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util/kconfig_lint: Turn handle_expressions() into a parser 

I wished there was a way to do this in smaller steps, but with
every line fixed an error somewhere else became visible. Here
is a (probably incomplete) list of the issues:

* Only one set of parentheses was supported. This is a hard
  to solve problem without a real parser (one solution is to
  use an recursive RE, see below).

* The precedence order was wrong. Might have been adapted just
  to give a positive result for the arbitrary state of the tree.

* Numbered match variables (e.g. $1, $2, etc.) are not local.
  Calling handle_expressions() recursively once with $1, then
  with $2, resulted in using the final $2 after the first
  recursive call (garbage, practically).

Also, symbol and expression parsing was mixed, making things
harder to follow.

To remedy the issues:

* Split handle_symbol() out. It is called with whitespace
  stripped, to keep the uglier REs in handle_expressions().

* Match balanced parentheses and quotes when splitting
  expressions. In this recursive RE

    /(\((?:[^\(\)]++|(?-1))*\))/

  the `(?-1)` references the outer-most group, thus the whole
  expression itself. So it matches a pair of parentheses with
  a mix of non-parentheses and the recursive rule itself inside.
  This allows us to:

* Order the expression matches according to their precedence
  rules. Now we can match `<expr> '||' <expr>` first as we should
  and everything else falls into its place.

* Remove the bail-out that silenced the undefined behavior.

Change-Id: Ibc1be79adc07792f0721f0dc08b50422b6da88a9
Signed-off-by: Nico Huber <nico.h@gmx.de>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/52067
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
This commit is contained in:
Nico Huber 2021-04-02 21:23:32 +02:00 committed by Patrick Georgi
parent 4681b2778b
commit f6b2baa3e8
1 changed files with 55 additions and 38 deletions
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93
util/lint/kconfig_lint
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@ -947,57 +947,74 @@ sub handle_if_line {
}
#-------------------------------------------------------------------------------
# handle_expressions - log which symbols are being used
# handle_symbol - log which symbols are being used
#-------------------------------------------------------------------------------
sub handle_symbol {
my ( $symbol, $filename, $line_no ) = @_;
#filter constant symbols first
if ( $symbol =~ /^[yn]$/ ) { # constant y/n
return;
}
if ( $symbol =~ /^-?(?:0x)?\p{XDigit}+$/ ) { # int/hex values
return;
}
if ( $symbol =~ /^"[^"]*"$/ ) { # string values
return;
}
if ( $symbol =~ /^([A-Za-z0-9_]+)$/ ) { # actual symbol
add_referenced_symbol( $1, $filename, $line_no, 'expression' );
}
else {
show_error("Unrecognized expression: expected symbol, "
. "found '$symbol' in $filename line $line_no.");
}
}
#-------------------------------------------------------------------------------
# handle_expressions - find symbols in expressions
#-------------------------------------------------------------------------------
sub handle_expressions {
my ( $exprline, $inside_config, $filename, $line_no ) = @_;
return unless ($exprline);
my $strip = qr/\s*(.*[^\s]+)\s*/;
#filter constant symbols first
if ( $exprline =~ /^\s*"?([yn])"?\s*$/ ) { # constant y/n
return;
}
elsif ( $exprline =~ /^\s*"?((?:-)\d+)"?\s*$/ ) { # int values
return;
}
elsif ( $exprline =~ /^\s*"?((?:-)?(?:0x)?\p{XDigit})+"?\s*$/ ) { # hex values
return;
}
elsif ( $exprline =~ /^\s*("[^"]*")\s*$/ ) { # String values
return;
}
elsif ( $exprline =~ /^\s*([A-Za-z0-9_]+)\s*$/ ) { # <symbol> (1)
add_referenced_symbol( $1, $filename, $line_no, 'expression' );
}
elsif ( $exprline =~ /^\s*!(.+)$/ ) { # '!' <expr> (5)
my $parens = qr/(\((?:[^\(\)]++|(?-1))*\))/;
my $quotes = qr/"[^"]*"/;
my $balanced = qr/((?:$parens|$quotes|[^\(\)"])+)/;
if ( $exprline =~ /^\s*$balanced\s*(?:\|\||&&)\s*(.+)$/ ) {
# <expr> '||' <expr>, <expr> '&&' <expr> (7)(6)
my ( $lhs, $rhs ) = ( $1, $3 );
handle_expressions( $lhs, $inside_config, $filename, $line_no );
handle_expressions( $rhs, $inside_config, $filename, $line_no );
}
elsif ( $exprline =~ /^\s*!(.+)$/ ) {
# '!' <expr> (5)
handle_expressions( $1, $inside_config, $filename, $line_no );
}
elsif ( $exprline =~ /^\s*\(([^)]+)\)\s*$/ ) { # '(' <expr> ')' (4)
elsif ( $exprline =~ /^\s*$parens\s*$/ ) {
# '(' <expr> ')' (4)
$exprline =~ /^\s*\((.*)\)\s*$/;
handle_expressions( $1, $inside_config, $filename, $line_no );
}
elsif ( $exprline =~ /^\s*(.+)\s*!=\s*(.+)\s*$/ ) { # <symbol> '!=' <symbol> (3)
handle_expressions( $1, $inside_config, $filename, $line_no );
handle_expressions( $2, $inside_config, $filename, $line_no );
elsif ( $exprline =~ /^\s*($quotes|[^"\s]+)\s*!=$strip$/ ) {
# <symbol> '!=' <symbol> (3)
my ( $lhs, $rhs ) = ( $1, $2 );
handle_symbol( $lhs, $filename, $line_no );
handle_symbol( $rhs, $filename, $line_no );
}
elsif ( $exprline =~ /^\s*(.+)\s*=\s*(.+)\s*$/ ) { # <symbol> '=' <symbol> (2)
handle_expressions( $1, $inside_config, $filename, $line_no );
handle_expressions( $2, $inside_config, $filename, $line_no );
elsif ( $exprline =~ /^\s*($quotes|[^"\s]+)\s*=$strip$/ ) {
# <symbol> '=' <symbol> (2)
my ( $lhs, $rhs ) = ( $1, $2 );
handle_symbol( $lhs, $filename, $line_no );
handle_symbol( $rhs, $filename, $line_no );
}
elsif ( $exprline =~ /^\s*([^(]+|\(.+\))\s*&&\s*(.+)\s*$/ ) { # <expr> '&&' <expr> (6)
handle_expressions( $1, $inside_config, $filename, $line_no );
handle_expressions( $2, $inside_config, $filename, $line_no );
elsif ( $exprline =~ /^$strip$/ ) {
# <symbol> (1)
handle_symbol( $1, $filename, $line_no );
}
elsif ( $exprline =~ /^\s*([^(]+|\(.+\))\s*\|\|\s*(.+)\s*$/ ) { # <expr> '||' <expr> (7)
handle_expressions( $1, $inside_config, $filename, $line_no );
handle_expressions( $2, $inside_config, $filename, $line_no );
}
else {
show_error("Unrecognized expression '$exprline' in $filename line $line_no.");
}
return;
}
#-------------------------------------------------------------------------------