flockit: init at 2012-08-11 #27902
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flockit: init at 2012-08-11 #27902
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Off topic. I was hoping for a flockit executable. Having to setup LD_PRELOAD yourself seems more work. |
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@bjornfor how about this? Now the following: can be simplified to: |
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Yes, that's an interface I like. Upstream it? |
bjornfor
approved these changes
Aug 3, 2017
NeQuissimus
requested changes
Aug 5, 2017
| cp ./libflockit.so $out/lib | ||
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| (cat <<EOI | ||
| #!${bash}/bin/bash |
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It probably would. I will change it to #!/bin/sh.
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I changed it.
Do note that #!/bin/sh is automatically rewritten to #!${pkgs.bash}/bin/sh during the post-installation fixups:
post-installation fixup
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/nix/store/fd7sj17pyja2wpm2yh5jzmim8nhkra15-flockit-2012-08-11/bin/flockit: interpreter directive changed from "/bin/sh" to "/nix/store/jjg5zsfjl35b239f6znp0nfa9775qy2a-bash-4.4-p12/bin/sh"
| chmod +x $out/bin/flockit | ||
| ''; | ||
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| meta = { |
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This does not seem to build on Darwin (see TravisCI), so should probably have a platform attribute to limit its exposure.
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Good point. I will add it.
The flockit library and tool exists solely because rsync doesn't have file locking. It's not used like a normal library; you don't link against it, and you don't have to patch your source code to use it. It's inserted between your program and its libraries by use of LD_PRELOAD. For example: $ env LD_PRELOAD=$(nix-build -A pkgs.flockit)/lib/libflockit.so FLOCKIT_FILE_PREFIX=test rsync SRC DEST Besides the library a handy executable is provided which can simplify the above to: $ $(nix-build -A pkgs.flockit)/bin/flockit test rsync SRC DEST Also see the following blog post: https://www.swiftstack.com/blog/2012/08/15/old-school-monkeypatching/
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Motivation for this change
flockit is a LD_PRELOAD shim to add file locking to programs that don't do it (I'm looking at you, rsync!)
I use it to backup graphite databases using rsync.
See this blog post for the motivation and an example.
Things done
Please check what applies. Note that these are not hard requirements but merely serve as information for reviewers.
(nix.useSandbox on NixOS,
or option
build-use-sandboxinnix.confon non-NixOS)
nix-shell -p nox --run "nox-review wip"./result/bin/)