303 lines
8.3 KiB
Go
303 lines
8.3 KiB
Go
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// Copyright 2015 Marc-Antoine Ruel. All rights reserved.
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// Use of this source code is governed under the Apache License, Version 2.0
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// that can be found in the LICENSE file.
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// This file contains the code to process sources, to be able to deduct the
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// original types.
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package stack
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import (
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"bytes"
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"fmt"
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"go/ast"
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"go/parser"
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"go/token"
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"io/ioutil"
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"log"
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"math"
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"strings"
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)
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// cache is a cache of sources on the file system.
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type cache struct {
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files map[string][]byte
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parsed map[string]*parsedFile
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}
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// Augment processes source files to improve calls to be more descriptive.
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//
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// It modifies goroutines in place.
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func Augment(goroutines []Goroutine) {
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c := &cache{}
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for i := range goroutines {
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c.augmentGoroutine(&goroutines[i])
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}
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}
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// augmentGoroutine processes source files to improve call to be more
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// descriptive.
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//
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// It modifies the routine.
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func (c *cache) augmentGoroutine(goroutine *Goroutine) {
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if c.files == nil {
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c.files = map[string][]byte{}
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}
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if c.parsed == nil {
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c.parsed = map[string]*parsedFile{}
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}
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// For each call site, look at the next call and populate it. Then we can
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// walk back and reformat things.
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for i := range goroutine.Stack.Calls {
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c.load(goroutine.Stack.Calls[i].LocalSourcePath())
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}
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// Once all loaded, we can look at the next call when available.
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for i := 0; i < len(goroutine.Stack.Calls)-1; i++ {
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// Get the AST from the previous call and process the call line with it.
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if f := c.getFuncAST(&goroutine.Stack.Calls[i]); f != nil {
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processCall(&goroutine.Stack.Calls[i], f)
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}
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}
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}
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// Private stuff.
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// load loads a source file and parses the AST tree. Failures are ignored.
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func (c *cache) load(fileName string) {
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if _, ok := c.parsed[fileName]; ok {
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return
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}
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c.parsed[fileName] = nil
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if !strings.HasSuffix(fileName, ".go") {
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// Ignore C and assembly.
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c.files[fileName] = nil
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return
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}
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log.Printf("load(%s)", fileName)
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if _, ok := c.files[fileName]; !ok {
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var err error
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if c.files[fileName], err = ioutil.ReadFile(fileName); err != nil {
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log.Printf("Failed to read %s: %s", fileName, err)
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c.files[fileName] = nil
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return
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}
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}
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fset := token.NewFileSet()
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src := c.files[fileName]
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parsed, err := parser.ParseFile(fset, fileName, src, 0)
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if err != nil {
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log.Printf("Failed to parse %s: %s", fileName, err)
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return
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}
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// Convert the line number into raw file offset.
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offsets := []int{0, 0}
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start := 0
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for l := 1; start < len(src); l++ {
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start += bytes.IndexByte(src[start:], '\n') + 1
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offsets = append(offsets, start)
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}
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c.parsed[fileName] = &parsedFile{offsets, parsed}
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}
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func (c *cache) getFuncAST(call *Call) *ast.FuncDecl {
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if p := c.parsed[call.LocalSourcePath()]; p != nil {
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return p.getFuncAST(call.Func.Name(), call.Line)
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}
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return nil
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}
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type parsedFile struct {
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lineToByteOffset []int
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parsed *ast.File
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}
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// getFuncAST gets the callee site function AST representation for the code
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// inside the function f at line l.
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func (p *parsedFile) getFuncAST(f string, l int) (d *ast.FuncDecl) {
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if len(p.lineToByteOffset) <= l {
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// The line number in the stack trace line does not exist in the file. That
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// can only mean that the sources on disk do not match the sources used to
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// build the binary.
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// TODO(maruel): This should be surfaced, so that source parsing is
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// completely ignored.
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return
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}
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// Walk the AST to find the lineToByteOffset that fits the line number.
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var lastFunc *ast.FuncDecl
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var found ast.Node
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// Inspect() goes depth first. This means for example that a function like:
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// func a() {
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// b := func() {}
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// c()
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// }
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//
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// Were we are looking at the c() call can return confused values. It is
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// important to look at the actual ast.Node hierarchy.
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ast.Inspect(p.parsed, func(n ast.Node) bool {
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if d != nil {
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return false
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}
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if n == nil {
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return true
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}
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if found != nil {
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// We are walking up.
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}
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if int(n.Pos()) >= p.lineToByteOffset[l] {
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// We are expecting a ast.CallExpr node. It can be harder to figure out
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// when there are multiple calls on a single line, as the stack trace
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// doesn't have file byte offset information, only line based.
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// gofmt will always format to one function call per line but there can
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// be edge cases, like:
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// a = A{Foo(), Bar()}
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d = lastFunc
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//p.processNode(call, n)
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return false
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} else if f, ok := n.(*ast.FuncDecl); ok {
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lastFunc = f
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}
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return true
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})
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return
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}
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func name(n ast.Node) string {
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switch t := n.(type) {
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case *ast.InterfaceType:
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return "interface{}"
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case *ast.Ident:
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return t.Name
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case *ast.SelectorExpr:
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return t.Sel.Name
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case *ast.StarExpr:
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return "*" + name(t.X)
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default:
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return "<unknown>"
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}
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}
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// fieldToType returns the type name and whether if it's an ellipsis.
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func fieldToType(f *ast.Field) (string, bool) {
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switch arg := f.Type.(type) {
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case *ast.ArrayType:
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return "[]" + name(arg.Elt), false
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case *ast.Ellipsis:
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return name(arg.Elt), true
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case *ast.FuncType:
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// Do not print the function signature to not overload the trace.
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return "func", false
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case *ast.Ident:
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return arg.Name, false
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case *ast.InterfaceType:
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return "interface{}", false
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case *ast.SelectorExpr:
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return arg.Sel.Name, false
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case *ast.StarExpr:
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return "*" + name(arg.X), false
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case *ast.MapType:
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return fmt.Sprintf("map[%s]%s", name(arg.Key), name(arg.Value)), false
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case *ast.ChanType:
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return fmt.Sprintf("chan %s", name(arg.Value)), false
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default:
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// TODO(maruel): Implement anything missing.
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return "<unknown>", false
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}
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}
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// extractArgumentsType returns the name of the type of each input argument.
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func extractArgumentsType(f *ast.FuncDecl) ([]string, bool) {
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var fields []*ast.Field
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if f.Recv != nil {
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if len(f.Recv.List) != 1 {
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panic("Expect only one receiver; please fix panicparse's code")
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}
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// If it is an object receiver (vs a pointer receiver), its address is not
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// printed in the stack trace so it needs to be ignored.
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if _, ok := f.Recv.List[0].Type.(*ast.StarExpr); ok {
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fields = append(fields, f.Recv.List[0])
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}
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}
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var types []string
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extra := false
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for _, arg := range append(fields, f.Type.Params.List...) {
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// Assert that extra is only set on the last item of fields?
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var t string
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t, extra = fieldToType(arg)
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mult := len(arg.Names)
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if mult == 0 {
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mult = 1
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}
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for i := 0; i < mult; i++ {
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types = append(types, t)
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}
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}
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return types, extra
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}
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// processCall walks the function and populate call accordingly.
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func processCall(call *Call, f *ast.FuncDecl) {
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values := make([]uint64, len(call.Args.Values))
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for i := range call.Args.Values {
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values[i] = call.Args.Values[i].Value
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}
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index := 0
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pop := func() uint64 {
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if len(values) != 0 {
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x := values[0]
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values = values[1:]
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index++
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return x
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}
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return 0
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}
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popName := func() string {
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n := call.Args.Values[index].Name
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v := pop()
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if len(n) == 0 {
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return fmt.Sprintf("0x%x", v)
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}
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return n
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}
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types, extra := extractArgumentsType(f)
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for i := 0; len(values) != 0; i++ {
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var t string
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if i >= len(types) {
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if !extra {
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// These are unexpected value! Print them as hex.
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call.Args.Processed = append(call.Args.Processed, popName())
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continue
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}
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t = types[len(types)-1]
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} else {
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t = types[i]
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}
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switch t {
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case "float32":
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call.Args.Processed = append(call.Args.Processed, fmt.Sprintf("%g", math.Float32frombits(uint32(pop()))))
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case "float64":
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call.Args.Processed = append(call.Args.Processed, fmt.Sprintf("%g", math.Float64frombits(pop())))
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case "int", "int8", "int16", "int32", "int64", "uint", "uint8", "uint16", "uint32", "uint64":
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call.Args.Processed = append(call.Args.Processed, fmt.Sprintf("%d", pop()))
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case "string":
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call.Args.Processed = append(call.Args.Processed, fmt.Sprintf("%s(%s, len=%d)", t, popName(), pop()))
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default:
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if strings.HasPrefix(t, "*") {
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call.Args.Processed = append(call.Args.Processed, fmt.Sprintf("%s(%s)", t, popName()))
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} else if strings.HasPrefix(t, "[]") {
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call.Args.Processed = append(call.Args.Processed, fmt.Sprintf("%s(%s len=%d cap=%d)", t, popName(), pop(), pop()))
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} else {
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// Assumes it's an interface. For now, discard the object value, which
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// is probably not a good idea.
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call.Args.Processed = append(call.Args.Processed, fmt.Sprintf("%s(%s)", t, popName()))
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pop()
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}
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}
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if len(values) == 0 && call.Args.Elided {
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return
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}
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}
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}
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