From 5994466353ecbd4e6fac738aa956b2cbd9f6308b Mon Sep 17 00:00:00 2001
From: Jo-Philipp Wich <jo@mein.io>
Date: Mon, 13 Jun 2022 15:23:23 +0200
Subject: [PATCH] fw4: simplify `is_loopback_dev()`

Use `fs.readfile()` to simplify the code reading flag values from sysfs.

Also add a mock implementation of `fs.readfile()` using the same mock
data files as `fs.open()`.

Signed-off-by: Jo-Philipp Wich <jo@mein.io>
---
 root/usr/share/ucode/fw4.uc       | 11 +----------
 tests/01_configuration/01_ruleset |  4 ++--
 tests/lib/mocklib/fs.uc           | 16 ++++++++++++++++
 3 files changed, 19 insertions(+), 12 deletions(-)

diff --git a/root/usr/share/ucode/fw4.uc b/root/usr/share/ucode/fw4.uc
index d600528..db1e580 100644
--- a/root/usr/share/ucode/fw4.uc
+++ b/root/usr/share/ucode/fw4.uc
@@ -1651,16 +1651,7 @@ return {
 	},
 
 	is_loopback_dev: function(dev) {
-		let fd = fs.open(`/sys/class/net/${dev}/flags`, "r");
-
-		if (!fd)
-			return false;
-
-		let flags = +fd.read("line");
-
-		fd.close();
-
-		return !!(flags & 0x8);
+		return !!(+fs.readfile(`/sys/class/net/${dev}/flags`) & 0x8);
 	},
 
 	is_loopback_addr: function(addr) {
diff --git a/tests/01_configuration/01_ruleset b/tests/01_configuration/01_ruleset
index dd9750c..1bf8f72 100644
--- a/tests/01_configuration/01_ruleset
+++ b/tests/01_configuration/01_ruleset
@@ -316,6 +316,6 @@ table inet fw4 {
 		}
 	' 2>/dev/null> timeout <null>
 [call] fs.popen cmdline </usr/sbin/nft --terse --json list flowtables inet> mode <r>
-[call] fs.open path </sys/class/net/br-lan/flags> mode <r>
-[call] fs.open path </sys/class/net/br-lan/flags> mode <r>
+[call] fs.readfile path </sys/class/net/br-lan/flags> limit <null>
+[call] fs.readfile path </sys/class/net/br-lan/flags> limit <null>
 -- End --
diff --git a/tests/lib/mocklib/fs.uc b/tests/lib/mocklib/fs.uc
index 3cb6252..10f3074 100644
--- a/tests/lib/mocklib/fs.uc
+++ b/tests/lib/mocklib/fs.uc
@@ -135,6 +135,22 @@ return {
 		};
 	},
 
+	readfile: (fpath, limit) => {
+		let path = sprintf("fs/open~%s.txt", replace(fpath, /[^A-Za-z0-9_-]+/g, '_')),
+		    mock = mocklib.read_data_file(path);
+
+		if (!mock) {
+			mocklib.I("No stdout fixture defined for fs.readfile() path %s.", fpath);
+			mocklib.I("Provide a mock output through the following text file:\n%s\n", path);
+
+			return null;
+		}
+
+		mocklib.trace_call("fs", "readfile", { path: fpath, limit });
+
+		return limit ? substr(mock, 0, limit) : mock;
+	},
+
 	opendir: (path) => {
 		let file = sprintf("fs/opendir~%s.json", replace(path, /[^A-Za-z0-9_-]+/g, '_')),
 		    mock = mocklib.read_json_file(file),
-- 
2.30.2