POSIX specification:
http://www.opengroup.org/onlinepubs/9699919799/basedefs/errno.h.html
Gnulib module: errno
Portability problems fixed by Gnulib:
EOVERFLOW, ENOLINK, EMULTIHOP are not defined
on some platforms:
OpenBSD 4.0, OSF/1 5.1, mingw.
ECANCELED is not defined on some platforms:
OpenBSD 4.0, Cygwin, mingw.
ENOMSG, EIDRM, EPROTO, EBADMSG,
ENOTSUP are not defined on some platforms:
OpenBSD 4.0, mingw.
ESTALE is not defined on some platforms:
mingw, Interix 3.5.
EDQUOT is not defined on some platforms:
NonStop Kernel, mingw.
EWOULDBLOCK, ETXTBSY, ELOOP, ENOTSOCK,
EDESTADDRREQ, EMSGSIZE, EPROTOTYPE, ENOPROTOOPT,
EPROTONOSUPPORT, EOPNOTSUPP, EAFNOSUPPORT,
EADDRINUSE, EADDRNOTAVAIL, ENETDOWN, ENETUNREACH,
ENETRESET, ECONNABORTED, ECONNRESET, ENOBUFS,
EISCONN, ENOTCONN, ETIMEDOUT, ECONNREFUSED,
EHOSTUNREACH, EALREADY, EINPROGRESS are not defined on
some platforms:
mingw.
Portability problems not fixed by Gnulib: