code.gitea.io/gitea@v1.19.3/modules/log/stack.go (about)

     1  // Copyright 2019 The Gitea Authors. All rights reserved.
     2  // SPDX-License-Identifier: MIT
     3  
     4  package log
     5  
     6  import (
     7  	"bytes"
     8  	"fmt"
     9  	"os"
    10  	"runtime"
    11  )
    12  
    13  var unknown = []byte("???")
    14  
    15  // Stack will skip back the provided number of frames and return a stack trace with source code.
    16  // Although we could just use debug.Stack(), this routine will return the source code and
    17  // skip back the provided number of frames - i.e. allowing us to ignore preceding function calls.
    18  // A skip of 0 returns the stack trace for the calling function, not including this call.
    19  // If the problem is a lack of memory of course all this is not going to work...
    20  func Stack(skip int) string {
    21  	buf := new(bytes.Buffer)
    22  
    23  	// Store the last file we opened as its probable that the preceding stack frame
    24  	// will be in the same file
    25  	var lines [][]byte
    26  	var lastFilename string
    27  	for i := skip + 1; ; i++ { // Skip over frames
    28  		programCounter, filename, lineNumber, ok := runtime.Caller(i)
    29  		// If we can't retrieve the information break - basically we're into go internals at this point.
    30  		if !ok {
    31  			break
    32  		}
    33  
    34  		// Print equivalent of debug.Stack()
    35  		fmt.Fprintf(buf, "%s:%d (0x%x)\n", filename, lineNumber, programCounter)
    36  		// Now try to print the offending line
    37  		if filename != lastFilename {
    38  			data, err := os.ReadFile(filename)
    39  			if err != nil {
    40  				// can't read this sourcefile
    41  				// likely we don't have the sourcecode available
    42  				continue
    43  			}
    44  			lines = bytes.Split(data, []byte{'\n'})
    45  			lastFilename = filename
    46  		}
    47  		fmt.Fprintf(buf, "\t%s: %s\n", functionName(programCounter), source(lines, lineNumber))
    48  	}
    49  	return buf.String()
    50  }
    51  
    52  // functionName converts the provided programCounter into a function name
    53  func functionName(programCounter uintptr) []byte {
    54  	function := runtime.FuncForPC(programCounter)
    55  	if function == nil {
    56  		return unknown
    57  	}
    58  	name := []byte(function.Name())
    59  
    60  	// Because we provide the filename we can drop the preceding package name.
    61  	if lastslash := bytes.LastIndex(name, []byte("/")); lastslash >= 0 {
    62  		name = name[lastslash+1:]
    63  	}
    64  	// And the current package name.
    65  	if period := bytes.Index(name, []byte(".")); period >= 0 {
    66  		name = name[period+1:]
    67  	}
    68  	// And we should just replace the interpunct with a dot
    69  	name = bytes.ReplaceAll(name, []byte("ยท"), []byte("."))
    70  	return name
    71  }
    72  
    73  // source returns a space-trimmed slice of the n'th line.
    74  func source(lines [][]byte, n int) []byte {
    75  	n-- // in stack trace, lines are 1-indexed but our array is 0-indexed
    76  	if n < 0 || n >= len(lines) {
    77  		return unknown
    78  	}
    79  	return bytes.TrimSpace(lines[n])
    80  }