src/cmd/pprof/internal/report/source.go - go - Git at Google

 // Copyright 2014 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.

 package report

 // This file contains routines related to the generation of annotated
 // source listings.

 import (
 	"bufio"
 	"fmt"
 	"html/template"
 	"io"
 	"os"
 	"path/filepath"
 	"sort"
 	"strconv"
 	"strings"

 	"cmd/pprof/internal/plugin"
 )

 // printSource prints an annotated source listing, include all
 // functions with samples that match the regexp rpt.options.symbol.
 // The sources are sorted by function name and then by filename to
 // eliminate potential nondeterminism.
 func printSource(w io.Writer, rpt *Report) error {
 	o := rpt.options
 	g, err := newGraph(rpt)
 	if err != nil {
 		return err
 	}

 	// Identify all the functions that match the regexp provided.
 	// Group nodes for each matching function.
 	var functions nodes
 	functionNodes := make(map[string]nodes)
 	for _, n := range g.ns {
 		if !o.Symbol.MatchString(n.info.name) {
 			continue
 		}
 		if functionNodes[n.info.name] == nil {
 			functions = append(functions, n)
 		}
 		functionNodes[n.info.name] = append(functionNodes[n.info.name], n)
 	}
 	functions.sort(nameOrder)

 	fmt.Fprintf(w, "Total: %s\n", rpt.formatValue(rpt.total))
 	for _, fn := range functions {
 		name := fn.info.name

 		// Identify all the source files associated to this function.
 		// Group nodes for each source file.
 		var sourceFiles nodes
 		fileNodes := make(map[string]nodes)
 		for _, n := range functionNodes[name] {
 			if n.info.file == "" {
 				continue
 			}
 			if fileNodes[n.info.file] == nil {
 				sourceFiles = append(sourceFiles, n)
 			}
 			fileNodes[n.info.file] = append(fileNodes[n.info.file], n)
 		}

 		if len(sourceFiles) == 0 {
 			fmt.Printf("No source information for %s\n", name)
 			continue
 		}

 		sourceFiles.sort(fileOrder)

 		// Print each file associated with this function.
 		for _, fl := range sourceFiles {
 			filename := fl.info.file
 			fns := fileNodes[filename]
 			flatSum, cumSum := sumNodes(fns)

 			fnodes, path, err := getFunctionSource(name, filename, fns, 0, 0)
 			fmt.Fprintf(w, "ROUTINE ======================== %s in %s\n", name, path)
 			fmt.Fprintf(w, "%10s %10s (flat, cum) %s of Total\n",
 				rpt.formatValue(flatSum), rpt.formatValue(cumSum),
 				percentage(cumSum, rpt.total))

 			if err != nil {
 				fmt.Fprintf(w, " Error: %v\n", err)
 				continue
 			}

 			for _, fn := range fnodes {
 				fmt.Fprintf(w, "%10s %10s %6d:%s\n", valueOrDot(fn.flat, rpt), valueOrDot(fn.cum, rpt), fn.info.lineno, fn.info.name)
 			}
 		}
 	}
 	return nil
 }

 // printWebSource prints an annotated source listing, include all
 // functions with samples that match the regexp rpt.options.symbol.
 func printWebSource(w io.Writer, rpt *Report, obj plugin.ObjTool) error {
 	o := rpt.options
 	g, err := newGraph(rpt)
 	if err != nil {
 		return err
 	}

 	// If the regexp source can be parsed as an address, also match
 	// functions that land on that address.
 	var address *uint64
 	if hex, err := strconv.ParseUint(o.Symbol.String(), 0, 64); err == nil {
 		address = &hex
 	}

 	// Extract interesting symbols from binary files in the profile and
 	// classify samples per symbol.
 	symbols := symbolsFromBinaries(rpt.prof, g, o.Symbol, address, obj)
 	symNodes := nodesPerSymbol(g.ns, symbols)

 	// Sort symbols for printing.
 	var syms objSymbols
 	for s := range symNodes {
 		syms = append(syms, s)
 	}
 	sort.Sort(syms)

 	if len(syms) == 0 {
 		return fmt.Errorf("no samples found on routines matching: %s", o.Symbol.String())
 	}

 	printHeader(w, rpt)
 	for _, s := range syms {
 		name := s.sym.Name[0]
 		// Identify sources associated to a symbol by examining
 		// symbol samples. Classify samples per source file.
 		var sourceFiles nodes
 		fileNodes := make(map[string]nodes)
 		for _, n := range symNodes[s] {
 			if n.info.file == "" {
 				continue
 			}
 			if fileNodes[n.info.file] == nil {
 				sourceFiles = append(sourceFiles, n)
 			}
 			fileNodes[n.info.file] = append(fileNodes[n.info.file], n)
 		}

 		if len(sourceFiles) == 0 {
 			fmt.Printf("No source information for %s\n", name)
 			continue
 		}

 		sourceFiles.sort(fileOrder)

 		// Print each file associated with this function.
 		for _, fl := range sourceFiles {
 			filename := fl.info.file
 			fns := fileNodes[filename]

 			asm := assemblyPerSourceLine(symbols, fns, filename, obj)
 			start, end := sourceCoordinates(asm)

 			fnodes, path, err := getFunctionSource(name, filename, fns, start, end)
 			if err != nil {
 				fnodes, path = getMissingFunctionSource(filename, asm, start, end)
 			}

 			flatSum, cumSum := sumNodes(fnodes)
 			printFunctionHeader(w, name, path, flatSum, cumSum, rpt)
 			for _, fn := range fnodes {
 				printFunctionSourceLine(w, fn, asm[fn.info.lineno], rpt)
 			}
 			printFunctionClosing(w)
 		}
 	}
 	printPageClosing(w)
 	return nil
 }

 // sourceCoordinates returns the lowest and highest line numbers from
 // a set of assembly statements.
 func sourceCoordinates(asm map[int]nodes) (start, end int) {
 	for l := range asm {
 		if start == 0 || l < start {
 			start = l
 		}
 		if end == 0 || l > end {
 			end = l
 		}
 	}
 	return start, end
 }

 // assemblyPerSourceLine disassembles the binary containing a symbol
 // and classifies the assembly instructions according to its
 // corresponding source line, annotating them with a set of samples.
 func assemblyPerSourceLine(objSyms []*objSymbol, rs nodes, src string, obj plugin.ObjTool) map[int]nodes {
 	assembly := make(map[int]nodes)
 	// Identify symbol to use for this collection of samples.
 	o := findMatchingSymbol(objSyms, rs)
 	if o == nil {
 		return assembly
 	}

 	// Extract assembly for matched symbol
 	insns, err := obj.Disasm(o.sym.File, o.sym.Start, o.sym.End)
 	if err != nil {
 		return assembly
 	}

 	srcBase := filepath.Base(src)
 	anodes := annotateAssembly(insns, rs, o.base)
 	var lineno = 0
 	for _, an := range anodes {
 		if filepath.Base(an.info.file) == srcBase {
 			lineno = an.info.lineno
 		}
 		if lineno != 0 {
 			assembly[lineno] = append(assembly[lineno], an)
 		}
 	}

 	return assembly
 }

 // findMatchingSymbol looks for the symbol that corresponds to a set
 // of samples, by comparing their addresses.
 func findMatchingSymbol(objSyms []*objSymbol, ns nodes) *objSymbol {
 	for _, n := range ns {
 		for _, o := range objSyms {
 			if filepath.Base(o.sym.File) == n.info.objfile &&
 				o.sym.Start <= n.info.address-o.base &&
 				n.info.address-o.base <= o.sym.End {
 				return o
 			}
 		}
 	}
 	return nil
 }

 // printHeader prints the page header for a weblist report.
 func printHeader(w io.Writer, rpt *Report) {
 	fmt.Fprintln(w, weblistPageHeader)

 	var labels []string
 	for _, l := range legendLabels(rpt) {
 		labels = append(labels, template.HTMLEscapeString(l))
 	}

 	fmt.Fprintf(w, `<div class="legend">%s<br>Total: %s</div>`,
 		strings.Join(labels, "<br>\n"),
 		rpt.formatValue(rpt.total),
 	)
 }

 // printFunctionHeader prints a function header for a weblist report.
 func printFunctionHeader(w io.Writer, name, path string, flatSum, cumSum int64, rpt *Report) {
 	fmt.Fprintf(w, `<h1>%s</h1>%s
 <pre onClick="pprof_toggle_asm()">
   Total:  %10s %10s (flat, cum) %s
 `,
 		template.HTMLEscapeString(name), template.HTMLEscapeString(path),
 		rpt.formatValue(flatSum), rpt.formatValue(cumSum),
 		percentage(cumSum, rpt.total))
 }

 // printFunctionSourceLine prints a source line and the corresponding assembly.
 func printFunctionSourceLine(w io.Writer, fn *node, assembly nodes, rpt *Report) {
 	if len(assembly) == 0 {
 		fmt.Fprintf(w,
 			"<span class=line> %6d</span> <span class=nop>  %10s %10s %s </span>\n",
 			fn.info.lineno,
 			valueOrDot(fn.flat, rpt), valueOrDot(fn.cum, rpt),
 			template.HTMLEscapeString(fn.info.name))
 		return
 	}

 	fmt.Fprintf(w,
 		"<span class=line> %6d</span> <span class=deadsrc>  %10s %10s %s </span>",
 		fn.info.lineno,
 		valueOrDot(fn.flat, rpt), valueOrDot(fn.cum, rpt),
 		template.HTMLEscapeString(fn.info.name))
 	fmt.Fprint(w, "<span class=asm>")
 	for _, an := range assembly {
 		var fileline string
 		class := "disasmloc"
 		if an.info.file != "" {
 			fileline = fmt.Sprintf("%s:%d", template.HTMLEscapeString(an.info.file), an.info.lineno)
 			if an.info.lineno != fn.info.lineno {
 				class = "unimportant"
 			}
 		}
 		fmt.Fprintf(w, " %8s %10s %10s %8x: %-48s <span class=%s>%s</span>\n", "",
 			valueOrDot(an.flat, rpt), valueOrDot(an.cum, rpt),
 			an.info.address,
 			template.HTMLEscapeString(an.info.name),
 			class,
 			template.HTMLEscapeString(fileline))
 	}
 	fmt.Fprintln(w, "</span>")
 }

 // printFunctionClosing prints the end of a function in a weblist report.
 func printFunctionClosing(w io.Writer) {
 	fmt.Fprintln(w, "</pre>")
 }

 // printPageClosing prints the end of the page in a weblist report.
 func printPageClosing(w io.Writer) {
 	fmt.Fprintln(w, weblistPageClosing)
 }

 // getFunctionSource collects the sources of a function from a source
 // file and annotates it with the samples in fns. Returns the sources
 // as nodes, using the info.name field to hold the source code.
 func getFunctionSource(fun, file string, fns nodes, start, end int) (nodes, string, error) {
 	f, file, err := adjustSourcePath(file)
 	if err != nil {
 		return nil, file, err
 	}

 	lineNodes := make(map[int]nodes)

 	// Collect source coordinates from profile.
 	const margin = 5 // Lines before first/after last sample.
 	if start == 0 {
 		if fns[0].info.startLine != 0 {
 			start = fns[0].info.startLine
 		} else {
 			start = fns[0].info.lineno - margin
 		}
 	} else {
 		start -= margin
 	}
 	if end == 0 {
 		end = fns[0].info.lineno
 	}
 	end += margin
 	for _, n := range fns {
 		lineno := n.info.lineno
 		nodeStart := n.info.startLine
 		if nodeStart == 0 {
 			nodeStart = lineno - margin
 		}
 		nodeEnd := lineno + margin
 		if nodeStart < start {
 			start = nodeStart
 		} else if nodeEnd > end {
 			end = nodeEnd
 		}
 		lineNodes[lineno] = append(lineNodes[lineno], n)
 	}

 	var src nodes
 	buf := bufio.NewReader(f)
 	lineno := 1
 	for {
 		line, err := buf.ReadString('\n')
 		if err != nil {
 			if line == "" || err != io.EOF {
 				return nil, file, err
 			}
 		}
 		if lineno >= start {
 			flat, cum := sumNodes(lineNodes[lineno])

 			src = append(src, &node{
 				info: nodeInfo{
 					name:   strings.TrimRight(line, "\n"),
 					lineno: lineno,
 				},
 				flat: flat,
 				cum:  cum,
 			})
 		}
 		lineno++
 		if lineno > end {
 			break
 		}
 	}
 	return src, file, nil
 }

 // getMissingFunctionSource creates a dummy function body to point to
 // the source file and annotates it with the samples in asm.
 func getMissingFunctionSource(filename string, asm map[int]nodes, start, end int) (nodes, string) {
 	var fnodes nodes
 	for i := start; i <= end; i++ {
 		lrs := asm[i]
 		if len(lrs) == 0 {
 			continue
 		}
 		flat, cum := sumNodes(lrs)
 		fnodes = append(fnodes, &node{
 			info: nodeInfo{
 				name:   "???",
 				lineno: i,
 			},
 			flat: flat,
 			cum:  cum,
 		})
 	}
 	return fnodes, filename
 }

 // adjustSourcePath adjusts the pathe for a source file by trimmming
 // known prefixes and searching for the file on all parents of the
 // current working dir.
 func adjustSourcePath(path string) (*os.File, string, error) {
 	path = trimPath(path)
 	f, err := os.Open(path)
 	if err == nil {
 		return f, path, nil
 	}

 	if dir, wderr := os.Getwd(); wderr == nil {
 		for {
 			parent := filepath.Dir(dir)
 			if parent == dir {
 				break
 			}
 			if f, err := os.Open(filepath.Join(parent, path)); err == nil {
 				return f, filepath.Join(parent, path), nil
 			}

 			dir = parent
 		}
 	}

 	return nil, path, err
 }

 // trimPath cleans up a path by removing prefixes that are commonly
 // found on profiles.
 func trimPath(path string) string {
 	basePaths := []string{
 		"/proc/self/cwd/./",
 		"/proc/self/cwd/",
 	}

 	sPath := filepath.ToSlash(path)

 	for _, base := range basePaths {
 		if strings.HasPrefix(sPath, base) {
 			return filepath.FromSlash(sPath[len(base):])
 		}
 	}
 	return path
 }
	// Copyright 2014 The Go Authors. All rights reserved.
	// Use of this source code is governed by a BSD-style
	// license that can be found in the LICENSE file.

	package report

	// This file contains routines related to the generation of annotated
	// source listings.

	import (
	"bufio"
	"fmt"
	"html/template"
	"io"
	"os"
	"path/filepath"
	"sort"
	"strconv"
	"strings"

	"cmd/pprof/internal/plugin"
	)

	// printSource prints an annotated source listing, include all
	// functions with samples that match the regexp rpt.options.symbol.
	// The sources are sorted by function name and then by filename to
	// eliminate potential nondeterminism.
	func printSource(w io.Writer, rpt *Report) error {
	o := rpt.options
	g, err := newGraph(rpt)
	if err != nil {
	return err
	}

	// Identify all the functions that match the regexp provided.
	// Group nodes for each matching function.
	var functions nodes
	functionNodes := make(map[string]nodes)
	for _, n := range g.ns {
	if !o.Symbol.MatchString(n.info.name) {
	continue
	}
	if functionNodes[n.info.name] == nil {
	functions = append(functions, n)
	}
	functionNodes[n.info.name] = append(functionNodes[n.info.name], n)
	}
	functions.sort(nameOrder)

	fmt.Fprintf(w, "Total: %s\n", rpt.formatValue(rpt.total))
	for _, fn := range functions {
	name := fn.info.name

	// Identify all the source files associated to this function.
	// Group nodes for each source file.
	var sourceFiles nodes
	fileNodes := make(map[string]nodes)
	for _, n := range functionNodes[name] {
	if n.info.file == "" {
	continue
	}
	if fileNodes[n.info.file] == nil {
	sourceFiles = append(sourceFiles, n)
	}
	fileNodes[n.info.file] = append(fileNodes[n.info.file], n)
	}

	if len(sourceFiles) == 0 {
	fmt.Printf("No source information for %s\n", name)
	continue
	}

	sourceFiles.sort(fileOrder)

	// Print each file associated with this function.
	for _, fl := range sourceFiles {
	filename := fl.info.file
	fns := fileNodes[filename]
	flatSum, cumSum := sumNodes(fns)

	fnodes, path, err := getFunctionSource(name, filename, fns, 0, 0)
	fmt.Fprintf(w, "ROUTINE ======================== %s in %s\n", name, path)
	fmt.Fprintf(w, "%10s %10s (flat, cum) %s of Total\n",
	rpt.formatValue(flatSum), rpt.formatValue(cumSum),
	percentage(cumSum, rpt.total))

	if err != nil {
	fmt.Fprintf(w, " Error: %v\n", err)
	continue
	}

	for _, fn := range fnodes {
	fmt.Fprintf(w, "%10s %10s %6d:%s\n", valueOrDot(fn.flat, rpt), valueOrDot(fn.cum, rpt), fn.info.lineno, fn.info.name)
	}
	}
	}
	return nil
	}

	// printWebSource prints an annotated source listing, include all
	// functions with samples that match the regexp rpt.options.symbol.
	func printWebSource(w io.Writer, rpt *Report, obj plugin.ObjTool) error {
	o := rpt.options
	g, err := newGraph(rpt)
	if err != nil {
	return err
	}

	// If the regexp source can be parsed as an address, also match
	// functions that land on that address.
	var address *uint64
	if hex, err := strconv.ParseUint(o.Symbol.String(), 0, 64); err == nil {
	address = &hex
	}

	// Extract interesting symbols from binary files in the profile and
	// classify samples per symbol.
	symbols := symbolsFromBinaries(rpt.prof, g, o.Symbol, address, obj)
	symNodes := nodesPerSymbol(g.ns, symbols)

	// Sort symbols for printing.
	var syms objSymbols
	for s := range symNodes {
	syms = append(syms, s)
	}
	sort.Sort(syms)

	if len(syms) == 0 {
	return fmt.Errorf("no samples found on routines matching: %s", o.Symbol.String())
	}

	printHeader(w, rpt)
	for _, s := range syms {
	name := s.sym.Name[0]
	// Identify sources associated to a symbol by examining
	// symbol samples. Classify samples per source file.
	var sourceFiles nodes
	fileNodes := make(map[string]nodes)
	for _, n := range symNodes[s] {
	if n.info.file == "" {
	continue
	}
	if fileNodes[n.info.file] == nil {
	sourceFiles = append(sourceFiles, n)
	}
	fileNodes[n.info.file] = append(fileNodes[n.info.file], n)
	}

	if len(sourceFiles) == 0 {
	fmt.Printf("No source information for %s\n", name)
	continue
	}

	sourceFiles.sort(fileOrder)

	// Print each file associated with this function.
	for _, fl := range sourceFiles {
	filename := fl.info.file
	fns := fileNodes[filename]

	asm := assemblyPerSourceLine(symbols, fns, filename, obj)
	start, end := sourceCoordinates(asm)

	fnodes, path, err := getFunctionSource(name, filename, fns, start, end)
	if err != nil {
	fnodes, path = getMissingFunctionSource(filename, asm, start, end)
	}

	flatSum, cumSum := sumNodes(fnodes)
	printFunctionHeader(w, name, path, flatSum, cumSum, rpt)
	for _, fn := range fnodes {
	printFunctionSourceLine(w, fn, asm[fn.info.lineno], rpt)
	}
	printFunctionClosing(w)
	}
	}
	printPageClosing(w)
	return nil
	}

	// sourceCoordinates returns the lowest and highest line numbers from
	// a set of assembly statements.
	func sourceCoordinates(asm map[int]nodes) (start, end int) {
	for l := range asm {
	if start == 0 \|\| l < start {
	start = l
	}
	if end == 0 \|\| l > end {
	end = l
	}
	}
	return start, end
	}

	// assemblyPerSourceLine disassembles the binary containing a symbol
	// and classifies the assembly instructions according to its
	// corresponding source line, annotating them with a set of samples.
	func assemblyPerSourceLine(objSyms []*objSymbol, rs nodes, src string, obj plugin.ObjTool) map[int]nodes {
	assembly := make(map[int]nodes)
	// Identify symbol to use for this collection of samples.
	o := findMatchingSymbol(objSyms, rs)
	if o == nil {
	return assembly
	}

	// Extract assembly for matched symbol
	insns, err := obj.Disasm(o.sym.File, o.sym.Start, o.sym.End)
	if err != nil {
	return assembly
	}

	srcBase := filepath.Base(src)
	anodes := annotateAssembly(insns, rs, o.base)
	var lineno = 0
	for _, an := range anodes {
	if filepath.Base(an.info.file) == srcBase {
	lineno = an.info.lineno
	}
	if lineno != 0 {
	assembly[lineno] = append(assembly[lineno], an)
	}
	}

	return assembly
	}

	// findMatchingSymbol looks for the symbol that corresponds to a set
	// of samples, by comparing their addresses.
	func findMatchingSymbol(objSyms []objSymbol, ns nodes) objSymbol {
	for _, n := range ns {
	for _, o := range objSyms {
	if filepath.Base(o.sym.File) == n.info.objfile &&
	o.sym.Start <= n.info.address-o.base &&
	n.info.address-o.base <= o.sym.End {
	return o
	}
	}
	}
	return nil
	}

	// printHeader prints the page header for a weblist report.
	func printHeader(w io.Writer, rpt *Report) {
	fmt.Fprintln(w, weblistPageHeader)

	var labels []string
	for _, l := range legendLabels(rpt) {
	labels = append(labels, template.HTMLEscapeString(l))
	}

	fmt.Fprintf(w, `<div class="legend">%s<br>Total: %s</div>`,
	strings.Join(labels, "<br>\n"),
	rpt.formatValue(rpt.total),
	)
	}

	// printFunctionHeader prints a function header for a weblist report.
	func printFunctionHeader(w io.Writer, name, path string, flatSum, cumSum int64, rpt *Report) {
	fmt.Fprintf(w, `<h1>%s</h1>%s
	<pre onClick="pprof_toggle_asm()">
	Total: %10s %10s (flat, cum) %s
	`,
	template.HTMLEscapeString(name), template.HTMLEscapeString(path),
	rpt.formatValue(flatSum), rpt.formatValue(cumSum),
	percentage(cumSum, rpt.total))
	}

	// printFunctionSourceLine prints a source line and the corresponding assembly.
	func printFunctionSourceLine(w io.Writer, fn node, assembly nodes, rpt Report) {
	if len(assembly) == 0 {
	fmt.Fprintf(w,
	"<span class=line> %6d</span> <span class=nop> %10s %10s %s </span>\n",
	fn.info.lineno,
	valueOrDot(fn.flat, rpt), valueOrDot(fn.cum, rpt),
	template.HTMLEscapeString(fn.info.name))
	return
	}

	fmt.Fprintf(w,
	"<span class=line> %6d</span> <span class=deadsrc> %10s %10s %s </span>",
	fn.info.lineno,
	valueOrDot(fn.flat, rpt), valueOrDot(fn.cum, rpt),
	template.HTMLEscapeString(fn.info.name))
	fmt.Fprint(w, "<span class=asm>")
	for _, an := range assembly {
	var fileline string
	class := "disasmloc"
	if an.info.file != "" {
	fileline = fmt.Sprintf("%s:%d", template.HTMLEscapeString(an.info.file), an.info.lineno)
	if an.info.lineno != fn.info.lineno {
	class = "unimportant"
	}
	}
	fmt.Fprintf(w, " %8s %10s %10s %8x: %-48s <span class=%s>%s</span>\n", "",
	valueOrDot(an.flat, rpt), valueOrDot(an.cum, rpt),
	an.info.address,
	template.HTMLEscapeString(an.info.name),
	class,
	template.HTMLEscapeString(fileline))
	}
	fmt.Fprintln(w, "</span>")
	}

	// printFunctionClosing prints the end of a function in a weblist report.
	func printFunctionClosing(w io.Writer) {
	fmt.Fprintln(w, "</pre>")
	}

	// printPageClosing prints the end of the page in a weblist report.
	func printPageClosing(w io.Writer) {
	fmt.Fprintln(w, weblistPageClosing)
	}

	// getFunctionSource collects the sources of a function from a source
	// file and annotates it with the samples in fns. Returns the sources
	// as nodes, using the info.name field to hold the source code.
	func getFunctionSource(fun, file string, fns nodes, start, end int) (nodes, string, error) {
	f, file, err := adjustSourcePath(file)
	if err != nil {
	return nil, file, err
	}

	lineNodes := make(map[int]nodes)

	// Collect source coordinates from profile.
	const margin = 5 // Lines before first/after last sample.
	if start == 0 {
	if fns[0].info.startLine != 0 {
	start = fns[0].info.startLine
	} else {
	start = fns[0].info.lineno - margin
	}
	} else {
	start -= margin
	}
	if end == 0 {
	end = fns[0].info.lineno
	}
	end += margin
	for _, n := range fns {
	lineno := n.info.lineno
	nodeStart := n.info.startLine
	if nodeStart == 0 {
	nodeStart = lineno - margin
	}
	nodeEnd := lineno + margin
	if nodeStart < start {
	start = nodeStart
	} else if nodeEnd > end {
	end = nodeEnd
	}
	lineNodes[lineno] = append(lineNodes[lineno], n)
	}

	var src nodes
	buf := bufio.NewReader(f)
	lineno := 1
	for {
	line, err := buf.ReadString('\n')
	if err != nil {
	if line == "" \|\| err != io.EOF {
	return nil, file, err
	}
	}
	if lineno >= start {
	flat, cum := sumNodes(lineNodes[lineno])

	src = append(src, &node{
	info: nodeInfo{
	name: strings.TrimRight(line, "\n"),
	lineno: lineno,
	},
	flat: flat,
	cum: cum,
	})
	}
	lineno++
	if lineno > end {
	break
	}
	}
	return src, file, nil
	}

	// getMissingFunctionSource creates a dummy function body to point to
	// the source file and annotates it with the samples in asm.
	func getMissingFunctionSource(filename string, asm map[int]nodes, start, end int) (nodes, string) {
	var fnodes nodes
	for i := start; i <= end; i++ {
	lrs := asm[i]
	if len(lrs) == 0 {
	continue
	}
	flat, cum := sumNodes(lrs)
	fnodes = append(fnodes, &node{
	info: nodeInfo{
	name: "???",
	lineno: i,
	},
	flat: flat,
	cum: cum,
	})
	}
	return fnodes, filename
	}

	// adjustSourcePath adjusts the pathe for a source file by trimmming
	// known prefixes and searching for the file on all parents of the
	// current working dir.
	func adjustSourcePath(path string) (*os.File, string, error) {
	path = trimPath(path)
	f, err := os.Open(path)
	if err == nil {
	return f, path, nil
	}

	if dir, wderr := os.Getwd(); wderr == nil {
	for {
	parent := filepath.Dir(dir)
	if parent == dir {
	break
	}
	if f, err := os.Open(filepath.Join(parent, path)); err == nil {
	return f, filepath.Join(parent, path), nil
	}

	dir = parent
	}
	}

	return nil, path, err
	}

	// trimPath cleans up a path by removing prefixes that are commonly
	// found on profiles.
	func trimPath(path string) string {
	basePaths := []string{
	"/proc/self/cwd/./",
	"/proc/self/cwd/",
	}

	sPath := filepath.ToSlash(path)

	for _, base := range basePaths {
	if strings.HasPrefix(sPath, base) {
	return filepath.FromSlash(sPath[len(base):])
	}
	}
	return path
	}