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authorKaz Kylheku <kaz@kylheku.com>2016-07-02 09:57:34 -0700
committerKaz Kylheku <kaz@kylheku.com>2017-11-16 19:34:49 -0800
commite6ea9f7f870c346a6f04c0b5d7ec49e5f2156164 (patch)
tree097ebe3e7c5aff7c44b9b280ce045a160a16d0c4
parenta143efde405d1a093201b7ba7cfa6d5b8140836c (diff)
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Fix spawned process window not foregrounding.
This patch addresses an issue whereby the window of a process created with CreateProcess fails to come to the foreground. This occurs when the calling process itself hasn't run any Windows event processing loop. A repro test case is to make a program with a main, and and call CreateProcess to spawn calc.exe or notepad.exe before doing anything else. It turns out that a dummy call to TranslateMessage makes this issue goes away. If such a call is made before CreateProcess, then the spawned process' window comes up in the foreground as expected. * winsup/cygwin/Makefile.in (DLL_IMPORTS): We need to link in user32.dll to call TranslateMessage. Condense the multiple ${shell ...} call repetition with a foreach. * winsup/cygwin/spawn.cc (child_info_spawn::worker): Do the dummy TranslateMessage call before the section of code that calls CreateProcess or CreateProcessAsUser.
-rw-r--r--winsup/cygwin/Makefile.in3
-rw-r--r--winsup/cygwin/spawn.cc6
2 files changed, 8 insertions, 1 deletions
diff --git a/winsup/cygwin/Makefile.in b/winsup/cygwin/Makefile.in
index 10e6b1f81..c8d267172 100644
--- a/winsup/cygwin/Makefile.in
+++ b/winsup/cygwin/Makefile.in
@@ -147,7 +147,8 @@ EXTRA_OFILES:=
MALLOC_OFILES:=malloc.o
-DLL_IMPORTS:=${shell $(CC) -print-file-name=w32api/libkernel32.a} ${shell $(CC) -print-file-name=w32api/libntdll.a}
+DLL_IMPORTS:=${foreach i,kernel32 user32 ntdll,\
+ ${shell $(CC) -print-file-name=w32api/lib${i}.a}}
MT_SAFE_OBJECTS:=
#
diff --git a/winsup/cygwin/spawn.cc b/winsup/cygwin/spawn.cc
index 05020952a..758447e9d 100644
--- a/winsup/cygwin/spawn.cc
+++ b/winsup/cygwin/spawn.cc
@@ -566,6 +566,12 @@ child_info_spawn::worker (const char *prog_arg, const char *const *argv,
SetHandleInformation (my_wr_proc_pipe, HANDLE_FLAG_INHERIT, 0);
parent_winpid = GetCurrentProcessId ();
+ /* Workaround for the issue of the window of a spawned process
+ not coming to the foreground. A useless call to TranslateMessage
+ cures this somehow. */
+ MSG dummy = { 0 };
+ (void) TranslateMessage(&dummy);
+
loop:
/* When ruid != euid we create the new process under the current original
account and impersonate in child, this way maintaining the different