GitTree: Allow tree reading to skip symlinks checker

This is useful when the caller already knows that the tree to look
up is valid, and thus the extra check step can be safely skipped.

2 files changed, 20 insertions, 12 deletions

diff --git a/src/buildtool/file_system/git_tree.cpp b/src/buildtool/file_system/git_tree.cpp
index ca0727fb..3b9f3a8e 100644
--- a/src/buildtool/file_system/git_tree.cpp
+++ b/src/buildtool/file_system/git_tree.cpp
@@ -86,14 +86,19 @@ auto GitTree::Read(std::filesystem::path const& repo_path,
 
 auto GitTree::Read(gsl::not_null<GitCASPtr> const& cas,
                    std::string const& tree_id,
-                   bool ignore_special) noexcept -> std::optional<GitTree> {
+                   bool ignore_special,
+                   bool skip_checks) noexcept -> std::optional<GitTree> {
     if (auto raw_id = FromHexString(tree_id)) {
         auto repo = GitRepo::Open(cas);
         if (repo != std::nullopt) {
-            if (auto entries = repo->ReadTree(*raw_id,
-                                              SymlinksChecker{cas},
-                                              /*is_hex_id=*/false,
-                                              ignore_special)) {
+            auto entries =
+                skip_checks ? repo->ReadDirectTree(
+                                  *raw_id, /*is_hex_id=*/false, ignore_special)
+                            : repo->ReadTree(*raw_id,
+                                             SymlinksChecker{cas},
+                                             /*is_hex_id=*/false,
+                                             ignore_special);
+            if (entries) {
                 // NOTE: the raw_id value is NOT recomputed when
                 // ignore_special==true.
                 return GitTree::FromEntries(
@@ -155,11 +160,13 @@ auto GitTreeEntry::Tree(bool ignore_special) const& noexcept
                 if (repo == std::nullopt) {
                     return std::nullopt;
                 }
-
-                if (auto entries = repo->ReadTree(raw_id_,
-                                                  SymlinksChecker{cas_},
-                                                  /*is_hex_id=*/false,
-                                                  ignore_special)) {
+                auto entries = repo->ReadTree(raw_id_,
+                                              SymlinksChecker{cas_},
+                                              /*is_hex_id=*/false,
+                                              ignore_special);
+                if (entries) {
+                    // NOTE: the raw_id value is NOT recomputed when
+                    // ignore_special==true.
                     return GitTree::FromEntries(
                         cas_, std::move(*entries), raw_id_, ignore_special);
                 }
diff --git a/src/buildtool/file_system/git_tree.hpp b/src/buildtool/file_system/git_tree.hpp
index 45c875d6..ccdb5803 100644
--- a/src/buildtool/file_system/git_tree.hpp
+++ b/src/buildtool/file_system/git_tree.hpp
@@ -53,11 +53,13 @@ class GitTree {
     /// \param cas      Git CAS that contains the tree id.
     /// \param tree_id  Tree id as as hex string.
     /// \param ignore_special   If set, treat symlinks as absent.
+    /// \param skip_checks      If set, skip any symlinks checks.
     /// NOTE: If ignore_special==true, the stored entries might differ from the
     /// actual tree, as some filesystem entries get skipped.
     [[nodiscard]] static auto Read(gsl::not_null<GitCASPtr> const& cas,
                                    std::string const& tree_id,
-                                   bool ignore_special = false) noexcept
+                                   bool ignore_special = false,
+                                   bool skip_checks = false) noexcept
         -> std::optional<GitTree>;
 
     /// \brief Lookup by dir entry name. '.' and '..' are not allowed.
@@ -147,7 +149,6 @@ class GitTreeEntry {
     [[nodiscard]] auto IsTree() const noexcept { return IsTreeObject(type_); }
 
     [[nodiscard]] auto Blob() const noexcept -> std::optional<std::string>;
-    [[nodiscard]] auto Tree(bool) && = delete;
     [[nodiscard]] auto Tree(bool ignore_special = false) const& noexcept
         -> std::optional<GitTree> const&;