More cleanup: volumes: do not export to stdout

This one got complicated, and deserves its own commit.

Problem: ginkgo logs have a lot of NUL characters, making them
difficult for logformatter to process and for humans to read.

Cause: Paul tracked it down to "podman volume export" without "-o"
(hence spitting out tar data to stdout).

Solution: add "-o tmpfile" to named podman-volume-export. In
the process, fix all sorts of other problems with that test.
And, since the e2e test no longer tests "volume export" by
itself, add a system test that does.

It is possible that there are other places that emit NULs.
One step at a time.

Signed-off-by: Ed Santiago <santiago@redhat.com>

test/e2e/volume_create_test.go

@@ -85,18 +85,30 @@ var _ = Describe("Podman volume create", func() {
 			Skip("Volume export check does not work with a remote client")
 		}
 
-		session := podmanTest.Podman([]string{"volume", "create", "myvol"})
+		volName := "my_vol_" + RandomString(10)
+		session := podmanTest.Podman([]string{"volume", "create", volName})
 		session.WaitWithDefaultTimeout()
-		volName := session.OutputToString()
 		Expect(session).Should(Exit(0))
+		Expect(session.OutputToString()).To(Equal(volName))
 
-		session = podmanTest.Podman([]string{"run", "--volume", volName + ":/data", ALPINE, "sh", "-c", "echo hello >> " + "/data/test"})
+		helloString := "hello-" + RandomString(20)
+		session = podmanTest.Podman([]string{"run", "--volume", volName + ":/data", ALPINE, "sh", "-c", "echo " + helloString + " >> /data/test"})
 		session.WaitWithDefaultTimeout()
 		Expect(session).Should(Exit(0))
 
-		check := podmanTest.Podman([]string{"volume", "export", volName})
+		// export to tar file...
+		helloTar := filepath.Join(podmanTest.TempDir, "hello.tar")
+		check := podmanTest.Podman([]string{"volume", "export", "-o", helloTar, volName})
 		check.WaitWithDefaultTimeout()
-		Expect(check.OutputToString()).To(ContainSubstring("hello"))
+		Expect(check).Should(Exit(0))
+
+		// ...then confirm that tar file has our desired content.
+		// These flags emit filename to stderr (-v), contents to stdout
+		tar := SystemExec("tar", []string{"-x", "-v", "--to-stdout", "-f", helloTar})
+		tar.WaitWithDefaultTimeout()
+		Expect(tar).To(Exit(0))
+		Expect(tar.ErrorToString()).To(Equal("test"))
+		Expect(tar.OutputToString()).To(Equal(helloString))
 	})
 
 	It("podman create and import volume", func() {
@@ -104,12 +116,13 @@ var _ = Describe("Podman volume create", func() {
 			Skip("Volume export check does not work with a remote client")
 		}
 
-		session := podmanTest.Podman([]string{"volume", "create", "my_vol"})
+		volName := "my_vol_" + RandomString(10)
+		session := podmanTest.Podman([]string{"volume", "create", volName})
 		session.WaitWithDefaultTimeout()
-		volName := session.OutputToString()
 		Expect(session).Should(Exit(0))
+		Expect(session.OutputToString()).To(Equal(volName))
 
-		session = podmanTest.Podman([]string{"run", "--volume", volName + ":/data", ALPINE, "sh", "-c", "echo hello >> " + "/data/test"})
+		session = podmanTest.Podman([]string{"run", "--volume", volName + ":/data", ALPINE, "sh", "-c", "echo hello >> /data/test"})
 		session.WaitWithDefaultTimeout()
 		Expect(session).Should(Exit(0))
 

test/system/160-volumes.bats

@@ -258,6 +258,34 @@ EOF
     run_podman volume rm my_vol2
 }
 
+# stdout with NULs is easier to test here than in ginkgo
+@test "podman volume export to stdout" {
+    skip_if_remote "N/A on podman-remote"
+
+    local volname="myvol_$(random_string 10)"
+    local mountpoint="/data$(random_string 8)"
+
+    run_podman volume create $volname
+    assert "$output" == "$volname" "volume create emits the name it was given"
+
+    local content="mycontent-$(random_string 20)-the-end"
+    run_podman run --rm --volume "$volname:$mountpoint" $IMAGE \
+               sh -c "echo $content >$mountpoint/testfile"
+    assert "$output" = ""
+
+    # We can't use run_podman because bash can't handle NUL characters.
+    # Can't even store them in variables, so we need immediate redirection
+    # The "-v" is only for debugging: tar will emit the filename to stderr.
+    # If this test ever fails, that may give a clue.
+    echo "$_LOG_PROMPT $PODMAN volume export $volname | tar -x ..."
+    tar_output="$($PODMAN volume export $volname | tar -x -v --to-stdout)"
+    echo "$tar_output"
+    assert "$tar_output" == "$content" "extracted content"
+
+    # Clean up
+    run_podman volume rm $volname
+}
+
 # Podman volume user test
 @test "podman volume user test" {
     is_rootless || skip "only meaningful when run rootless"