fix race condition in builtins Makefile

CWRU/CWRU.chlog

@@ -3624,3 +3624,23 @@ builtins/suspend.def
 
 doc/{bash.1,bashref.texi}
 	- suspend: updated description to include expanded -f behavior
+
+				   5/25
+				   ----
+builtins/mkbuiltins.c
+	- -includefile: new argument, specifies extern filename to insert
+	  into the #include statement in the structfile (builtins.c) and
+	  the filename in the comment in the extern file (builtext.h).
+	  From Alexander Kanavin <alex.kanavin@gmail.com> via
+	  https://savannah.gnu.org/patch/?10210
+
+builtins/Makefile.in
+	- builtins.c: change call to mkbuiltins to add -includefile option
+	- builtins.c: change recipe to run all the commands in the same shell
+	  invocation
+	- builtins.c: change recipe to specify new filenames in the call to
+	  mkbuiltins and move them onto builtins.c/builtext.h if the new ones
+	  are different; make the new filenames use the current make recipe
+	  shell pid in the filename ($$RECPID).
+	  Inspired by Alexander Kanavin <alex.kanavin@gmail.com> via
+	  https://savannah.gnu.org/patch/?10210

builtins/Makefile.in

@@ -1,6 +1,6 @@
 # This Makefile for building libbuiltins.a is in -*- text -*- for Emacs.
 #
-# Copyright (C) 1996-2021 Free Software Foundation, Inc.
+# Copyright (C) 1996-2022 Free Software Foundation, Inc.
 
 #   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
@@ -186,20 +186,22 @@ gen-helpfiles:	tmpbuiltins.o gen-helpfiles.o
 	$(CC_FOR_BUILD) $(LDFLAGS_FOR_BUILD) -o $@ gen-helpfiles.o tmpbuiltins.o $(LIBS_FOR_BUILD)
 
 builtext.h builtins.c: $(MKBUILTINS) $(DEFSRC)
-	@-if test -f builtins.c; then mv -f builtins.c old-builtins.c; fi
-	@-if test -f builtext.h; then mv -f builtext.h old-builtext.h; fi
-	./$(MKBUILTINS) -externfile builtext.h -structfile builtins.c \
-	    -noproduction $(DIRECTDEFINE) $(HELPDIRDEFINE) $(HELPSTRINGS) $(DEFSRC)
-	@-if cmp -s old-builtext.h builtext.h 2>/dev/null; then \
-		mv old-builtext.h builtext.h; \
-	 else \
-		$(RM) old-builtext.h; \
-	 fi
-	@-if cmp -s old-builtins.c builtins.c 2>/dev/null; then \
-		mv old-builtins.c builtins.c; \
-	 else \
-		$(RM) old-builtins.c; \
-	 fi
+	@RECPID=$$$$ ; \
+	NEW_BUILTEXT=builtext-$$RECPID.h NEW_BUILTINS=builtins-$$RECPID.c ; \
+	./$(MKBUILTINS) -externfile $$NEW_BUILTEXT \
+	    -includefile builtext.h \
+	    -structfile $$NEW_BUILTINS \
+	    -noproduction $(DIRECTDEFINE) $(HELPDIRDEFINE) $(HELPSTRINGS) $(DEFSRC) ; \
+	if cmp -s $$NEW_BUILTEXT builtext.h 2>/dev/null; then \
+		$(RM) $$NEW_BUILTEXT; \
+	else \
+		mv $$NEW_BUILTEXT builtext.h; \
+	fi ; \
+	if cmp -s $$NEW_BUILTINS builtins.c 2>/dev/null; then \
+		$(RM) $$NEW_BUILTINS ; \
+	else \
+		mv $$NEW_BUILTINS builtins.c; \
+	fi
 
 helpdoc:	gen-helpfiles
 	./gen-helpfiles ${HELPDIRDEFINE}

builtins/mkbuiltins.c

@@ -1,7 +1,7 @@
 /* mkbuiltins.c - Create builtins.c, builtext.h, and builtdoc.c from
    a single source file called builtins.def. */
 
-/* Copyright (C) 1987-2021 Free Software Foundation, Inc.
+/* Copyright (C) 1987-2022 Free Software Foundation, Inc.
 
    This file is part of GNU Bash, the Bourne Again SHell.
 
@@ -113,6 +113,12 @@ char *struct_filename = (char *)NULL;
 /* The name of the external declaration file. */
 char *extern_filename = (char *)NULL;
 
+/* The name of the include file to write into the structure file, if it's
+   different from extern_filename. */
+char *include_filename = (char *)NULL;
+
+/* The name of the include file to put into the generated struct filename. */
+
 /* Here is a structure for manipulating arrays of data. */
 typedef struct {
   int size;		/* Number of slots allocated to array. */
@@ -241,6 +247,8 @@ main (argc, argv)
 
       if (strcmp (arg, "-externfile") == 0)
 	extern_filename = argv[arg_index++];
+      else if (strcmp (arg, "-includefile") == 0)
+	include_filename = argv[arg_index++];
       else if (strcmp (arg, "-structfile") == 0)
 	struct_filename = argv[arg_index++];
       else if (strcmp (arg, "-noproduction") == 0)
@@ -284,6 +292,9 @@ main (argc, argv)
 	}
     }
 
+  if (include_filename == 0)
+    include_filename = extern_filename;
+
   /* If there are no files to process, just quit now. */
   if (arg_index == argc)
     exit (0);
@@ -1125,7 +1136,7 @@ char *structfile_header[] = {
   "/* This file is manufactured by ./mkbuiltins, and should not be",
   "   edited by hand.  See the source to mkbuiltins for details. */",
   "",
-  "/* Copyright (C) 1987-2021 Free Software Foundation, Inc.",
+  "/* Copyright (C) 1987-2022 Free Software Foundation, Inc.",
   "",
   "   This file is part of GNU Bash, the Bourne Again SHell.",
   "",
@@ -1187,7 +1198,7 @@ write_file_headers (structfile, externfile)
 	fprintf (structfile, "%s\n", structfile_header[i]);
 
       fprintf (structfile, "#include \"%s\"\n",
-	       extern_filename ? extern_filename : "builtext.h");
+	       include_filename ? include_filename : "builtext.h");
 
       fprintf (structfile, "#include \"bashintl.h\"\n");
 
@@ -1197,7 +1208,7 @@ write_file_headers (structfile, externfile)
   if (externfile)
     fprintf (externfile,
 	     "/* %s - The list of builtins found in libbuiltins.a. */\n",
-	     extern_filename ? extern_filename : "builtext.h");
+	     include_filename ? include_filename : "builtext.h");
 }
 
 /* Write out any necessary closing information for

examples/scripts/bcalc

@@ -34,14 +34,30 @@ init()
 	coproc BC { bc -q 2>&1; }
 	# set scale
 	printf "scale = 10\n" >&${BC[1]}
+	# bash automatically sets BC_PID to the coproc pid; we store it so we
+	# can be sure to use it even after bash reaps the coproc and unsets
+	# the variables
+	coproc_pid=$BC_PID
 }
 
 # not strictly necessary; the pipes will be closed when the program exits
+# but we can use it in reset() below
 fini()
 {
 	eval exec "${BC[1]}>&- ${BC[0]}<&-"
 }
 
+reset()
+{
+	fini	# close the old pipes
+
+	sleep 1
+	kill -1 $coproc_pid >/dev/null 2>&1	# make sure the coproc is dead
+	unset coproc_pid
+
+	init		
+}
+	
 # set a read timeout of a half second to avoid synchronization problems
 calc()
 {
@@ -71,6 +87,7 @@ do
 	case "$EQN" in
 	'')		continue ;;
 	exit|quit)	break ;;
+	reset)		reset ; continue ;;
 	esac
 
 	# save to the history list

execute_cmd.c

@@ -2515,9 +2515,6 @@ execute_pipeline (command, asynchronous, pipe_in, pipe_out, fds_to_close)
   prev = pipe_in;
   cmd = command;
 
-if (asynchronous)
-  itrace("execute_pipeline: asynchronous = 1");
-
   while (cmd && cmd->type == cm_connection &&
 	 cmd->value.Connection && cmd->value.Connection->connector == '|')
     {