Linked VHDs in subfolders doesn't work

[MrMEEE]

Describe the bug

When trying to mount a linked VHD, located in a relativ path (subfolder), mounting fails..

Steps to reproduce the behaviour

Prior to testing this, #5143 must be applied to get linked VHDs to work on Linux

1. Create a subfolder outside of Dosbox (mkdir test)
2. Create a VHD in current dir or a subfolder (imgmake test.vhd -t vhd -size 100)
3. Create a VHD in the subfolder which is linked (vhdmake -l test.vhd test/subfolder_test.vhd)
4. Try to mount the VHD (imgmount test/subfolder_test.vhd)

Expected behavior

VHD will be mounted

What operating system(s) this bug have occurred on?

Ubuntu 24.04

What version(s) of DOSBox-X have this bug?

2024.07.01

Used configuration

No response

Output log

See screenshot

Additional information

No response

Have you checked that no similar bug report(s) exist?

• I have searched and didn't find any similar bug report.

Code of Conduct & Contributing Guidelines

• I agree to follow the code of conduct and the contributing guidelines.

[MrMEEE]

[MrMEEE]

dosbox-x/src/ints/bios_vhd.cpp

Lines 762 to 769 in 33f9033

	//write Parent Locator sectors
	wchar_t* w_basename = (wchar_t*)malloc(platsize);
	memset(w_basename, 0, platsize);
	for(uint32_t i = 0; i < l_basename; i++)
	//dirty hack to quickly convert ASCII -> UTF-16 *LE* and fix slashes
	w_basename[i] = SDL_SwapLE16(basename[i]=='/'? (uint16_t)'\\' : (uint16_t)basename[i]);
	if (fwrite(w_basename, 1, platsize, vhd) != platsize) STATUS = ERROR_WRITING;
	if (fwrite(w_basename, 1, platsize, vhd) != platsize) STATUS = ERROR_WRITING;

I guess that something here might be the issue..

[MrMEEE]

hmmm.. apparently the path for the base is written correctly to the files, but when trying to mount the file, the path of the linked image is prepended to the path of the baseimage??

So if:
Linked image: test/test_linked.vhd
Base image: test4/base.vhd

Then dosbox will try to use /test/test4/base.vhd as the base image?

This is really weird..