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Source file src/debug/gosym/pclntab_test.go

Documentation: debug/gosym

  // Copyright 2009 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 gosym
  
  import (
  	"bytes"
  	"debug/elf"
  	"internal/testenv"
  	"io/ioutil"
  	"os"
  	"os/exec"
  	"path/filepath"
  	"runtime"
  	"strings"
  	"testing"
  )
  
  var (
  	pclineTempDir    string
  	pclinetestBinary string
  )
  
  func dotest(t *testing.T) {
  	testenv.MustHaveGoBuild(t)
  	// For now, only works on amd64 platforms.
  	if runtime.GOARCH != "amd64" {
  		t.Skipf("skipping on non-AMD64 system %s", runtime.GOARCH)
  	}
  	var err error
  	pclineTempDir, err = ioutil.TempDir("", "pclinetest")
  	if err != nil {
  		t.Fatal(err)
  	}
  	// This command builds pclinetest from pclinetest.asm;
  	// the resulting binary looks like it was built from pclinetest.s,
  	// but we have renamed it to keep it away from the go tool.
  	pclinetestBinary = filepath.Join(pclineTempDir, "pclinetest")
  	cmd := exec.Command(testenv.GoToolPath(t), "tool", "asm", "-o", pclinetestBinary+".o", "pclinetest.asm")
  	cmd.Stdout = os.Stdout
  	cmd.Stderr = os.Stderr
  	if err := cmd.Run(); err != nil {
  		t.Fatal(err)
  	}
  
  	// stamp .o file as being 'package main' so that go tool link will accept it
  	data, err := ioutil.ReadFile(pclinetestBinary + ".o")
  	if err != nil {
  		t.Fatal(err)
  	}
  	i := bytes.IndexByte(data, '\n')
  	if i < 0 {
  		t.Fatal("bad binary")
  	}
  	data = append(append(data[:i:i], "\nmain"...), data[i:]...)
  	if err := ioutil.WriteFile(pclinetestBinary+".o", data, 0666); err != nil {
  		t.Fatal(err)
  	}
  
  	cmd = exec.Command(testenv.GoToolPath(t), "tool", "link", "-H", "linux",
  		"-o", pclinetestBinary, pclinetestBinary+".o")
  	cmd.Stdout = os.Stdout
  	cmd.Stderr = os.Stderr
  	if err := cmd.Run(); err != nil {
  		t.Fatal(err)
  	}
  }
  
  func endtest() {
  	if pclineTempDir != "" {
  		os.RemoveAll(pclineTempDir)
  		pclineTempDir = ""
  		pclinetestBinary = ""
  	}
  }
  
  // skipIfNotELF skips the test if we are not running on an ELF system.
  // These tests open and examine the test binary, and use elf.Open to do so.
  func skipIfNotELF(t *testing.T) {
  	switch runtime.GOOS {
  	case "dragonfly", "freebsd", "linux", "netbsd", "openbsd", "solaris":
  		// OK.
  	default:
  		t.Skipf("skipping on non-ELF system %s", runtime.GOOS)
  	}
  }
  
  func getTable(t *testing.T) *Table {
  	f, tab := crack(os.Args[0], t)
  	f.Close()
  	return tab
  }
  
  func crack(file string, t *testing.T) (*elf.File, *Table) {
  	// Open self
  	f, err := elf.Open(file)
  	if err != nil {
  		t.Fatal(err)
  	}
  	return parse(file, f, t)
  }
  
  func parse(file string, f *elf.File, t *testing.T) (*elf.File, *Table) {
  	s := f.Section(".gosymtab")
  	if s == nil {
  		t.Skip("no .gosymtab section")
  	}
  	symdat, err := s.Data()
  	if err != nil {
  		f.Close()
  		t.Fatalf("reading %s gosymtab: %v", file, err)
  	}
  	pclndat, err := f.Section(".gopclntab").Data()
  	if err != nil {
  		f.Close()
  		t.Fatalf("reading %s gopclntab: %v", file, err)
  	}
  
  	pcln := NewLineTable(pclndat, f.Section(".text").Addr)
  	tab, err := NewTable(symdat, pcln)
  	if err != nil {
  		f.Close()
  		t.Fatalf("parsing %s gosymtab: %v", file, err)
  	}
  
  	return f, tab
  }
  
  func TestLineFromAline(t *testing.T) {
  	skipIfNotELF(t)
  
  	tab := getTable(t)
  	if tab.go12line != nil {
  		// aline's don't exist in the Go 1.2 table.
  		t.Skip("not relevant to Go 1.2 symbol table")
  	}
  
  	// Find the sym package
  	pkg := tab.LookupFunc("debug/gosym.TestLineFromAline").Obj
  	if pkg == nil {
  		t.Fatalf("nil pkg")
  	}
  
  	// Walk every absolute line and ensure that we hit every
  	// source line monotonically
  	lastline := make(map[string]int)
  	final := -1
  	for i := 0; i < 10000; i++ {
  		path, line := pkg.lineFromAline(i)
  		// Check for end of object
  		if path == "" {
  			if final == -1 {
  				final = i - 1
  			}
  			continue
  		} else if final != -1 {
  			t.Fatalf("reached end of package at absolute line %d, but absolute line %d mapped to %s:%d", final, i, path, line)
  		}
  		// It's okay to see files multiple times (e.g., sys.a)
  		if line == 1 {
  			lastline[path] = 1
  			continue
  		}
  		// Check that the is the next line in path
  		ll, ok := lastline[path]
  		if !ok {
  			t.Errorf("file %s starts on line %d", path, line)
  		} else if line != ll+1 {
  			t.Fatalf("expected next line of file %s to be %d, got %d", path, ll+1, line)
  		}
  		lastline[path] = line
  	}
  	if final == -1 {
  		t.Errorf("never reached end of object")
  	}
  }
  
  func TestLineAline(t *testing.T) {
  	skipIfNotELF(t)
  
  	tab := getTable(t)
  	if tab.go12line != nil {
  		// aline's don't exist in the Go 1.2 table.
  		t.Skip("not relevant to Go 1.2 symbol table")
  	}
  
  	for _, o := range tab.Files {
  		// A source file can appear multiple times in a
  		// object.  alineFromLine will always return alines in
  		// the first file, so track which lines we've seen.
  		found := make(map[string]int)
  		for i := 0; i < 1000; i++ {
  			path, line := o.lineFromAline(i)
  			if path == "" {
  				break
  			}
  
  			// cgo files are full of 'Z' symbols, which we don't handle
  			if len(path) > 4 && path[len(path)-4:] == ".cgo" {
  				continue
  			}
  
  			if minline, ok := found[path]; path != "" && ok {
  				if minline >= line {
  					// We've already covered this file
  					continue
  				}
  			}
  			found[path] = line
  
  			a, err := o.alineFromLine(path, line)
  			if err != nil {
  				t.Errorf("absolute line %d in object %s maps to %s:%d, but mapping that back gives error %s", i, o.Paths[0].Name, path, line, err)
  			} else if a != i {
  				t.Errorf("absolute line %d in object %s maps to %s:%d, which maps back to absolute line %d\n", i, o.Paths[0].Name, path, line, a)
  			}
  		}
  	}
  }
  
  func TestPCLine(t *testing.T) {
  	dotest(t)
  	defer endtest()
  
  	f, tab := crack(pclinetestBinary, t)
  	defer f.Close()
  	text := f.Section(".text")
  	textdat, err := text.Data()
  	if err != nil {
  		t.Fatalf("reading .text: %v", err)
  	}
  
  	// Test PCToLine
  	sym := tab.LookupFunc("linefrompc")
  	wantLine := 0
  	for pc := sym.Entry; pc < sym.End; pc++ {
  		off := pc - text.Addr // TODO(rsc): should not need off; bug in 8g
  		if textdat[off] == 255 {
  			break
  		}
  		wantLine += int(textdat[off])
  		t.Logf("off is %d %#x (max %d)", off, textdat[off], sym.End-pc)
  		file, line, fn := tab.PCToLine(pc)
  		if fn == nil {
  			t.Errorf("failed to get line of PC %#x", pc)
  		} else if !strings.HasSuffix(file, "pclinetest.asm") || line != wantLine || fn != sym {
  			t.Errorf("PCToLine(%#x) = %s:%d (%s), want %s:%d (%s)", pc, file, line, fn.Name, "pclinetest.asm", wantLine, sym.Name)
  		}
  	}
  
  	// Test LineToPC
  	sym = tab.LookupFunc("pcfromline")
  	lookupline := -1
  	wantLine = 0
  	off := uint64(0) // TODO(rsc): should not need off; bug in 8g
  	for pc := sym.Value; pc < sym.End; pc += 2 + uint64(textdat[off]) {
  		file, line, fn := tab.PCToLine(pc)
  		off = pc - text.Addr
  		if textdat[off] == 255 {
  			break
  		}
  		wantLine += int(textdat[off])
  		if line != wantLine {
  			t.Errorf("expected line %d at PC %#x in pcfromline, got %d", wantLine, pc, line)
  			off = pc + 1 - text.Addr
  			continue
  		}
  		if lookupline == -1 {
  			lookupline = line
  		}
  		for ; lookupline <= line; lookupline++ {
  			pc2, fn2, err := tab.LineToPC(file, lookupline)
  			if lookupline != line {
  				// Should be nothing on this line
  				if err == nil {
  					t.Errorf("expected no PC at line %d, got %#x (%s)", lookupline, pc2, fn2.Name)
  				}
  			} else if err != nil {
  				t.Errorf("failed to get PC of line %d: %s", lookupline, err)
  			} else if pc != pc2 {
  				t.Errorf("expected PC %#x (%s) at line %d, got PC %#x (%s)", pc, fn.Name, line, pc2, fn2.Name)
  			}
  		}
  		off = pc + 1 - text.Addr
  	}
  }
  

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