* Makefile.in (DLL_OFILES): Add hookapi.o. Eliminate some cruft.

* cygheap.h (cygheap_types): Add new enum: HEAP_1_HOOK.
(hook_chain): New struct.
(init_cygheap::hooks): Define new element.
* cygheap.cc (cygheap_fixup_in_child): Zero hook chain on exec.
* dcrt0.cc (dll_crt0_1): Call ld_preload just before calling main function.
* external.cc (cygwin_internal): Implement CW_HOOK.
* fork.cc (fork_child): Call fixup_hooks_after_fork.
* init.cc (cygwin_hmodule): Reinstate after a long absence.
* include/sys/cygwin.h: Define CW_HOOK.
* hookapi.cc: New file.
* select.cc (start_thread_socket): Add debugging output.
* fhandler_disk_file.cc (fhandler_disk_file::fchmod): gcc 4.x accommodation.
* fhandler_socket.cc (fhandler_socket::connect): Make sure that err is
initialized.

winsup/cygwin/external.cc

@@ -28,6 +28,8 @@ details. */
 #include "pwdgrp.h"
 #include "cygtls.h"
 
+void *hook_cygwin (const char *, const void *);
+
 static external_pinfo *
 fillout_pinfo (pid_t pid, int winpid)
 {
@@ -298,6 +300,12 @@ cygwin_internal (cygwin_getinfo_types t, ...)
 	    }
 	  return p.binmode ();
 	}
+      case CW_HOOK:
+	{
+	  const char *name = va_arg (arg, const char *);
+	  const void *hookfn = va_arg (arg, const void *);
+	  return (unsigned long) hook_cygwin (name, hookfn);
+	}
       default:
 	return (DWORD) -1;
     }