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use io;
use sector;
use errors;
def mbr_lba: size = 0;
export type nombr = !void;
export type mbr = struct {
bootsector_sec: sector::sector,
bootsector: *bootsector
};
export type bootsector = struct {
@offset(0) bootstrap: [440]u8,
@offset(440) udid: u32,
@offset(444) reserved: u16,
@offset(446) entries: [4]entry,
@offset(510) magic: u16,
};
export type entry = struct {
@offset(0) attributes: u8,
@offset(4) part_type: u8,
@offset(8) lba_begin: u32,
@offset(12) length: u32,
};
export fn bootsector_validate(self: *bootsector) bool = {
if (self.magic != 0xaa55) {
return false;
};
return true;
};
export fn from(fd: io::file) (*mbr | nombr | io::error) = {
const bootsector_sec = sector::map(fd, 0, 1);
sector::fetch(&bootsector_sec)?;
const bootsector = bootsector_sec.buf: *[*]u8: *bootsector;
if (!bootsector_validate(bootsector)) {
sector::finish(&bootsector_sec);
return nombr;
};
let self = alloc(mbr {
bootsector_sec = bootsector_sec,
bootsector = bootsector
});
return self;
};
export fn partstream_reader(self: *mbr, entry: *entry) (io::limitstream | io::error) = {
const fd = self.bootsector_sec.fd;
const part = entry.lba_begin * sector::sector_length;
const length = entry.length * sector::sector_length;
io::seek(fd, part: io::off, io::whence::SET)?;
return io::limitreader(fd, length);
};
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