abc.h

#ifndef __ABC____H
#define __ABC____H

/* Generated with cbindgen:0.12.0 */

#include <stdarg.h>
#include <stdbool.h>
#include <stdint.h>
#include <stdlib.h>

#ifdef __cplusplus
extern "C" {
#endif // __cplusplus

bool read_all_from_file(FILE *file);

#ifdef __cplusplus
} // extern "C"
#endif // __cplusplus

#endif /* __ABC____H */

lib.rs

use libc::{FILE, fread, feof, ferror};

#[no_mangle]
pub extern "C" fn read_all_from_file(file: *mut FILE) -> bool {
    let mut buf = [0u8; 1 << 12];
    let mut r = 0;
    println!("fread() starts");
    while unsafe { feof(file) } == 0 {
        let hr = unsafe { fread(buf.as_mut_ptr().cast(), 1, 1 << 12, file) };
        println!("fread() got {} bytes", hr);
        if hr == 0 {
            if unsafe { feof(file) } != 0 {
                println!("feof(file) returns non-zero");
		            break;
            }
            if unsafe { ferror(file) } != 0 {
                println!("ferror() returns non-zero");
                return false;
            }
        } else {
            r += hr;
        }
    }
    println!("fread() got {} bytes totally", r);
    true
}

main.cpp

#include <stdio.h>
#include "abc.h"
#pragma comment(lib, "abc.dll.lib")

int main(int argc, char* argv[]) {
	if (argc != 2) {
		fprintf(stderr, "Usage: %s PATH\n", argv[0]);
		return 1;
	}

	errno_t err;
	FILE *file;
	err = fopen_s(&file, argv[1], "rb");

	if (err) {
		fprintf(stderr, "Error for _wfopen_s()\n");
		return 2;
	}

	printf("calling read_all_from_file()\n");
	if (read_all_from_file(file)) {
		printf("OK\n");
	}
	else {
		printf("Error\n");
	}

	fclose(file);
	return 0;
}