flockit: init at 2012-08-11

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/

1 files changed, 51 insertions, 0 deletions

diff --git a/pkgs/tools/backup/flockit/default.nix b/pkgs/tools/backup/flockit/default.nix
new file mode 100644
index 00000000000..e569d9b6d59
--- /dev/null
+++ b/pkgs/tools/backup/flockit/default.nix
@@ -0,0 +1,51 @@
+{ stdenv, fetchFromGitHub }:
+
+stdenv.mkDerivation rec {
+  name = "flockit-${version}";
+  version = "2012-08-11";
+
+  src = fetchFromGitHub {
+    owner  = "smerritt";
+    repo   = "flockit";
+    rev    = "5c2b2092f8edcc8e3e2eb6ef66c968675dbfa686";
+    sha256 = "0vajck9q2677gpn9a4flkyz7mw69ql1647cjwqh834nrcr2b5164";
+  };
+
+  installPhase = ''
+    mkdir -p $out/lib $out/bin
+    cp ./libflockit.so $out/lib
+
+    (cat <<EOI
+    #!/bin/sh
+    env LD_PRELOAD="$out/lib/libflockit.so" FLOCKIT_FILE_PREFIX=\$1 \''${@:2}
+    EOI
+    ) > $out/bin/flockit
+    chmod +x $out/bin/flockit
+  '';
+
+  meta = with stdenv.lib; {
+    description = "LD_PRELOAD shim to add file locking to programs that don't do it (I'm looking at you, rsync!)";
+    longDescription = ''
+      This 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/
+    '';
+    homepage = https://github.com/smerritt/flockit;
+    license = licenses.asl20;
+    platforms = platforms.linux;
+    maintainers = [ maintainers.basvandijk ];
+  };
+}