nativelibc/process/wait.c

/*	A part of the Native C Library for Windows NT
	Copyright 2007-2015 PC GO Ld.

	This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version.

	This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
*/

#include <sys/wait.h>
#include <windows.h>
#include <nt.h>
#include <errno.h>
#include <unistd.h>
#include <process.h>
#include <ntstatus.h>
#include <assert.h>

struct child {
	//int vaild;
	pid_t pid;
	void *handle;
};

static struct child child_table[64];

int __child_process_table_add(pid_t pid, void *handle) {
	int i = 0;
	while(child_table[i].pid > 0) {
		if(++i == 64) {
			errno = EAGAIN;
			return -1;
		}
	}
	child_table[i].pid = pid;
	child_table[i].handle = handle;
	return 0;
}

// Return index or -1 if not found
static int find_child_by_pid(pid_t pid, void **handle) {
	int i;
	for(i=0; i<64; i++) {
		if(child_table[i].pid == pid) {
			*handle = child_table[i].handle;
			return i;
		}
	}
	return -1;
}

// Return index or -1 if not found
// Handle not a common pointer type, don't add the const to the argument
static int find_child_by_handle(void *handle, pid_t *pid) {
	int i;
	for(i=0; i<64; i++) {
		if(child_table[i].handle == handle) {
			*pid = child_table[i].pid;
			return i;
		}
	}
	return -1;
}

static unsigned int find_children(void **handles) {
	int count = 0, i;
	for(i=0; i<64; i++) {
		if(child_table[i].pid > 0) {
			handles[count++] = child_table[i].handle;
		}
	}
	return count;
}

pid_t waitpid(pid_t pid, int *status, int options) {
	int i;
	void *handle;
	long int ntstatus;
	if(pid == -1) {
		void *handles[64];
		int count = find_children(handles);
		if(!count) {
			errno = ECHILD;
			return -1;
		}
		if(options & WNOHANG) return 0;
		ntstatus = NtWaitForMultipleObjects(count, handles, WaitAny, 0, NULL);
		if(ntstatus < 0) {
			__set_errno_from_ntstatus(ntstatus);
			return -1;
		}
		if(ntstatus == STATUS_ALERTED || ntstatus == STATUS_USER_APC) {
			errno = EINTR;
			return -1;
		}
		assert(ntstatus < count);
		handle = handles[ntstatus];
		i = find_child_by_handle(handle, &pid);
		assert(i >= 0 && pid > 0);
	} else {
		if(pid <= 0) {
			errno = ENOSYS;
			return -1;
		}
		i = find_child_by_pid(pid, &handle);
		if(i == -1) {
			errno = ECHILD;
			return -1;
		}
		if(options & WNOHANG) return pid;
		ntstatus = NtWaitForSingleObject(handle, 0, NULL);
		if(ntstatus < 0) {
			__set_errno_from_ntstatus(ntstatus);
			return -1;
		}
		if(ntstatus == STATUS_ALERTED || ntstatus == STATUS_USER_APC) {
			errno = EINTR;
			return -1;
		}
	}
	child_table[i].pid = -1;
	child_table[i].handle = (void *)-1;
	if(status) {
		PROCESS_BASIC_INFORMATION pbi;
		ntstatus = NtQueryInformationProcess(handle, ProcessBasicInformation, &pbi, sizeof pbi, NULL);
		if(ntstatus < 0) {
			NtClose(handle);
			__set_errno_from_ntstatus(ntstatus);
			return -1;
		}
		*status = pbi.ExitStatus;
	}
	NtClose(handle);
	return pid;
}

pid_t wait(int *status) {
	return waitpid(-1, status, 0);
}