From 93448fea67d371989492be8f5be1adf049365991 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Fr=C3=A9d=C3=A9ric=20Mangano?= <fmang@mg0.fr>
Date: Tue, 1 Jan 2013 21:33:46 +0100
Subject: [PATCH] refuse to read and write to the same file

---
 opustags.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/opustags.c b/opustags.c
index f6fc851..a5f9bde 100644
--- a/opustags.c
+++ b/opustags.c
@@ -1,5 +1,6 @@
 #include <errno.h>
 #include <getopt.h>
+#include <limits.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
@@ -247,6 +248,15 @@ int main(int argc, char **argv){
         return EXIT_FAILURE;
     }
     path_in = argv[optind];
+    if(path_out != NULL && strcmp(path_in, "-") != 0){
+        char canon_in[PATH_MAX+1], canon_out[PATH_MAX+1];
+        if(realpath(path_in, canon_in) && realpath(path_out, canon_out)){
+            if(strcmp(canon_in, canon_out) == 0){
+                fputs("error: the input and output files are the same\n", stderr);
+                return EXIT_FAILURE;
+            }
+        }
+    }
     FILE *out = NULL;
     if(path_out != NULL){
         if(strcmp(path_out, "-") == 0)