[ruby-core:63949] [ruby-trunk - Bug #9036] [PATCH] io.c: make IO#reopen("pathname") atomic for non-stdio

Issue #9036 has been updated by Yui NARUSE.

Backport changed from 1.9.3: UNKNOWN, 2.0.0: UNKNOWN to 1.9.3: REQUIRED, 2.0.0: REQUIRED, 2.1: REQUIRED

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Bug #9036: [PATCH] io.c: make IO#reopen("pathname") atomic for non-stdio
https://bugs.ruby-lang.org/issues/9036#change-47971

* Author: Eric Wong
* Status: Closed
* Priority: Normal
* Assignee: 
* Category: 
* Target version: 
* ruby -v: ruby 2.1.0dev (2013-10-20 trunk 43369) [x86_64-linux]
* Backport: 1.9.3: REQUIRED, 2.0.0: REQUIRED, 2.1: REQUIRED
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Since rb_sysopen releases the GVL, calling close(fptr->fd) would
leave a window where accessing the file from another thread can hit
IOError on a closed stream

Instead, create a new, temporary FD via rb_sysopen and call
rb_cloexec_dup2 on it to atomically replace the file fptr->fd points
to.  This leaves no possible window where fptr->fd is invalid to
userspace (even for any threads running w/o GVL).

Without this patch, I need to maintain separate code paths for
atomically reopening (e.g. log rotation) std{in,out,err} vs
other files in a multithreaded application.


---Files--------------------------------
0001-io.c-make-IO-reopen-pathname-atomic.patch (1.47 KB)


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