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atomic_write is not completely atomic

#5155

In activesupport/lib/active_support/core_ext/file/atomic.rb, the chown and chmod should be done on temp_file before the mv, otherwise the file metadata will be inconsistent for a window of time after the mv. mv will carry the file ownership and permissions from temp_file, therefore it is best to set the ownership and permissions on temp_file first.

This:

# Overwrite original file with temp file
FileUtils.mv(temp_file.path, file_name)

# Set correct permissions on new file
chown(old_stat.uid, old_stat.gid, file_name)
chmod(old_stat.mode, file_name)

Should be:

# Set correct permissions on new file
chown(old_stat.uid, old_stat.gid, temp_file)
chmod(old_stat.mode, temp_file)

# Overwrite original file with temp file
FileUtils.mv(temp_file.path, file_name)

Reported by Dominique Brezinski · July 19th, 2010 @ 11:22 PM

Activity

Santiago Pastorino
- State changed from new to open
This issue has been automatically marked as stale because it has not been commented on for at least three months.

The resources of the Rails core team are limited, and so we are asking for your help. If you can still reproduce this error on the 3-0-stable branch or on master, please reply with all of the information you have about it and add "[state:open]" to your comment. This will reopen the ticket for review. Likewise, if you feel that this is a very important feature for Rails to include, please reply with your explanation so we can consider it.

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February 2nd, 2011 @ 04:51 PM
Santiago Pastorino
- State changed from open to stale
February 2nd, 2011 @ 04:51 PM