[Ada] Handle errors and limit simultaneous wait objects number in win32_wait

[Pierre-Marie de Rodat]

Everything is in the subject.

Tested on x86_64-pc-linux-gnu, committed on trunk

2017-09-25  Vasiliy Fofanov  <fofa...@adacore.com>

        * adaint.c (win32_wait): Properly handle error and take into account
        the WIN32 limitation on the number of simultaneous wait objects.


Index: adaint.c
===================================================================
--- adaint.c    (revision 253141)
+++ adaint.c    (working copy)
@@ -2551,6 +2551,7 @@
   DWORD res;
   int hl_len;
   int found;
+  int pos;
 
  START_WAIT:
 
@@ -2563,7 +2564,15 @@
   /* -------------------- critical section -------------------- */
   EnterCS();
 
+  /* ??? We can't wait for more than MAXIMUM_WAIT_OBJECTS due to a Win32
+     limitation */
+  if (plist_length < MAXIMUM_WAIT_OBJECTS)
   hl_len = plist_length;
+  else
+    {
+      errno = EINVAL;
+      return -1;
+    }
 
 #ifdef CERT
   hl = (HANDLE *) xmalloc (sizeof (HANDLE) * hl_len);
@@ -2586,6 +2595,13 @@
 
   res = WaitForMultipleObjects (hl_len, hl, FALSE, INFINITE);
 
+  /* If there was an error, exit now */
+  if (res == WAIT_FAILED)
+    {
+      errno = EINVAL;
+      return -1;
+    }
+
   /* if the ProcListEvt has been signaled then the list of processes has been
      updated to add or remove a handle, just loop over */
 
@@ -2596,9 +2612,17 @@
       goto START_WAIT;
     }
 
-  h = hl[res - WAIT_OBJECT_0];
+  /* Handle two distinct groups of return codes: finished waits and abandoned
+     waits */
+
+  if (res < WAIT_ABANDONED_0)
+    pos = res - WAIT_OBJECT_0;
+  else
+    pos = res - WAIT_ABANDONED_0;
+
+  h = hl[pos];
   GetExitCodeProcess (h, &exitcode);
-  pid = pidl [res - WAIT_OBJECT_0];
+  pid = pidl [pos];
 
   found = __gnat_win32_remove_handle (h, -1);