github.com/varialus/godfly@v0.0.0-20130904042352-1934f9f095ab/src/pkg/runtime/debug/stack.go (about)

     1  // Copyright 2011 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  // Package debug contains facilities for programs to debug themselves while
     6  // they are running.
     7  package debug
     8  
     9  import (
    10  	"bytes"
    11  	"fmt"
    12  	"io/ioutil"
    13  	"os"
    14  	"runtime"
    15  )
    16  
    17  var (
    18  	dunno     = []byte("???")
    19  	centerDot = []byte("·")
    20  	dot       = []byte(".")
    21  )
    22  
    23  // PrintStack prints to standard error the stack trace returned by Stack.
    24  func PrintStack() {
    25  	os.Stderr.Write(stack())
    26  }
    27  
    28  // Stack returns a formatted stack trace of the goroutine that calls it.
    29  // For each routine, it includes the source line information and PC value,
    30  // then attempts to discover, for Go functions, the calling function or
    31  // method and the text of the line containing the invocation.
    32  //
    33  // This function is deprecated. Use package runtime's Stack instead.
    34  func Stack() []byte {
    35  	return stack()
    36  }
    37  
    38  // stack implements Stack, skipping 2 frames
    39  func stack() []byte {
    40  	buf := new(bytes.Buffer) // the returned data
    41  	// As we loop, we open files and read them. These variables record the currently
    42  	// loaded file.
    43  	var lines [][]byte
    44  	var lastFile string
    45  	for i := 2; ; i++ { // Caller we care about is the user, 2 frames up
    46  		pc, file, line, ok := runtime.Caller(i)
    47  		if !ok {
    48  			break
    49  		}
    50  		// Print this much at least.  If we can't find the source, it won't show.
    51  		fmt.Fprintf(buf, "%s:%d (0x%x)\n", file, line, pc)
    52  		if file != lastFile {
    53  			data, err := ioutil.ReadFile(file)
    54  			if err != nil {
    55  				continue
    56  			}
    57  			lines = bytes.Split(data, []byte{'\n'})
    58  			lastFile = file
    59  		}
    60  		line-- // in stack trace, lines are 1-indexed but our array is 0-indexed
    61  		fmt.Fprintf(buf, "\t%s: %s\n", function(pc), source(lines, line))
    62  	}
    63  	return buf.Bytes()
    64  }
    65  
    66  // source returns a space-trimmed slice of the n'th line.
    67  func source(lines [][]byte, n int) []byte {
    68  	if n < 0 || n >= len(lines) {
    69  		return dunno
    70  	}
    71  	return bytes.Trim(lines[n], " \t")
    72  }
    73  
    74  // function returns, if possible, the name of the function containing the PC.
    75  func function(pc uintptr) []byte {
    76  	fn := runtime.FuncForPC(pc)
    77  	if fn == nil {
    78  		return dunno
    79  	}
    80  	name := []byte(fn.Name())
    81  	// The name includes the path name to the package, which is unnecessary
    82  	// since the file name is already included.  Plus, it has center dots.
    83  	// That is, we see
    84  	//	runtime/debug.*T·ptrmethod
    85  	// and want
    86  	//	*T.ptrmethod
    87  	if period := bytes.Index(name, dot); period >= 0 {
    88  		name = name[period+1:]
    89  	}
    90  	name = bytes.Replace(name, centerDot, dot, -1)
    91  	return name
    92  }