Change /proc/PID/cmdline to read environment vector.

- Change proc to return envp on overwrite of argv with limitations from
upstream.
- Add unit tests
- Change layout of argv/envp on the stack so that end of argv is contiguous with
beginning of envp.

PiperOrigin-RevId: 232506107
Change-Id: I993880499ab2c1220f6dc456a922235c49304dec

1 files changed, 1 insertions, 0 deletions

diff --git a/test/util/multiprocess_util.h b/test/util/multiprocess_util.h
index c09d6167f..ba5f2601f 100644
--- a/test/util/multiprocess_util.h
+++ b/test/util/multiprocess_util.h
@@ -74,6 +74,7 @@ class ExecveArray {
   ExecveArray& operator=(ExecveArray&&) = delete;
 
   char* const* get() const { return ptrs_.data(); }
+  size_t get_size() { return str_.size(); }
 
  private:
   std::vector<char> str_;