prefixdevname/SOURCES/0004-core-if-interface-already-has-name-in-expected-forma.patch

From 7f395e0bdb529f2ea6fe2234956e04869a3464e6 Mon Sep 17 00:00:00 2001
From: Michal Sekletar <msekleta@redhat.com>
Date: Fri, 2 Nov 2018 12:10:12 +0000
Subject: [PATCH] core: if interface already has name in expected format (i.e.
 <prefix><number>) print the name to stdout

This is needed in order to prevent renaming back to name given by one of
built-in naming schemes.

For example, NIC appears in initrd (during system installation) and gets
renamed to net0. Later we switch root to anaconda's stage2 and all HW is
cold-plugged. Prefixdevname should figure out that renaming is not
necessary. However, if we don't print anything to stdout (i.e. nothing
gets assigned to NAME= variable) then logic in subsequent rules
eventually renames interface to some other name determined by net_id.
---
 src/main.rs |  6 ++++--
 src/util.rs | 20 ++++++++++----------
 2 files changed, 14 insertions(+), 12 deletions(-)

diff --git a/src/main.rs b/src/main.rs
index 5c1a42b..b0c02b8 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -37,8 +37,10 @@ fn main() {
         exit_maybe_unlock(None, 0);
     }
 
-    if ! rename_needed(&prefix).unwrap() {
-        info!("Interface name already has expected format, not renaming again");
+    let ifname = event_device_name();
+
+    if ! rename_needed(&ifname, &prefix).unwrap() {
+        println!("{}", ifname);
         exit_maybe_unlock(None, 0);
     }
 
diff --git a/src/util.rs b/src/util.rs
index 8727074..98eb32f 100644
--- a/src/util.rs
+++ b/src/util.rs
@@ -11,14 +11,18 @@ use regex::Regex;
 
 use sema::*;
 
-pub fn rename_needed(prefix: &str) -> Result<bool, Box<Error>> {
-    // TODO: if INTERFACE is unset we should probably check sysname
-    let ifname = env::var("INTERFACE").unwrap_or("".to_string());
+pub fn rename_needed(ifname: &str, prefix: &str) -> Result<bool, Box<Error>> {
     let re: Regex = Regex::new(&format!("{}\\d+", prefix)).unwrap();
 
     Ok(!re.is_match(&ifname))
 }
 
+pub fn event_device_name() -> String {
+    let ifname = env::var("INTERFACE").unwrap_or("".to_string());
+
+    ifname.to_string()
+}
+
 pub fn hwaddr_valid<T: ToString>(hwaddr: &T) -> bool {
     use std::num::ParseIntError;
 
@@ -172,20 +176,16 @@ mod tests {
 
     #[test]
     fn rename_is_needed() {
-        env::set_var("INTERFACE", "eth0");
-
-        assert_eq!(rename_needed("net").unwrap(), true);
+        assert_eq!(rename_needed("eth0", "net").unwrap(), true);
     }
 
     #[test]
     fn rename_not_needed() {
-        env::set_var("INTERFACE", "net0");
-
-        assert_eq!(rename_needed("net").unwrap(), false);
+        assert_eq!(rename_needed("net0", "net").unwrap(), false);
     }
 
     #[test]
     fn rename_needed_interface_unset() {
-        assert_eq!(rename_needed("net").unwrap(), true);
+        assert_eq!(rename_needed("", "net").unwrap(), true);
     }
 }
-- 
2.17.2