On 05/03/2012 04:09 PM, Ronald F. Guilmette wrote: > > The only problem with the approach outlined above is that sometimes (rarely) > some Makefiles and/or other tools used as part of a build process (e.g. > automake) may occasionally make the assumption that every regular file > within the current (build) tree is writable, and that thus, when one of these > tools is about to perform some operation that will attempt to effectively > over-write some such file, the over-write can be performed _without_ first > deleting the file in question.
Nothing against your style of coding, but I do want to point out that recommending anyone delete a file before rebuilding its contents is racy. If things crash in the middle, you can be left without the file, or with a file with incomplete contents. It is always better to recommend a style of atomic changes - make your target file in a temporary location (generally in the same directory as the destination), then use an atomic rename() to overwrite the original file with the updated file in one go. > > I want to reemphasize what I just said. Removing a given regular file before > attempting some operation that is intended to fully replace the contents of > that file is a simple and altogether reasonable precaution... I want to reemphasize what I just said - removing a given regular file before rebuilding it is prone to awful surprises when your build process is interrupted unexpectedly. Always write to a temporary name and then use mv to move it into place, for the best safety. -- Eric Blake ebl...@redhat.com +1-919-301-3266 Libvirt virtualization library http://libvirt.org
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