cmd/pack: r command create output file if not exist

Go 1.15 pack's r command creates the output file if it does not
exist. The system "ar" command does this as well. Do the same.

For bazelbuild/rules_go#2762.

Change-Id: Icd88396b5c714b735c859a29ab29851e4301f4d2
Reviewed-on: https://go-review.googlesource.com/c/go/+/279516
Trust: Cherry Zhang <cherryyz@google.com>
Run-TryBot: Cherry Zhang <cherryyz@google.com>
Reviewed-by: Than McIntosh <thanm@google.com>
TryBot-Result: Go Bot <gobot@golang.org>

diff --git a/src/cmd/pack/pack.go b/src/cmd/pack/pack.go
index 3dffabe5ec81fd9c7376b73bc21eca674fdac1a7..412ea36d60fa905ffbe3987d301640b5d21f666a 100644 (file)
--- a/src/cmd/pack/pack.go
+++ b/src/cmd/pack/pack.go
@@ -43,7 +43,7 @@ func main() {
                ar = openArchive(os.Args[2], os.O_RDONLY, os.Args[3:])
                ar.scan(ar.printContents)
        case 'r':
-               ar = openArchive(os.Args[2], os.O_RDWR, os.Args[3:])
+               ar = openArchive(os.Args[2], os.O_RDWR|os.O_CREATE, os.Args[3:])
                ar.addFiles()
        case 'c':
                ar = openArchive(os.Args[2], os.O_RDWR|os.O_TRUNC|os.O_CREATE, os.Args[3:])
@@ -124,10 +124,13 @@ func openArchive(name string, mode int, files []string) *Archive {
                log.Fatal(err)
        }
        var a *archive.Archive
-       if mode&os.O_CREATE != 0 { // the c command
+       if mode&os.O_TRUNC != 0 { // the c command
                a, err = archive.New(f)
        } else {
                a, err = archive.Parse(f, verbose)
+               if err != nil && mode&os.O_CREATE != 0 { // the r command
+                       a, err = archive.New(f)
+               }
        }
        if err != nil {
                log.Fatal(err)

diff --git a/src/cmd/pack/pack_test.go b/src/cmd/pack/pack_test.go
index 16a51358009f685b7ac3574c1d0a462379e5456d..118376f9df6b88337a0362a29282dc51fbe3961c 100644 (file)
--- a/src/cmd/pack/pack_test.go
+++ b/src/cmd/pack/pack_test.go
@@ -303,7 +303,7 @@ func TestIssue21703(t *testing.T) {
 }
 
 // Test the "c" command can "see through" the archive generated by the compiler.
-// This is peculiar. (See issue )
+// This is peculiar. (See issue #43271)
 func TestCreateWithCompilerObj(t *testing.T) {
        testenv.MustHaveGoBuild(t)
 
@@ -368,6 +368,29 @@ func TestCreateWithCompilerObj(t *testing.T) {
        }
 }
 
+// Test the "r" command creates the output file if it does not exist.
+func TestRWithNonexistentFile(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", "-o", "p.o", "p.go")
+       run("./pack", "r", "p.a", "p.o") // should succeed
+}
+
 // 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:]...)