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cmd/pack: treat compiler's -linkobj output as "compiler object"

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Treat the compiler's -linkobj output as "compiler object, which
means "pack c" will "see through" the file and add individual
entry to the new archive, instead of the object as a whole.

This is somewhat peculiar. But Go 1.15's cmd/pack does this,
although seemingly accidental. We just do the same. FWIW, it
does make things more consistent with/without -linkobj flag.

Fixes #43271.

Change-Id: I6b2d99256db7ebf0fa430f85afa7464e334f6bcb
Reviewed-on: https://go-review.googlesource.com/c/go/+/279483
Trust: Cherry Zhang <cherryyz@google.com>
Run-TryBot: Cherry Zhang <cherryyz@google.com>
Reviewed-by: Jeremy Faller <jeremy@golang.org>
Reviewed-by: Than McIntosh <thanm@google.com>
This commit is contained in:
Cherry Zhang 2020-12-21 14:11:02 -05:00
parent bc7e4d9257
commit 9b6147120a
2 changed files with 84 additions and 13 deletions
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31
src/cmd/pack/pack.go
View file

@ -315,20 +315,25 @@ func (ar *Archive) extractContents1(e *archive.Entry, out io.Writer) {
}
// isGoCompilerObjFile reports whether file is an object file created
// by the Go compiler, which is an archive file with exactly two entries:
// __.PKGDEF and _go_.o.
// by the Go compiler, which is an archive file with exactly one entry
// of __.PKGDEF, or _go_.o, or both entries.
func isGoCompilerObjFile(a *archive.Archive) bool {
if len(a.Entries) != 2 {
switch len(a.Entries) {
case 1:
return (a.Entries[0].Type == archive.EntryGoObj && a.Entries[0].Name == "_go_.o") ||
(a.Entries[0].Type == archive.EntryPkgDef && a.Entries[0].Name == "__.PKGDEF")
case 2:
var foundPkgDef, foundGo bool
for _, e := range a.Entries {
if e.Type == archive.EntryPkgDef && e.Name == "__.PKGDEF" {
foundPkgDef = true
}
if e.Type == archive.EntryGoObj && e.Name == "_go_.o" {
foundGo = true
}
}
return foundPkgDef && foundGo
default:
return false
}
var foundPkgDef, foundGo bool
for _, e := range a.Entries {
if e.Type == archive.EntryPkgDef && e.Name == "__.PKGDEF" {
foundPkgDef = true
}
if e.Type == archive.EntryGoObj && e.Name == "_go_.o" {
foundGo = true
}
}
return foundPkgDef && foundGo
}

66
src/cmd/pack/pack_test.go
View file

@ -302,6 +302,72 @@ func TestIssue21703(t *testing.T) {
run(goBin, "tool", "compile", "-I", ".", "b.go")
}
// Test the "c" command can "see through" the archive generated by the compiler.
// This is peculiar. (See issue )
func TestCreateWithCompilerObj(t *testing.T) {
testenv.MustHaveGoBuild(t)
dir := tmpDir(t)
defer os.RemoveAll(dir)
src := filepath.Join(dir, "p.go")
prog := "package p; var X = 42\n"
err := os.WriteFile(src, []byte(prog), 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", "-pack", "-o", "p.a", "p.go")
run("./pack", "c", "packed.a", "p.a")
fi, err := os.Stat(filepath.Join(dir, "p.a"))
if err != nil {
t.Fatalf("stat p.a failed: %v", err)
}
fi2, err := os.Stat(filepath.Join(dir, "packed.a"))
if err != nil {
t.Fatalf("stat packed.a failed: %v", err)
}
// For compiler-generated object file, the "c" command is
// expected to get (essentially) the same file back, instead
// of packing it into a new archive with a single entry.
if want, got := fi.Size(), fi2.Size(); want != got {
t.Errorf("packed file with different size: want %d, got %d", want, got)
}
// Test -linkobj flag as well.
run(goBin, "tool", "compile", "-linkobj", "p2.a", "-o", "p.x", "p.go")
run("./pack", "c", "packed2.a", "p2.a")
fi, err = os.Stat(filepath.Join(dir, "p2.a"))
if err != nil {
t.Fatalf("stat p2.a failed: %v", err)
}
fi2, err = os.Stat(filepath.Join(dir, "packed2.a"))
if err != nil {
t.Fatalf("stat packed2.a failed: %v", err)
}
if want, got := fi.Size(), fi2.Size(); want != got {
t.Errorf("packed file with different size: want %d, got %d", want, got)
}
run("./pack", "c", "packed3.a", "p.x")
fi, err = os.Stat(filepath.Join(dir, "p.x"))
if err != nil {
t.Fatalf("stat p.x failed: %v", err)
}
fi2, err = os.Stat(filepath.Join(dir, "packed3.a"))
if err != nil {
t.Fatalf("stat packed3.a failed: %v", err)
}
if want, got := fi.Size(), fi2.Size(); want != got {
t.Errorf("packed file with different size: want %d, got %d", want, got)
}
}
// 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:]...)