overhaul syscall description generation process

This splits generation process into two phases:
1. Extract values of constants from linux kernel sources.
2. Generate Go code.

Constant values are checked in.
The advantage is that the second phase is now completely independent
from linux source files, kernel version, presence of headers for
particular drivers, etc. This allows to change what Go code we generate
any time without access to all kernel headers (which in future won't be
limited to only upstream headers).

Constant extraction process does require proper kernel sources,
but this can be done only once by the person who added the driver
and has access to the required sources. Then the constant values
are checked in for others to use.
Consant extraction process is per-file/per-arch. That is,
if I am adding a driver that is not present upstream and that
works only on a single arch, I will check in constants only for
that driver and for that arch.

1 files changed, 220 insertions, 0 deletions

diff --git a/sysparser/lexer.go b/sysparser/lexer.go
new file mode 100644
index 000000000..09fd3a911
--- /dev/null
+++ b/sysparser/lexer.go
@@ -0,0 +1,220 @@
+// Copyright 2015/2016 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 sysparser
+
+import (
+	"fmt"
+	"io"
+	"os"
+	"sort"
+	"strings"
+)
+
+type Syscall struct {
+	Name     string
+	CallName string
+	Args     [][]string
+	Ret      []string
+}
+
+type Struct struct {
+	Name    string
+	Flds    [][]string
+	IsUnion bool
+	Packed  bool
+	Varlen  bool
+	Align   int
+}
+
+func Parse(in io.Reader) (includes []string, defines map[string]string, syscalls []Syscall, structs map[string]Struct, unnamed map[string][]string, flags map[string][]string) {
+	p := newParser(in)
+	defines = make(map[string]string)
+	structs = make(map[string]Struct)
+	unnamed = make(map[string][]string)
+	flags = make(map[string][]string)
+	var str *Struct
+	for p.Scan() {
+		if p.EOF() || p.Char() == '#' {
+			continue
+		}
+		if str != nil {
+			// Parsing a struct.
+			if p.Char() == '}' || p.Char() == ']' {
+				p.Parse(p.Char())
+				for _, attr := range parseType1(p, unnamed, flags, "")[1:] {
+					if str.IsUnion {
+						switch attr {
+						case "varlen":
+							str.Varlen = true
+						default:
+							failf("unknown union %v attribute: %v", str.Name, attr)
+						}
+					} else {
+						switch attr {
+						case "packed":
+							str.Packed = true
+						case "align_1":
+							str.Align = 1
+						case "align_2":
+							str.Align = 2
+						case "align_4":
+							str.Align = 4
+						case "align_8":
+							str.Align = 8
+						default:
+							failf("unknown struct %v attribute: %v", str.Name, attr)
+						}
+					}
+				}
+				structs[str.Name] = *str
+				str = nil
+			} else {
+				p.SkipWs()
+				fld := []string{p.Ident()}
+				fld = append(fld, parseType(p, unnamed, flags)...)
+				str.Flds = append(str.Flds, fld)
+			}
+		} else {
+			name := p.Ident()
+			if name == "include" {
+				p.Parse('<')
+				var include []byte
+				for {
+					ch := p.Char()
+					if ch == '>' {
+						break
+					}
+					p.Parse(ch)
+					include = append(include, ch)
+				}
+				p.Parse('>')
+				includes = append(includes, string(include))
+			} else if name == "define" {
+				key := p.Ident()
+				var val []byte
+				for !p.EOF() {
+					ch := p.Char()
+					p.Parse(ch)
+					val = append(val, ch)
+				}
+				if defines[key] != "" {
+					failf("%v define is defined multiple times", key)
+				}
+				defines[key] = fmt.Sprintf("(%s)", val)
+			} else {
+				switch ch := p.Char(); ch {
+				case '(':
+					// syscall
+					p.Parse('(')
+					var args [][]string
+					for p.Char() != ')' {
+						arg := []string{p.Ident()}
+						arg = append(arg, parseType(p, unnamed, flags)...)
+						args = append(args, arg)
+						if p.Char() != ')' {
+							p.Parse(',')
+						}
+					}
+					p.Parse(')')
+					var ret []string
+					if !p.EOF() {
+						ret = parseType(p, unnamed, flags)
+					}
+					callName := name
+					if idx := strings.IndexByte(callName, '$'); idx != -1 {
+						callName = callName[:idx]
+					}
+					syscalls = append(syscalls, Syscall{name, callName, args, ret})
+				case '=':
+					// flag
+					p.Parse('=')
+					vals := []string{p.Ident()}
+					for !p.EOF() {
+						p.Parse(',')
+						vals = append(vals, p.Ident())
+					}
+					flags[name] = vals
+				case '{', '[':
+					p.Parse(ch)
+					if _, ok := structs[name]; ok {
+						failf("%v struct is defined multiple times", name)
+					}
+					str = &Struct{Name: name, IsUnion: ch == '['}
+				default:
+					failf("bad line (%v)", p.Str())
+				}
+			}
+		}
+		if !p.EOF() {
+			failf("trailing data (%v)", p.Str())
+		}
+	}
+	sort.Sort(syscallArray(syscalls))
+	return
+}
+
+func isIdentifier(s string) bool {
+	for i, c := range s {
+		if c == '_' || (c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z') || i > 0 && (c >= '0' && c <= '9') {
+			continue
+		}
+		return false
+	}
+	return true
+}
+
+func parseType(p *parser, unnamed map[string][]string, flags map[string][]string) []string {
+	return parseType1(p, unnamed, flags, p.Ident())
+}
+
+var (
+	unnamedSeq int
+	constSeq   int
+)
+
+func parseType1(p *parser, unnamed map[string][]string, flags map[string][]string, name string) []string {
+	typ := []string{name}
+	if !p.EOF() && p.Char() == '[' {
+		p.Parse('[')
+		for {
+			id := p.Ident()
+			if p.Char() == '[' {
+				inner := parseType1(p, unnamed, flags, id)
+				id = fmt.Sprintf("unnamed%v", unnamedSeq)
+				unnamedSeq++
+				unnamed[id] = inner
+			}
+			typ = append(typ, id)
+			if p.Char() == ']' {
+				break
+			}
+			p.Parse(',')
+		}
+		p.Parse(']')
+	}
+	if name == "const" && len(typ) > 1 {
+		// Create a fake flag with the const value.
+		id := fmt.Sprintf("const_flag_%v", constSeq)
+		constSeq++
+		flags[id] = typ[1:2]
+	}
+	if name == "array" && len(typ) > 2 {
+		// Create a fake flag with the const value.
+		id := fmt.Sprintf("const_flag_%v", constSeq)
+		constSeq++
+		flags[id] = typ[2:3]
+	}
+	return typ
+}
+
+type syscallArray []Syscall
+
+func (a syscallArray) Len() int           { return len(a) }
+func (a syscallArray) Less(i, j int) bool { return a[i].Name < a[j].Name }
+func (a syscallArray) Swap(i, j int)      { a[i], a[j] = a[j], a[i] }
+
+func failf(msg string, args ...interface{}) {
+	fmt.Fprintf(os.Stderr, msg+"\n", args...)
+	os.Exit(1)
+}