1// Copyright 2013 The Go Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style
3// license that can be found in the LICENSE file.
4
5// This file implements the visitor that computes the (line, column)-(line-column) range for each function.
6
7package main
8
9import (
10	"bufio"
11	"bytes"
12	"encoding/json"
13	"errors"
14	"fmt"
15	"go/ast"
16	"go/parser"
17	"go/token"
18	"io"
19	"os"
20	"os/exec"
21	"path"
22	"path/filepath"
23	"runtime"
24	"strings"
25	"text/tabwriter"
26
27	"golang.org/x/tools/cover"
28)
29
30// funcOutput takes two file names as arguments, a coverage profile to read as input and an output
31// file to write ("" means to write to standard output). The function reads the profile and produces
32// as output the coverage data broken down by function, like this:
33//
34//	fmt/format.go:30:	init			100.0%
35//	fmt/format.go:57:	clearflags		100.0%
36//	...
37//	fmt/scan.go:1046:	doScan			100.0%
38//	fmt/scan.go:1075:	advance			96.2%
39//	fmt/scan.go:1119:	doScanf			96.8%
40//	total:		(statements)			91.9%
41
42func funcOutput(profile, outputFile string) error {
43	profiles, err := cover.ParseProfiles(profile)
44	if err != nil {
45		return err
46	}
47
48	dirs, err := findPkgs(profiles)
49	if err != nil {
50		return err
51	}
52
53	var out *bufio.Writer
54	if outputFile == "" {
55		out = bufio.NewWriter(os.Stdout)
56	} else {
57		fd, err := os.Create(outputFile)
58		if err != nil {
59			return err
60		}
61		defer fd.Close()
62		out = bufio.NewWriter(fd)
63	}
64	defer out.Flush()
65
66	tabber := tabwriter.NewWriter(out, 1, 8, 1, '\t', 0)
67	defer tabber.Flush()
68
69	var total, covered int64
70	for _, profile := range profiles {
71		fn := profile.FileName
72		file, err := findFile(dirs, fn)
73		if err != nil {
74			return err
75		}
76		funcs, err := findFuncs(file)
77		if err != nil {
78			return err
79		}
80		// Now match up functions and profile blocks.
81		for _, f := range funcs {
82			c, t := f.coverage(profile)
83			fmt.Fprintf(tabber, "%s:%d:\t%s\t%.1f%%\n", fn, f.startLine, f.name, percent(c, t))
84			total += t
85			covered += c
86		}
87	}
88	fmt.Fprintf(tabber, "total:\t(statements)\t%.1f%%\n", percent(covered, total))
89
90	return nil
91}
92
93// findFuncs parses the file and returns a slice of FuncExtent descriptors.
94func findFuncs(name string) ([]*FuncExtent, error) {
95	fset := token.NewFileSet()
96	parsedFile, err := parser.ParseFile(fset, name, nil, 0)
97	if err != nil {
98		return nil, err
99	}
100	visitor := &FuncVisitor{
101		fset:    fset,
102		name:    name,
103		astFile: parsedFile,
104	}
105	ast.Walk(visitor, visitor.astFile)
106	return visitor.funcs, nil
107}
108
109// FuncExtent describes a function's extent in the source by file and position.
110type FuncExtent struct {
111	name      string
112	startLine int
113	startCol  int
114	endLine   int
115	endCol    int
116}
117
118// FuncVisitor implements the visitor that builds the function position list for a file.
119type FuncVisitor struct {
120	fset    *token.FileSet
121	name    string // Name of file.
122	astFile *ast.File
123	funcs   []*FuncExtent
124}
125
126// Visit implements the ast.Visitor interface.
127func (v *FuncVisitor) Visit(node ast.Node) ast.Visitor {
128	switch n := node.(type) {
129	case *ast.FuncDecl:
130		if n.Body == nil {
131			// Do not count declarations of assembly functions.
132			break
133		}
134		start := v.fset.Position(n.Pos())
135		end := v.fset.Position(n.End())
136		fe := &FuncExtent{
137			name:      n.Name.Name,
138			startLine: start.Line,
139			startCol:  start.Column,
140			endLine:   end.Line,
141			endCol:    end.Column,
142		}
143		v.funcs = append(v.funcs, fe)
144	}
145	return v
146}
147
148// coverage returns the fraction of the statements in the function that were covered, as a numerator and denominator.
149func (f *FuncExtent) coverage(profile *cover.Profile) (num, den int64) {
150	// We could avoid making this n^2 overall by doing a single scan and annotating the functions,
151	// but the sizes of the data structures is never very large and the scan is almost instantaneous.
152	var covered, total int64
153	// The blocks are sorted, so we can stop counting as soon as we reach the end of the relevant block.
154	for _, b := range profile.Blocks {
155		if b.StartLine > f.endLine || (b.StartLine == f.endLine && b.StartCol >= f.endCol) {
156			// Past the end of the function.
157			break
158		}
159		if b.EndLine < f.startLine || (b.EndLine == f.startLine && b.EndCol <= f.startCol) {
160			// Before the beginning of the function
161			continue
162		}
163		total += int64(b.NumStmt)
164		if b.Count > 0 {
165			covered += int64(b.NumStmt)
166		}
167	}
168	return covered, total
169}
170
171// Pkg describes a single package, compatible with the JSON output from 'go list'; see 'go help list'.
172type Pkg struct {
173	ImportPath string
174	Dir        string
175	Error      *struct {
176		Err string
177	}
178}
179
180func findPkgs(profiles []*cover.Profile) (map[string]*Pkg, error) {
181	// Run go list to find the location of every package we care about.
182	pkgs := make(map[string]*Pkg)
183	var list []string
184	for _, profile := range profiles {
185		if strings.HasPrefix(profile.FileName, ".") || filepath.IsAbs(profile.FileName) {
186			// Relative or absolute path.
187			continue
188		}
189		pkg := path.Dir(profile.FileName)
190		if _, ok := pkgs[pkg]; !ok {
191			pkgs[pkg] = nil
192			list = append(list, pkg)
193		}
194	}
195
196	if len(list) == 0 {
197		return pkgs, nil
198	}
199
200	// Note: usually run as "go tool cover" in which case $GOROOT is set,
201	// in which case runtime.GOROOT() does exactly what we want.
202	goTool := filepath.Join(runtime.GOROOT(), "bin/go")
203	cmd := exec.Command(goTool, append([]string{"list", "-e", "-json"}, list...)...)
204	var stderr bytes.Buffer
205	cmd.Stderr = &stderr
206	stdout, err := cmd.Output()
207	if err != nil {
208		return nil, fmt.Errorf("cannot run go list: %v\n%s", err, stderr.Bytes())
209	}
210	dec := json.NewDecoder(bytes.NewReader(stdout))
211	for {
212		var pkg Pkg
213		err := dec.Decode(&pkg)
214		if err == io.EOF {
215			break
216		}
217		if err != nil {
218			return nil, fmt.Errorf("decoding go list json: %v", err)
219		}
220		pkgs[pkg.ImportPath] = &pkg
221	}
222	return pkgs, nil
223}
224
225// findFile finds the location of the named file in GOROOT, GOPATH etc.
226func findFile(pkgs map[string]*Pkg, file string) (string, error) {
227	if strings.HasPrefix(file, ".") || filepath.IsAbs(file) {
228		// Relative or absolute path.
229		return file, nil
230	}
231	pkg := pkgs[path.Dir(file)]
232	if pkg != nil {
233		if pkg.Dir != "" {
234			return filepath.Join(pkg.Dir, path.Base(file)), nil
235		}
236		if pkg.Error != nil {
237			return "", errors.New(pkg.Error.Err)
238		}
239	}
240	return "", fmt.Errorf("did not find package for %s in go list output", file)
241}
242
243func percent(covered, total int64) float64 {
244	if total == 0 {
245		total = 1 // Avoid zero denominator.
246	}
247	return 100.0 * float64(covered) / float64(total)
248}
249