add encryption executable code

src/encrypt.zig

@@ -0,0 +1,45 @@
+const std = @import("std");
+const crypt = @import("crypt.zig");
+
+pub fn main() !u8 {
+    var gpa = std.heap.GeneralPurposeAllocator(.{}){};
+    defer _ = gpa.deinit();
+    const allocator = gpa.allocator();
+    var args = std.process.args();
+    defer args.deinit();
+    var first = true;
+    while (args.next(allocator)) |arg_or_err| {
+        const arg = try arg_or_err;
+        defer allocator.free(arg);
+        if (first) {
+            // skip argv[0]
+            first = false;
+            continue;
+        }
+        const key = try getKey(allocator);
+        defer allocator.free(key);
+        const encrypted = try crypt.encryptWithKey(allocator, key.*, arg);
+        defer allocator.free(encrypted);
+        try std.io.getStdOut().writeAll(encrypted);
+        break;
+    }
+
+    return 0;
+}
+
+fn getKey(allocator: std.mem.Allocator) !*[crypt.key_size]u8 {
+    const passfile = std.fs.cwd().openFile(".clippy", .{}) catch |e| {
+        if (e == error.FileNotFound) {
+            const cwd = std.fs.realpathAlloc(allocator, ".") catch "could not determine";
+            defer allocator.free(cwd);
+            std.log.err("Could not find '.clippy' file in directory {s}. Please add a password to this file", .{cwd});
+        }
+        return e;
+    };
+    defer passfile.close();
+    const pass = try passfile.readToEndAlloc(allocator, std.math.maxInt(usize));
+    defer allocator.free(pass);
+
+    const tmp_key = try crypt.keyFromPassword(allocator, pass, ""); // reuse key - this is slow
+    return tmp_key;
+}