1 /***
2 *wait.c - wait for child process to terminate
3 *
4 * Copyright (c) Microsoft Corporation. All rights reserved.
5 *
6 *Purpose:
7 * defines _wait() - wait for child process to terminate
8 *
9 *******************************************************************************/
10
11 #include <corecrt_internal.h>
12 #include <errno.h>
13 #include <process.h>
14 #include <stdlib.h>
15
16 /***
17 *int _cwait(stat_loc, process_id, action_code) - wait for specific child
18 * process
19 *
20 *Purpose:
21 * The function _cwait() suspends the calling-process until the specified
22 * child-process terminates. If the specifed child-process terminated
23 * prior to the call to _cwait(), return is immediate.
24 *
25 *Entry:
26 * int *stat_loc - pointer to where status is stored or nullptr
27 * process_id - specific process id to be interrogated (0 means any)
28 * action_code - specific action to perform on process ID
29 * either _WAIT_CHILD or _WAIT_GRANDCHILD
30 *
31 *Exit:
32 * process ID of terminated child or -1 on error
33 *
34 * *stat_loc is updated to contain the following:
35 * Normal termination: lo-byte = 0, hi-byte = child exit code
36 * Abnormal termination: lo-byte = term status, hi-byte = 0
37 *
38 *Exceptions:
39 *
40 *******************************************************************************/
41
_cwait(int * const exit_code_result,intptr_t const process_id,int const action_code)42 extern "C" intptr_t __cdecl _cwait(
43 int* const exit_code_result,
44 intptr_t const process_id,
45 int const action_code
46 )
47 {
48 DBG_UNREFERENCED_PARAMETER(action_code);
49
50 if (exit_code_result)
51 *exit_code_result = static_cast<DWORD>(-1);
52
53 // Explicitly check for process ids -1 and -2. In Windows NT, -1 is a handle
54 // to the current process and -2 is a handle to the current thread, and the
55 // OS will let you wait (forever) on either.
56 _VALIDATE_RETURN_NOEXC(process_id != -1 && process_id != -2, ECHILD, -1);
57
58 __crt_unique_handle process_handle(reinterpret_cast<HANDLE>(process_id));
59
60 // Wait for the child process and get its exit code:
61 DWORD exit_code;
62 if (WaitForSingleObject(process_handle.get(), static_cast<DWORD>(-1)) == 0 &&
63 GetExitCodeProcess(process_handle.get(), &exit_code))
64 {
65 if (exit_code_result)
66 *exit_code_result = exit_code;
67
68 return process_id;
69 }
70
71 // One of the API calls failed; map the error and return failure.
72 DWORD const os_error = GetLastError();
73 if (os_error == ERROR_INVALID_HANDLE)
74 {
75 errno = ECHILD;
76 _doserrno = os_error;
77 }
78 else
79 {
80 __acrt_errno_map_os_error(os_error);
81 }
82
83 if (exit_code_result)
84 *exit_code_result = static_cast<DWORD>(-1);
85
86 return -1;
87 }
88