Deflake exec test.

- Only use MAXSYMLINKS/2+1 symlinks for each of the interpreter and script
  paths in SymlinkLimitRefreshedForInterpreter to tolerate cases where the
  original paths (/tmp, /bin, or /bin/echo) themselves contain symlinks.

- Ensure that UnshareFiles performs execve immediately after clone(CLONE_VFORK)
  (no heap allocation for ExecveArray/RunfilesPath).

- Use lstat() rather than stat() for the existence check in fs_util's Exists;
  the latter will fail if the symlink target does not exist, even if the
  symlink does.

PiperOrigin-RevId: 320110156

1 files changed, 6 insertions, 1 deletions

diff --git a/test/util/fs_util.h b/test/util/fs_util.h
index caf19b24d..8cdac23a1 100644
--- a/test/util/fs_util.h
+++ b/test/util/fs_util.h
@@ -44,9 +44,14 @@ PosixErrorOr<std::string> GetCWD();
 // can't be determined.
 PosixErrorOr<bool> Exists(absl::string_view path);
 
-// Returns a stat structure for the given path or an error.
+// Returns a stat structure for the given path or an error. If the path
+// represents a symlink, it will be traversed.
 PosixErrorOr<struct stat> Stat(absl::string_view path);
 
+// Returns a stat structure for the given path or an error. If the path
+// represents a symlink, it will not be traversed.
+PosixErrorOr<struct stat> Lstat(absl::string_view path);
+
 // Returns a stat struct for the given fd.
 PosixErrorOr<struct stat> Fstat(int fd);