[syslinux] Adding image file support for Windows

[Phil Garcia]

> -----Original Message-----
> From: Shao Miller [mailto:sha0.miller at gmail.com]
> Sent: Saturday, March 12, 2016 10:39 AM
> To: Phil Garcia <phil at thinkedge.com>
> Subject: Re: [syslinux] Adding image file support for Windows
> 
> On 3/12/2016 13:16, Phil Garcia wrote:
> > On 3/12/2016 12:21, Shao Miller wrote:
> >
> >> On 3/11/2016 22:32, Phil Garcia via Syslinux wrote:
> >>> I would like to request that SYSLINUX be extended to install on a
> >>> filesystem image file on the Windows platform. This feature is
> >>> available on Linux (option -t); however, on Windows SYSLINUX only
> >>> installs with a raw device path.
> >>>
> >>> This feature would be use by another open source project. As an
> >>> small incentive, I'll offer a small, token bounty ($50) for the
> >>> developer that implements and successfully merges the code into the
> >>> SYSLINUX source code repository.
> >>
> >> Which filesystem(s) and which Windows version(s)?
> >>
> >> For NTFS, there is a significant challenge: Windows' NTFS driver is
> >> the only reliable driver for writing new files to a Windows-formatted
> >> NTFS filesystem.  That driver happens to require a disk, as opposed
> >> to an image-file.
> >>
> >> Depending on your Windows version, drivers such as WinVBlock,
> >> Firadisk, ImDisk might be options for you.  Newer Windows versions
> >> support certain image-file formats as virtual disks, as well.
> >>
> >> - Shao Miller
> > Hi Shao -
> >
> > SYSLINUX would only need to find the ldlinux.sys file within an
> > existing virtual disk image with a FAT filesystem and patch it
> > appropriately. On Linux, it can already do this. Thus no NTFS
> > required, no special drivers, and no administrator privileges.
> >
> > I wrote a tool that does this for Syslinux v3.72, but by v6.03 the
> > data structures changed significantly. Rather than re-invest in
> > updating the tool, it would be better to add this feature upstream into
> SYSLINUX.
> 
> Although I personally prefer "top-posting," you are bound to be scolded by
> at least one individual if you continue to do so.  I find that scolding
sufficiently
> irritating to go out of my way to painstakingly re-arrange every single
post to
> this mailing-list, despite setting my e-mail program's regular behaviour
to my
> preference.  I hope it's appreciated.
> 
> In your first message, you'd mentioned "to install", but now you've
explained
> that the image-file will have an "existing" ldlinux.sys.  I don't quite
follow how
> these two are consistent. Would it be worth-while detailing the scenario
in a
> little more detail, in case of other discrepancies?  Have I misunderstood?
> 
> - Shao Miller

I'm apologize if I was not clear.  Let me restart with the use case:

I have a raw disk image file which already has a master boot record (MBR)
created, fat filesystem as the first partition, and the associated SYSLINUX
files (ldlinux.sys, mboot.c32, syslinux.cfg) on the filesystem. The MBR code
and fat boot code (ldlinux.bin) are already been written to the disk image
as well. However, this is not sufficient to actually boot an operating
system. The ldlinux.sys file and fat boot sector still need to be patched.
This is what the the syslinux_patch() function in syslxmod.c does. 

In the end, I would to execute "syslinux.exe --install disk.img" on Windows.