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// Copyright 2014 Google Inc. All Rights Reserved.
//
// 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 binutils
import (
"bufio"
"fmt"
"io"
"os/exec"
"strconv"
"strings"
"sync"
"github.com/google/pprof/internal/plugin"
)
const (
defaultLLVMSymbolizer = "llvm-symbolizer"
)
// llvmSymbolizer is a connection to an llvm-symbolizer command for
// obtaining address and line number information from a binary.
type llvmSymbolizer struct {
sync.Mutex
filename string
rw lineReaderWriter
base uint64
}
type llvmSymbolizerJob struct {
cmd *exec.Cmd
in io.WriteCloser
out *bufio.Reader
}
func (a *llvmSymbolizerJob) write(s string) error {
_, err := fmt.Fprint(a.in, s+"\n")
return err
}
func (a *llvmSymbolizerJob) readLine() (string, error) {
return a.out.ReadString('\n')
}
// close releases any resources used by the llvmSymbolizer object.
func (a *llvmSymbolizerJob) close() {
a.in.Close()
a.cmd.Wait()
}
// newLlvmSymbolizer starts the given llvmSymbolizer command reporting
// information about the given executable file. If file is a shared
// library, base should be the address at which it was mapped in the
// program under consideration.
func newLLVMSymbolizer(cmd, file string, base uint64) (*llvmSymbolizer, error) {
if cmd == "" {
cmd = defaultLLVMSymbolizer
}
j := &llvmSymbolizerJob{
cmd: exec.Command(cmd, "-inlining", "-demangle=false"),
}
var err error
if j.in, err = j.cmd.StdinPipe(); err != nil {
return nil, err
}
outPipe, err := j.cmd.StdoutPipe()
if err != nil {
return nil, err
}
j.out = bufio.NewReader(outPipe)
if err := j.cmd.Start(); err != nil {
return nil, err
}
a := &llvmSymbolizer{
filename: file,
rw: j,
base: base,
}
return a, nil
}
func (d *llvmSymbolizer) readString() (string, error) {
s, err := d.rw.readLine()
if err != nil {
return "", err
}
return strings.TrimSpace(s), nil
}
// readFrame parses the llvm-symbolizer output for a single address. It
// returns a populated plugin.Frame and whether it has reached the end of the
// data.
func (d *llvmSymbolizer) readFrame() (plugin.Frame, bool) {
funcname, err := d.readString()
if err != nil {
return plugin.Frame{}, true
}
switch funcname {
case "":
return plugin.Frame{}, true
case "??":
funcname = ""
}
fileline, err := d.readString()
if err != nil {
return plugin.Frame{Func: funcname}, true
}
linenumber := 0
if fileline == "??:0" {
fileline = ""
} else {
switch split := strings.Split(fileline, ":"); len(split) {
case 1:
// filename
fileline = split[0]
case 2, 3:
// filename:line , or
// filename:line:disc , or
fileline = split[0]
if line, err := strconv.Atoi(split[1]); err == nil {
linenumber = line
}
default:
// Unrecognized, ignore
}
}
return plugin.Frame{Func: funcname, File: fileline, Line: linenumber}, false
}
// addrInfo returns the stack frame information for a specific program
// address. It returns nil if the address could not be identified.
func (d *llvmSymbolizer) addrInfo(addr uint64) ([]plugin.Frame, error) {
d.Lock()
defer d.Unlock()
if err := d.rw.write(fmt.Sprintf("%s 0x%x", d.filename, addr-d.base)); err != nil {
return nil, err
}
var stack []plugin.Frame
for {
frame, end := d.readFrame()
if end {
break
}
if frame != (plugin.Frame{}) {
stack = append(stack, frame)
}
}
return stack, nil
}
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