Bug #63908 [Com]: file_put_contents is not atomic.

From: Date: Tue, 08 Jan 2013 00:35:43 +0000
Subject: Bug #63908 [Com]: file_put_contents is not atomic.
References: 1  Groups: php.bugs 
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Edit report at https://bugs.php.net/bug.php?id=63908&edit=1

 ID:                 63908
 Comment by:         Awm086 at gmail dot com
 Reported by:        awm086 at gmail dot com
 Summary:            file_put_contents is not atomic.
 Status:             Not a bug
 Type:               Bug
 Package:            Filesystem function related
 Operating System:   LINUX
 PHP Version:        Irrelevant
 Block user comment: N
 Private report:     N

 New Comment:

Sorry I meant tempnam does creat a file even if the directory is full.


Previous Comments:
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[2013-01-08 00:22:20] rasmus@php.net

You mean tempnam and no, not at all. tempnam() creates an empty file, it doesn't 
put anything in it. You can't check disk space, create a file and write to it, 
all in one atomic operation.

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[2013-01-07 23:48:20] awm086 at gmail dot com

I noticed that function tempname does the same thing. Is that the case?

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[2013-01-06 00:33:34] rasmus@php.net

http://lxr.php.net/xref/PHP_5_4/ext/standard/file.c#564

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[2013-01-06 00:24:42] awm086 at gmail dot com

Where can I find the C implementation of the function. I am just curious now.

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[2013-01-06 00:09:16] rasmus@php.net

Nope, sorry, there isn't. The false indicates that the function wasn't able to 
complete its operation. Much like the underlying filesystem calls, there is no 
such thing as transactions or anything along those lines where you can group a 
bunch of operations into a single atomic unit. That's simply not how filesystem 
operations work.

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