tiny.profiling.fingerprint

1const std = @import("std");2const sys = @import("sys");34pub const Digest = [std.crypto.hash.sha2.Sha256.digest_length]u8;5pub const Hex = [std.crypto.hash.sha2.Sha256.digest_length * 2]u8;67pub const File = struct {8    bytes: u64,9    sha256: Digest,1011    pub fn hex(self: File) Hex {12        return std.fmt.bytesToHex(self.sha256, .lower);13    }14};1516pub fn inspect(path: []const u8) !File {17    var file = if (std.fs.path.isAbsolute(path))18        try sys.fs.openAbsoluteFile(path, .{})19    else20        try sys.fs.cwd().openFile(sys.fs.debugIo(), path, .{});21    defer file.close(sys.fs.debugIo());22    const before = try file.stat(sys.fs.debugIo());23    var hasher = std.crypto.hash.sha2.Sha256.init(.{});24    var reader_buffer: [16 * 1024]u8 = undefined;25    var chunk: [16 * 1024]u8 = undefined;26    var reader = file.reader(sys.fs.debugIo(), &reader_buffer);27    var bytes: u64 = 0;28    while (true) {29        const count = reader.interface.readSliceShort(&chunk) catch |err| switch (err) {30            error.ReadFailed => return reader.err orelse error.ReadFailed,31        };32        if (count == 0) break;33        hasher.update(chunk[0..count]);34        bytes = std.math.add(u64, bytes, count) catch return error.FileTooLarge;35    }36    const after = try file.stat(sys.fs.debugIo());37    if (before.size != after.size or38        before.inode != after.inode or39        !std.meta.eql(before.mtime, after.mtime) or40        bytes != after.size)41    {42        return error.InputChanged;43    }44    var digest: Digest = undefined;45    hasher.final(&digest);46    return .{ .bytes = bytes, .sha256 = digest };47}4849test "profiling fingerprint hashes empty files without allocation" {50    var temporary = std.testing.tmpDir(.{});51    defer temporary.cleanup();52    try temporary.dir.writeFile(std.Options.debug_io, .{53        .sub_path = "empty",54        .data = "",55    });56    var arena_state = std.heap.ArenaAllocator.init(std.testing.allocator);57    defer arena_state.deinit();58    const path = try temporary.parent_dir.realPathFileAlloc(59        std.Options.debug_io,60        temporary.sub_path[0..],61        arena_state.allocator(),62    );63    const file_path = try std.fs.path.join(64        arena_state.allocator(),65        &.{ path, "empty" },66    );67    const result = try inspect(file_path);68    const result_hex = result.hex();69    try std.testing.expectEqual(@as(u64, 0), result.bytes);70    try std.testing.expectEqualStrings(71        "e3b0c44298fc1c149afbf4c8996fb924" ++72            "27ae41e4649b934ca495991b7852b855",73        &result_hex,74    );75}

1pub const fingerprint = @import("fingerprint.zig");