| 1 | #ifndef EXIT_PROCESS_H |
| 2 | #define EXIT_PROCESS_H |
| 3 | |
| 4 | /* |
| 5 | * This file contains functions to terminate a Win32 process, as gently as |
| 6 | * possible. |
| 7 | * |
| 8 | * At first, we will attempt to inject a thread that calls ExitProcess(). If |
| 9 | * that fails, we will fall back to terminating the entire process tree. |
| 10 | * |
| 11 | * For simplicity, these functions are marked as file-local. |
| 12 | */ |
| 13 | |
| 14 | #include <tlhelp32.h> |
| 15 | |
| 16 | /* |
| 17 | * Terminates the process corresponding to the process ID and all of its |
| 18 | * directly and indirectly spawned subprocesses. |
| 19 | * |
| 20 | * This way of terminating the processes is not gentle: the processes get |
| 21 | * no chance of cleaning up after themselves (closing file handles, removing |
| 22 | * .lock files, terminating spawned processes (if any), etc). |
| 23 | */ |
| 24 | static int terminate_process_tree(HANDLE main_process, int exit_status) |
| 25 | { |
| 26 | HANDLE snapshot = CreateToolhelp32Snapshot(TH32CS_SNAPPROCESS, 0); |
| 27 | PROCESSENTRY32 entry; |
| 28 | DWORD pids[16384]; |
| 29 | int max_len = sizeof(pids) / sizeof(*pids), i, len, ret = 0; |
| 30 | pid_t pid = GetProcessId(main_process); |
| 31 | |
| 32 | pids[0] = (DWORD)pid; |
| 33 | len = 1; |
| 34 | |
| 35 | /* |
| 36 | * Even if Process32First()/Process32Next() seem to traverse the |
| 37 | * processes in topological order (i.e. parent processes before |
| 38 | * child processes), there is nothing in the Win32 API documentation |
| 39 | * suggesting that this is guaranteed. |
| 40 | * |
| 41 | * Therefore, run through them at least twice and stop when no more |
| 42 | * process IDs were added to the list. |
| 43 | */ |
| 44 | for (;;) { |
| 45 | int orig_len = len; |
| 46 | |
| 47 | memset(&entry, 0, sizeof(entry)); |
| 48 | entry.dwSize = sizeof(entry); |
| 49 | |
| 50 | if (!Process32First(snapshot, &entry)) |
| 51 | break; |
| 52 | |
| 53 | do { |
| 54 | for (i = len - 1; i >= 0; i--) { |
| 55 | if (pids[i] == entry.th32ProcessID) |
| 56 | break; |
| 57 | if (pids[i] == entry.th32ParentProcessID) |
| 58 | pids[len++] = entry.th32ProcessID; |
| 59 | } |
| 60 | } while (len < max_len && Process32Next(snapshot, &entry)); |
| 61 | |
| 62 | if (orig_len == len || len >= max_len) |
| 63 | break; |
| 64 | } |
| 65 | |
| 66 | for (i = len - 1; i > 0; i--) { |
| 67 | HANDLE process = OpenProcess(PROCESS_TERMINATE, FALSE, pids[i]); |
| 68 | |
| 69 | if (process) { |
| 70 | if (!TerminateProcess(process, exit_status)) |
| 71 | ret = -1; |
| 72 | CloseHandle(process); |
| 73 | } |
| 74 | } |
| 75 | if (!TerminateProcess(main_process, exit_status)) |
| 76 | ret = -1; |
| 77 | CloseHandle(main_process); |
| 78 | |
| 79 | return ret; |
| 80 | } |
| 81 | |
| 82 | /** |
| 83 | * Determine whether a process runs in the same architecture as the current |
| 84 | * one. That test is required before we assume that GetProcAddress() returns |
| 85 | * a valid address *for the target process*. |
| 86 | */ |
| 87 | static inline int process_architecture_matches_current(HANDLE process) |
| 88 | { |
| 89 | static BOOL current_is_wow = -1; |
| 90 | BOOL is_wow; |
| 91 | |
| 92 | if (current_is_wow == -1 && |
| 93 | !IsWow64Process (GetCurrentProcess(), ¤t_is_wow)) |
| 94 | current_is_wow = -2; |
| 95 | if (current_is_wow == -2) |
| 96 | return 0; /* could not determine current process' WoW-ness */ |
| 97 | if (!IsWow64Process (process, &is_wow)) |
| 98 | return 0; /* cannot determine */ |
| 99 | return is_wow == current_is_wow; |
| 100 | } |
| 101 | |
| 102 | /** |
| 103 | * Inject a thread into the given process that runs ExitProcess(). |
| 104 | * |
| 105 | * Note: as kernel32.dll is loaded before any process, the other process and |
| 106 | * this process will have ExitProcess() at the same address. |
| 107 | * |
| 108 | * This function expects the process handle to have the access rights for |
| 109 | * CreateRemoteThread(): PROCESS_CREATE_THREAD, PROCESS_QUERY_INFORMATION, |
| 110 | * PROCESS_VM_OPERATION, PROCESS_VM_WRITE, and PROCESS_VM_READ. |
| 111 | * |
| 112 | * The idea comes from the Dr Dobb's article "A Safer Alternative to |
| 113 | * TerminateProcess()" by Andrew Tucker (July 1, 1999), |
| 114 | * http://www.drdobbs.com/a-safer-alternative-to-terminateprocess/184416547 |
| 115 | * |
| 116 | * If this method fails, we fall back to running terminate_process_tree(). |
| 117 | */ |
| 118 | static int exit_process(HANDLE process, int exit_code) |
| 119 | { |
| 120 | DWORD code; |
| 121 | |
| 122 | if (GetExitCodeProcess(process, &code) && code == STILL_ACTIVE) { |
| 123 | static int initialized; |
| 124 | static LPTHREAD_START_ROUTINE exit_process_address; |
| 125 | PVOID arg = (PVOID)(intptr_t)exit_code; |
| 126 | DWORD thread_id; |
| 127 | HANDLE thread = NULL; |
| 128 | |
| 129 | if (!initialized) { |
| 130 | HINSTANCE kernel32 = GetModuleHandleA("kernel32"); |
| 131 | if (!kernel32) |
| 132 | die("BUG: cannot find kernel32"); |
| 133 | exit_process_address = |
| 134 | (LPTHREAD_START_ROUTINE)(void (*)(void)) |
| 135 | GetProcAddress(kernel32, "ExitProcess"); |
| 136 | initialized = 1; |
| 137 | } |
| 138 | if (!exit_process_address || |
| 139 | !process_architecture_matches_current(process)) |
| 140 | return terminate_process_tree(process, exit_code); |
| 141 | |
| 142 | thread = CreateRemoteThread(process, NULL, 0, |
| 143 | exit_process_address, |
| 144 | arg, 0, &thread_id); |
| 145 | if (thread) { |
| 146 | CloseHandle(thread); |
| 147 | /* |
| 148 | * If the process survives for 10 seconds (a completely |
| 149 | * arbitrary value picked from thin air), fall back to |
| 150 | * killing the process tree via TerminateProcess(). |
| 151 | */ |
| 152 | if (WaitForSingleObject(process, 10000) == |
| 153 | WAIT_OBJECT_0) { |
| 154 | CloseHandle(process); |
| 155 | return 0; |
| 156 | } |
| 157 | } |
| 158 | |
| 159 | return terminate_process_tree(process, exit_code); |
| 160 | } |
| 161 | |
| 162 | CloseHandle(process); |
| 163 | return 0; |
| 164 | } |
| 165 | |
| 166 | #endif |