From 7e21bc648346d494785e35f26d9416698a566125 Mon Sep 17 00:00:00 2001
From: Colin Walters <walters@verbum.org>
Date: Thu, 6 Jul 2023 05:15:25 -0400
Subject: [PATCH] container: Add an API to serialize `Transport`

This will fix the need demonstrated by
https://github.com/containers/bootc/pull/106/files#diff-c163debeb7fdf9b238e5c589e0000c80684ca9a09abd408242df4bad489626a6R38

We made a historical mistake here in having our `Display` include
the `:`...but it's hard to deal with because inherently the format
is messy because of the `://` in `docker://`.
---
 lib/src/container/mod.rs | 37 +++++++++++++++++++++++++++++++++----
 1 file changed, 33 insertions(+), 4 deletions(-)

diff --git a/lib/src/container/mod.rs b/lib/src/container/mod.rs
index 239d7529..a0d4491e 100644
--- a/lib/src/container/mod.rs
+++ b/lib/src/container/mod.rs
@@ -100,15 +100,32 @@ impl TryFrom<&str> for Transport {
 
     fn try_from(value: &str) -> Result<Self> {
         Ok(match value {
-            "registry" | "docker" => Self::Registry,
-            "oci" => Self::OciDir,
-            "oci-archive" => Self::OciArchive,
-            "containers-storage" => Self::ContainerStorage,
+            Self::REGISTRY_STR | "docker" => Self::Registry,
+            Self::OCI_STR => Self::OciDir,
+            Self::OCI_ARCHIVE_STR => Self::OciArchive,
+            Self::CONTAINERS_STORAGE_STR => Self::ContainerStorage,
             o => return Err(anyhow!("Unknown transport '{}'", o)),
         })
     }
 }
 
+impl Transport {
+    const OCI_STR: &str = "oci";
+    const OCI_ARCHIVE_STR: &str = "oci-archive";
+    const CONTAINERS_STORAGE_STR: &str = "containers-storage";
+    const REGISTRY_STR: &str = "registry";
+
+    /// Retrieve an identifier that can then be re-parsed from [`Transport::try_from::<&str>`].
+    pub fn serializable_name(&self) -> &'static str {
+        match self {
+            Transport::Registry => Self::REGISTRY_STR,
+            Transport::OciDir => Self::OCI_STR,
+            Transport::OciArchive => Self::OCI_ARCHIVE_STR,
+            Transport::ContainerStorage => Self::CONTAINERS_STORAGE_STR,
+        }
+    }
+}
+
 impl TryFrom<&str> for ImageReference {
     type Error = anyhow::Error;
 
@@ -428,6 +445,18 @@ mod tests {
 
     use super::*;
 
+    #[test]
+    fn test_serializable_transport() {
+        for v in [
+            Transport::Registry,
+            Transport::ContainerStorage,
+            Transport::OciArchive,
+            Transport::OciDir,
+        ] {
+            assert_eq!(Transport::try_from(v.serializable_name()).unwrap(), v);
+        }
+    }
+
     const INVALID_IRS: &[&str] = &["", "foo://", "docker:blah", "registry:", "foo:bar"];
     const VALID_IRS: &[&str] = &[
         "containers-storage:localhost/someimage",