From 18d8083de350ef07161b7ceb5812617337a0c4a3 Mon Sep 17 00:00:00 2001
From: John Mulligan <jmulligan@redhat.com>
Date: Mon, 4 May 2020 15:00:53 -0400
Subject: [PATCH] implements: add initial code for process Go sources

This code makes use of Go's native AST processing packages and allows us
to analyze our source code using the go-ceph conventions.

Signed-off-by: John Mulligan <jmulligan@redhat.com>
---
 .../implements/internal/implements/gosrc.go   | 124 ++++++++++++++++++
 .../internal/implements/inspector.go          |  64 +++++++++
 2 files changed, 188 insertions(+)
 create mode 100644 contrib/implements/internal/implements/gosrc.go
 create mode 100644 contrib/implements/internal/implements/inspector.go

diff --git a/contrib/implements/internal/implements/gosrc.go b/contrib/implements/internal/implements/gosrc.go
new file mode 100644
index 0000000..f73ccea
--- /dev/null
+++ b/contrib/implements/internal/implements/gosrc.go
@@ -0,0 +1,124 @@
+package implements
+
+import (
+	"go/ast"
+	"go/build"
+	"go/parser"
+	"go/token"
+	"io/ioutil"
+	"path"
+	"regexp"
+	"strings"
+)
+
+type visitor struct {
+	inFunction *ast.FuncDecl
+
+	callMap map[string]string
+	docMap  map[string]string
+}
+
+func newVisitor() *visitor {
+	return &visitor{
+		callMap: map[string]string{},
+		docMap:  map[string]string{},
+	}
+}
+
+func (v *visitor) checkDocImplements(fdec *ast.FuncDecl) {
+	dtext := fdec.Doc.Text()
+	lines := strings.Split(dtext, "\n")
+	for i := range lines {
+		if lines[i] == "Implements:" {
+			cfunc := cfuncFromComment(lines[i+1])
+			if cfunc == "" {
+				return
+			}
+			v.docMap[cfunc] = fdec.Name.Name
+			logger.Printf("updated %s in doc map\n", cfunc)
+		}
+	}
+}
+
+func (v *visitor) checkCalled(s *ast.SelectorExpr) {
+	ident, ok := s.X.(*ast.Ident)
+	if !ok {
+		return
+	}
+	if "C" == ident.String() {
+		v.callMap[s.Sel.String()] = v.inFunction.Name.Name
+		logger.Printf("updated %s in call map\n", s.Sel.String())
+	}
+}
+
+func (v *visitor) Visit(node ast.Node) ast.Visitor {
+	switch {
+	case node == nil:
+		return nil
+	case v.inFunction == nil:
+	case node.Pos() > v.inFunction.End():
+		logger.Printf("left function %v\n", v.inFunction.Name.Name)
+		v.inFunction = nil
+	}
+
+	switch n := node.(type) {
+	case *ast.File:
+		v.inFunction = nil
+		return v
+	case *ast.FuncDecl:
+		logger.Printf("checking function: %v\n", n.Name.Name)
+		v.checkDocImplements(n)
+		v.inFunction = n
+		return v
+	case *ast.CallExpr:
+		if v.inFunction == nil {
+			return nil
+		}
+		if s, ok := n.Fun.(*ast.SelectorExpr); ok {
+			v.checkCalled(s)
+		}
+	}
+	if v.inFunction != nil {
+		return v
+	}
+	return nil
+}
+
+func cfuncFromComment(ctext string) string {
+	m := regexp.MustCompile(` ([a-zA-Z0-9_]+)\(`).FindAllSubmatch([]byte(ctext), 1)
+	if len(m) < 1 {
+		return ""
+	}
+	return string(m[0][1])
+}
+
+// CephGoFunctions will look for C functions called by the code code and
+// update the found functions for the package within the inspector.
+func CephGoFunctions(source, packageName string, ii *Inspector) error {
+	p, err := build.Import("./"+packageName, source, 0)
+	if err != nil {
+		return err
+	}
+
+	toCheck := []string{}
+	toCheck = append(toCheck, p.GoFiles...)
+	toCheck = append(toCheck, p.CgoFiles...)
+	for _, fname := range toCheck {
+		logger.Printf("Reading go file: %v\n", fname)
+		src, err := ioutil.ReadFile(path.Join(p.Dir, fname))
+		if err != nil {
+			return err
+		}
+		fset := token.NewFileSet()
+		f, err := parser.ParseFile(
+			fset,
+			fname,
+			src,
+			parser.ParseComments|parser.AllErrors)
+		if err != nil {
+			return err
+		}
+		ast.Walk(ii.visitor, f)
+	}
+	return nil
+}
diff --git a/contrib/implements/internal/implements/inspector.go b/contrib/implements/internal/implements/inspector.go
new file mode 100644
index 0000000..147f924
--- /dev/null
+++ b/contrib/implements/internal/implements/inspector.go
@@ -0,0 +1,64 @@
+package implements
+
+import (
+	"strings"
+)
+
+type foundFlags int
+
+const (
+	isCalled     = foundFlags(1)
+	isDocumented = foundFlags(2)
+	isDeprecated = foundFlags(4)
+)
+
+// Inspector types collect the high-level results from C and Go
+// code scans.
+type Inspector struct {
+	visitor *visitor
+
+	expected          CFunctions
+	found             map[string]foundFlags
+	deprecatedMissing int
+}
+
+// SetExpected sets the expected C functions, asuming the supplied prefix.
+func (ii *Inspector) SetExpected(prefix string, expected CFunctions) error {
+	ii.expected = make([]CFunction, 0, len(expected))
+	for _, cfunc := range expected {
+		if strings.HasPrefix(cfunc.Name, prefix) {
+			logger.Printf("C function \"%s\" has matching prefix", cfunc.Name)
+			ii.expected = append(ii.expected, cfunc)
+		}
+	}
+	_, err := ii.expected.ensure()
+	return err
+}
+
+func (ii *Inspector) update() {
+	ii.found = map[string]foundFlags{}
+	ii.deprecatedMissing = 0
+	for i := range ii.expected {
+		n := ii.expected[i].Name
+		if _, found := ii.visitor.callMap[n]; found {
+			ii.found[n] |= isCalled
+		}
+		if _, found := ii.visitor.docMap[n]; found {
+			ii.found[n] |= isDocumented
+		}
+		if ii.expected[i].isDeprecated() {
+			if _, found := ii.found[n]; found {
+				ii.found[n] |= isDeprecated
+			} else {
+				ii.deprecatedMissing++
+			}
+		}
+	}
+}
+
+// NewInspector returns a newly created code inspector object.
+func NewInspector() *Inspector {
+	return &Inspector{
+		visitor: newVisitor(),
+	}
+}