Fixed issues where WaitForMultipleObjects may hang when given a NULL process. Caused by incorrect placement into an array of valid processes.

include/uniproc.h

@@ -1,26 +1,33 @@
 #pragma once
+#ifdef __cplusplus
+extern "C"
+{
+#endif
 #include <stdio.h>
 #include <stdlib.h>
 #include <stdint.h>
 #include <Windows.h>
-typedef struct {
+	typedef struct {
 
-	uint64_t userdata;
-	FILE* in;
-	FILE* out;
-	FILE* err;
+		uint64_t userdata;
+		FILE* in;
+		FILE* out;
+		FILE* err;
 
-	// OS-dependent handle to the process
-	uint32_t _proc_hdl;
+		// OS-dependent handle to the process
+		uint32_t _proc_hdl;
 
-} uniproc_process;
+	} uniproc_process;
 
-uniproc_process uniproc_create_process(const char* cmd, const size_t num_args, const char** argv);
-void uniproc_await_processes(const uniproc_process* p, int* return_codes, const size_t num_processes);
-void uniproc_close_process(uniproc_process* p);
-int uniproc_are_processes_finished(const uniproc_process* p, const size_t num_processes);
-void uniproc_nullify_processes(uniproc_process* p, const size_t num_processes);
-int uniproc_is_process_null(const uniproc_process* p);
-void uniproc_await_any_processes(const uniproc_process* p, const size_t num_processes);
-void uniproc_set_userdata(uniproc_process* p, void const* userdata);
-void* uniproc_get_userdata(uniproc_process* p);
+	uniproc_process uniproc_create_process(const char* cmd, const size_t num_args, const char** argv);
+	void uniproc_await_processes(const uniproc_process* p, int* return_codes, const size_t num_processes);
+	void uniproc_close_process(uniproc_process* p);
+	int uniproc_are_processes_finished(const uniproc_process* p, const size_t num_processes);
+	void uniproc_nullify_processes(uniproc_process* p, const size_t num_processes);
+	int uniproc_is_process_null(const uniproc_process* p);
+	void uniproc_await_any_processes(const uniproc_process* p, const size_t num_processes);
+	void uniproc_set_userdata(uniproc_process* p, void const* userdata);
+	void* uniproc_get_userdata(uniproc_process* p);
+#ifdef __cplusplus
+}
+#endif

src/uniproc_win64.c

@@ -155,10 +155,9 @@ void uniproc_await_processes(const uniproc_process* p, int* return_codes, const
 	for (size_t i = 0; i < num_processes; ++i)
 	{
 		if (uniproc_is_process_null(p + i)) continue;
-		h[i] = (HANDLE)p[i]._proc_hdl;
-		num_valid_handles++;
+		h[num_valid_handles++] = (HANDLE)p[i]._proc_hdl;
 	}
-
+	if (num_valid_handles == 0) return;
 	WaitForMultipleObjects(num_valid_handles, h, 1, INFINITE);
 	free(h);
 
@@ -191,6 +190,7 @@ int uniproc_are_processes_finished(const uniproc_process* p, const size_t num_pr
 		h[i] = (HANDLE)p[i]._proc_hdl;
 		num_valid_handles++;
 	}
+	if (num_valid_handles == 0) return 1;
 	DWORD ret = WaitForMultipleObjects(num_valid_handles, h, 1, 0);
 	free(h);
 	return ret >= WAIT_OBJECT_0 && ret < WAIT_OBJECT_0 + num_valid_handles;
@@ -212,7 +212,8 @@ void uniproc_await_any_processes(const uniproc_process* p, const size_t num_proc
 		h[i] = (HANDLE)p[i]._proc_hdl;
 		num_valid_handles++;
 	}
-	WaitForMultipleObjects(num_valid_handles, h, false, INFINITE);
+	if (num_valid_handles == 0) return;
+	WaitForMultipleObjects(num_valid_handles, h, 0, INFINITE);
 	free(h);
 }