podman unshare keep exit code

cmd/podman/system/unshare.go

@@ -2,6 +2,7 @@ package system
 
 import (
 	"os"
+	"os/exec"
 
 	"github.com/containers/common/pkg/completion"
 	"github.com/containers/podman/v3/cmd/podman/registry"
@@ -50,5 +51,23 @@ func unshare(cmd *cobra.Command, args []string) error {
 		args = []string{shell}
 	}
 
-	return registry.ContainerEngine().Unshare(registry.Context(), args, unshareOptions)
+	err := registry.ContainerEngine().Unshare(registry.Context(), args, unshareOptions)
+	if err != nil {
+		if exitError, ok := err.(*exec.ExitError); ok {
+			// the user command inside the unshare env has failed
+			// we set the exit code, do not return the error to the user
+			// otherwise "exit status X" will be printed
+			registry.SetExitCode(exitError.ExitCode())
+			return nil
+		}
+		// cmd.Run() can return fs.ErrNotExist, fs.ErrPermission or exec.ErrNotFound
+		// follow podman run/exec standard with the exit codes
+		if errors.Is(err, os.ErrNotExist) || errors.Is(err, exec.ErrNotFound) {
+			registry.SetExitCode(127)
+		} else if errors.Is(err, os.ErrPermission) {
+			registry.SetExitCode(126)
+		}
+		return err
+	}
+	return nil
 }

docs/source/markdown/podman-unshare.1.md

@@ -37,6 +37,35 @@ connect to a rootless container via IP address (CNI networking). This is otherwi
 not possible from the host network namespace.
 _Note: Using this option with more than one unshare session can have unexpected results._
 
+## Exit Codes
+
+The exit code from `podman unshare` gives information about why the container
+failed to run or why it exited.  When `podman unshare` commands exit with a non-zero code,
+the exit codes follow the `chroot` standard, see below:
+
+  **125** The error is with podman **_itself_**
+
+    $ podman unshare --foo; echo $?
+    Error: unknown flag: --foo
+    125
+
+  **126** Executing a _contained command_ and the _command_ cannot be invoked
+
+    $ podman unshare /etc; echo $?
+    Error: fork/exec /etc: permission denied
+    126
+
+  **127** Executing a _contained command_ and the _command_ cannot be found
+
+    $ podman run busybox foo; echo $?
+    Error: fork/exec /usr/bin/bogus: no such file or directory
+    127
+
+  **Exit code** _contained command_ exit code
+
+    $ podman run busybox /bin/sh -c 'exit 3'; echo $?
+    3
+
 ## EXAMPLE
 
 ```

test/e2e/unshare_test.go

@@ -47,8 +47,7 @@ var _ = Describe("Podman unshare", func() {
 		session := podmanTest.Podman([]string{"unshare", "readlink", "/proc/self/ns/user"})
 		session.WaitWithDefaultTimeout()
 		Expect(session).Should(Exit(0))
-		ok, _ := session.GrepString(userNS)
-		Expect(ok).To(BeFalse())
+		Expect(session.OutputToString()).ToNot(ContainSubstring(userNS))
 	})
 
 	It("podman unshare --rootles-cni", func() {
@@ -57,4 +56,36 @@ var _ = Describe("Podman unshare", func() {
 		Expect(session).Should(Exit(0))
 		Expect(session.OutputToString()).To(ContainSubstring("tap0"))
 	})
+
+	It("podman unshare exit codes", func() {
+		session := podmanTest.Podman([]string{"unshare", "false"})
+		session.WaitWithDefaultTimeout()
+		Expect(session).Should(Exit(1))
+		Expect(session.OutputToString()).Should(Equal(""))
+		Expect(session.ErrorToString()).Should(Equal(""))
+
+		session = podmanTest.Podman([]string{"unshare", "/usr/bin/bogus"})
+		session.WaitWithDefaultTimeout()
+		Expect(session).Should(Exit(127))
+		Expect(session.OutputToString()).Should(Equal(""))
+		Expect(session.ErrorToString()).Should(ContainSubstring("no such file or directory"))
+
+		session = podmanTest.Podman([]string{"unshare", "bogus"})
+		session.WaitWithDefaultTimeout()
+		Expect(session).Should(Exit(127))
+		Expect(session.OutputToString()).Should(Equal(""))
+		Expect(session.ErrorToString()).Should(ContainSubstring("executable file not found in $PATH"))
+
+		session = podmanTest.Podman([]string{"unshare", "/usr"})
+		session.WaitWithDefaultTimeout()
+		Expect(session).Should(Exit(126))
+		Expect(session.OutputToString()).Should(Equal(""))
+		Expect(session.ErrorToString()).Should(ContainSubstring("permission denied"))
+
+		session = podmanTest.Podman([]string{"unshare", "--bogus"})
+		session.WaitWithDefaultTimeout()
+		Expect(session).Should(Exit(125))
+		Expect(session.OutputToString()).Should(Equal(""))
+		Expect(session.ErrorToString()).Should(ContainSubstring("unknown flag: --bogus"))
+	})
 })