.credential_tuple
+            err = C.git_cred_ssh_key_new(ccred, to_bytes(name),
+                                         to_bytes(pubkey), to_bytes(privkey),
+                                         to_bytes(passphrase))
     else:
         raise TypeError("unsupported credential type")
 

test/test_credentials.py

@@ -31,6 +31,7 @@
 import unittest
 import pygit2
 from pygit2 import GIT_CREDTYPE_USERPASS_PLAINTEXT
+from pygit2 import UserPass, Keypair, KeypairFromAgent
 from pygit2 import UserPass, Keypair
 from . import utils
 
@@ -60,6 +61,13 @@ class CredentialCreateTest(utils.NoRepoTestCase):
         cred = Keypair(username, pubkey, privkey, passphrase)
         self.assertEqual((username, pubkey, privkey, passphrase), cred.credential_tuple)
 
+    def test_ssh_agent(self):
+        username = "git"
+ 
+        cred = KeypairFromAgent(username)
+        self.assertEqual((username, None, None, None), cred.credential_tuple)
+
+
 class CredentialCallback(utils.RepoTestCase):
     def test_callback(self):
         def credentials_cb(url, username, allowed):