Implements 'Repository.create_blob_fromiobase'.

This commit allows blobs to be constructed from implementatons of the
'RawIOBase' ABC.  This allows any conformant stream implementation to be added
as a blob.

This is useful in the case where the contents of the blob would be too large to
create from memory (as 'create_blob_fromstring' allows) and avoids having to
write the data to disk (as 'create_blob_fromworkdir' allows).  The latter
operation is especially useful when reading data from a network socket, since
it avoids having to first commit all the data to disk.

docs/objects.rst

@@ -132,6 +132,7 @@ them to the Git object database:
 
 .. automethod:: pygit2.Repository.create_blob_fromworkdir
 .. automethod:: pygit2.Repository.create_blob_fromdisk
+.. automethod:: pygit2.Repository.create_blob_fromiobase
 
 There are also some functions to calculate the id for a byte string without
 creating the blob object:

src/repository.c

@@ -736,6 +736,66 @@ Repository_create_blob_fromdisk(Repository *self, PyObject *args)
 }
 
 
+PyDoc_STRVAR(Repository_create_blob_fromiobase__doc__,
+    "create_blob_fromiobase(io.IOBase) -> Oid\n"
+    "\n"
+    "Create a new blob from an IOBase object.");
+
+
+int read_chunk(char *content, size_t max_length, void *payload)
+{
+    PyObject   *py_file;
+    PyObject   *py_bytes;
+    char       *bytes;
+    Py_ssize_t  size;
+
+    py_file  = (PyObject *)payload;
+    py_bytes = PyObject_CallMethod(py_file, "read", "i", max_length);
+    if (!py_bytes) {
+        return 0;
+    }
+
+    bytes = PyBytes_AsString(py_bytes);
+    size  = PyBytes_Size(py_bytes);
+    memcpy(content, bytes, size);
+
+    Py_DECREF(py_bytes);
+    return size;
+}
+
+PyObject *
+Repository_create_blob_fromiobase(Repository *self, PyObject *args)
+{
+    git_oid   oid;
+    PyObject *py_is_readable;
+    PyObject *py_file;
+    int       err;
+
+    if (!PyArg_ParseTuple(args, "O", &py_file))
+        return NULL;
+
+    py_is_readable = PyObject_CallMethod(py_file, "readable", NULL);
+    if (!py_is_readable || !PyObject_IsTrue(py_is_readable)) {
+        PyErr_SetString(PyExc_TypeError, "expected readable IO type");
+        Py_DECREF(py_is_readable);
+        return NULL;
+    }
+    Py_DECREF(py_is_readable);
+
+    err = git_blob_create_fromchunks(&oid,
+                                     self->repo,
+                                     NULL,
+                                     &read_chunk,
+                                     py_file);
+    Py_DECREF(py_file);
+
+    if (err < 0)
+        return Error_set(err);
+
+    return git_oid_to_python(&oid);
+}
+
+
 PyDoc_STRVAR(Repository_create_commit__doc__,
   "create_commit(reference, author, committer, message, tree, parents[, encoding]) -> Oid\n"
   "\n"
@@ -1386,6 +1446,7 @@ PyMethodDef Repository_methods[] = {
     METHOD(Repository, create_blob, METH_VARARGS),
     METHOD(Repository, create_blob_fromworkdir, METH_VARARGS),
     METHOD(Repository, create_blob_fromdisk, METH_VARARGS),
+    METHOD(Repository, create_blob_fromiobase, METH_VARARGS),
     METHOD(Repository, create_commit, METH_VARARGS),
     METHOD(Repository, create_tag, METH_VARARGS),
     METHOD(Repository, TreeBuilder, METH_VARARGS),

test/test_blob.py

@@ -30,6 +30,7 @@
 from __future__ import absolute_import
 from __future__ import unicode_literals
 from os.path import dirname, join
+import io
 import unittest
 
 import pygit2
@@ -112,6 +113,17 @@ class BlobTest(utils.RepoTestCase):
         self.assertTrue(isinstance(blob, pygit2.Blob))
         self.assertEqual(pygit2.GIT_OBJ_BLOB, blob.type)
 
+    def test_create_blob_fromiobase(self):
+        f = io.BytesIO(BLOB_CONTENT)
+        blob_oid = self.repo.create_blob_fromiobase(f)
+        blob = self.repo[blob_oid]
+
+        self.assertTrue(isinstance(blob, pygit2.Blob))
+        self.assertEqual(pygit2.GIT_OBJ_BLOB, blob.type)
+
+        self.assertEqual(blob_oid, blob.id)
+        self.assertEqual(BLOB_SHA, blob_oid.hex)
+
     def test_diff_blob(self):
         blob = self.repo[BLOB_SHA]
         old_blob = self.repo['3b18e512dba79e4c8300dd08aeb37f8e728b8dad']