[newlib-cygwin/cygwin-3_3-branch] Cygwin: console: Prevent the exec'ed bash from exiting by Ctrl-C.

[Corinna Vinschen <corinna@sourceware.org>]

https://sourceware.org/git/gitweb.cgi?p=newlib-cygwin.git;h=b3d2f35cb1a62daf92d88e1aecc2a235d843dbca

commit b3d2f35cb1a62daf92d88e1aecc2a235d843dbca
Author: Takashi Yano <takashi.yano@nifty.ne.jp>
Date:   Wed Nov 3 15:14:42 2021 +0900

    Cygwin: console: Prevent the exec'ed bash from exiting by Ctrl-C.
    
    - Currently, bash occasionally exits by Ctrl-C with the following
      scenario.
        1) Start bash in the command prompt.
        2) Run 'exec bash'.
        3) Press Ctrl-C several times.
      This patch fixes the issue.

Diff:
---
 winsup/cygwin/sigproc.cc | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/winsup/cygwin/sigproc.cc b/winsup/cygwin/sigproc.cc
index 47352c213..dff797915 100644
--- a/winsup/cygwin/sigproc.cc
+++ b/winsup/cygwin/sigproc.cc
@@ -594,6 +594,14 @@ sig_send (_pinfo *p, siginfo_t& si, _cygtls *tls)
       p = myself;
     }
 
+  /* If myself is the stub process, send signal to the child process
+     rather than myself. The fact that myself->dwProcessId is not equal
+     to the current process id indicates myself is the stub process. */
+  if (its_me && myself->dwProcessId != GetCurrentProcessId ())
+    {
+      wait_for_completion = false;
+      its_me = false;
+    }
 
   if (its_me)
     sendsig = my_sendsig;