Intro

The files in this subdirectory and musl C source files referenced in the main Makefile constitute the subset of libc implementation in OSv. Most of the network related functions (bind(), listen(), accept(), socket(), etc) are actually located under the bsd/ part of the tree (see /bsd/sys/kern/uipc_syscalls_wrap.cc as an example). Please note that our libc implementation aims to be glibc (GNU libc) compatible even though much of the implementation comes from musl. For more details please read the Linux ABI Compatibility and the Components of OSv wikis.

Please note that because OSv is a unikernel, much of its libc functionality has been implemented from scratch (all the C++ files in this directory). In ideal world the source files would either come from musl as-is or be implemented natively in OSv. But in reality some of the files in this directory originate from musl and have been adapted to make it work with OSv internals for following major reasons:

• syscall() invocations in many stdio, stdlib, network functions have been replaced with direct local functions like SYS_open(filename, flags, ...) to open(filename, flags, ...) (see syscall_to_function.h for details).
• the locking logic in some of the files in musl stdio have been tweaked to use OSv mutexes

History

Original commit

Previous is 0.9.12

State

The current version of musl that OSv uses is 1.1.24. Most of the musl C files (grep -P '^musl \+=' Makefile - 577 files at this point) are directly referenced in the main makefile via a musl/ symlink that currently points to the /musl_1.1.24 git subproject. Some of the musl files are also symlinked from /libc subdirectory. Please also note that most header files under /include/api symlink to the the musl copies under musl/include directory, but some are actually modified copies of original musl files. The internal musl headers under /include/api/internal_musl_headers symlink to files under [musl/src/include](/musl/src/include].

All C++ (*.cc/*.hh) files under libc/ have been natively implemented in OSv. Also all FORTIFY functions for glibc compatibility (files ending with _chk.c) have been implemented natively.

Following libc modules have been natively implemented in OSv as C++ files and do NOT originate from musl:

• ldso (dynamic linker)
• malloc
• mman
• process
• sched
• signal (some implementation is from musl as is)
• thread
• unistd
• vdso

Following libc modules orginate from musl as-is:

• crypt
• ctype
• dirent
• fenv
• math (all but finitel.c which is missing in musl)
• multibyte
• regex
• temp
• termios
• time (all but __tz.c) that comes from musl 1.1.24 and has been adapted

Some files in the folowing libc modules originate from musl as-is or have been adapted from original musl sources or are original OSv implementations or originate from other open source projects:

• arch
• env
• errno
• locale
• misc
• network
• prng
• stdio
• stdlib
• string

Files that should never change (besides C++) - TODO (list them)

Files in libc/ subject to musl upgrade.

Possibly syslog.c might need to get updated.

Upgrades

Any upcoming upgrade to a newer version of musl (> 1.1.24) would require at least updating the files from mosl that have been adapded for OSv purposes (the last group, see above) and ideally analyzing files used as-is to see if any of those need to be adapted.

Obviously we want to keep the number of adapted files to the minimum to minimize the future upgrade efforts.