Primer on a single-file, self-contained, fully statically-linked build of Perl, embedding a virtual, read-only file system (with all *.pm files and arbitrary files)

• build Perl into a single, self-contained, fully statically-linked executable
• builds all builtin modules statically and then links them statically
• showcases using Alpine Linux and musl libc for static linking with libc
• embeds *.pm modules into the executable
• showcases embedding a user Perl script (for illustration is used perlpack.pl, see Makefile)
• showcases embedding arbitrary files along (see Makefile and add files into the packfs directory)

Limitations

• not all I/O function calls are reimplemented
• it's only a proof-of-concept, very little tested

Files of interest

• perlpack.c - the main C program which embeds Perl, includes perlpack.h and override I/O callback to enable transparent access to the embedded files
• perlpack.pl - generates in place a more non-empty perlpack.h, default perlpack.h provided only from illustrative purposes
• Makefile - showcases building of main binaries perlpackstatic (and embedded myscript.o, perlpack.o)
• .github/workflows/perlpack.yml - showcases testing command sequence
• libc_perlpack.a - built in Makefile, a musl libc modification which renames file-related functions like open(...) -> orig_open(...), this enables overriding these file-related functions without dynamic loading (a typical way of using a shared library with overrides and LD_PRELOAD loader mechanism for tracing file-related function calls is at https://gist.github.com/vadimkantorov/2a4e092889b7132acd3b7ddfc2f2f907)
• perlpackstatic - built in Makefile, the main binary with embedded Perl (using /mnt/packperl/ as the "mount-point" for the embedded, read-only virtual FS)

Overridden functions

• open
• access
• stat
• fstat
• lseek
• read
• close
• fopen
• fileno

Prior complete, but also more complex approaches

• https://metacpan.org/dist/App-Staticperl/view/staticperl.pod
• http://staticperl.schmorp.de/smallperl.html
• http://staticperl.schmorp.de/smallperl.bundle
• http://staticperl.schmorp.de/bigperl.bundle
• https://metacpan.org/pod/PAR::Packer

References and alternatives

• https://metacpan.org/pod/PerlIO
• https://perldoc.perl.org/perlembed
• https://perldoc.perl.org/open
• https://perl.mines-albi.fr/perl5.8.5/5.8.5/sun4-solaris/Encode/PerlIO.html
• https://perldoc.perl.org/Encode::PerlIO
• https://linux.die.net/man/1/perliol
• https://docs.mojolicious.org/perliol
• https://stackoverflow.com/questions/12729545/why-is-this-xs-code-that-returns-a-perlio-leaky
• https://perldoc.perl.org/perlembed
• https://perldoc.perl.org/perlguts
• https://www.perlmonks.org/?node_id=385469
• https://github.com/Perl/perl5/commit/0301e899536a22752f40481d8a1d141b7a7dda82
• Perl/perl5#16565
• https://www.postgresql.org/message-id/23260.1527026547%40sss.pgh.pa.us
• https://medium.com/booking-com-development/native-extensions-for-perl-without-smoke-and-mirrors-40479999dfc8
• https://github.com/xsawyerx/xs-fun
• https://perldoc.perl.org/perlxs
• https://perldoc.perl.org/perlapi
• https://stackoverflow.com/questions/10763394/how-to-build-a-c-program-using-a-custom-version-of-glibc-and-static-linking