Execution API: support cwd

... following the remote-execution standard that all output paths (but
none of the input paths) are relative to the working directory.
Therefore, the executor has to do the path translation. For our
implementation of the API interface
- the local API now handles cwd correctly,
- the remote API forwards cwd correctly, and
- the git API continues to report actions as not implemented.

2 files changed, 29 insertions, 11 deletions

diff --git a/src/buildtool/execution_engine/executor/TARGETS b/src/buildtool/execution_engine/executor/TARGETS
index bac83670..15ca2441 100644
--- a/src/buildtool/execution_engine/executor/TARGETS
+++ b/src/buildtool/execution_engine/executor/TARGETS
@@ -19,6 +19,7 @@
     , ["src/buildtool/execution_api/remote", "bazel"]
     , ["src/buildtool/progress_reporting", "progress"]
     , ["src/utils/cpp", "hex_string"]
+    , ["src/utils/cpp", "path_rebase"]
     , ["src/utils/cpp", "prefix"]
     , ["@", "gsl", "", "gsl"]
     , ["src/buildtool/common", "common"]
diff --git a/src/buildtool/execution_engine/executor/executor.hpp b/src/buildtool/execution_engine/executor/executor.hpp
index 6541fe24..bf107e31 100644
--- a/src/buildtool/execution_engine/executor/executor.hpp
+++ b/src/buildtool/execution_engine/executor/executor.hpp
@@ -46,6 +46,7 @@
 #include "src/buildtool/logging/logger.hpp"
 #include "src/buildtool/progress_reporting/progress.hpp"
 #include "src/utils/cpp/hex_string.hpp"
+#include "src/utils/cpp/path_rebase.hpp"
 #include "src/utils/cpp/prefix.hpp"
 
 /// \brief Implementations for executing actions and uploading artifacts.
@@ -125,11 +126,17 @@ class ExecutorImpl {
             }
         }
 
+        auto base = action->Content().Cwd();
+        auto cwd_relative_output_files =
+            RebasePathStringsRelativeTo(base, action->OutputFilePaths());
+        auto cwd_relative_output_dirs =
+            RebasePathStringsRelativeTo(base, action->OutputDirPaths());
         auto remote_action = (alternative_api ? *alternative_api : api)
                                  .CreateAction(*root_digest,
                                                action->Command(),
-                                               action->OutputFilePaths(),
-                                               action->OutputDirPaths(),
+                                               base,
+                                               cwd_relative_output_files,
+                                               cwd_relative_output_dirs,
                                                action->Env(),
                                                merged_properties);
 
@@ -477,11 +484,16 @@ class ExecutorImpl {
         IExecutionResponse::ArtifactInfos const& artifacts,
         gsl::not_null<DependencyGraph::ActionNode const*> const& action,
         bool fail_artifacts) noexcept {
+        auto base = action->Content().Cwd();
         for (auto const& [name, node] : action->OutputFiles()) {
-            node->Content().SetObjectInfo(artifacts.at(name), fail_artifacts);
+            node->Content().SetObjectInfo(
+                artifacts.at(RebasePathStringRelativeTo(base, name)),
+                fail_artifacts);
         }
         for (auto const& [name, node] : action->OutputDirs()) {
-            node->Content().SetObjectInfo(artifacts.at(name), fail_artifacts);
+            node->Content().SetObjectInfo(
+                artifacts.at(RebasePathStringRelativeTo(base, name)),
+                fail_artifacts);
         }
     }
 
@@ -507,11 +519,14 @@ class ExecutorImpl {
     /// are present in the artifacts map
     [[nodiscard]] static auto CheckOutputsExist(
         IExecutionResponse::ArtifactInfos const& artifacts,
-        std::vector<Action::LocalPath> const& outputs) noexcept -> bool {
-        return std::all_of(
-            outputs.begin(), outputs.end(), [&artifacts](auto const& output) {
-                return artifacts.contains(output);
-            });
+        std::vector<Action::LocalPath> const& outputs,
+        std::string base) noexcept -> bool {
+        return std::all_of(outputs.begin(),
+                           outputs.end(),
+                           [&artifacts, &base](auto const& output) {
+                               return artifacts.contains(
+                                   RebasePathStringRelativeTo(base, output));
+                           });
     }
 
     /// \brief Parse response and write object info to DAG's artifact nodes.
@@ -566,8 +581,10 @@ class ExecutorImpl {
         auto output_dirs = action->OutputDirPaths();
 
         if (artifacts.empty() or
-            not CheckOutputsExist(artifacts, output_files) or
-            not CheckOutputsExist(artifacts, output_dirs)) {
+            not CheckOutputsExist(
+                artifacts, output_files, action->Content().Cwd()) or
+            not CheckOutputsExist(
+                artifacts, output_dirs, action->Content().Cwd())) {
             logger.Emit(LogLevel::Error, [&] {
                 std::string message{
                     "action executed with missing outputs.\n"