mingw: add a helper function to attach GDB to the current process

When debugging Git, the criss-cross spawning of processes can make
things quite a bit difficult, especially when a Unix shell script is
thrown in the mix that calls a `git.exe` that then segfaults.

To help debugging such things, we introduce the `open_in_gdb()` function
which can be called at a code location where the segfault happens (or as
close as one can get); This will open a new MinTTY window with a GDB
that already attached to the current process.

Inspired by Derrick Stolee.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 13 insertions, 0 deletions

diff --git a/compat/mingw.c b/compat/mingw.c
index bd24d91..6b36d03 100644
--- a/compat/mingw.c
+++ b/compat/mingw.c
@@ -13,6 +13,19 @@
 
 static const int delay[] = { 0, 1, 10, 20, 40 };
 
+void open_in_gdb(void)
+{
+	static struct child_process cp = CHILD_PROCESS_INIT;
+	extern char *_pgmptr;
+
+	argv_array_pushl(&cp.args, "mintty", "gdb", NULL);
+	argv_array_pushf(&cp.args, "--pid=%d", getpid());
+	cp.clean_on_exit = 1;
+	if (start_command(&cp) < 0)
+		die_errno("Could not start gdb");
+	sleep(1);
+}
+
 int err_win_to_posix(DWORD winerr)
 {
 	int error = ENOSYS;