runfiles.bash: fallback to using directory for relative paths

shell/runfiles/runfiles.bash

@@ -128,6 +128,31 @@ function __runfiles_escape_grep() {
 }
 export -f __runfiles_escape_grep
 
+# When manifest lookup returns a relative path (e.g., from a symlink created
+# with ctx.actions.symlink target_path), the -e existence check in
+# runfiles_rlocation_checked fails because the path isn't anchored. This helper
+# derives the runfiles directory from the manifest path and retries the lookup
+# using the original rlocation key, resolving symlinks through the filesystem.
+function __runfiles_try_dir_lookup() {
+  local dir=""
+  if [[ "${RUNFILES_MANIFEST_FILE}" == *_manifest \
+        && -d "${RUNFILES_MANIFEST_FILE%_manifest}" ]]; then
+    dir="${RUNFILES_MANIFEST_FILE%_manifest}"
+  elif [[ "${RUNFILES_MANIFEST_FILE}" == */MANIFEST \
+          && -d "${RUNFILES_MANIFEST_FILE%/MANIFEST}" ]]; then
+    dir="${RUNFILES_MANIFEST_FILE%/MANIFEST}"
+  fi
+  if [[ -n "$dir" && -e "$dir/$1" ]]; then
+    if [[ "${RUNFILES_LIB_DEBUG:-}" == 1 ]]; then
+      echo >&2 "INFO[runfiles.bash]: rlocation($1): resolved relative manifest entry via directory ($dir), return"
+    fi
+    echo "$dir/$1"
+    return 0
+  fi
+  return 1
+}
+export -f __runfiles_try_dir_lookup
+
 # Prints to stdout the runtime location of a data-dependency.
 # The optional second argument can be used to specify the canonical name of the
 # repository whose repository mapping should be used to resolve the repository
@@ -447,6 +472,9 @@ function runfiles_rlocation_checked() {
           echo "$candidate"
           return 0
         fi
+        if [[ "$prefix_result" != /* ]] && __runfiles_try_dir_lookup "$1"; then
+          return 0
+        fi
         # At this point, the manifest lookup of prefix has been successful,
         # but the file at the relative path given by the suffix does not
         # exist. We do not continue the lookup with a shorter prefix for two
@@ -476,6 +504,8 @@ function runfiles_rlocation_checked() {
           echo >&2 "INFO[runfiles.bash]: rlocation($1): found in manifest as ($result)"
         fi
         echo "$result"
+      elif [[ "$result" != /* ]] && __runfiles_try_dir_lookup "$1"; then
+        :
       else
         if [[ "${RUNFILES_LIB_DEBUG:-}" == 1 ]]; then
           echo >&2 "INFO[runfiles.bash]: rlocation($1): found in manifest as ($result), but file does not exist"

tests/runfiles/runfiles_test.bash

@@ -512,6 +512,46 @@ EOF
   [[ "$(rlocation "repo2+/foo/runfile" "my_module++ext+repo1" || echo failed)" == "$tmpdir/repo2+/runfile" ]] || fail
 }
 
+function test_manifest_based_rlocation_relative_symlink() {
+  local tmpdir="$(mktemp -d $TEST_TMPDIR/tmp.XXXXXXXX)"
+
+  # Create the runfiles directory alongside the manifest.
+  local runfiles_dir="$tmpdir/foo.runfiles"
+  mkdir -p "$runfiles_dir/a/b"
+  touch "$runfiles_dir/a/b/target"
+  mkdir -p "$runfiles_dir/pkg/dir/sub"
+  touch "$runfiles_dir/pkg/dir/file"
+  touch "$runfiles_dir/pkg/dir/sub/file"
+
+  # Manifest entries with relative paths as values, simulating
+  # ctx.actions.symlink(target_path=...) which produces relative symlinks.
+  # We don't need to create the asctual symlink here, it just needs to be an
+  # unresolvable relative path in the manifest that would trigger the fallback
+  cat > "$tmpdir/foo.runfiles_manifest" << EOF
+a/b/target ../relative/target
+pkg/dir relative_dir
+EOF
+
+  export RUNFILES_DIR=
+  export RUNFILES_MANIFEST_FILE="$tmpdir/foo.runfiles_manifest"
+  source "$runfiles_lib_path"
+
+  # Exact match: manifest value is relative, but the file exists in the
+  # runfiles directory at the original key. __runfiles_try_dir_lookup resolves
+  # it via the directory.
+  [[ "$(rlocation a/b/target || echo failed)" == "$runfiles_dir/a/b/target" ]] || fail
+
+  # Prefix match: manifest maps "pkg/dir" to a relative path. Looking up a
+  # file under that prefix constructs a relative candidate that fails -e, then
+  # __runfiles_try_dir_lookup resolves via the directory.
+  [[ "$(rlocation pkg/dir/file || echo failed)" == "$runfiles_dir/pkg/dir/file" ]] || fail
+  [[ "$(rlocation pkg/dir/sub/file || echo failed)" == "$runfiles_dir/pkg/dir/sub/file" ]] || fail
+
+  # Nonexistent files still return empty even with the fallback.
+  [[ -z "$(rlocation a/b/nonexistent || echo failed)" ]] || fail
+  [[ -z "$(rlocation pkg/dir/nonexistent || echo failed)" ]] || fail
+}
+
 function test_directory_based_envvars() {
   export RUNFILES_DIR=mock/runfiles
   export RUNFILES_MANIFEST_FILE=