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const builtin = @import("builtin");
const std = @import("std");
const assert = std.debug.assert;
const segfault = true;
pub const JournalHeader = packed struct {
hash_chain_root: u128 = undefined,
prev_hash_chain_root: u128,
checksum: u128 = undefined,
magic: u64,
command: u32,
size: u32,
pub fn calculate_checksum(self: *const JournalHeader, entry: []const u8) u128 {
assert(entry.len >= @sizeOf(JournalHeader));
assert(entry.len == self.size);
const checksum_offset = @offsetOf(JournalHeader, "checksum");
const checksum_size = @sizeOf(@TypeOf(self.checksum));
assert(checksum_offset == 0 + 16 + 16);
assert(checksum_size == 16);
var target: [32]u8 = undefined;
std.crypto.hash.Blake3.hash(entry[checksum_offset + checksum_size ..], target[0..], .{});
return @bitCast(u128, target[0..checksum_size].*);
}
pub fn calculate_hash_chain_root(self: *const JournalHeader) u128 {
const hash_chain_root_size = @sizeOf(@TypeOf(self.hash_chain_root));
assert(hash_chain_root_size == 16);
const prev_hash_chain_root_offset = @offsetOf(JournalHeader, "prev_hash_chain_root");
const prev_hash_chain_root_size = @sizeOf(@TypeOf(self.prev_hash_chain_root));
assert(prev_hash_chain_root_offset == 0 + 16);
assert(prev_hash_chain_root_size == 16);
const checksum_offset = @offsetOf(JournalHeader, "checksum");
const checksum_size = @sizeOf(@TypeOf(self.checksum));
assert(checksum_offset == 0 + 16 + 16);
assert(checksum_size == 16);
assert(prev_hash_chain_root_offset + prev_hash_chain_root_size == checksum_offset);
const header = @bitCast([@sizeOf(JournalHeader)]u8, self.*);
const source = header[prev_hash_chain_root_offset .. checksum_offset + checksum_size];
assert(source.len == prev_hash_chain_root_size + checksum_size);
var target: [32]u8 = undefined;
std.crypto.hash.Blake3.hash(source, target[0..], .{});
if (segfault) {
return @bitCast(u128, target[0..hash_chain_root_size].*);
} else {
var array = target[0..hash_chain_root_size].*;
return @bitCast(u128, array);
}
}
pub fn set_checksum_and_hash_chain_root(self: *JournalHeader, entry: []const u8) void {
self.checksum = self.calculate_checksum(entry);
self.hash_chain_root = self.calculate_hash_chain_root();
}
};
test "fixed" {
if (builtin.zig_backend == .stage2_wasm) return error.SkipZigTest; // TODO
if (builtin.zig_backend == .stage2_c) return error.SkipZigTest; // TODO
if (builtin.zig_backend == .stage2_x86_64) return error.SkipZigTest; // TODO
if (builtin.zig_backend == .stage2_arm) return error.SkipZigTest; // TODO
if (builtin.zig_backend == .stage2_aarch64) return error.SkipZigTest; // TODO
var buffer align(@alignOf(JournalHeader)) = [_]u8{0} ** 65536;
var entry = std.mem.bytesAsValue(JournalHeader, buffer[0..@sizeOf(JournalHeader)]);
entry.* = .{
.prev_hash_chain_root = 0,
.magic = 0,
.command = 0,
.size = 64 + 128,
};
entry.set_checksum_and_hash_chain_root(buffer[0..entry.size]);
try std.io.null_writer.print("{}\n", .{entry});
}
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