From af95c08df61287f4835efd2a92bf0edcd7667198 Mon Sep 17 00:00:00 2001
From: Yasumasa Suenaga <yasuenag@gmail.com>
Date: Tue, 15 Oct 2024 17:31:42 +0900
Subject: [PATCH] Resolve TTY path before opening

---
 tty-resizer/tty-resizer.c | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/tty-resizer/tty-resizer.c b/tty-resizer/tty-resizer.c
index 3a3a4fe..84b4d15 100644
--- a/tty-resizer/tty-resizer.c
+++ b/tty-resizer/tty-resizer.c
@@ -19,7 +19,9 @@
 #include <sys/ioctl.h>
 #include <sys/stat.h>
 #include <stdio.h>
+#include <limits.h>
 #include <stdlib.h>
+#include <string.h>
 #include <fcntl.h>
 #include <unistd.h>
 #include <bpf/libbpf.h>
@@ -27,7 +29,7 @@
 #include "common.h"
 
 
-static const char *ttypath;
+static char ttypath[PATH_MAX];
 static ino_t tty_ino;
 static struct tty_resizer_bpf *skel = NULL;
 static struct ring_buffer *rb = NULL;
@@ -119,16 +121,21 @@ static int setup_bpf(){
 int main(int argc, char *argv[]){
   if((argc == 3) && (strcmp(argv[1], "-v") == 0)){
     libbpf_set_print(libbpf_print);
-    ttypath = argv[2];
+    realpath(argv[2], ttypath);
   }
   else if(argc == 2){
-    ttypath = argv[1];
+    realpath(argv[1], ttypath);
   }
   else{
     printf("Usage: %s <-v> [TTY device file]\n", argv[0]);
     return -100;
   }
 
+  if(strncmp(ttypath, "/dev/tty", 8) != 0){
+    fprintf(stderr, "Not a valid TTY device: %s\n", ttypath);
+    return -150;
+  }
+
   if((setup_tty() == 0) && (setup_bpf() == 0)){
     while(true){
       int ret = ring_buffer__poll(rb, -1);