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, 2 insertions, 2 deletions

diff --git a/test/util/fs_util.cc b/test/util/fs_util.cc
index 052781445..5418948fe 100644
--- a/test/util/fs_util.cc
+++ b/test/util/fs_util.cc
@@ -125,12 +125,12 @@ PosixErrorOr<struct stat> Fstat(int fd) {
 
 PosixErrorOr<bool> Exists(absl::string_view path) {
   struct stat stat_buf;
-  int res = stat(std::string(path).c_str(), &stat_buf);
+  int res = lstat(std::string(path).c_str(), &stat_buf);
   if (res < 0) {
     if (errno == ENOENT) {
       return false;
     }
-    return PosixError(errno, absl::StrCat("stat ", path));
+    return PosixError(errno, absl::StrCat("lstat ", path));
   }
   return true;
 }