git repo fetch: support "inherit env"

When fetching git repositories, just-mr routinely shells out to
git. In this case, allow the user to specify via "inherit env",
which environment variables from the host environment should be
made available in this action. Typical variables to inherit are
ones providing credentials, like SSH_AUTH_SOCK. As the repository
description specifies the commit that will be taken, and hence the
resulting tree, correctness is not affected by the environement
leaking in here.

1 files changed, 23 insertions, 0 deletions

diff --git a/src/other_tools/repo_map/repos_to_setup_map.cpp b/src/other_tools/repo_map/repos_to_setup_map.cpp
index 3bad60f4..aec57868 100644
--- a/src/other_tools/repo_map/repos_to_setup_map.cpp
+++ b/src/other_tools/repo_map/repos_to_setup_map.cpp
@@ -137,12 +137,35 @@ void GitCheckout(ExpressionPtr const& repo_desc,
     auto pragma_absent_value = pragma_absent and
                                pragma_absent->get()->IsBool() and
                                pragma_absent->get()->Bool();
+    std::vector<std::string> inherit_env{};
+    auto repo_desc_inherit_env =
+        repo_desc->Get("inherit env", Expression::kEmptyList);
+    if (not repo_desc_inherit_env->IsList()) {
+        (*logger)(fmt::format("GitCheckout: optional field \"inherit env\" "
+                              "should be a list of strings, but found {}",
+                              repo_desc_inherit_env->ToString()),
+                  true);
+        return;
+    }
+    for (auto const& var : repo_desc_inherit_env->List()) {
+        if (not var->IsString()) {
+            (*logger)(
+                fmt::format("GitCheckout: optional field \"inherit env\" "
+                            "should be a list of strings, but found entry {}",
+                            var->ToString()),
+                true);
+            return;
+        }
+        inherit_env.emplace_back(var->String());
+    }
+
     // populate struct
     GitRepoInfo git_repo_info = {
         .hash = repo_desc_commit->get()->String(),
         .repo_url = repo_desc_repository->get()->String(),
         .branch = repo_desc_branch->get()->String(),
         .subdir = subdir.empty() ? "." : subdir.string(),
+        .inherit_env = inherit_env,
         .mirrors = std::move(mirrors),
         .origin = repo_name,
         .ignore_special = pragma_special_value == PragmaSpecial::Ignore,