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:

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


Previous Comments:
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[2013-01-06 00:33:34] ras...@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] ras...@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.

------------------------------------------------------------------------
[2013-01-05 23:40:34] awm086 at gmail dot com

I cannot belive that a function returns false, indicating that a file failed to 
be 
written, and still write to the file system. There must be a way.

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[2013-01-04 23:56:46] ras...@php.net

Sorry, there is no way to guarantee that. Even if we were to check before 
starting to write, there is no way to do an atomic check+write, so in between 
checking and writing even though the check said there should be space to write 
to 
completion, the filesystem could have filled up by the time we actually do the 
write. If you need this, you have to do it in userspace and apply whatever 
logic 
makes sense for your environment to ensure that the write is safe.

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