| Notes on POSIX |
| ============== |
| |
| There are few instances where OpenSSL requires a POSIX C library, at least |
| version 1-2008, or compatible enough functionality. |
| |
| There are exceptions, though, for platforms that do not have a POSIX |
| library, or where there are quirks that need working around. A notable |
| platform is Windows, where POSIX functionality may be available, but where |
| the function names are prefixed with an underscore, and where some POSIX |
| types are not present (such as `ssize_t`). |
| |
| Platforms that do have a POSIX library may still not have them accessible |
| unless the following macros are defined: |
| |
| _POSIX_C_SOURCE=200809L |
| _XOPEN_SOURCE=1 |
| |
| This is, for example, the case when building with gcc or clang and using the |
| flag `-ansi`. |
