KEEP IN SYNC WITH lib/posix.h
this header makes available commonly used POSIX (Portable Operating System Interface) definitions, e.g. thread, file I/O and socket APIs. on Linux and OS X we just include the requisite headers; Win32 doesn't really support POSIX (+), so we have to implement everything ourselves.
rationale: this is preferable to a wrapper for several reasons:
- less code (implementation is only needed on Win32)
- no lock-in (the abstraction may prevent not-designed-for operations that the POSIX interface would have allowed)
- familiarity (many coders already know POSIX)
if a useful definition is missing, feel free to add it!
implementation reference is the Single Unix Specification v3 - it's similar to the POSIX standard (superset?) and freely available.
+ Win32 does have a POSIX subsystem (mandated by a government contract), but it is crippled. only apps with the PE header 'subsystem' field set to "POSIX" can use the appendant DLL, and then they can't call the regular Windows APIs. this is obviously unacceptable - GDI is needed to set up OpenGL.
we therefore need to emulate POSIX functions using the Win32 API. fortunately, many POSIX functions are already implemented in the VC CRT and need only be renamed (e.g. _open, _stat).