Re: "tail +140" no longer works.

[Alan Modra <amodra at bigpond dot net dot au>]

On Fri, Mar 13, 2009 at 04:41:02AM +0000, Dave Korn wrote:
>   Confirmed that "tail -c +140" fails and "tail -c +220" (note '+'
> accidentally omitted in Nick's post) works perfectly.
> 
>   How portable is this though?  I'm a bit out of date but I seem to remember
> Solaris having a quirky set of command-line options.  Should we consider an
> alternative solution using some/any/all of od/sed/grep-v maybe?

Why don't we leave someone else to worry about portability, and use
gcc's bootstrap compare?  It isn't exactly easy to use, but after
quite some fiddling around I managed to get it all working.  The
difficulty is that do_compare is intended for use as a shell command
and has embedded $f1 and $f2 variable expansions.  I found these were
getting lost inside runtest or expect somewhere, so opted to simply
remove the '$' rather than trying to get quoting right to pass it down
unchanged to the ld testsuite tcl functions.

ld/
	* configure.in: Invoke ACX_PROG_CMP_IGNORE_INITIAL.
	* Makefile.am (check-DEJAGNU): Set DO_COMPARE.
	* aclocal.m4: Regenerate.
	* configure: Regenerate.
	* Makefile.in: Regenerate.
ld/testsuite/
	* ld-bootstrap/bootstrap.exp: Use DO_COMPARE.  Remove unnecessary
	cleanup and log output.

Index: ld/configure.in
===================================================================
RCS file: /cvs/src/src/ld/configure.in,v
retrieving revision 1.58
diff -u -p -r1.58 configure.in
--- ld/configure.in	3 Feb 2009 15:54:05 -0000	1.58
+++ ld/configure.in	16 Mar 2009 05:41:52 -0000
@@ -125,6 +125,7 @@ AM_PROG_LEX
 
 AM_MAINTAINER_MODE
 AM_CONDITIONAL(GENINSRC_NEVER, false)
+ACX_PROG_CMP_IGNORE_INITIAL
 
 . ${srcdir}/configure.host
 
Index: ld/Makefile.am
===================================================================
RCS file: /cvs/src/src/ld/Makefile.am,v
retrieving revision 1.261
diff -u -p -r1.261 Makefile.am
--- ld/Makefile.am	3 Mar 2009 02:41:14 -0000	1.261
+++ ld/Makefile.am	16 Mar 2009 05:41:42 -0000
@@ -1767,6 +1767,7 @@ check-DEJAGNU: site.exp
 		CC_FOR_HOST="$(CC)" CFLAGS_FOR_HOST="$(CFLAGS)" \
 		OFILES="$(OFILES)" BFDLIB="$(TESTBFDLIB)" \
 		LIBIBERTY="$(LIBIBERTY) $(LIBINTL)" LIBS="$(LIBS)" \
+		DO_COMPARE="`echo '$(do_compare)' | sed -e 's,\\$$,,g'`" \
 		$(RUNTESTFLAGS); \
 	else echo "WARNING: could not find \`runtest'" 1>&2; :;\
 	fi
Index: ld/testsuite/ld-bootstrap/bootstrap.exp
===================================================================
RCS file: /cvs/src/src/ld/testsuite/ld-bootstrap/bootstrap.exp,v
retrieving revision 1.15
diff -u -p -r1.15 bootstrap.exp
--- ld/testsuite/ld-bootstrap/bootstrap.exp	6 Jul 2007 14:09:42 -0000	1.15
+++ ld/testsuite/ld-bootstrap/bootstrap.exp	16 Mar 2009 05:52:47 -0000
@@ -137,8 +137,6 @@ foreach flags {"" "strip" "--static" "--
 	}
     }
 
-    send_log "compare (tail of) tmpdir/ld2 tmpdir/ld3\n"
-    verbose  "compare (tail of) tmpdir/ld2 tmpdir/ld3"
     if {[istarget "*-*-pe"]
 	|| [istarget "*-*-wince"]
 	|| [istarget "*-*-cygwin*"]
@@ -147,19 +145,19 @@ foreach flags {"" "strip" "--static" "--
 	|| [istarget "*-*-interix*"]
 	|| [istarget "*-*-beospe*"]
 	|| [istarget "*-*-netbsdpe*"]} {
-        # Trim off the date present in PE binaries by only looking
-        #   at the ends of the files
-        # Although this works, a way to set the date would be better.
-        # Removing or zeroing the date stamp in the binary produced by
-        # the linker is not possible as it is required by the target OS.
-        exec tail +140 tmpdir/ld2 >tmpdir/ld2tail
-        exec tail +140 tmpdir/ld3 >tmpdir/ld3tail
-        catch "exec cmp tmpdir/ld2tail tmpdir/ld3tail" exec_output
-        exec rm tmpdir/ld2tail tmpdir/ld3tail
+	# Trim off the date present in PE binaries by only looking
+	#   at the ends of the files
+	# Although this works, a way to set the date would be better.
+	# Removing or zeroing the date stamp in the binary produced by
+	# the linker is not possible as it is required by the target OS.
+	set do_compare [string map {16 220 f1 tmpdir/ld2 f2 tmpdir/ld3 tmp-foo1 tmpdir/ld2tail tmp-foo2 tmpdir/ld3tail} $DO_COMPARE]
+	send_log "$do_compare\n"
+	verbose  "$do_compare"
+	catch "exec [concat sh -c [list $do_compare]]" exec_output
     } else {
-        send_log "cmp tmpdir/ld2 tmpdir/ld3\n"
-        verbose  "cmp tmpdir/ld2 tmpdir/ld3"
-        catch "exec cmp tmpdir/ld2 tmpdir/ld3" exec_output
+	send_log "cmp tmpdir/ld2 tmpdir/ld3\n"
+	verbose  "cmp tmpdir/ld2 tmpdir/ld3"
+	catch "exec cmp tmpdir/ld2 tmpdir/ld3" exec_output
     }
     set exec_output [prune_warnings $exec_output]
 
@@ -174,4 +172,4 @@ foreach flags {"" "strip" "--static" "--
 }
 
 catch "exec rm -f tmpdir/ld-partial.o tmpdir/ld1 tmpdir/ld2 tmpdir/ld3" status
-catch "exec rm -f tmpdir/ld1tail tmpdir/ld2tail tmpdir/ld3tail" status
+catch "exec rm -f tmpdir/ld2tail tmpdir/ld3tail" status

-- 
Alan Modra
Australia Development Lab, IBM