[newlib-cygwin] Cygwin: open: Add missing unlock on error

[Takashi Yano]

https://sourceware.org/git/gitweb.cgi?p=newlib-cygwin.git;h=0d3ea0ee653f63e50c66c444e8059256d72f03bf

commit 0d3ea0ee653f63e50c66c444e8059256d72f03bf
Author: Takashi Yano <takashi.yano@nifty.ne.jp>
Date:   Mon Aug 3 12:11:20 2026 +0900

    Cygwin: open: Add missing unlock on error
    
    the commit 524d75ff7398 ("Cygwin: open: Unlock fdtab before open_
    with_arch()") introduced a bug that fdtab lock was not unlocked
    when new fd cannot be allocated due to an error.
    
    This patch adds missing unlock for fdtab lock on error.
    
    Fixes: 524d75ff7398 ("Cygwin: open: Unlock fdtab before open_with_arch()")
    Suggested-by: Johannes Schindelin <Johannes.Schindelin@gmx.de>
    Signed-off-by: Takashi Yano <takashi.yano@nifty.ne.jp>
    Reviewed-by: Mark Geisert <mark@maxrnd.com>

Diff:
---
 winsup/cygwin/syscalls.cc | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/winsup/cygwin/syscalls.cc b/winsup/cygwin/syscalls.cc
index e3ba8c65c..5465d6c09 100644
--- a/winsup/cygwin/syscalls.cc
+++ b/winsup/cygwin/syscalls.cc
@@ -1554,7 +1554,10 @@ open (const char *unix_path, int flags, ...)
       cygheap->fdtab.lock();
       fd = cygheap->fdtab.find_unused_handle ();
       if (fd < 0)
-	__leave;		/* errno already set */
+	{
+	  cygheap->fdtab.unlock ();
+	  __leave;		/* errno already set */
+	}
       cygheap->fdtab[fd] = fh; /* tentative setting to mark as used */
       cygheap->fdtab.unlock();