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// Copyright 2014 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package runtime
// Frames may be used to get function/file/line information for a
// slice of PC values returned by Callers.
type Frames struct {
// callers is a slice of PCs that have not yet been expanded.
callers []uintptr
// The last PC we saw.
last uintptr
// The number of times we've seen last.
lastCount int
}
// Frame is the information returned by Frames for each call frame.
type Frame struct {
// PC is the program counter for the location in this frame.
// For a frame that calls another frame, this will be the
// program counter of a call instruction. Because of inlining,
// multiple frames may have the same PC value, but different
// symbolic information.
PC uintptr
// Func is the Func value of this call frame. This may be nil
// for non-Go code or fully inlined functions.
Func *Func
// Function is the package path-qualified function name of
// this call frame. If non-empty, this string uniquely
// identifies a single function in the program.
// This may be the empty string if not known.
// If Func is not nil then Function == Func.Name().
Function string
// File and Line are the file name and line number of the
// location in this frame. For non-leaf frames, this will be
// the location of a call. These may be the empty string and
// zero, respectively, if not known.
File string
Line int
// Entry point program counter for the function; may be zero
// if not known. If Func is not nil then Entry ==
// Func.Entry().
Entry uintptr
}
// CallersFrames takes a slice of PC values returned by Callers and
// prepares to return function/file/line information.
// Do not change the slice until you are done with the Frames.
func CallersFrames(callers []uintptr) *Frames {
return &Frames{callers: callers}
}
// Next returns frame information for the next caller.
// If more is false, there are no more callers (the Frame value is valid).
func (ci *Frames) Next() (frame Frame, more bool) {
if len(ci.callers) == 0 {
return Frame{}, false
}
pc := ci.callers[0]
ci.callers = ci.callers[1:]
i := 0
if pc == ci.last {
ci.lastCount++
i = ci.lastCount
} else {
ci.last = pc
ci.lastCount = 0
}
more = len(ci.callers) > 0
// Subtract 1 from PC to undo the 1 we added in callback in
// go-callers.c.
function, file, line := funcfileline(pc-1, int32(i))
if function == "" && file == "" {
return Frame{}, more
}
entry := funcentry(pc - 1)
f := &Func{name: function, entry: entry}
xpc := pc
if xpc > entry {
xpc--
}
frame = Frame{
PC: xpc,
Func: f,
Function: function,
File: file,
Line: line,
Entry: entry,
}
return frame, more
}
// NOTE: Func does not expose the actual unexported fields, because we return *Func
// values to users, and we want to keep them from being able to overwrite the data
// with (say) *f = Func{}.
// All code operating on a *Func must call raw() to get the *_func
// or funcInfo() to get the funcInfo instead.
// A Func represents a Go function in the running binary.
type Func struct {
name string
entry uintptr
}
// A FuncID identifies particular functions that need to be treated
// specially by the runtime.
// Note that in some situations involving plugins, there may be multiple
// copies of a particular special runtime function.
// Note: this list must match the list in cmd/internal/objabi/funcid.go.
type funcID uint32
const (
funcID_normal funcID = iota // not a special function
funcID_runtime_main
funcID_goexit
funcID_jmpdefer
funcID_mcall
funcID_morestack
funcID_mstart
funcID_rt0_go
funcID_asmcgocall
funcID_sigpanic
funcID_runfinq
funcID_gcBgMarkWorker
funcID_systemstack_switch
funcID_systemstack
funcID_cgocallback_gofunc
funcID_gogo
funcID_externalthreadhandler
funcID_debugCallV1
)
// FuncForPC returns a *Func describing the function that contains the
// given program counter address, or else nil.
//
// If pc represents multiple functions because of inlining, it returns
// the *Func describing the outermost function.
func FuncForPC(pc uintptr) *Func {
name, _, _ := funcfileline(pc, -1)
if name == "" {
return nil
}
entry := funcentry(pc)
return &Func{name: name, entry: entry}
}
// Name returns the name of the function.
func (f *Func) Name() string {
if f == nil {
return ""
}
return f.name
}
// Entry returns the entry address of the function.
func (f *Func) Entry() uintptr {
if f == nil {
return 0
}
return f.entry
}
// FileLine returns the file name and line number of the
// source code corresponding to the program counter pc.
// The result will not be accurate if pc is not a program
// counter within f.
func (f *Func) FileLine(pc uintptr) (file string, line int) {
_, file, line = funcfileline(pc, -1)
return file, line
}
// implemented in go-caller.c
func funcfileline(uintptr, int32) (string, string, int)
func funcentry(uintptr) uintptr
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