Convert libpq regress script to Perl

This should ease its use on the Windows build environment.

Author: alvherre

src/interfaces/libpq/test/Makefile

@@ -15,7 +15,7 @@ all: $(PROGS)
 
 installcheck: all
 	SRCDIR='$(top_srcdir)' SUBDIR='$(subdir)' \
-		   $(SHELL) $(top_srcdir)/$(subdir)/regress.sh
+		   $(PERL) $(top_srcdir)/$(subdir)/regress.pl
 
 clean distclean maintainer-clean:
 	rm -f $(PROGS)

src/interfaces/libpq/test/regress.pl

@@ -0,0 +1,62 @@
+#!/usr/bin/perl -w
+
+use strict;
+
+# use of SRCDIR/SUBDIR is required for supporting VPath builds
+my $srcdir = $ENV{'SRCDIR'} or die 'SRCDIR environment variable is not set';
+my $subdir = $ENV{'SUBDIR'} or die 'SUBDIR environment variable is not set';
+
+my $regress_in   = "$srcdir/$subdir/regress.in";
+my $expected_out = "$srcdir/$subdir/expected.out";
+
+# the output file should land in the build_dir of VPath, or just in
+# the current dir, if VPath isn't used
+my $regress_out = "regress.out";
+
+# open input file first, so possible error isn't sent to redirected STDERR
+open(REGRESS_IN, "<", $regress_in)
+  or die "can't open $regress_in for reading: $!";
+
+# save STDOUT/ERR and redirect both to regress.out
+open(OLDOUT, ">&", \*STDOUT) or die "can't dup STDOUT: $!";
+open(OLDERR, ">&", \*STDERR) or die "can't dup STDERR: $!";
+
+open(STDOUT, ">", $regress_out)
+  or die "can't open $regress_out for writing: $!";
+open(STDERR, ">&", \*STDOUT) or die "can't dup STDOUT: $!";
+
+# read lines from regress.in and run uri-regress on them
+while (<REGRESS_IN>)
+  {
+	  chomp;
+	  print "trying $_\n";
+	  system("./uri-regress \"$_\"");
+	  print "\n";
+}
+
+# restore STDOUT/ERR so we can print the outcome to the user
+open(STDERR, ">&", \*OLDERR) or die; # can't complain as STDERR is still duped
+open(STDOUT, ">&", \*OLDOUT) or die "Can't restore STDOUT: $!";
+
+# just in case
+close REGRESS_IN;
+
+my $diff_status = system(
+	  "diff -c \"$srcdir/$subdir/expected.out\" regress.out >regress.diff");
+if ($diff_status == 0)
+  {
+	  print "=" x 70, "\n";
+	  print "All tests passed\n";
+	  exit 0;
+}
+else
+  {
+	  print "=" x 70, "\n";
+	  print <<EOF;
+FAILED: the test result differs from the expected output
+
+Review the difference in "$subdir/regress.diff"
+EOF
+	  print "=" x 70, "\n";
+	  exit 1;
+}