feat: pass any additional arguments to targetpid discovery

Author: vjar

README.md

@@ -19,15 +19,16 @@ $ macvtap-mknod-for-unprivileged-netns mytap
 
 ## Configuration
 
-This tool executes `/bin/macvtap-mknod-targetpid-discovery [interface name]` to
-discover which network namespace to access. From under `/proc/PID/ns` the files
-`user` and `net` are used to enter the respective namespaces.
+This tool executes `/bin/macvtap-mknod-targetpid-discovery [...]` to discover
+which network namespace to access. From under `/proc/PID/ns` the files `user`
+and `net` are used to enter the respective namespaces.
 
 `make install` creates this path as a symbolic link, which points to a script
 for rootless Podman. This can be replaced to support differently initialised
 network namespaces.
 
-The ifname argument is not used, but it may be used in custom implementations.
+None of the arguments are used for target PID discovery, but all arguments are
+passed and may be used in custom implementations.
 
 
 ## Security considerations

src/main.c

@@ -296,8 +296,8 @@ bool dev_valid_name(const char *name) {
 }
 
 int32_t main(int32_t argc, char *argv[]) {
-	if (argc != 2) {
-		fprintf(stderr, "usage: %s [interface name]\n", argv[0]);
+	if (argc < 2) {
+		fprintf(stderr, "usage: %s [interface name] [additional arguments to pass to targetpid discovery]\n", argv[0]);
 		return 1;
 	}