TeX Live: mptopdf is broken

[williamyaoh]

Issue description

The mptopdf executable installed as part of texlive.combined.scheme-basic errors out no matter
what arguments it's called with, with an error:

/nix/store/.../bin/bash -S: invalid option

Steps to reproduce

1. Install the basic TeX Live setup
   nix-env -f '<nixpkgs>' -iA texlive.combined.scheme-basic
2. Run mptopdf

Notes

The problem seems to come from these lines at the very beginning of the mptopdf.pl Perl script that
the TeX Live derivation wraps around:

eval '(exit $?0)' && eval 'exec perl -S $0 ${1+"$@"}' && eval 'exec perl -S $0 $argv:q'
        if 0;

It's using exec and $0 to do what a shebang does instead of... just using a shebang.
The Perl call is expecting $0 to point directly to the mptopdf.pl script, but the Nix wrapper
script is setting $0 to whatever command it was called with; in this case, the raw string "mptopdf".

Placing these lines in a separate executable file (let's say mptopdf.sh) and simulating
what the wrapper script does, reproduces the error message:

$ bash -c 'exec -a mptopdf ./mptopdf.sh
/nix/store/.../bin/bash -S: invalid option

After replacing the instance of perl in the first exec call with an absolute store path,
and $0 with the store path to mptopdf.pl, the command above then works and calls mptopdf
as intended.

The TeX Live distribution installed on my Ubuntu setup looks like it just replaced those first
two lines in mptopdf.pl with #! /usr/bin/perl -w. So it seems like the easiest way would be either
to patch mptopdf.pl to use a shebang line pointing directly to Perl, or to patch the wrapper script
created around mptopdf to pass something else as $0; that is, change this line in the wrapper
script:

exec -a "$0" "/nix/store/...-mptopdf-2016/scripts/context/perl/mptopdf.pl"  "${extraFlagsArray[@]}" "$@"

to this:

exec "/nix/store/...-mptopdf-2016/scripts/context/perl/mptopdf.pl"  "${extraFlagsArray[@]}" "$@"

so that the Perl script can find and call itself.

Technical details

• System: 17.03beta685.1dbb962 (Gorilla)
• Nix version: 1.11.8
• Nixpkgs version: 17.03beta685.1dbb962

[williamyaoh]

There are some other Perl scripts in the TeX Live source repo that also have this weird
pseudo-shebang line:

https://www.tug.org/svn/texlive/trunk/Master/texmf-dist/scripts/context/perl/

They're not installed as part of the basic-scheme derivation, but they might be installed as
part of other TeX packages, and would likely need patching as well.

[vcunat]

I haven't noticed this ticket; it should be OK now on both master and 17.03.

These ugly pseudo-shebangs are now detected and wrapped by perl -w instead of bash.