src/debug/dwarf/line_test.go

// Copyright 2015 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 dwarf_test

import (
	. "debug/dwarf"
	"io"
	"testing"
)

var (
	file1C = &LineFile{Name: "/home/austin/go.dev/src/debug/dwarf/testdata/line1.c"}
	file1H = &LineFile{Name: "/home/austin/go.dev/src/debug/dwarf/testdata/line1.h"}
	file2C = &LineFile{Name: "/home/austin/go.dev/src/debug/dwarf/testdata/line2.c"}
)

func TestLineELFGCC(t *testing.T) {
	// Generated by:
	//   # gcc --version | head -n1
	//   gcc (Ubuntu 4.8.2-19ubuntu1) 4.8.2
	//   # gcc -g -o line-gcc.elf line*.c

	// Line table based on readelf --debug-dump=rawline,decodedline
	want := []LineEntry{
		{Address: 0x40059d, File: file1H, Line: 2, IsStmt: true},
		{Address: 0x4005a5, File: file1H, Line: 2, IsStmt: true},
		{Address: 0x4005b4, File: file1H, Line: 5, IsStmt: true},
		{Address: 0x4005bd, File: file1H, Line: 6, IsStmt: true, Discriminator: 2},
		{Address: 0x4005c7, File: file1H, Line: 5, IsStmt: true, Discriminator: 2},
		{Address: 0x4005cb, File: file1H, Line: 5, IsStmt: false, Discriminator: 1},
		{Address: 0x4005d1, File: file1H, Line: 7, IsStmt: true},
		{Address: 0x4005e7, File: file1C, Line: 6, IsStmt: true},
		{Address: 0x4005eb, File: file1C, Line: 7, IsStmt: true},
		{Address: 0x4005f5, File: file1C, Line: 8, IsStmt: true},
		{Address: 0x4005ff, File: file1C, Line: 9, IsStmt: true},
		{Address: 0x400601, EndSequence: true},

		{Address: 0x400601, File: file2C, Line: 4, IsStmt: true},
		{Address: 0x400605, File: file2C, Line: 5, IsStmt: true},
		{Address: 0x40060f, File: file2C, Line: 6, IsStmt: true},
		{Address: 0x400611, EndSequence: true},
	}

	testLineTable(t, want, elfData(t, "testdata/line-gcc.elf"))
}

func TestLineELFClang(t *testing.T) {
	// Generated by:
	//   # clang --version | head -n1
	//   Ubuntu clang version 3.4-1ubuntu3 (tags/RELEASE_34/final) (based on LLVM 3.4)
	//   # clang -g -o line-clang.elf line*.

	want := []LineEntry{
		{Address: 0x400530, File: file1C, Line: 6, IsStmt: true},
		{Address: 0x400534, File: file1C, Line: 7, IsStmt: true, PrologueEnd: true},
		{Address: 0x400539, File: file1C, Line: 8, IsStmt: true},
		{Address: 0x400545, File: file1C, Line: 9, IsStmt: true},
		{Address: 0x400550, File: file1H, Line: 2, IsStmt: true},
		{Address: 0x400554, File: file1H, Line: 5, IsStmt: true, PrologueEnd: true},
		{Address: 0x400568, File: file1H, Line: 6, IsStmt: true},
		{Address: 0x400571, File: file1H, Line: 5, IsStmt: true},
		{Address: 0x400581, File: file1H, Line: 7, IsStmt: true},
		{Address: 0x400583, EndSequence: true},

		{Address: 0x400590, File: file2C, Line: 4, IsStmt: true},
		{Address: 0x4005a0, File: file2C, Line: 5, IsStmt: true, PrologueEnd: true},
		{Address: 0x4005a7, File: file2C, Line: 6, IsStmt: true},
		{Address: 0x4005b0, EndSequence: true},
	}

	testLineTable(t, want, elfData(t, "testdata/line-clang.elf"))
}

func TestLineSeek(t *testing.T) {
	d := elfData(t, "testdata/line-gcc.elf")

	// Get the line table for the first CU.
	cu, err := d.Reader().Next()
	if err != nil {
		t.Fatal("d.Reader().Next:", err)
	}
	lr, err := d.LineReader(cu)
	if err != nil {
		t.Fatal("d.LineReader:", err)
	}

	// Read entries forward.
	var line LineEntry
	var posTable []LineReaderPos
	var table []LineEntry
	for {
		posTable = append(posTable, lr.Tell())

		err := lr.Next(&line)
		if err != nil {
			if err == io.EOF {
				break
			}
			t.Fatal("lr.Next:", err)
		}
		table = append(table, line)
	}

	// Test that Reset returns to the first line.
	lr.Reset()
	if err := lr.Next(&line); err != nil {
		t.Fatal("lr.Next after Reset failed:", err)
	} else if line != table[0] {
		t.Fatal("lr.Next after Reset returned", line, "instead of", table[0])
	}

	// Check that entries match when seeking backward.
	for i := len(posTable) - 1; i >= 0; i-- {
		lr.Seek(posTable[i])
		err := lr.Next(&line)
		if i == len(posTable)-1 {
			if err != io.EOF {
				t.Fatal("expected io.EOF after seek to end, got", err)
			}
		} else if err != nil {
			t.Fatal("lr.Next after seek to", posTable[i], "failed:", err)
		} else if line != table[i] {
			t.Fatal("lr.Next after seek to", posTable[i], "returned", line, "instead of", table[i])
		}
	}

	// Check that seeking to a PC returns the right line.
	if err := lr.SeekPC(table[0].Address-1, &line); err != ErrUnknownPC {
		t.Fatalf("lr.SeekPC to %#x returned %v instead of ErrUnknownPC", table[0].Address-1, err)
	}
	for i, testLine := range table {
		if testLine.EndSequence {
			if err := lr.SeekPC(testLine.Address, &line); err != ErrUnknownPC {
				t.Fatalf("lr.SeekPC to %#x returned %v instead of ErrUnknownPC", testLine.Address, err)
			}
			continue
		}

		nextPC := table[i+1].Address
		for pc := testLine.Address; pc < nextPC; pc++ {
			if err := lr.SeekPC(pc, &line); err != nil {
				t.Fatalf("lr.SeekPC to %#x failed: %v", pc, err)
			} else if line != testLine {
				t.Fatalf("lr.SeekPC to %#x returned %v instead of %v", pc, line, testLine)
			}
		}
	}
}

func testLineTable(t *testing.T, want []LineEntry, d *Data) {
	// Get line table from d.
	var got []LineEntry
	dr := d.Reader()
	for {
		ent, err := dr.Next()
		if err != nil {
			t.Fatal("dr.Next:", err)
		} else if ent == nil {
			break
		}

		if ent.Tag != TagCompileUnit {
			dr.SkipChildren()
			continue
		}

		// Decode CU's line table.
		lr, err := d.LineReader(ent)
		if err != nil {
			t.Fatal("d.LineReader:", err)
		} else if lr == nil {
			continue
		}

		for {
			var line LineEntry
			err := lr.Next(&line)
			if err != nil {
				if err == io.EOF {
					break
				}
				t.Fatal("lr.Next:", err)
			}
			got = append(got, line)
		}
	}

	// Compare line tables.
	if !compareLines(got, want) {
		t.Log("Line tables do not match. Got:")
		dumpLines(t, got)
		t.Log("Want:")
		dumpLines(t, want)
		t.FailNow()
	}
}

func compareLines(a, b []LineEntry) bool {
	if len(a) != len(b) {
		return false
	}

	for i := range a {
		al, bl := a[i], b[i]
		// If both are EndSequence, then the only other valid
		// field is Address. Otherwise, test equality of all
		// fields.
		if al.EndSequence && bl.EndSequence && al.Address == bl.Address {
			continue
		}
		if al.File.Name != bl.File.Name {
			return false
		}
		al.File = nil
		bl.File = nil
		if al != bl {
			return false
		}
	}
	return true
}

func dumpLines(t *testing.T, lines []LineEntry) {
	for _, l := range lines {
		t.Logf("  %+v File:%+v", l, l.File)
	}
}