[newlib-cygwin] Cygwin: fhandler_fifo: reduce size

[Ken Brown <kbrown@sourceware.org>]

https://sourceware.org/git/gitweb.cgi?p=newlib-cygwin.git;h=f505e7a032665e30b6a33c68c4b8739a0fcd3a27

commit f505e7a032665e30b6a33c68c4b8739a0fcd3a27
Author: Ken Brown <kbrown@cornell.edu>
Date:   Sun Nov 8 12:02:39 2020 -0500

    Cygwin: fhandler_fifo: reduce size
    
    Replace the 'WCHAR pipe_name_buf[48]' class member by 'PWCHAR
    pipe_name_buf', and allocate space for the latter as needed.
    
    Change the default constructor to accommodate this change, and add a
    destructor that frees the allocated space.
    
    Also change get_pipe_name and clone to accommodate this change.

Diff:
---
 winsup/cygwin/fhandler.h       | 12 +++++++-----
 winsup/cygwin/fhandler_fifo.cc | 11 +++++++----
 2 files changed, 14 insertions(+), 9 deletions(-)

diff --git a/winsup/cygwin/fhandler.h b/winsup/cygwin/fhandler.h
index d7bd0ac06..fe76c0781 100644
--- a/winsup/cygwin/fhandler.h
+++ b/winsup/cygwin/fhandler.h
@@ -1384,7 +1384,7 @@ class fhandler_fifo: public fhandler_base
   HANDLE thr_sync_evt;          /* The thread has terminated. */
 
   UNICODE_STRING pipe_name;
-  WCHAR pipe_name_buf[CYGWIN_FIFO_PIPE_NAME_LEN + 1];
+  PWCHAR pipe_name_buf;
   fifo_client_handler *fc_handler;     /* Dynamically growing array. */
   int shandlers;                       /* Size (capacity) of the array. */
   int nhandlers;                       /* Number of elements in the array. */
@@ -1467,6 +1467,11 @@ class fhandler_fifo: public fhandler_base
 
 public:
   fhandler_fifo ();
+  ~fhandler_fifo ()
+  {
+    if (pipe_name_buf)
+      cfree (pipe_name_buf);
+  }
   /* Called if we appear to be at EOF after polling fc_handlers. */
   bool hit_eof () const
   { return !nwriters () && !IsEventSignalled (writer_opening); }
@@ -1512,11 +1517,8 @@ public:
   {
     void *ptr = (void *) ccalloc (malloc_type, 1, sizeof (fhandler_fifo));
     fhandler_fifo *fhf = new (ptr) fhandler_fifo (ptr);
-    /* We don't want our client list to change any more. */
     copyto (fhf);
-    /* fhf->pipe_name_buf is a *copy* of this->pipe_name_buf, but
-       fhf->pipe_name.Buffer == this->pipe_name_buf. */
-    fhf->pipe_name.Buffer = fhf->pipe_name_buf;
+    fhf->pipe_name_buf = NULL;
     return fhf;
   }
 };
diff --git a/winsup/cygwin/fhandler_fifo.cc b/winsup/cygwin/fhandler_fifo.cc
index 3af7e2f72..eff05d242 100644
--- a/winsup/cygwin/fhandler_fifo.cc
+++ b/winsup/cygwin/fhandler_fifo.cc
@@ -131,25 +131,28 @@ fhandler_fifo::fhandler_fifo ():
   fhandler_base (),
   read_ready (NULL), write_ready (NULL), writer_opening (NULL),
   owner_needed_evt (NULL), owner_found_evt (NULL), update_needed_evt (NULL),
-  cancel_evt (NULL), thr_sync_evt (NULL),
+  cancel_evt (NULL), thr_sync_evt (NULL), pipe_name_buf (NULL),
   fc_handler (NULL), shandlers (0), nhandlers (0),
   reader (false), writer (false), duplexer (false),
   max_atomic_write (DEFAULT_PIPEBUFSIZE),
   me (null_fr_id), shmem_handle (NULL), shmem (NULL),
   shared_fc_hdl (NULL), shared_fc_handler (NULL)
 {
-  pipe_name_buf[0] = L'\0';
   need_fork_fixup (true);
 }
 
 PUNICODE_STRING
 fhandler_fifo::get_pipe_name ()
 {
-  if (!pipe_name_buf[0])
+  if (!pipe_name_buf)
     {
+      pipe_name.Length = CYGWIN_FIFO_PIPE_NAME_LEN * sizeof (WCHAR);
+      pipe_name.MaximumLength = pipe_name.Length + sizeof (WCHAR);
+      pipe_name_buf = (PWCHAR) cmalloc_abort (HEAP_STR,
+					      pipe_name.MaximumLength);
+      pipe_name.Buffer = pipe_name_buf;
       __small_swprintf (pipe_name_buf, L"%S-fifo.%08x.%016X",
 			&cygheap->installation_key, get_dev (), get_ino ());
-      RtlInitUnicodeString (&pipe_name, pipe_name_buf);
     }
   return &pipe_name;
 }