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These VU functions define a trivial file system implementation in which all functions act like the file is /dev/null but no actual system calls are performed.
Virtual /dev/null is considered a universally readable/writable,
permanently 0-length file whose permissions bits and ownerships can
not be changed by anyone (including root). It's access,
modification and change times are permanently 0
.
The closure for opened files is the access flags cast to (void *).
Function
vu_make_virtual_null_fd
int vu_make_virtual_null_fd (int * errn, int flags);
Return a new (pseudo) descriptor opened for virtual /dev/null .
Function
vu_make_virtual_null_fd_ge_n
int vu_make_virtual_null_fd_ge_n (int * errn, int n, int flags);
Return a new (pseudo) descriptor opened for virtual /dev/null .
The new descriptor is greater than or equal to n
.
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