1 files changed, 71 insertions, 0 deletions
diff --git a/third_party/nix/src/nix/log.cc b/third_party/nix/src/nix/log.cc
new file mode 100644
index 0000000000..f07ec4e93a
--- /dev/null
+++ b/third_party/nix/src/nix/log.cc
@@ -0,0 +1,71 @@
+#include "command.hh"
+#include "common-args.hh"
+#include "shared.hh"
+#include "store-api.hh"
+#include "progress-bar.hh"
+
+using namespace nix;
+
+struct CmdLog : InstallableCommand
+{
+    CmdLog()
+    {
+    }
+
+    std::string name() override
+    {
+        return "log";
+    }
+
+    std::string description() override
+    {
+        return "show the build log of the specified packages or paths, if available";
+    }
+
+    Examples examples() override
+    {
+        return {
+            Example{
+                "To get the build log of GNU Hello:",
+                "nix log nixpkgs.hello"
+            },
+            Example{
+                "To get the build log of a specific path:",
+                "nix log /nix/store/lmngj4wcm9rkv3w4dfhzhcyij3195hiq-thunderbird-52.2.1"
+            },
+            Example{
+                "To get a build log from a specific binary cache:",
+                "nix log --store https://cache.nixos.org nixpkgs.hello"
+            },
+        };
+    }
+
+    void run(ref<Store> store) override
+    {
+        settings.readOnlyMode = true;
+
+        auto subs = getDefaultSubstituters();
+
+        subs.push_front(store);
+
+        auto b = installable->toBuildable();
+
+        RunPager pager;
+        for (auto & sub : subs) {
+            auto log = b.drvPath != "" ? sub->getBuildLog(b.drvPath) : nullptr;
+            for (auto & output : b.outputs) {
+                if (log) break;
+                log = sub->getBuildLog(output.second);
+            }
+            if (!log) continue;
+            stopProgressBar();
+            printInfo("got build log for '%s' from '%s'", installable->what(), sub->getUri());
+            std::cout << *log;
+            return;
+        }
+
+        throw Error("build log of '%s' is not available", installable->what());
+    }
+};
+
+static RegisterCommand r1(make_ref<CmdLog>());