lumine

UEFI x86_64 bootloader for linux kernel images

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src/luefi.zig

1943 bytes raw

 1//! lumine uefi abstractions
 2const std = @import("std");
 3const uefi = std.os.uefi;
 4
 5const Path = @import("./Config.zig").Path;
 6
 7pub fn posixPathToUefi(path: []u16) void {
 8    for (0..path.len) |i|
 9        switch (path[i]) {
10            '/' => path[i] = '\\',
11            else => {},
12        };
13}
14
15pub fn fileOpenBoot(path: []const u8) !*uefi.protocol.File {
16    const boot_svc = uefi.system_table.boot_services.?;
17    const allocator = uefi.pool_allocator;
18
19    const loaded_img = try boot_svc.openProtocol(uefi.protocol.LoadedImage, uefi.handle, .{
20        .get_protocol = .{ .agent = uefi.handle },
21    }) orelse unreachable;
22
23    const device_handle = loaded_img.device_handle orelse unreachable;
24    const simple_fs = try boot_svc.openProtocol(uefi.protocol.SimpleFileSystem, device_handle, .{
25        .get_protocol = .{ .agent = uefi.handle },
26    }) orelse unreachable;
27
28    const root_fs = try simple_fs.openVolume();
29    defer root_fs.close() catch unreachable;
30
31    // is allocating a good idea?
32    const utf16_path = try std.unicode.utf8ToUtf16LeAllocZ(allocator, path);
33    defer allocator.free(utf16_path);
34
35    posixPathToUefi(utf16_path);
36
37    return root_fs.open(utf16_path, .read, .{});
38}
39
40pub fn fileOpen(path: Path) !*uefi.protocol.File {
41    return switch (path) {
42        .boot => |boot_path| fileOpenBoot(boot_path),
43    };
44}
45
46pub fn fileSize(file: *uefi.protocol.File) !usize {
47    const allocator = uefi.pool_allocator;
48
49    const info_size = try file.getInfoSize(.file);
50    const info_buf = try allocator.alignedAlloc(u8, .@"8", info_size);
51    defer allocator.free(info_buf);
52
53    const info = try file.getInfo(.file, info_buf);
54    return info.file_size;
55}
56
57pub fn fileReadSlice(file: *uefi.protocol.File, slice: []u8) !void {
58    var read: usize = 0;
59
60    while (read < slice.len) {
61        const chunk = try file.read(slice[read..]);
62        if (chunk == 0) return error.ReadShort;
63        read += chunk;
64    }
65}