From 14c16992b563a77330478bcc6fecdb54df4300b5 Mon Sep 17 00:00:00 2001 From: Prashanth Pai Date: Tue, 23 Jun 2015 20:04:30 +0530 Subject: Add readinto() API readinto() This method is useful when you have to read a large file over multiple read calls. While read() allocates a buffer every time it's invoked, readinto() copies data to an already allocated buffer passed to it. Change-Id: Ic8a3aa0e544e09e05101c983b329c91864832e4a Signed-off-by: Prashanth Pai --- gluster/gfapi.py | 23 +++++++++++++++++++++++ 1 file changed, 23 insertions(+) (limited to 'gluster') diff --git a/gluster/gfapi.py b/gluster/gfapi.py index fa0e1b3..d6f847d 100755 --- a/gluster/gfapi.py +++ b/gluster/gfapi.py @@ -328,6 +328,29 @@ class File(object): err = ctypes.get_errno() raise OSError(err, os.strerror(err)) + def readinto(self, buf): + """ + Read up to len(buf) bytes into buf which must be a bytearray. + (buf cannot be a string as strings are immutable in python) + + This method is useful when you have to read a large file over + multiple read calls. While read() allocates a buffer every time + it's invoked, readinto() copies data to an already allocated + buffer passed to it. + + Returns the number of bytes read (0 for EOF). + """ + if type(buf) is bytearray: + buf_ptr = (ctypes.c_ubyte * len(buf)).from_buffer(buf) + else: + # TODO: Allow reading other types such as array.array + raise TypeError("buffer must of type bytearray") + nread = api.glfs_read(self.fd, buf_ptr, len(buf_ptr), 0) + if nread < 0: + err = ctypes.get_errno() + raise OSError(err, os.strerror(err)) + return nread + def write(self, data, flags=0): """ Write data to the file. -- cgit