1 // Copyright 2014 Google Inc. All Rights Reserved. 2 // 3 // Licensed under the Apache License, Version 2.0 (the "License"); 4 // you may not use this file except in compliance with the License. 5 // You may obtain a copy of the License at 6 // 7 // http://www.apache.org/licenses/LICENSE-2.0 8 // 9 // Unless required by applicable law or agreed to in writing, software 10 // distributed under the License is distributed on an "AS IS" BASIS, 11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 12 // See the License for the specific language governing permissions and 13 // limitations under the License. 14 15 package binutils 16 17 import ( 18 "bufio" 19 "fmt" 20 "io" 21 "os/exec" 22 "strconv" 23 "strings" 24 "sync" 25 26 "github.com/google/pprof/internal/plugin" 27 ) 28 29 const ( 30 defaultLLVMSymbolizer = "llvm-symbolizer" 31 ) 32 33 // llvmSymbolizer is a connection to an llvm-symbolizer command for 34 // obtaining address and line number information from a binary. 35 type llvmSymbolizer struct { 36 sync.Mutex 37 filename string 38 rw lineReaderWriter 39 base uint64 40 } 41 42 type llvmSymbolizerJob struct { 43 cmd *exec.Cmd 44 in io.WriteCloser 45 out *bufio.Reader 46 } 47 48 func (a *llvmSymbolizerJob) write(s string) error { 49 _, err := fmt.Fprint(a.in, s+"\n") 50 return err 51 } 52 53 func (a *llvmSymbolizerJob) readLine() (string, error) { 54 return a.out.ReadString('\n') 55 } 56 57 // close releases any resources used by the llvmSymbolizer object. 58 func (a *llvmSymbolizerJob) close() { 59 a.in.Close() 60 a.cmd.Wait() 61 } 62 63 // newLlvmSymbolizer starts the given llvmSymbolizer command reporting 64 // information about the given executable file. If file is a shared 65 // library, base should be the address at which it was mapped in the 66 // program under consideration. 67 func newLLVMSymbolizer(cmd, file string, base uint64) (*llvmSymbolizer, error) { 68 if cmd == "" { 69 cmd = defaultLLVMSymbolizer 70 } 71 72 j := &llvmSymbolizerJob{ 73 cmd: exec.Command(cmd, "-inlining", "-demangle=false"), 74 } 75 76 var err error 77 if j.in, err = j.cmd.StdinPipe(); err != nil { 78 return nil, err 79 } 80 81 outPipe, err := j.cmd.StdoutPipe() 82 if err != nil { 83 return nil, err 84 } 85 86 j.out = bufio.NewReader(outPipe) 87 if err := j.cmd.Start(); err != nil { 88 return nil, err 89 } 90 91 a := &llvmSymbolizer{ 92 filename: file, 93 rw: j, 94 base: base, 95 } 96 97 return a, nil 98 } 99 100 func (d *llvmSymbolizer) readString() (string, error) { 101 s, err := d.rw.readLine() 102 if err != nil { 103 return "", err 104 } 105 return strings.TrimSpace(s), nil 106 } 107 108 // readFrame parses the llvm-symbolizer output for a single address. It 109 // returns a populated plugin.Frame and whether it has reached the end of the 110 // data. 111 func (d *llvmSymbolizer) readFrame() (plugin.Frame, bool) { 112 funcname, err := d.readString() 113 if err != nil { 114 return plugin.Frame{}, true 115 } 116 117 switch funcname { 118 case "": 119 return plugin.Frame{}, true 120 case "??": 121 funcname = "" 122 } 123 124 fileline, err := d.readString() 125 if err != nil { 126 return plugin.Frame{Func: funcname}, true 127 } 128 129 linenumber := 0 130 if fileline == "??:0" { 131 fileline = "" 132 } else { 133 switch split := strings.Split(fileline, ":"); len(split) { 134 case 1: 135 // filename 136 fileline = split[0] 137 case 2, 3: 138 // filename:line , or 139 // filename:line:disc , or 140 fileline = split[0] 141 if line, err := strconv.Atoi(split[1]); err == nil { 142 linenumber = line 143 } 144 default: 145 // Unrecognized, ignore 146 } 147 } 148 149 return plugin.Frame{Func: funcname, File: fileline, Line: linenumber}, false 150 } 151 152 // addrInfo returns the stack frame information for a specific program 153 // address. It returns nil if the address could not be identified. 154 func (d *llvmSymbolizer) addrInfo(addr uint64) ([]plugin.Frame, error) { 155 d.Lock() 156 defer d.Unlock() 157 158 if err := d.rw.write(fmt.Sprintf("%s 0x%x", d.filename, addr-d.base)); err != nil { 159 return nil, err 160 } 161 162 var stack []plugin.Frame 163 for { 164 frame, end := d.readFrame() 165 if end { 166 break 167 } 168 169 if frame != (plugin.Frame{}) { 170 stack = append(stack, frame) 171 } 172 } 173 174 return stack, nil 175 } 176
