As far as I can tell, struct File in std.stdio does not have a direct way to construct a File object from a low-level file descriptor, à la fdopen.
I ran into this issue when using fork and pipe to create a pipe between two processes; having started a child process I wanted to parse the child's standard output using high-level File functions, and for that purpose I wanted to create a File object from a file descriptor.
After some head-scratching, I was finally able to work around the issue by extern-declaring fdopen and using the sparsely documented File.wrapFile function (which is labelled "unsafe") to construct a File object, but that was inconvenient and obscure.
Implementing fdopen in File would make systems programming with Phobos easier.
Comment #1 by andrej.mitrovich — 2011-05-24T20:34:36Z
fdopen is declared in core\sys\posix\stdio.d
It seems there's at least one function which uses it:
D:\DMD\dmd2\src\phobos\std\stdio.d:2540: FILE* fp = enforce(fdopen(s, "w+".ptr));
Hope that helps in any way!