How to share file with C?

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1

My program contains some libraries written in C, and both the Julia part and the C part will write to the same log file. How can I share the file between Julia and C?
I didn’t find a way to use FILE* in Julia. The file descriptor can be used by open(fd::OS_HANDLE) -> IO, but the document claims that Do not call this on a handle that's already owned by some other part of the system, so I suspect it cannot be used either?

2

The easiest solution is not to share a file handle. Either write a function to write to log in C and call that function from Julia, or do it the other way round.

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3

The docstring also says “Call open(Libc.dup(fd)) to avoid the ownership capture of the original handle” so try that?

4

Did you see Libc.FILE?

That should do exactly what you want. Open the file io = open(...) on the Julia side, and pass Libc.File(io) as a FILE* to the C side so that C can use it for writing. Close it on the Julia side when you are done.

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