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>
This commit is contained in:
Johannes Schindelin 2020-02-13 21:49:53 +00:00 committed by Junio C Hamano
parent b6d4d82bd5
commit 08809c09aa
2 changed files with 23 additions and 0 deletions

View file

@ -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;

View file

@ -591,6 +591,16 @@ extern CRITICAL_SECTION pinfo_cs;
int wmain(int argc, const wchar_t **w_argv);
int main(int argc, const char **argv);
/*
* For debugging: if a problem occurs, say, in a Git process that is spawned
* from another Git process which in turn is spawned from yet another Git
* process, it can be quite daunting to figure out what is going on.
*
* Call this function to open a new MinTTY (this assumes you are in Git for
* Windows' SDK) with a GDB that attaches to the current process right away.
*/
extern void open_in_gdb(void);
/*
* Used by Pthread API implementation for Windows
*/