A library for making self-extracting tar files.
This was created specifically for the
s6-overlay project.
It is not currently recommended for creating generic, self-extracting
tar files - it has behavior that is specific to the s6-overlay project,
is only tested with GNU tar, and only tested with the s6-overlay tar
file.
The library is compiled as a static archive with a main function
already defined. The main function will extract the contents
of a tar file, it expects for three symbols to exist:
unsigned char _binary_payload_tar_start[]unsigned char _binary_payload_tar_end[]size_t _binary_payload_tar_size
main will extract the payload to a given destination.
It will only create directories on the filesystem if they do not exist. This
is primarily to support distributions that have replaced /bin with a
symlink to /usr/bin. Most tar implementations will remove /bin and replace
it with a directory (assuming /bin is a directory inside the tarfile).
To produce the payload object you can use ld:
ld -r -b binary payload.tar -o payload.o
Then link everything together into an executable:
gcc -static -o installer libjustc_installer.a payload.o -lskarnet
You'll now have a self-extracting executable.