bin/53553: gpt biosboot forcibly prepends /usr/mdec to any other paht

[eric%cirr.com@localhost]

>Number:         53553
>Category:       bin
>Synopsis:       gpt biosboot forcibly prepends /usr/mdec to any other paht
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    bin-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Sat Aug 25 22:20:00 +0000 2018
>Originator:     eric%cirr.com@localhost
>Release:        NetBSD 8.0_STABLE
>Organization:
Eric Schnoebelen		eric%cirr.com@localhost		http://www.cirr.com
    IBM is really really good at documentation. They may implement
    something so amazingly stupid it makes you slap your forehead,
    but darn if they don't document what they did. -- Kevin P. Neal
>Environment:
System: NetBSD snoopy 8.0_STABLE NetBSD 8.0_STABLE (GENERIC) #3: Thu Aug 16 22:38:01 CDT 2018 eric@bob-the-builder:/work/eric/NetBSD-8/obj/amd64/sys/arch/amd64/compile/GENERIC amd64
Architecture: x86_64
Machine: amd64
>Description:
	Attempting to use a gpt(8) biosboot subcommand with a file
	in any location other than /usr/mdec gets /usr/mdec forcibly
	prepended to the path.
>How-To-Repeat:
	I was attempting to install the -HEAD version of gptmbr.bin
	on a disk, on a system running NetBSD 8.  The file was in
	a subdirectory of my home directory.

	Below is a copy of the sessions:

snoopy-> sudo gpt -v biosboot -A -c usr/mdec/gptmbr.bin -i 1 sd0
/dev/rsd0d: mediasize=3000592982016; sectorsize=512; blocks=5860533168
gpt: /dev/rsd0d: Can't open `/usr/mdec/usr/mdec/gptmbr.bin' (No such
file or directory)
gpt: /dev/rsd0d: Error reading bootcode

snoopy-> sudo gpt -v biosboot -A -c ./usr/mdec/gptmbr.bin -i 1 sd0
/dev/rsd0d: mediasize=3000592982016; sectorsize=512; blocks=5860533168
gpt: /dev/rsd0d: Can't open `/usr/mdec/./usr/mdec/gptmbr.bin' (No such
file or directory)
gpt: /dev/rsd0d: Error reading bootcode

snoopy-> sudo install usr/mdec/gptmbr.bin /usr/mdec/gptmbr-8.99.22.bin

snoopy-> sudo gpt -v biosboot -A -c !$ -i 1 sd0
sudo gpt -v biosboot -A -c /usr/mdec/gptmbr-8.99.22.bin -i 1 sd0
/dev/rsd0d: mediasize=3000592982016; sectorsize=512; blocks=5860533168
/dev/rsd0d: Partition 1 marked as bootable
snoopy-> 

	For giggles and grins, I decided to change to the directory
	where the gptmbr.bin file is located, and it works.

snoopy-> pushd usr/mdec/
~/usr/mdec ~ 

snoopy-> sudo gpt -v biosboot -A -c gptmbr.bin -i 1 sd0
/dev/rsd0d: mediasize=3000592982016; sectorsize=512; blocks=5860533168
/dev/rsd0d: Partition 1 marked as bootable

snoopy-> sudo gpt -v biosboot -A -c ./gptmbr.bin -i 1 sd0
/dev/rsd0d: mediasize=3000592982016; sectorsize=512; blocks=5860533168
/dev/rsd0d: Partition 1 marked as bootable
snoopy-> 

	It seems that gpt is forcibly prepending '/usr/mdec' on
	any path that has a directory seperator in it?  Or any file
	that is not in the current working directory? (I haven't
	examined the code, but I did quickly check to see if the
	code was unchanged between netbsd-8 and HEAD.

>Fix:
	Work-around: move to the same directory as the biosboot image file.

	Fix: Unknown, I haven't examined the code beyond a 'cvs diff'
	between netbsd-8 and -HEAD