From: Tom Lane <tgl@sss.pgh.pa.us>

Making PQrequestCancel safe to call in a signal handler turned out to be
much easier than I feared.  So here are the diffs.

Some notes:
  * I modified the postmaster's packet "iodone" callback interface to allow
    the callback routine to return a continue-or-drop-connection return
    code; this was necessary to allow the connection to be closed after
    receiving a Cancel, rather than proceeding to launch a new backend...
    Being a neatnik, I also made the iodone proc have a typechecked
    parameter list.
  * I deleted all code I could find that had to do with OOB.
  * I made some edits to ensure that all signals mentioned in the code
    are referred to symbolically not by numbers ("SIGUSR2" not "2").
    I think Bruce may have already done at least some of the same edits;
    I hope that merging these patches is not too painful.

src/include/commands/dbcommands.h

@@ -6,7 +6,7 @@
  *
  * Copyright (c) 1994, Regents of the University of California
  *
- * $Id: dbcommands.h,v 1.1 1997/11/24 05:32:51 momjian Exp $
+ * $Id: dbcommands.h,v 1.2 1998/07/09 03:28:56 scrappy Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -17,8 +17,7 @@
  * Originally from tmp/daemon.h. The functions declared in daemon.h does not
  * exist; hence removed.		-- AY 7/29/94
  */
-#define SIGKILLDAEMON1	SIGINT
-#define SIGKILLDAEMON2	SIGTERM
+#define SIGKILLDAEMON1	SIGTERM
 
 extern void createdb(char *dbname, char *dbpath);
 extern void destroydb(char *dbname);