pkg/ast: new parser for sys descriptions

The old parser in sys/sysparser is too hacky, difficult to extend
and drops debug info too early, so that we can't produce proper error messages.

Add a new parser that is build like a proper language parser
and preserves full debug info for every token.

1 files changed, 118 insertions, 0 deletions

diff --git a/pkg/ast/ast.go b/pkg/ast/ast.go
new file mode 100644
index 000000000..27497b2a9
--- /dev/null
+++ b/pkg/ast/ast.go
@@ -0,0 +1,118 @@
+// Copyright 2017 syzkaller project authors. All rights reserved.
+// Use of this source code is governed by Apache 2 LICENSE that can be found in the LICENSE file.
+
+// Package ast parses and formats sys files.
+package ast
+
+// Pos represents source info for AST nodes.
+type Pos struct {
+	File string
+	Off  int // byte offset, starting at 0
+	Line int // line number, starting at 1
+	Col  int // column number, starting at 1 (byte count)
+}
+
+// Top-level AST nodes:
+
+type NewLine struct {
+	Pos Pos
+}
+
+type Comment struct {
+	Pos  Pos
+	Text string
+}
+
+type Include struct {
+	Pos  Pos
+	File *String
+}
+
+type Incdir struct {
+	Pos Pos
+	Dir *String
+}
+
+type Define struct {
+	Pos   Pos
+	Name  *Ident
+	Value *Int
+}
+
+type Resource struct {
+	Pos    Pos
+	Name   *Ident
+	Base   *Ident
+	Values []*Int
+}
+
+type Call struct {
+	Pos  Pos
+	Name *Ident
+	Args []*Field
+	Ret  *Type
+}
+
+type Struct struct {
+	Pos      Pos
+	Name     *Ident
+	Fields   []*Field
+	Attrs    []*Ident
+	Comments []*Comment
+	IsUnion  bool
+}
+
+type IntFlags struct {
+	Pos    Pos
+	Name   *Ident
+	Values []*Int
+}
+
+type StrFlags struct {
+	Pos    Pos
+	Name   *Ident
+	Values []*String
+}
+
+// Not top-level AST nodes:
+
+type Ident struct {
+	Pos  Pos
+	Name string
+}
+
+type String struct {
+	Pos   Pos
+	Value string
+}
+
+type Int struct {
+	Pos Pos
+	// Only one of Value, Ident, CExpr is filled.
+	Value    uint64
+	ValueHex bool // says if value was in hex (for formatting)
+	Ident    string
+	CExpr    string
+}
+
+type Type struct {
+	Pos Pos
+	// Only one of Value, Ident, String is filled.
+	Value    uint64
+	ValueHex bool
+	Ident    string
+	String   string
+	// Part after COLON (for ranges and bitfields).
+	Value2    uint64
+	Value2Hex bool
+	Ident2    string
+	Args      []*Type
+}
+
+type Field struct {
+	Pos      Pos
+	Name     *Ident
+	Type     *Type
+	NewBlock bool // separated from previous fields by a new line
+	Comments []*Comment
+}