diff options
Diffstat (limited to 'vendor/github.com/pkg/errors/stack.go')
-rw-r--r-- | vendor/github.com/pkg/errors/stack.go | 187 |
1 files changed, 187 insertions, 0 deletions
diff --git a/vendor/github.com/pkg/errors/stack.go b/vendor/github.com/pkg/errors/stack.go new file mode 100644 index 000000000..b485761a7 --- /dev/null +++ b/vendor/github.com/pkg/errors/stack.go @@ -0,0 +1,187 @@ +package errors + +import ( + "fmt" + "io" + "path" + "runtime" + "strings" +) + +// Frame represents a program counter inside a stack frame. +type Frame uintptr + +// pc returns the program counter for this frame; +// multiple frames may have the same PC value. +func (f Frame) pc() uintptr { return uintptr(f) - 1 } + +// file returns the full path to the file that contains the +// function for this Frame's pc. +func (f Frame) file() string { + fn := runtime.FuncForPC(f.pc()) + if fn == nil { + return "unknown" + } + file, _ := fn.FileLine(f.pc()) + return file +} + +// line returns the line number of source code of the +// function for this Frame's pc. +func (f Frame) line() int { + fn := runtime.FuncForPC(f.pc()) + if fn == nil { + return 0 + } + _, line := fn.FileLine(f.pc()) + return line +} + +// Format formats the frame according to the fmt.Formatter interface. +// +// %s source file +// %d source line +// %n function name +// %v equivalent to %s:%d +// +// Format accepts flags that alter the printing of some verbs, as follows: +// +// %+s function name and path of source file relative to the compile time +// GOPATH separated by \n\t (<funcname>\n\t<path>) +// %+v equivalent to %+s:%d +func (f Frame) Format(s fmt.State, verb rune) { + switch verb { + case 's': + switch { + case s.Flag('+'): + pc := f.pc() + fn := runtime.FuncForPC(pc) + if fn == nil { + io.WriteString(s, "unknown") + } else { + file, _ := fn.FileLine(pc) + fmt.Fprintf(s, "%s\n\t%s", fn.Name(), file) + } + default: + io.WriteString(s, path.Base(f.file())) + } + case 'd': + fmt.Fprintf(s, "%d", f.line()) + case 'n': + name := runtime.FuncForPC(f.pc()).Name() + io.WriteString(s, funcname(name)) + case 'v': + f.Format(s, 's') + io.WriteString(s, ":") + f.Format(s, 'd') + } +} + +// StackTrace is stack of Frames from innermost (newest) to outermost (oldest). +type StackTrace []Frame + +// Format formats the stack of Frames according to the fmt.Formatter interface. +// +// %s lists source files for each Frame in the stack +// %v lists the source file and line number for each Frame in the stack +// +// Format accepts flags that alter the printing of some verbs, as follows: +// +// %+v Prints filename, function, and line number for each Frame in the stack. +func (st StackTrace) Format(s fmt.State, verb rune) { + switch verb { + case 'v': + switch { + case s.Flag('+'): + for _, f := range st { + fmt.Fprintf(s, "\n%+v", f) + } + case s.Flag('#'): + fmt.Fprintf(s, "%#v", []Frame(st)) + default: + fmt.Fprintf(s, "%v", []Frame(st)) + } + case 's': + fmt.Fprintf(s, "%s", []Frame(st)) + } +} + +// stack represents a stack of program counters. +type stack []uintptr + +func (s *stack) Format(st fmt.State, verb rune) { + switch verb { + case 'v': + switch { + case st.Flag('+'): + for _, pc := range *s { + f := Frame(pc) + fmt.Fprintf(st, "\n%+v", f) + } + } + } +} + +func (s *stack) StackTrace() StackTrace { + f := make([]Frame, len(*s)) + for i := 0; i < len(f); i++ { + f[i] = Frame((*s)[i]) + } + return f +} + +func callers() *stack { + const depth = 32 + var pcs [depth]uintptr + n := runtime.Callers(3, pcs[:]) + var st stack = pcs[0:n] + return &st +} + +// funcname removes the path prefix component of a function's name reported by func.Name(). +func funcname(name string) string { + i := strings.LastIndex(name, "/") + name = name[i+1:] + i = strings.Index(name, ".") + return name[i+1:] +} + +func trimGOPATH(name, file string) string { + // Here we want to get the source file path relative to the compile time + // GOPATH. As of Go 1.6.x there is no direct way to know the compiled + // GOPATH at runtime, but we can infer the number of path segments in the + // GOPATH. We note that fn.Name() returns the function name qualified by + // the import path, which does not include the GOPATH. Thus we can trim + // segments from the beginning of the file path until the number of path + // separators remaining is one more than the number of path separators in + // the function name. For example, given: + // + // GOPATH /home/user + // file /home/user/src/pkg/sub/file.go + // fn.Name() pkg/sub.Type.Method + // + // We want to produce: + // + // pkg/sub/file.go + // + // From this we can easily see that fn.Name() has one less path separator + // than our desired output. We count separators from the end of the file + // path until it finds two more than in the function name and then move + // one character forward to preserve the initial path segment without a + // leading separator. + const sep = "/" + goal := strings.Count(name, sep) + 2 + i := len(file) + for n := 0; n < goal; n++ { + i = strings.LastIndex(file[:i], sep) + if i == -1 { + // not enough separators found, set i so that the slice expression + // below leaves file unmodified + i = -len(sep) + break + } + } + // get back to 0 or trim the leading separator + file = file[i+len(sep):] + return file +} |