(In my frustration to fix gdb, I deleted all my custom scripts. Here’s one recipe that was particularly difficult to recreate.)
Ctrl-C doesn’t work to interrupt Rack from a mingw64 terminal. Instead, set up a command in a second mingw64 terminal to suspend Rack’s execution in gdb.
Overview of steps:
gcc -o debugbreak -mthreads debugbreak.c # source below
./debugbreak.exe `ps -W | grep Rack.exe | awk '{print $4}'`
(debugbreak.c source comes from mingw.org, and needed light editing to work)
// from http://www.mingw.org/wiki/Workaround_for_GDB_Ctrl_C_Interrupt
/* BEGIN debugbreak.c */
#ifndef _WIN32_WINNT
#define _WIN32_WINNT 0x0501
#endif
#if _WIN32_WINNT < 0x0501
#error Must target Windows NT 5.0.1 or later for DebugBreakProcess
#endif
#include <Windows.h>
#include <stddef.h>
#include <stdio.h>
#include <stdlib.h>
/* Compile with this line:
gcc -o debugbreak -mthreads debugbreak.c
*/
static char errbuffer[256];
static const char *geterrstr(DWORD errcode)
{
size_t skip = 0;
DWORD chars;
chars = FormatMessage(
FORMAT_MESSAGE_FROM_SYSTEM | FORMAT_MESSAGE_IGNORE_INSERTS,
NULL, errcode, 0, errbuffer, sizeof(errbuffer)-1, 0);
errbuffer[sizeof(errbuffer)-1] = 0;
if (chars) {
while (errbuffer[chars-1] == '\r' || errbuffer[chars-1] == '\n') {
errbuffer[--chars] = 0;
}
}
if (chars && errbuffer[chars-1] == '.') errbuffer[--chars] = 0;
if (chars >= 2 && errbuffer[0] == '%' && errbuffer[1] >= '0'
&& errbuffer[1] <= '9')
{
skip = 2;
while (chars > skip && errbuffer[skip] == ' ') ++skip;
if (chars >= skip+2 && errbuffer[skip] == 'i'
&& errbuffer[skip+1] == 's')
{
skip += 2;
while (chars > skip && errbuffer[skip] == ' ') ++skip;
}
}
if (chars > skip && errbuffer[skip] >= 'A' && errbuffer[skip] <= 'Z') {
errbuffer[skip] += 'a' - 'A';
}
return errbuffer+skip;
}
int main(int argc, char *argv[])
{
HANDLE proc;
unsigned proc_id = 0;
BOOL break_result;
if (argc != 2) {
printf("Usage: debugbreak process_id_number\n");
return 1;
}
proc_id = (unsigned) strtol(argv[1], NULL, 0);
if (proc_id == 0) {
printf("Invalid process id %u\n", proc_id);
return 1;
}
proc = OpenProcess(PROCESS_ALL_ACCESS, FALSE, (DWORD)proc_id);
if (proc == NULL) {
DWORD lastError = GetLastError();
printf("Failed to open process %u\n", proc_id);
printf("Error code is %lu (%s)\n", (unsigned long)lastError,
geterrstr(lastError));
return 1;
}
break_result = DebugBreakProcess(proc);
if (!break_result) {
DWORD lastError = GetLastError();
printf("Failed to debug break process %u\n", proc_id);
printf("Error code is %lu (%s)\n", (unsigned long)lastError,
geterrstr(lastError));
CloseHandle(proc);
return 1;
}
printf("DebugBreak sent successfully to process id %u\n", proc_id);
CloseHandle(proc);
return 0;
}
/* END debugbreak.c */