Intermediate changes

commit_hash:0440953ee45e859ed9f13c00cc38df246289314f

2 files changed, 24 insertions, 3 deletions

diff --git a/library/python/fs/__init__.py b/library/python/fs/__init__.py
index 0beaf6665a6..f6bf04a7218 100644
--- a/library/python/fs/__init__.py
+++ b/library/python/fs/__init__.py
@@ -296,12 +296,27 @@ def copy_tree(src, dst, copy_function=shutil.copy2):
 # File read
 # Throws OSError
 @errorfix_win
-def read_file(path, binary=True):
+def read_file(path, binary=True, size=-1):
+    """
+    Read file contents
+
+    :param path:
+        File path
+
+    :param binary:
+        If `True`, read in binary mode. Read in text mode otherwise.
+
+    :param size:
+        An optional numeric argument.
+        When size is omitted or negative, the entire contents of the file will be read and returned;
+        it’s your problem if the file is twice as large as your machine’s memory.
+        Otherwise, at most size characters (in text mode) or size bytes (in binary mode) are read and returned.
+    """
     kwargs = {}
     if not binary and six.PY3:
         kwargs['encoding'] = sys.getfilesystemencoding()
     with open(path, 'r' + ('b' if binary else ''), **kwargs) as f:
-        return f.read()
+        return f.read(size)
 
 
 # Text file read
diff --git a/library/python/fs/test/test_fs.py b/library/python/fs/test/test_fs.py
index 9e2c70c0690..066c0237a4a 100644
--- a/library/python/fs/test/test_fs.py
+++ b/library/python/fs/test/test_fs.py
@@ -808,6 +808,10 @@ def test_read_file(path):
     mkfile(path('src'), 'SRC')
     assert library.python.fs.read_file(path('src')).decode(library.python.strings.fs_encoding()) == 'SRC'
     assert library.python.fs.read_file(path('src'), binary=False) == 'SRC'
+    # test size
+    assert library.python.fs.read_file(path('src'), size=2, binary=False) == 'SR'
+    assert library.python.fs.read_file(path('src'), size=100, binary=False) == 'SRC'
+    assert library.python.fs.read_file(path('src'), size=-1, binary=False) == 'SRC'
 
 
 @in_env
@@ -1023,7 +1027,9 @@ def test_copy2():
 
 def test_commonpath():
     pj = os.path.join
-    pja = lambda *x: os.path.abspath(pj(*x))
+
+    def pja(*x):
+        return os.path.abspath(pj(*x))
 
     assert library.python.fs.commonpath(['a', 'b']) == ''
     assert library.python.fs.commonpath([pj('t', '1')]) == pj('t', '1')