William PitcockandRich Felker
061843340f
notes added by maintainer: this function is a GNU extension. it was chosen over the similar BSD function funopen because the latter depends on fpos_t being an arithmetic type as part of its public API, conflicting with our definition of fpos_t and with the intent that it be an opaque type. it was accepted for inclusion because, despite not being widely used, it is usually very difficult to extricate software using it from the dependency on it. calling pattern for the read and write callbacks is not likely to match glibc or other implementations, but should work with any reasonable callbacks. in particular the read function is never called without at least one byte being needed to satisfy its caller, so that spurious blocking is not introduced. contracts for what callbacks called from inside libc/stdio can do are always complicated, and at some point still need to be specified explicitly. at the very least, the callbacks must return or block indefinitely (they cannot perform nonlocal exits) and they should not make calls to stdio using their own FILE as an argument.
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/