Fix all instances of file.write() for py3

In python 3, file.write() may do a partial write and returns the number of characters written.
In order to not lose data, we need to wrap every instance of file.write() with our new
common.writeall() wrapper that loops until the data is actually written.

backfiller/backfiller/main.py

@@ -149,7 +149,7 @@ def get_remote_segment(base_dir, node, channel, quality, hour, missing_segment,
 
 		with open(temp_path, 'wb') as f:
 			for chunk in resp.iter_content(8192):
-				f.write(chunk)
+				common.writeall(f.write, chunk)
 				hash.update(chunk)
 
 		filename_hash = common.parse_segment_path(missing_segment).hash

common/common/__init__.py

@@ -103,3 +103,22 @@ def jitter(interval):
 	smooth out patterns and prevent everything from retrying at the same time.
 	"""
 	return interval * (0.9 + 0.2 * random.random())
+
+
+def writeall(write, value):
+	"""Helper for writing a complete string to a file-like object.
+	Pass the write function and the value to write, and it will loop if needed to ensure
+	all data is written.
+	Works for both text and binary files, as long as you pass the right value type for
+	the write function.
+	"""
+	while value:
+		n = write(value)
+		if n is None:
+			# The write func doesn't return the amount written, assume it always writes everything
+			break
+		if n == 0:
+			# This would cause an infinite loop...blow up instead so it's clear what the problem is
+			raise Exception("Wrote 0 chars while calling {} with {}-char {}".format(write, len(value), type(value).__name__))
+		# remove the first n chars and go again if we have anything left
+		value = value[n:]

cutter/cutter/upload_backends.py

@@ -6,6 +6,7 @@ import os
 import re
 import uuid
 
+import common
 from common.googleapis import GoogleAPIClient
 
 
@@ -242,14 +243,14 @@ class Local(UploadBackend):
 		try:
 			if self.write_info:
 				with open(os.path.join(self.path, '{}-{}.json'.format(safe_title, video_id)), 'w') as f:
-					f.write(json.dumps({
+					common.writeall(f.write, json.dumps({
 						'title': title,
 						'description': description,
 						'tags': tags,
 					}) + '\n')
 			with open(filepath, 'wb') as f:
 				for chunk in data:
-					f.write(chunk)
+					common.writeall(f.write, chunk)
 		except (OSError, IOError) as e:
 			# Because duplicate videos don't actually matter with this backend,
 			# we consider all disk errors retryable.

downloader/downloader/main.py

@@ -565,7 +565,7 @@ class SegmentGetter(object):
 					# we may lose part of the last chunk even though we did receive it.
 					# This is a small enough amount of data that we don't really care.
 					for chunk in resp.iter_content(8192):
-						f.write(chunk)
+						common.writeall(f.write, chunk)
 						hash.update(chunk)
 		except Exception as e:
 			if file_created:

segment_coverage/segment_coverage/main.py

@@ -232,7 +232,7 @@ class CoverageChecker(object):
 		final_path = '{}_coverage.html'.format(path_prefix)
 		common.ensure_directory(temp_path)
 		with open(temp_path, 'w') as f:
-			f.write(html)
+			common.writeall(f.write, html)
 		os.rename(temp_path, final_path)
 		self.logger.info('Coverage page for {} created'.format(quality))