Rich Felker
c49d3c8ada
such loading is unsafe, and can happen when programs use their own logic to locate a .so file then pass the absolute pathname to dlopen, or if an absolute pathname ends up in DT_NEEDED headers. multiple loads with only the base name were already precluded, provided libc was named appropriately, by special-casing standard library names. one function symbol (in the reserved namespace, but public, since it's part of the crt1 entry point ABI) and one data symbol are checked. this way we avoid likely false positives, particularly from libraries interposing and wrapping functions. there is no hard requirement to avoid breaking such usage, since trying to run a hook before libc is even initialized is not a supported usage case, but it's friendlier not to break things.
musl libc
musl, pronounced like the word "mussel", is an MIT-licensed
implementation of the standard C library targetting the Linux syscall
API, suitable for use in a wide range of deployment environments. musl
offers efficient static and dynamic linking support, lightweight code
and low runtime overhead, strong fail-safe guarantees under correct
usage, and correctness in the sense of standards conformance and
safety. musl is built on the principle that these goals are best
achieved through simple code that is easy to understand and maintain.
The 1.1 release series for musl features coverage for all interfaces
defined in ISO C99 and POSIX 2008 base, along with a number of
non-standardized interfaces for compatibility with Linux, BSD, and
glibc functionality.
For basic installation instructions, see the included INSTALL file.
Information on full musl-targeted compiler toolchains, system
bootstrapping, and Linux distributions built on musl can be found on
the project website:
http://www.musl-libc.org/