diff --git a/compat/mingw.c b/compat/mingw.c index c71e58593457ad..5ae279441b448d 100644 --- a/compat/mingw.c +++ b/compat/mingw.c @@ -8,6 +8,7 @@ #include "../strbuf.h" #include "../run-command.h" #include "../cache.h" +#include "win32/exit-process.h" #include "win32/lazyload.h" #include "../config.h" #include "dir.h" @@ -2158,16 +2159,28 @@ int mingw_execvp(const char *cmd, char *const *argv) int mingw_kill(pid_t pid, int sig) { if (pid > 0 && sig == SIGTERM) { - HANDLE h = OpenProcess(PROCESS_TERMINATE, FALSE, pid); - - if (TerminateProcess(h, -1)) { + HANDLE h = OpenProcess(PROCESS_CREATE_THREAD | + PROCESS_QUERY_INFORMATION | + PROCESS_VM_OPERATION | PROCESS_VM_WRITE | + PROCESS_VM_READ | PROCESS_TERMINATE, + FALSE, pid); + int ret; + + if (h) + ret = exit_process(h, 128 + sig); + else { + h = OpenProcess(PROCESS_TERMINATE, FALSE, pid); + if (!h) { + errno = err_win_to_posix(GetLastError()); + return -1; + } + ret = terminate_process_tree(h, 128 + sig); + } + if (ret) { + errno = err_win_to_posix(GetLastError()); CloseHandle(h); - return 0; } - - errno = err_win_to_posix(GetLastError()); - CloseHandle(h); - return -1; + return ret; } else if (pid > 0 && sig == 0) { HANDLE h = OpenProcess(PROCESS_QUERY_INFORMATION, FALSE, pid); if (h) { diff --git a/compat/win32/exit-process.h b/compat/win32/exit-process.h new file mode 100644 index 00000000000000..d53989884cfb0c --- /dev/null +++ b/compat/win32/exit-process.h @@ -0,0 +1,165 @@ +#ifndef EXIT_PROCESS_H +#define EXIT_PROCESS_H + +/* + * This file contains functions to terminate a Win32 process, as gently as + * possible. + * + * At first, we will attempt to inject a thread that calls ExitProcess(). If + * that fails, we will fall back to terminating the entire process tree. + * + * For simplicity, these functions are marked as file-local. + */ + +#include + +/* + * Terminates the process corresponding to the process ID and all of its + * directly and indirectly spawned subprocesses. + * + * This way of terminating the processes is not gentle: the processes get + * no chance of cleaning up after themselves (closing file handles, removing + * .lock files, terminating spawned processes (if any), etc). + */ +static int terminate_process_tree(HANDLE main_process, int exit_status) +{ + HANDLE snapshot = CreateToolhelp32Snapshot(TH32CS_SNAPPROCESS, 0); + PROCESSENTRY32 entry; + DWORD pids[16384]; + int max_len = sizeof(pids) / sizeof(*pids), i, len, ret = 0; + pid_t pid = GetProcessId(main_process); + + pids[0] = (DWORD)pid; + len = 1; + + /* + * Even if Process32First()/Process32Next() seem to traverse the + * processes in topological order (i.e. parent processes before + * child processes), there is nothing in the Win32 API documentation + * suggesting that this is guaranteed. + * + * Therefore, run through them at least twice and stop when no more + * process IDs were added to the list. + */ + for (;;) { + int orig_len = len; + + memset(&entry, 0, sizeof(entry)); + entry.dwSize = sizeof(entry); + + if (!Process32First(snapshot, &entry)) + break; + + do { + for (i = len - 1; i >= 0; i--) { + if (pids[i] == entry.th32ProcessID) + break; + if (pids[i] == entry.th32ParentProcessID) + pids[len++] = entry.th32ProcessID; + } + } while (len < max_len && Process32Next(snapshot, &entry)); + + if (orig_len == len || len >= max_len) + break; + } + + for (i = len - 1; i > 0; i--) { + HANDLE process = OpenProcess(PROCESS_TERMINATE, FALSE, pids[i]); + + if (process) { + if (!TerminateProcess(process, exit_status)) + ret = -1; + CloseHandle(process); + } + } + if (!TerminateProcess(main_process, exit_status)) + ret = -1; + CloseHandle(main_process); + + return ret; +} + +/** + * Determine whether a process runs in the same architecture as the current + * one. That test is required before we assume that GetProcAddress() returns + * a valid address *for the target process*. + */ +static inline int process_architecture_matches_current(HANDLE process) +{ + static BOOL current_is_wow = -1; + BOOL is_wow; + + if (current_is_wow == -1 && + !IsWow64Process (GetCurrentProcess(), ¤t_is_wow)) + current_is_wow = -2; + if (current_is_wow == -2) + return 0; /* could not determine current process' WoW-ness */ + if (!IsWow64Process (process, &is_wow)) + return 0; /* cannot determine */ + return is_wow == current_is_wow; +} + +/** + * Inject a thread into the given process that runs ExitProcess(). + * + * Note: as kernel32.dll is loaded before any process, the other process and + * this process will have ExitProcess() at the same address. + * + * This function expects the process handle to have the access rights for + * CreateRemoteThread(): PROCESS_CREATE_THREAD, PROCESS_QUERY_INFORMATION, + * PROCESS_VM_OPERATION, PROCESS_VM_WRITE, and PROCESS_VM_READ. + * + * The idea comes from the Dr Dobb's article "A Safer Alternative to + * TerminateProcess()" by Andrew Tucker (July 1, 1999), + * http://www.drdobbs.com/a-safer-alternative-to-terminateprocess/184416547 + * + * If this method fails, we fall back to running terminate_process_tree(). + */ +static int exit_process(HANDLE process, int exit_code) +{ + DWORD code; + + if (GetExitCodeProcess(process, &code) && code == STILL_ACTIVE) { + static int initialized; + static LPTHREAD_START_ROUTINE exit_process_address; + PVOID arg = (PVOID)(intptr_t)exit_code; + DWORD thread_id; + HANDLE thread = NULL; + + if (!initialized) { + HINSTANCE kernel32 = GetModuleHandleA("kernel32"); + if (!kernel32) + die("BUG: cannot find kernel32"); + exit_process_address = + (LPTHREAD_START_ROUTINE)(void (*)(void)) + GetProcAddress(kernel32, "ExitProcess"); + initialized = 1; + } + if (!exit_process_address || + !process_architecture_matches_current(process)) + return terminate_process_tree(process, exit_code); + + thread = CreateRemoteThread(process, NULL, 0, + exit_process_address, + arg, 0, &thread_id); + if (thread) { + CloseHandle(thread); + /* + * If the process survives for 10 seconds (a completely + * arbitrary value picked from thin air), fall back to + * killing the process tree via TerminateProcess(). + */ + if (WaitForSingleObject(process, 10000) == + WAIT_OBJECT_0) { + CloseHandle(process); + return 0; + } + } + + return terminate_process_tree(process, exit_code); + } + + return 0; +} + +#endif