148 lines
3.3 KiB
Go
148 lines
3.3 KiB
Go
package errors
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import (
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"fmt"
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"io"
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"path"
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"runtime"
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"strings"
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)
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// Frame represents a program counter inside a stack frame.
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type Frame uintptr
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// pc returns the program counter for this frame;
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// multiple frames may have the same PC value.
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func (f Frame) pc() uintptr { return uintptr(f) - 1 }
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// file returns the full path to the file that contains the
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// function for this Frame's pc.
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func (f Frame) file() string {
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fn := runtime.FuncForPC(f.pc())
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if fn == nil {
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return "unknown"
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}
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file, _ := fn.FileLine(f.pc())
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return file
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}
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// line returns the line number of source code of the
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// function for this Frame's pc.
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func (f Frame) line() int {
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fn := runtime.FuncForPC(f.pc())
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if fn == nil {
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return 0
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}
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_, line := fn.FileLine(f.pc())
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return line
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}
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// Format formats the frame according to the fmt.Formatter interface.
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//
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// %s source file
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// %d source line
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// %n function name
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// %v equivalent to %s:%d
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//
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// Format accepts flags that alter the printing of some verbs, as follows:
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//
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// %+s function name and path of source file relative to the compile time
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// GOPATH separated by \n\t (<funcname>\n\t<path>)
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// %+v equivalent to %+s:%d
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func (f Frame) Format(s fmt.State, verb rune) {
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switch verb {
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case 's':
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switch {
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case s.Flag('+'):
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pc := f.pc()
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fn := runtime.FuncForPC(pc)
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if fn == nil {
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io.WriteString(s, "unknown")
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} else {
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file, _ := fn.FileLine(pc)
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fmt.Fprintf(s, "%s\n\t%s", fn.Name(), file)
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}
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default:
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io.WriteString(s, path.Base(f.file()))
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}
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case 'd':
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fmt.Fprintf(s, "%d", f.line())
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case 'n':
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name := runtime.FuncForPC(f.pc()).Name()
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io.WriteString(s, funcname(name))
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case 'v':
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f.Format(s, 's')
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io.WriteString(s, ":")
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f.Format(s, 'd')
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}
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}
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// StackTrace is stack of Frames from innermost (newest) to outermost (oldest).
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type StackTrace []Frame
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// Format formats the stack of Frames according to the fmt.Formatter interface.
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//
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// %s lists source files for each Frame in the stack
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// %v lists the source file and line number for each Frame in the stack
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//
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// Format accepts flags that alter the printing of some verbs, as follows:
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//
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// %+v Prints filename, function, and line number for each Frame in the stack.
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func (st StackTrace) Format(s fmt.State, verb rune) {
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switch verb {
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case 'v':
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switch {
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case s.Flag('+'):
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for _, f := range st {
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fmt.Fprintf(s, "\n%+v", f)
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}
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case s.Flag('#'):
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fmt.Fprintf(s, "%#v", []Frame(st))
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default:
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fmt.Fprintf(s, "%v", []Frame(st))
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}
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case 's':
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fmt.Fprintf(s, "%s", []Frame(st))
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}
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}
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// stack represents a stack of program counters.
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type stack []uintptr
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func (s *stack) Format(st fmt.State, verb rune) {
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switch verb {
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case 'v':
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switch {
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case st.Flag('+'):
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for _, pc := range *s {
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f := Frame(pc)
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fmt.Fprintf(st, "\n%+v", f)
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}
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}
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}
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}
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func (s *stack) StackTrace() StackTrace {
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f := make([]Frame, len(*s))
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for i := 0; i < len(f); i++ {
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f[i] = Frame((*s)[i])
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}
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return f
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}
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func callers() *stack {
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const depth = 32
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var pcs [depth]uintptr
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n := runtime.Callers(3, pcs[:])
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var st stack = pcs[0:n]
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return &st
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}
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// funcname removes the path prefix component of a function's name reported by func.Name().
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func funcname(name string) string {
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i := strings.LastIndex(name, "/")
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name = name[i+1:]
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i = strings.Index(name, ".")
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return name[i+1:]
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}
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