1 files changed, 29 insertions, 0 deletions
diff --git a/src/libstore/builtins/unpack-channel.cc b/src/libstore/builtins/unpack-channel.cc
new file mode 100644
index 000000000..d18e3ddaf
--- /dev/null
+++ b/src/libstore/builtins/unpack-channel.cc
@@ -0,0 +1,29 @@
+#include "builtins.hh"
+#include "tarfile.hh"
+
+namespace nix {
+
+void builtinUnpackChannel(const BasicDerivation & drv)
+{
+    auto getAttr = [&](const string & name) {
+        auto i = drv.env.find(name);
+        if (i == drv.env.end()) throw Error("attribute '%s' missing", name);
+        return i->second;
+    };
+
+    Path out = getAttr("out");
+    auto channelName = getAttr("channelName");
+    auto src = getAttr("src");
+
+    createDirs(out);
+
+    unpackTarfile(src, out);
+
+    auto entries = readDirectory(out);
+    if (entries.size() != 1)
+        throw Error("channel tarball '%s' contains more than one file", src);
+    if (rename((out + "/" + entries[0].name).c_str(), (out + "/" + channelName).c_str()) == -1)
+        throw SysError("renaming channel directory");
+}
+
+}