From: Richard Levitte <levitte@openssl.org>
Date: Tue, 10 Mar 2015 21:04:44 +0000 (+0100)
Subject: Rethink templates.
X-Git-Tag: OpenSSL_1_1_0-pre1~1532
X-Git-Url: https://git.openssl.org/gitweb/?p=openssl.git;a=commitdiff_plain;h=b124552999b0b05cdccc891191b89bf562ba2b90;ds=sidebyside

Rethink templates.

Because base templates express inheritance of values, the attribute is
renamed to 'inherit_from', and texts about this talk about 'inheritance(s)'
rather than base templates.

As they were previously implemented, base templates that were listed
together would override one another, the first one acting as defaults for
the next and so on.

However, it was pointed out that a strength of inheritance would be to
base configurations on several templates - for example one for CPU, one
for operating system and one for compiler - and that requires a different
way of combining those templates.  With this change, inherited values
from several inheritances are concatenated by default (keep on reading).

Also, in-string templates with the double-curly syntax are removed,
replaced with the possibility to have a configuration value be a coderef
(i.e. a 'sub { /* your code goes here */ }') that gets the list of values
from all inheritances as the list @_.  The result of executing such a
coderef on a list of values is assumed to become a string.  ANY OTHER
FORM OF VALUE WILL CURRENTLY BREAK.

As a matter of fact, an attribute in the current config with no value is
assumed to have this coderef as value:

    sub { join(' ', @_) }

While we're at it, rename debug-[cl]flags to debug_[cl]flags and
nodebug-[cl]flags to release_[cl]flags.

Reviewed-by: Andy Polyakov <appro@openssl.org>
---

diff --git a/Configure b/Configure
index 5e5205c2ed..1e2282ae7d 100755
--- a/Configure
+++ b/Configure
@@ -218,14 +218,14 @@ my $BSDthreads="-pthread -D_THREAD_SAFE -D_REENTRANT";
 #	{
 #	  cc => $cc,
 #	  cflags => $cflags,
-#	  "debug-cflags" => $debug_cflags,
-#	  "nodebug-cflags" => $nodebug_cflags,
+#	  debug_cflags => $debug_cflags,
+#	  release_cflags => $release_cflags,
 #	  unistd => $unistd,
 #	  thread_cflag => $thread_cflag,
 #	  sys_id => $sys_id,
 #	  lflags => $lflags,
-#	  "debug-lflags" => $debug_lflags,
-#	  "nodebug-lflags" => $nodebug_lflags,
+#	  debug_lflags => $debug_lflags,
+#	  release_lflags => $release_lflags,
 #	  bn_ops => $bn_ops,
 #	  cpuid_obj => $cpuid_obj,
 #	  bn_obj => $bn_obj,
@@ -259,48 +259,80 @@ my $BSDthreads="-pthread -D_THREAD_SAFE -D_REENTRANT";
 #
 # The configuration hashes can refer to templates in two different manners:
 #
-# - as part of the hash, one can have a key called 'base_templates' that
+# - as part of the hash, one can have a key called 'inherit_from' that
 #   indicate what other configuration hashes to inherit data from.
 #   These are resolved recursively.
 #
+#   Inheritance works as a set of default values that can be overriden
+#   by corresponding attribute values in the inheriting configuration.
+#
+#   If several configurations are given in the 'inherit_from' array, the
+#   values of same attribute are concatenated with space separation.
+#   With this, it's possible to have several smaller templates for
+#   different configuration aspects that can be combined into a complete
+#   configuration.
+#
 #   Example:
 #
+#	"foo" => {
+#		template => 1,
+#		haha => "haha",
+#		hoho => "ho"
+#	},
 #	"bar" => {
-#		haha => "haha"
+#		template => 1,
+#		hoho => "ho",
+#		hehe => "hehe"
 #	},
-#	"foo" => {
-#		base_templates => [ "bar" ],
-#		hoho => "hoho"
+#	"laughter" => {
+#		inherit_from => [ "foo", "bar" ],
 #	}
 #
 #	The entry for "foo" will become as follows after processing:
 #
-#	"foo" => {
+#	"laughter" => {
 #		haha => "haha",
-#		hoho => "hoho"
+#		hoho => "ho ho",
+#		hehe => "hehe"
 #	}
 #
 #   Note 1: any entry from the table can be used as a template.
 #   Note 2: pure templates have the attribute 'template => 1' and cannot
-#           be used as targets
+#           be used as targets.
 #
-# - as part of any string, one can have a template reference wrapped in
-#   double braces, and when processing templates, this will be replaced
-#   with the corresponding string from the template.
+# - instead of a string, one can have a code block of the form
+#   'sub { /* your code here */ }', where the arguments are the list of
+#   inherited values for that key.  In fact, the concatenation of strings
+#   is really done by using 'sub { join(" ",@_) }' on the list of inherited
+#   values.
 #
 #   Example:
 #
+#	"foo" => {
+#		template => 1,
+#		haha => "ha ha",
+#		hoho => "ho",
+#		ignored => "This should not appear in the end result",
+#	},
 #	"bar" => {
-#		haha => "haha"
+#		template => 1,
+#		haha => "ah",
+#		hoho => "haho",
+#		hehe => "hehe"
 #	},
-#	"foo" => {
-#		haha => "{{bar}} !!!!"
+#	"laughter" => {
+#		inherit_from => [ "foo", "bar" ],
+#		hehe => sub { join(" ",(@_,"!!!")) },
+#		ignored => "",
 #	}
 #
 #	The entry for "foo" will become as follows after processing:
 #
-#	"foo" => {
-#		haha => "haha !!!!"
+#	"laughter" => {
+#		haha => "ha ha ah",
+#		hoho => "ho haho",
+#		hehe => "hehe !!!",
+#		ignored => ""
 #	}
 #
 
@@ -355,7 +387,7 @@ my %table=(
     },
     x86_elf_asm => {
 	template	=> 1,
-	base_templates	=> [ "x86_asm" ],
+	inherit_from	=> [ "x86_asm" ],
 	perlasm_scheme	=> "elf"
     },
 
@@ -418,9 +450,9 @@ my %table=(
 	sha1_obj        => "sha1-mips.o sha256-mips.o",
     },
     mips64_asm => {
-	base_templates	=> [ "mips32_asm" ],
+	inherit_from	=> [ "mips32_asm" ],
 	template	=> 1,
-	sha1_obj        => "{{mips32_asm}} sha512-mips.o",
+	sha1_obj        => sub { join(" ", @_, "sha512-mips.o") }
     },
     s390x_asm => {
 	template	=> 1,
@@ -477,7 +509,7 @@ my %table=(
 	modes_obj       => "ghashp8-ppc.o",
     },
     ppc32_asm => {
-	base_templates	=> [ "ppc64_asm" ],
+	inherit_from	=> [ "ppc64_asm" ],
 	template	=> 1
     },
 );
@@ -526,32 +558,6 @@ sub stringtohash {
     return { map { shift @stringsequence => $_ } split /:/, $in };
 };
 
-# Support function to look for and resolve template references.
-# It uses breadcrumbs to check for circular template references.
-#
-# Note: Any configuration value is also a template.
-sub lookup_templates {
-    my $tableref = shift;
-    my $target = shift;
-    my @breadcrumbs = @_;
-
-    if (grep { $_ eq $target } @breadcrumbs) {
-	die "Template loop!  target backtrace:\n  ",join("\n  ",
-							 $target,
-							 @breadcrumbs),"\n";
-    }
-
-    foreach my $key (keys %{$tableref->{$target}}) {
-	my $value = $tableref->{$target}->{$key};
-	while ($value =~ /{{([-\w]+)}}/) {
-	    lookup_templates($tableref, $1, $target, @breadcrumbs);
-	    $value = $`.$tableref->{$1}->{$key}.$';
-	}
-	$tableref->{$target}->{$key} = $value;
-    }
-};
-
-
 # Read configuration target stanzas from a file, so that people can have
 # local files with their own definitions
 sub read_config {
@@ -621,9 +627,9 @@ sub read_config {
 			# First, check that the non-debug variant isn't
 			# already built up with all it should have.
 			if ($nondebug->{debug_cflags}
-			    || $nondebug->{nodebug_cflags}
+			    || $nondebug->{release_cflags}
 			    || $nondebug->{debug_lflags}
-			    || $nondebug->{nodebug_lflags}) {
+			    || $nondebug->{release_lflags}) {
 			    warn "there's a debug target $debugkey to be merged with a target $nondebugkey, but the latter seems to already have both nodebug and debug information.  This requires human intervention.  Skipping $debugkey...";
 			    next;
 			}
@@ -653,11 +659,11 @@ sub read_config {
 			    # becomes the merged variant when we're done.
 			    # for each of cflags and lflags, they are
 			    # replaced with cflags, debug_cflags,
-			    # nodebug_cflags and similar for lflags.
+			    # release_cflags and similar for lflags.
 			    #
 			    # The purpose is that 'cflags' should be
 			    # used together with 'debug_cflags' or
-			    # 'nodebug_cflags' depending on what the
+			    # 'release_cflags' depending on what the
 			    # user asks for.
 			    foreach (("cflags", "lflags")) {
 				my @list_d = split /\s+/, $debug->{$_};
@@ -693,57 +699,98 @@ sub read_config {
 
 	%table = (%table, %targets);
 
-	# Go through all new targets and resolve template references.
-	foreach (keys %targets) {
-	    # Start with resolving the base templates
-	    my @breadcrumbs = ();
-	    while (my @base_templates =
-		   $table{$_}->{base_templates} ?
-		   @{$table{$_}->{base_templates}} : ()) {
-		my %new_template_data = ();
-		my %new_base_templates = ();
-		foreach my $base_template (@base_templates) {
-		    if (grep { $_ eq $base_template } @breadcrumbs) {
-			die "Base template loop!  target backtrace:\n  "
-			    ,$base_template,"\n  "
-			    ,join("\n  ",
-				  map { "[ ".join(", ", @{$_})." ]" } @breadcrumbs)
-			    ,"\n";
+	# Local function to resolve inheritance
+	my $resolve_inheritance;
+	$resolve_inheritance =
+	    sub {
+		my $target = shift;
+		my @breadcrumbs = @_;
+
+		if (grep { $_ eq $target } @breadcrumbs) {
+		    die "inherit_from loop!  target backtrace:\n  "
+			,$target,"\n  ",join("\n  ", @breadcrumbs),"\n";
+		}
+
+		# Recurse through all inheritances.  They will be resolved on
+		# the fly, so when this operation is done, they will all just
+		# be a bunch of attributes with string values.
+		# What we get here, though, are keys with references to lists
+		# of the combined values of them all.  We will deal with lists
+		# after this stage is done.
+		my %combined_inheritance = ();
+		if ($table{$target}->{inherit_from}) {
+		    foreach (@{$table{$target}->{inherit_from}}) {
+			my %inherited_config =
+			    $resolve_inheritance->($_, $target, @breadcrumbs);
+
+			# 'template' is a marker that's considered private to
+			# the config that had it.
+			delete $inherited_config{template};
+
+			map {
+			    if (!$combined_inheritance{$_}) {
+				$combined_inheritance{$_} = [];
+			    }
+			    push @{$combined_inheritance{$_}}, $inherited_config{$_};
+			} keys %inherited_config;
+		    }
+		}
+
+		# We won't need inherit_from in this target any more, since
+		# we've resolved all the inheritances that lead to this
+		delete $table{$target}->{inherit_from};
+
+		# Now is the time to deal with those lists.  Here's the place
+		# to decide what shall be done with those lists, all based on
+		# the values of the target we're currently dealing with.
+		# - If a value is a coderef, it will be executed with the list
+		#   of inherited values as arguments.
+		# - If the corresponding key doesn't have a value at all or is
+		#   the emoty string, the inherited value list will be run
+		#   through the default combiner (below), and the result
+		#   becomes this target's value.
+		# - Otherwise, this target's value is assumed to be a string
+		#   that will simply override the inherited list of values.
+		my $default_combiner = sub { join(' ',@_) };
+
+		my %all_keys =
+		    map { $_ => 1 } (keys %combined_inheritance,
+				     keys %{$table{$target}});
+		foreach (sort keys %all_keys) {
+
+		    # Current target doesn't have a value for the current key?
+		    # Assign it the default combiner, the rest of this loop
+		    # body will handle it just like any other coderef.
+		    if (!exists $table{$target}->{$_}) {
+			$table{$target}->{$_} = $default_combiner;
 		    }
 
-		    if ($table{$base_template}) {
-			%new_base_templates =
-			    (
-			     %new_base_templates,
-			     map { $_ => 1 } @{$table{$base_template}->{base_templates}}
-			    );
-			%new_template_data =
-			    (
-			     %new_template_data,
-			     %{$table{$base_template}}
-			    );
-			delete $new_template_data{template};
+		    my $valuetype = ref($table{$target}->{$_});
+		    if ($valuetype eq "CODE") {
+			# CODE reference, execute it with the inherited values
+			# as arguments.
+			$table{$target}->{$_} =
+			    $table{$target}->{$_}->(@{$combined_inheritance{$_}});
+		    } elsif ($valuetype eq "") {
+			# Scalar, just leave it as is.
 		    } else {
-			# There are unresolved base templates.  That's no good
-			warn "Target $_ has unresolved base templates.  Removing...";
-			delete $table{$_};
-			goto NEXT;
+			# Some other type of reference that we don't handle.
+			# Better to abort at this point.
+			die "cannot handle reference type $valuetype,"
+			    ," found in target $target -> $_\n";
 		    }
 		}
 
-		@breadcrumbs = ( [ @base_templates ], @breadcrumbs );
-		# Now, we rebuild the target, using the newly fetched template
-		# data, overlaying that with the target's original data, and
-		# overlaying the new base template list on top of that
-		$table{$_} = {
-		    %new_template_data,
-		    %{$table{$_}},
-		    base_templates => [ keys %new_base_templates ]
-		}
-	    }
+		# Finally done, return the result.
+		%{$table{$target}};
+	};
 
-	    lookup_templates(\%table, $_);
-	  NEXT:
+	# Go through all new targets and resolve inheritance and template
+	# references.
+	foreach (keys %targets) {
+	    # We're ignoring the returned values here, they are only valuable
+	    # to the inner recursion of this function.
+	    $resolve_inheritance->($_);
 	}
 }
 
@@ -1142,15 +1189,15 @@ if ($target =~ m/^CygWin32(-.*)$/) {
 print "Configuring for $target\n";
 
 my ($d, $t) = $target =~ m/^(debug-)?(.*)$/;
-my $debug_prefix = "nodebug-";
+my $debug_prefix = "release_";
 if ($d) {
-    $debug_prefix = "debug-";
+    $debug_prefix = "debug_";
 
     # If we do not find debug-foo in the table, the target is set to foo,
-    # but only if the foo target has a noon-empty debug-cflags or debug-lflags
+    # but only if the foo target has a noon-empty debug_cflags or debug_lflags
     # attribute.
-    if (!$table{$target} && ($table{$t}->{"debug-cflags"}
-			     || $table{$t}->{"debug-lflags"})) {
+    if (!$table{$target} && ($table{$t}->{debug_cflags}
+			     || $table{$t}->{debug_lflags})) {
 	$target = $t;
     }
 }
@@ -1262,7 +1309,7 @@ print "IsMK1MF=$IsMK1MF\n";
 # Allow environment CC to override compiler...
 my $cc = $ENV{CC} || $table{$t}->{cc};
 
-# For cflags and lflags, add the debug- or nodebug- attributes
+# For cflags and lflags, add the debug_ or release_ attributes
 # Do it in such a way that no spurious space is appended (hence the grep).
 my $cflags = join(" ",
 		  grep { $_ } ($table{$t}->{cflags},
@@ -2251,11 +2298,6 @@ sub print_table_entry
 	my $target = shift;
 	my $type = shift;
 
-	my $debug_cflags = "debug-cflags";
-	my $nodebug_cflags = "nodebug-cflags";
-	my $debug_lflags = "debug-lflags";
-	my $nodebug_lflags = "nodebug-lflags";
-
 	# Don't print the templates
 	return if $table{$target}->{template};
 
@@ -2265,14 +2307,14 @@ sub print_table_entry
 *** $target
 \$cc           = $table{$target}->{cc}
 \$cflags       = $table{$target}->{cflags}
-\$debug_cflags   = $table{$target}->{$debug_cflags}
-\$nodebug_cflags = $table{$target}->{$nodebug_cflags}
+\$debug_cflags   = $table{$target}->{debug_cflags}
+\$release_cflags = $table{$target}->{release_cflags}
 \$unistd       = $table{$target}->{unistd}
 \$thread_cflag = $table{$target}->{thread_cflag}
 \$sys_id       = $table{$target}->{sys_id}
 \$lflags       = $table{$target}->{lflags}
-\$debug_lflags   = $table{$target}->{$debug_lflags}
-\$nodebug_lflags = $table{$target}->{$nodebug_lflags}
+\$debug_lflags   = $table{$target}->{debug_lflags}
+\$release_lflags = $table{$target}->{release_lflags}
 \$bn_ops       = $table{$target}->{bn_ops}
 \$cpuid_obj    = $table{$target}->{cpuid_obj}
 \$bn_obj       = $table{$target}->{bn_obj}
@@ -2304,14 +2346,14 @@ EOF
 	    my @sequence = (
 		"cc",
 		"cflags",
-		"debug-cflags",
-		"nodebug-cflags",
+		"debug_cflags",
+		"release_cflags",
 		"unistd",
 		"thread_cflag",
 		"sys_id",
 		"lflags",
-		"debug-lflags",
-		"nodebug-lflags",
+		"debug_lflags",
+		"release_lflags",
 		"bn_ops",
 		"cpuid_obj",
 		"bn_obj",