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cmd/pack: fix export data truncation bug

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The binary export data format includes escaping to prevent "\n$$" from
appearing internally, but not "\n!\n". This could result in a false
positive when cmd/pack searched for "\n!\n" as the delimiter between
package definition and linker object.

To address this, this CL changes cmd/pack to also be aware of the
"\n$$" markers, and to ignore "\n!\n" within the export data.

Fixes #21703.

Change-Id: I71ea8ba49dbd066c7afb7717ddc0190e38fe5649
Reviewed-on: https://go-review.googlesource.com/60773
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
This commit is contained in:
Matthew Dempsky 2017-08-31 11:26:28 -07:00
parent 08347648a6
commit 3d7042fba3
2 changed files with 42 additions and 1 deletions
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12
src/cmd/pack/pack.go
View File

@ -426,8 +426,15 @@ func readPkgdef(file string) (data []byte, err error) {
// Read from file, collecting header for __.PKGDEF.
// The header is from the beginning of the file until a line
// containing just "!". The first line must begin with "go object ".
//
// Note: It's possible for "\n!\n" to appear within the binary
// package export data format. To avoid truncating the package
// definition prematurely (issue 21703), we keep keep track of
// how many "$$" delimiters we've seen.
rbuf := bufio.NewReader(f)
var wbuf bytes.Buffer
markers := 0
for {
line, err := rbuf.ReadBytes('\n')
if err != nil {
@ -436,9 +443,12 @@ func readPkgdef(file string) (data []byte, err error) {
if wbuf.Len() == 0 && !bytes.HasPrefix(line, []byte("go object ")) {
return nil, errors.New("not a Go object file")
}
if bytes.Equal(line, []byte("!\n")) {
if markers%2 == 0 && bytes.Equal(line, []byte("!\n")) {
break
}
if bytes.HasPrefix(line, []byte("$$")) {
markers++
}
wbuf.Write(line)
}
return wbuf.Bytes(), nil

31
src/cmd/pack/pack_test.go
View File

@ -295,6 +295,37 @@ func TestLargeDefs(t *testing.T) {
}
}
// Test that "\n!\n" inside export data doesn't result in a truncated
// package definition when creating a .a archive from a .o Go object.
func TestIssue21703(t *testing.T) {
testenv.MustHaveGoBuild(t)
dir := tmpDir(t)
defer os.RemoveAll(dir)
const aSrc = `package a; const X = "\n!\n"`
err := ioutil.WriteFile(filepath.Join(dir, "a.go"), []byte(aSrc), 0666)
if err != nil {
t.Fatal(err)
}
const bSrc = `package b; import _ "a"`
err = ioutil.WriteFile(filepath.Join(dir, "b.go"), []byte(bSrc), 0666)
if err != nil {
t.Fatal(err)
}
run := func(args ...string) string {
return doRun(t, dir, args...)
}
goBin := testenv.GoToolPath(t)
run(goBin, "build", "cmd/pack") // writes pack binary to dir
run(goBin, "tool", "compile", "a.go")
run("./pack", "c", "a.a", "a.o")
run(goBin, "tool", "compile", "-I", ".", "b.go")
}
// doRun runs a program in a directory and returns the output.
func doRun(t *testing.T, dir string, args ...string) string {
cmd := exec.Command(args[0], args[1:]...)