Add --early-fixup and --late-fixup to bisect.pl, for user-controlled patching.

These provide a way to run code or to conditionally or unconditionally
apply patches for each revision tested during git bisect. This is very
useful when for the commit range, operating system and configuration options
tested, the behaviour otherwise would be to fail to build for a wide range
of revisions, and hence the bisect would finish without finding culprit
commit due to getting bogged down in 'skipped' revisions.

1 files changed, 119 insertions, 1 deletions

diff --git a/Porting/bisect-runner.pl b/Porting/bisect-runner.pl
index 2f29840672..246d62ace6 100755
--- a/Porting/bisect-runner.pl
+++ b/Porting/bisect-runner.pl
@@ -53,7 +53,7 @@ unless(GetOptions(\%options,
                       $options{'expect-pass'} = 0;
                   },
                   'force-manifest', 'force-regen', 'test-build', 'validate',
-                  'all-fixups',
+                  'all-fixups', 'early-fixup=s@', 'late-fixup=s@',
                   'check-args', 'check-shebang!', 'usage|help|?', 'A=s@',
                   'D=s@' => sub {
                       my (undef, $val) = @_;
@@ -466,6 +466,63 @@ please report it as a bug, giving the OS and problem revision.
 
 =item *
 
+--early-fixup file
+
+=item *
+
+--late-fixup file
+
+Specify a file containing a patch or other fixup for the source code. The
+action to take depends on the first line of the fixup file
+
+=over 4
+
+=item *
+
+C<#!perl>
+
+If the first line starts C<#!perl> then the file is run using C<$^X>
+
+=item *
+
+C<#!/absolute/path>
+
+If a shebang line is present the file is executed using C<system>
+
+=item *
+
+C<I<filename> =~ /I<pattern>/>
+
+=item *
+
+C<I<filename> !~ /I<pattern>/>
+
+If I<filename> does not exist then the fixup file's contents are ignored.
+Otherwise, for C<=~>, if it contains a line matching I<pattern>, then the
+file is fed to C<patch -p1> on standard input. For C<=~>, the patch is
+applied if no lines match the pattern.
+
+As the empty pattern in Perl is a special case (it matches the most recent
+sucessful match) which is not useful here, an the treatment of empty pattern
+is special-cased. C<I<filename> =~ //> applies the patch if filename is
+present. C<I<filename> !~ //> applies the patch if filename missing. This
+makes it easy to unconditionally apply patches to files, and to use a patch
+as a way of creating a new file.
+
+=item *
+
+Otherwise, the file is assumed to be a patch, and always applied.
+
+=back
+
+I<early-fixup>s are applied before F<./Configure> is run. I<late-fixup>s are
+applied just after F<./Configure> is run.
+
+These options can be specified more than once. I<file> is actually expanded
+as a glob pattern. Globs that do not match are errors, as are missing files.
+
+=item *
+
 --no-clean
 
 Tell F<bisect-runner.pl> not to clean up after the build. This allows one
@@ -547,6 +604,26 @@ sub die_255 {
 die_255("$0: Can't build $target")
     if defined $target && !grep {@targets} $target;
 
+foreach my $phase (qw(early late)) {
+    next unless $options{"$phase-fixup"};
+    my $bail_out;
+    require File::Glob;
+    my @expanded;
+    foreach my $glob (@{$options{"$phase-fixup"}}) {
+        my @got = File::Glob::bsd_glob($glob);
+        push @expanded, @got ? @got : $glob;
+    }
+    @expanded = sort @expanded;
+    $options{"$phase-fixup"} = \@expanded;
+    foreach (@expanded) {
+        unless (-f $_) {
+            print STDERR "$phase-fixup '$_' is not a readable file\n";
+            ++$bail_out;
+        }
+    }
+    exit 255 if $bail_out;
+}
+
 unless (exists $defines{cc}) {
     # If it fails, the heuristic of 63f9ec3008baf7d6 is noisy, and hence
     # confusing.
@@ -935,6 +1012,7 @@ if ($options{'all-fixups'}) {
     patch_C();
     patch_ext();
 }
+apply_fixups($options{'early-fixup'});
 
 # if Encode is not needed for the test, you can speed up the bisect by
 # excluding it from the runs with -Dnoextensions=Encode
@@ -1014,6 +1092,7 @@ waitpid $pid, 0
     or die_255("wait for Configure, pid $pid failed: $!");
 
 patch_SH() unless $options{'all-fixups'};
+apply_fixups($options{'late-fixup'});
 
 if (-f 'config.sh') {
     # Emulate noextensions if Configure doesn't support it.
@@ -3065,6 +3144,45 @@ EOFIX
     }
 }
 
+sub apply_fixups {
+    my $fixups = shift;
+    return unless $fixups;
+    foreach my $file (@$fixups) {
+        my $fh = open_or_die($file);
+        my $line = <$fh>;
+        close_or_die($fh);
+        if ($line =~ /^#!perl\b/) {
+            system $^X, $file
+                and die_255("$^X $file failed: \$!=$!, \$?=$?");
+        } elsif ($line =~ /^#!(\/\S+)/) {
+            system $file
+                and die_255("$file failed: \$!=$!, \$?=$?");
+        } else {
+            if (my ($target, $action, $pattern)
+                = $line =~ m#^(\S+) ([=!])~ /(.*)/#) {
+                if (length $pattern) {
+                    next unless -f $target;
+                    if ($action eq '=') {
+                        next unless extract_from_file($target, $pattern);
+                    } else {
+                        next if extract_from_file($target, $pattern);
+                    }
+                } else {
+                    # Avoid the special case meaning of the empty pattern,
+                    # and instead use this to simply test for the file being
+                    # present or absent
+                    if ($action eq '=') {
+                        next unless -f $target;
+                    } else {
+                        next if -f $target;
+                    }
+                }
+            }
+            system_or_die("patch -p1 <$file");
+        }
+    }
+}
+
 # Local variables:
 # cperl-indent-level: 4
 # indent-tabs-mode: nil