Refactor repository layout and convert build system to Mage.

This commit implements a massive refactor of the repository, and
moves the build system over to use Mage (magefile.org) which should
allow seamless building across multiple platforms.

tools/vendor/github.com/GoASTScanner/gas/issue.go

@@ -0,0 +1,118 @@
+// (c) Copyright 2016 Hewlett Packard Enterprise Development LP
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package gas
+
+import (
+	"encoding/json"
+	"fmt"
+	"go/ast"
+	"os"
+	"strconv"
+)
+
+// Score type used by severity and confidence values
+type Score int
+
+const (
+	// Low severity or confidence
+	Low Score = iota
+	// Medium severity or confidence
+	Medium
+	// High severity or confidence
+	High
+)
+
+// Issue is returnd by a GAS rule if it discovers an issue with the scanned code.
+type Issue struct {
+	Severity   Score  `json:"severity"`   // issue severity (how problematic it is)
+	Confidence Score  `json:"confidence"` // issue confidence (how sure we are we found it)
+	What       string `json:"details"`    // Human readable explanation
+	File       string `json:"file"`       // File name we found it in
+	Code       string `json:"code"`       // Impacted code line
+	Line       string `json:"line"`       // Line number in file
+}
+
+// MetaData is embedded in all GAS rules. The Severity, Confidence and What message
+// will be passed tbhrough to reported issues.
+type MetaData struct {
+	Severity   Score
+	Confidence Score
+	What       string
+}
+
+// MarshalJSON is used convert a Score object into a JSON representation
+func (c Score) MarshalJSON() ([]byte, error) {
+	return json.Marshal(c.String())
+}
+
+// String converts a Score into a string
+func (c Score) String() string {
+	switch c {
+	case High:
+		return "HIGH"
+	case Medium:
+		return "MEDIUM"
+	case Low:
+		return "LOW"
+	}
+	return "UNDEFINED"
+}
+
+func codeSnippet(file *os.File, start int64, end int64, n ast.Node) (string, error) {
+	if n == nil {
+		return "", fmt.Errorf("Invalid AST node provided")
+	}
+
+	size := (int)(end - start) // Go bug, os.File.Read should return int64 ...
+	file.Seek(start, 0)        // #nosec
+
+	buf := make([]byte, size)
+	if nread, err := file.Read(buf); err != nil || nread != size {
+		return "", fmt.Errorf("Unable to read code")
+	}
+	return string(buf), nil
+}
+
+// NewIssue creates a new Issue
+func NewIssue(ctx *Context, node ast.Node, desc string, severity Score, confidence Score) *Issue {
+	var code string
+	fobj := ctx.FileSet.File(node.Pos())
+	name := fobj.Name()
+
+	start, end := fobj.Line(node.Pos()), fobj.Line(node.End())
+	line := strconv.Itoa(start)
+	if start != end {
+		line = fmt.Sprintf("%d-%d", start, end)
+	}
+
+	if file, err := os.Open(fobj.Name()); err == nil {
+		defer file.Close()
+		s := (int64)(fobj.Position(node.Pos()).Offset) // Go bug, should be int64
+		e := (int64)(fobj.Position(node.End()).Offset) // Go bug, should be int64
+		code, err = codeSnippet(file, s, e, node)
+		if err != nil {
+			code = err.Error()
+		}
+	}
+
+	return &Issue{
+		File:       name,
+		Line:       line,
+		What:       desc,
+		Confidence: confidence,
+		Severity:   severity,
+		Code:       code,
+	}
+}