c++ - Getting the file-mode from the FILE struct? -

i have piece of c code, function specific, operates on file*.

depending on mode file* opened there things can , cannot do.

is there way can obtain mode file* opened with?

that file* info can rely on, because created somewhere else in program , actual file-name long lost before reaches function, , cannot influence.

i prefer portable solution.

edit: i'm not interested in file-restrictions specifying users can file. irrelevant dealt upon file-opening. bit of code care open-mode.

on posix (and sufficiently similar) systems, fcntl(fileno(f), f_getfl) return mode/flags open file in form passed open (not fopen). check whether opened read-only, read-write, or write-only, can like:

int mode = fcntl(fileno(f), f_getfl); switch (mode & o_accmode) { case o_rdonly: ... case o_wronly: ... case o_rdwr: ... } 

you can check flags o_append, etc.