From 31a0d99de63c3290ca05c94e20b5870f81db11f2 Mon Sep 17 00:00:00 2001
From: maxpat78 <maxpat78@yahoo.it>
Date: Mon, 5 Aug 2024 11:10:09 +0200
Subject: [PATCH] Update bios_vhd.cpp

fixes a couple corner cases, where files are in different disks or in the same directory
---
 src/ints/bios_vhd.cpp | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/src/ints/bios_vhd.cpp b/src/ints/bios_vhd.cpp
index 0a29792ec9..6eeca0b318 100644
--- a/src/ints/bios_vhd.cpp
+++ b/src/ints/bios_vhd.cpp
@@ -49,7 +49,7 @@
 *
 */
 
-// returns the path of "base" in a form relative to "child", where both exist
+// returns the path of "base" in a form relative to "child"
 char* calc_relative_path(const char* base, const char* child) {
 #ifndef WIN32
     char abs_base[PATH_MAX];
@@ -76,6 +76,8 @@ char* calc_relative_path(const char* base, const char* child) {
     // strips common subpath, if any
     while(*p++ == *q++);
     p--, q--;
+    // returns base if they don't share anything
+    if(!strcmp(p, abs_base)) return strdup(base);
     x = q;
     // count slashes
     while(*x) {
@@ -83,8 +85,12 @@ char* calc_relative_path(const char* base, const char* child) {
         x++;
     }
     // allocates space for the resulting string
-    y = (char*)malloc(strlen(q) + n * 3); // n * strlen("..\\")
+    y = (char*)malloc(strlen(q) + n * 3 + 2); // n * strlen("..\\")
     z = y;
+    if(!n) {
+        strcpy(z, ".\\");
+        z += 2;
+    }
     while(n--) {
         strcpy(z, "..\\");
         z += 3;