integrate change#17566 from maint-5.6 branch

on windows, ensure child processes that get run via backticks get
the right pipe handle at stdin/stdout; this is needed to make
subprocesses see the correct standard handles such that backticks
and piped open()s work when run from within GUI applications

this also makes it possible to launch wperl.exe in backticks
from within an application that has no std handles without a
new blank console window popping up
p4raw-link: @17566 on //depot/maint-5.6/perl: c7efefc2a43b65746e10207fe89bc47b7f7c27ea

p4raw-id: //depot/perl@17567

1 files changed, 24 insertions, 1 deletions

diff --git a/win32/win32.c b/win32/win32.c
index ba2af59fd8..6f96431603 100644
--- a/win32/win32.c
+++ b/win32/win32.c
@@ -2718,17 +2718,22 @@ win32_popen(const char *command, const char *mode)
     int stdfd, oldfd;
     int ourmode;
     int childpid;
+    DWORD nhandle;
+    HANDLE old_h;
+    int lock_held = 0;
 
     /* establish which ends read and write */
     if (strchr(mode,'w')) {
         stdfd = 0;		/* stdin */
         parent = 1;
         child = 0;
+	nhandle = STD_INPUT_HANDLE;
     }
     else if (strchr(mode,'r')) {
         stdfd = 1;		/* stdout */
         parent = 0;
         child = 1;
+	nhandle = STD_OUTPUT_HANDLE;
     }
     else
         return NULL;
@@ -2744,7 +2749,7 @@ win32_popen(const char *command, const char *mode)
     /* the child doesn't inherit handles */
     ourmode |= O_NOINHERIT;
 
-    if (win32_pipe( p, 512, ourmode) == -1)
+    if (win32_pipe(p, 512, ourmode) == -1)
         return NULL;
 
     /* save current stdfd */
@@ -2759,12 +2764,25 @@ win32_popen(const char *command, const char *mode)
     /* close the child end in parent */
     win32_close(p[child]);
 
+    /* save the old std handle, and set the std handle */
+    OP_REFCNT_LOCK;
+    lock_held = 1;
+    old_h = GetStdHandle(nhandle);
+    SetStdHandle(nhandle, (HANDLE)_get_osfhandle(stdfd));
+
     /* start the child */
     {
 	dTHX;
 	if ((childpid = do_spawn_nowait((char*)command)) == -1)
 	    goto cleanup;
 
+	/* restore the old std handle */
+	if (lock_held) {
+	    SetStdHandle(nhandle, old_h);
+	    OP_REFCNT_UNLOCK;
+	    lock_held = 0;
+	}
+
 	/* revert stdfd to whatever it was before */
 	if (win32_dup2(oldfd, stdfd) == -1)
 	    goto cleanup;
@@ -2787,6 +2805,11 @@ cleanup:
     /* we don't need to check for errors here */
     win32_close(p[0]);
     win32_close(p[1]);
+    if (lock_held) {
+	SetStdHandle(nhandle, old_h);
+	OP_REFCNT_UNLOCK;
+	lock_held = 0;
+    }
     if (oldfd != -1) {
         win32_dup2(oldfd, stdfd);
         win32_close(oldfd);