/*
 * Helper program for killing lingering python[_d].exe processes before
 * building, thus attempting to avoid build failures due to files being
 * locked.
 */

#include <windows.h>
#include <wchar.h>
#include <tlhelp32.h>
#include <stdio.h>

#pragma comment(lib, "psapi")

#ifdef _DEBUG
#define PYTHON_EXE (L"python_d.exe")
#define PYTHON_EXE_LEN (12)
#define KILL_PYTHON_EXE (L"kill_python_d.exe")
#define KILL_PYTHON_EXE_LEN (17)
#else
#define PYTHON_EXE (L"python.exe")
#define PYTHON_EXE_LEN (10)
#define KILL_PYTHON_EXE (L"kill_python.exe")
#define KILL_PYTHON_EXE_LEN (15)
#endif

int
main(int argc, char **argv)
{
 HANDLE hp, hsp, hsm; /* process, snapshot processes, snapshot modules */
 DWORD dac, our_pid;
 size_t len;
 wchar_t path[MAX_PATH+1];

 MODULEENTRY32W me;
 PROCESSENTRY32W pe;

 me.dwSize = sizeof(MODULEENTRY32W);
 pe.dwSize = sizeof(PROCESSENTRY32W);

 memset(path, 0, MAX_PATH+1);

 our_pid = GetCurrentProcessId();

 hsm = CreateToolhelp32Snapshot(TH32CS_SNAPMODULE, our_pid);
 if (hsm == INVALID_HANDLE_VALUE) {
 printf("CreateToolhelp32Snapshot[1] failed: %d\n", GetLastError());
 return 1;
 }

 if (!Module32FirstW(hsm, &me)) {
 printf("Module32FirstW[1] failed: %d\n", GetLastError());
 CloseHandle(hsm);
 return 1;
 }

 /*
 * Enumerate over the modules for the current process in order to find
 * kill_process[_d].exe, then take a note of the directory it lives in.
 */
 do {
 if (_wcsnicmp(me.szModule, KILL_PYTHON_EXE, KILL_PYTHON_EXE_LEN))
 continue;

 len = wcsnlen_s(me.szExePath, MAX_PATH) - KILL_PYTHON_EXE_LEN;
 wcsncpy_s(path, MAX_PATH+1, me.szExePath, len); 

 break;

 } while (Module32NextW(hsm, &me));

 CloseHandle(hsm);

 if (path == NULL) {
 printf("failed to discern directory of running process\n");
 return 1;
 }

 /*
 * Take a snapshot of system processes. Enumerate over the snapshot,
 * looking for python processes. When we find one, verify it lives
 * in the same directory we live in. If it does, kill it. If we're
 * unable to kill it, treat this as a fatal error and return 1.
 * 
 * The rationale behind this is that we're called at the start of the 
 * build process on the basis that we'll take care of killing any
 * running instances, such that the build won't encounter permission
 * denied errors during linking. If we can't kill one of the processes,
 * we can't provide this assurance, and the build shouldn't start.
 */

 hsp = CreateToolhelp32Snapshot(TH32CS_SNAPPROCESS, 0);
 if (hsp == INVALID_HANDLE_VALUE) {
 printf("CreateToolhelp32Snapshot[2] failed: %d\n", GetLastError());
 return 1;
 }

 if (!Process32FirstW(hsp, &pe)) {
 printf("Process32FirstW failed: %d\n", GetLastError());
 CloseHandle(hsp);
 return 1;
 }

 dac = PROCESS_QUERY_INFORMATION | PROCESS_VM_READ | PROCESS_TERMINATE;
 do {

 /*
 * XXX TODO: if we really wanted to be fancy, we could check the 
 * modules for all processes (not just the python[_d].exe ones)
 * and see if any of our DLLs are loaded (i.e. python30[_d].dll),
 * as that would also inhibit our ability to rebuild the solution.
 * Not worth loosing sleep over though; for now, a simple check 
 * for just the python executable should be sufficient.
 */

 if (_wcsnicmp(pe.szExeFile, PYTHON_EXE, PYTHON_EXE_LEN))
 /* This isn't a python process. */
 continue;

 /* It's a python process, so figure out which directory it's in... */
 hsm = CreateToolhelp32Snapshot(TH32CS_SNAPMODULE, pe.th32ProcessID);
 if (hsm == INVALID_HANDLE_VALUE)
 /* 
 * If our module snapshot fails (which will happen if we don't own
 * the process), just ignore it and continue. (It seems different
 * versions of Windows return different values for GetLastError()
 * in this situation; it's easier to just ignore it and move on vs.
 * stopping the build for what could be a false positive.)
 */
 continue;

 if (!Module32FirstW(hsm, &me)) {
 printf("Module32FirstW[2] failed: %d\n", GetLastError());
 CloseHandle(hsp);
 CloseHandle(hsm);
 return 1;
 }

 do {
 if (_wcsnicmp(me.szModule, PYTHON_EXE, PYTHON_EXE_LEN))
 /* Wrong module, we're looking for python[_d].exe... */
 continue;

 if (_wcsnicmp(path, me.szExePath, len))
 /* Process doesn't live in our directory. */
 break;

 /* Python process residing in the right directory, kill it! */
 hp = OpenProcess(dac, FALSE, pe.th32ProcessID);
 if (!hp) {
 printf("OpenProcess failed: %d\n", GetLastError());
 CloseHandle(hsp);
 CloseHandle(hsm);
 return 1;
 }

 if (!TerminateProcess(hp, 1)) {
 printf("TerminateProcess failed: %d\n", GetLastError());
 CloseHandle(hsp);
 CloseHandle(hsm);
 CloseHandle(hp);
 return 1;
 }

 CloseHandle(hp);
 break;

 } while (Module32NextW(hsm, &me));

 CloseHandle(hsm);

 } while (Process32NextW(hsp, &pe));

 CloseHandle(hsp);

 return 0;
}

/* vi: set ts=8 sw=4 sts=4 expandtab */