Add builtins.fetchGitArchive

src/libexpr/primops/fetchGitArchive.cc

@@ -0,0 +1,121 @@
+#include "primops.hh"
+#include "store-api.hh"
+#include "cache.hh"
+
+namespace nix {
+
+static void prim_fetchGitArchive(EvalState & state, const PosIdx pos, Value * * args, Value & v)
+{
+    std::optional<Hash> expectedHash;
+    std::string name = "source.tar.gz";
+    std::string remote = "";
+    std::string format = "tar.gz";
+    std::string version = "HEAD";
+
+    state.forceValue(*args[0], pos);
+    for (auto & attr : *args[0]->attrs) {
+        std::string_view n(state.symbols[attr.name]);
+        if (n == "name")
+            name = state.forceStringNoCtx(*attr.value, attr.pos, "while evaluating the name of the git archive we should fetch");
+        else if (n == "sha256")
+            expectedHash = newHashAllowEmpty(state.forceStringNoCtx(*attr.value, attr.pos, "while evaluating the sha256 of the git archive we should fetch"), htSHA256);
+        else if (n == "remote")
+            remote = state.forceStringNoCtx(*attr.value, attr.pos, "while evaluating the remote of the git archive we should fetch");
+        else if (n == "format")
+            format = state.forceStringNoCtx(*attr.value, attr.pos, "while evaluating the format of the git archive we should fetch");
+        else if (n == "version")
+            version = state.forceStringNoCtx(*attr.value, attr.pos, "while evaluating the version of the git archive we should fetch");
+        else
+            state.debugThrowLastTrace(EvalError({
+                .msg = hintfmt("unsupported argument '%s' to 'fetchGitArchive'", n),
+                .errPos = state.positions[attr.pos]
+            }));
+    }
+
+    if (evalSettings.pureEval && !expectedHash) {
+        state.debugThrowLastTrace(EvalError({
+            .msg = hintfmt("in pure evaluation mode, 'fetchGitArchive' requires a 'sha256' argument"),
+            .errPos = state.positions[pos]
+        }));
+    }
+    if (expectedHash) {
+        auto expectedPath = state.store->makeFixedOutputPath(FileIngestionMethod::Recursive, *expectedHash, name, {});
+        if (state.store->isValidPath(expectedPath)) {
+            state.allowAndSetStorePathString(expectedPath, v);
+            return;
+        }
+    }
+
+    auto inAttrs = fetchers::Attrs({
+        {"type", "git-archive"},
+        {"name", name},
+        {"remote", remote},
+        {"version", version},
+        {"format", format}
+    });
+
+    if (auto res = fetchers::getCache()->lookup(state.store, inAttrs)) {
+        auto infoAttrs = res->first;
+        auto storePath = res->second;
+        state.allowAndSetStorePathString(storePath, v);
+        return;
+    }
+
+    // Run `git archive`
+    auto [errorCode, programOutput] = runProgram(RunOptions {
+        .program = "git",
+        .args = {"archive", "--format=" + format, "--remote=" + remote, version},
+        .mergeStderrToStdout = true
+    });
+    if (errorCode) {
+        state.debugThrowLastTrace(EvalError({
+            .msg = hintfmt(programOutput),
+            .errPos = state.positions[pos]
+        }));
+    }
+
+    // Add archive to nix store
+    auto hash = expectedHash ? expectedHash.value() : hashString(htSHA256, programOutput);
+    auto storePath = state.store->makeFixedOutputPath(FileIngestionMethod::Flat, hash, name);
+
+    StringSink narSink;
+    narSink << "nix-archive-1" << "(" << "type" << "regular" << "contents" << programOutput << ")";
+    auto narSource = StringSource(narSink.s);
+    auto narHash = hashString(htSHA256, narSink.s);
+    auto narSize = narSink.s.size();
+
+    auto info = ValidPathInfo { storePath, narHash };
+    info.narSize = narSize;
+    info.ca = FixedOutputHash { FileIngestionMethod::Flat, hash };
+
+    state.store->addToStore(info, narSource, NoRepair, NoCheckSigs);
+    state.allowAndSetStorePathString(storePath, v);
+
+    bool locked = (bool) expectedHash;
+    fetchers::getCache()->add(state.store, inAttrs, {}, storePath, locked);
+}
+
+static RegisterPrimOp primop_fetchGitArchive({
+    .name = "fetchGitArchive",
+    .args = {"args"},
+    .doc = R"(
+      Fetch a git archive using the git-archive command.
+      See https://git-scm.com/docs/git-archive
+      *args* is an attribute set with the following attributes:
+      - `name`
+      - `remote`
+      - `format`
+      - `version`
+      - `sha256`
+
+      To fetch a version from a private repository over SSH:
+      ```nix
+      builtins.fetchGitArchive {
+      remote = "git@gitlab.com:my-secret/repository.git";
+      version = "v1.2.3";
+      }
+      ```
+    )",
+    .fun = prim_fetchGitArchive,
+});
+}