read file

readfile.zig

fn openAndRead(alloc: std.mem.Allocator, in_file: []const u8) !void {
    var f = std.fs.cwd().openFile(in_file, .{}) catch |err| {
        fatal("unable to open file '{s}': {s}\n", .{ in_file, @errorName(err) });
    };
    defer f.close();
    const stat = try f.stat();
    if (stat.size > std.math.maxInt(u32))
        return error.FileTooBig;
    const source = try alloc.allocSentinel(u8, @intCast(usize, stat.size), 0);
    errdefer alloc.free(source);
    const amt = try f.readAll(source);
    if (amt <= 1)
        return error.EmptyFile;
    if (amt != stat.size)
        return error.UnexpectedEndOfFile;
    _ = amt;
}