Bug#587377: debian-policy: Decide on arbitrary file/path names limit

[Jonathan Nieder <jrnieder@gmail.com>]

user debian-policy@packages.debian.org
usertags 587377 + normative issue
quit

Guillem Jover wrote:

> This is not really a dpkg bug, the limitation is not actually coming
> from it, it's coming from the kernel and/or specific file system
> implementation. I don't consider it appropriate to add an arbitrary
> limit in dpkg itself, when it can handle long file/path names just
> fine.
>
> Given that this might cause problems depending on the different support
> from the build and host machines this should be considered a matter of
> policy, and as such “enforced” by lintian or ftp-master for example, if
> at all. I'm thus reassigning it to debian-policy, so that an arbitrary
> limit can be decided if desired.

This is a hard one.  I agree that dpkg shouldn't enforce this (though
perhaps it could recover better).

 * _POSIX_PATH_MAX is 256.  _POSIX_NAME_MAX is 14 (yikes).
 * _XOPEN_PATH_MAX is 1024.  _XOPEN_NAME_MAX is 255.
 * Linux PATH_MAX is 4096.
 * NTFS's maximum path length is 32768.
 * naive file access in Windows has a maximum path length of 260.
 * the maximum path length on this laptop[1] is 170:

	[...]/src/gcc/[...]/ \
	MBeanServerPermission$ \
	MBeanServerPermissionCollection$ \
	MBeanServerPermissionEnumeration.class

To throw out a strawman, I suppose 256 characters should be a reasonable
maximum for paths in Debian packages.

I'd be happier with data from the lintian lab to support that.  Any
takers?

Thanks.
Jonathan

[1]
	find / |
	awk '
		BEGIN {
			maxstr = "";
			maxlength = 0
		}
		length($0) > maxlength {
			maxlength = length($0);
			maxstr = $0;
			print maxlength;
			print maxstr;
		}
	'