From: nobu@...
Date: 2014-08-25T02:49:17+00:00
Subject: [ruby-core:64541] [ruby-trunk - Bug #10153] [Assigned] File.open block does not throw "No space left on device (Errno::ENOSPC)" if the data fits the buffer of IO.write

Issue #10153 has been updated by Nobuyoshi Nakada.

Status changed from Open to Assigned
Assignee set to Yukihiro Matsumoto

This behavior was introduced at r10623 by matz, but the commit log is only:

    * io.c (io_close): always calls "close" method of the receiver.
      [ruby-core:6911] [ruby-core:8112]


----------------------------------------
Bug #10153: File.open block does not throw "No space left on device (Errno::ENOSPC)" if the data fits the buffer of IO.write 
https://bugs.ruby-lang.org/issues/10153#change-48469

* Author: Marvin Reyes
* Status: Assigned
* Priority: Normal
* Assignee: Yukihiro Matsumoto
* Category: core
* Target version: current: 2.2.0
* ruby -v: ruby 1.9.3p484 (2013-11-22) [x86_64-linux]
* Backport: 2.0.0: UNKNOWN, 2.1: UNKNOWN
----------------------------------------
When writing to file in disk using File.open with a block as an argument, if the diskspace is full and IO.write does not flush right away, the block just exits successfully instead of throwing Errno:ENOSPC.


Setup: Drive partition needs to be full

Eg. of a write that will succeed normally with no exception given that the drive is full (this means that the expected failure is being swallowed)

~~~
File.open('/full_drive/test.txt','wb') do |file|
  file.write("test")
end

#This will complete normally because the "test" data does not get flushed
#This will leave a 0kb file on the disk
~~~

Eg. force a flush to see the error

~~~
File.open('/full_drive/test.txt','wb') do |file|
  file.write("test")
  file.flush
end

#This will throw Errno::ENOSPC
#This will leave a 0kb file on the disk
~~~

Eg. write a large enough data that file.write will flush by itself (most likely it hits the buffer cap)

~~~
fills = '1'*1048576
File.open('/full_drive/test.txt','wb') do |file|
  file.write(fills)
end

#This will throw Errno::ENOSPC
#This will leave a 0kb file on the disk
~~~

Eg. When not using File.open block argument and closing the IO with an ensure block

~~~
begin
  io = File.open('/full_drive/test.txt', 'wb')
  io.write("test")
ensure
  io.close
end

#This will throw Errno::ENOSPC
#This will leave a 0kb file on the disk
~~~


Currently tested in RHEL5.

Notes:
- I've encountered this in ruby-1.9.2
- I've tested this with ruby-2.1.2
- I'm not sure if the issue is because of File.open usage of c-extension rb_ensure or io_close. reference: (http://ruby-doc.org/core-1.9.3/File.html#method-c-open)




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