ash: improve performance of ctrl-c

The WIN32 port uses a console control handler to detect crtl-c.  This
replaces the signal handler used in POSIX.  The control handler sets
an event that can be detected in waitpid_child.  However this only
works when a wait is in progress, which makes it impossible to
break out of a simple shell loop with ctrl-c:

   while true; do
   sleep 1
   echo hi
   done

Better performance can be achieved by setting the pending_int flag in
the control handler, similar to what's done in the signal handler.
The deferred signal is processed in int_on.

Or at least it would be but for a bug in the WIN32 code to handle
shellexec:  interrupts weren't being properly turned off and on.
So this had to be fixed too.

1 files changed, 4 insertions, 0 deletions

diff --git a/shell/ash.c b/shell/ash.c
index b71c749aa..441da4d85 100644
--- a/shell/ash.c
+++ b/shell/ash.c
@@ -4306,6 +4306,7 @@ static BOOL WINAPI ctrl_handler(DWORD dwCtrlType)
 {
         if (dwCtrlType == CTRL_C_EVENT || dwCtrlType == CTRL_BREAK_EVENT) {
                 SetEvent(hSIGINT);
+                pending_int = 1;
                 return TRUE;
         }
         return FALSE;
@@ -4369,6 +4370,7 @@ waitpid_child(int *status, int wait_flags)
         if (!idx) {             /* hSIGINT */
                 int i;
                 ResetEvent(hSIGINT);
+                pending_int = 0;
                 for (i = 1; i < pid_nr; i++)
                         TerminateProcess(proclist[i], 1);
                 pid = pidlist[1];
@@ -10282,6 +10284,7 @@ evalcommand(union node *cmd, int flags)
                         /* No, forking off a child is necessary */
                         struct forkshell fs;
 
+                        INT_OFF;
                         memset(&fs, 0, sizeof(fs));
                         fs.fpid = FS_SHELLEXEC;
                         fs.argv = argv;
@@ -14492,6 +14495,7 @@ forkshell_shellexec(struct forkshell *fs)
         char **argv = fs->argv;
         char *path = fs->string;
 
+        FORCE_INT_ON;
         listsetvar(varlist, VEXPORT|VSTACK);
         shellexec(argv[0], argv, path, idx);
 }