Import new Cytoplasm library based off of code from Telodendria.

Telodendria doesn't use this library yet, but it will soon.

src/include/Base64.h

@@ -0,0 +1,99 @@
+/*
+ * Copyright (C) 2022-2023 Jordan Bancino <@jordan:bancino.net>
+ *
+ * Permission is hereby granted, free of charge, to any person
+ * obtaining a copy of this software and associated documentation files
+ * (the "Software"), to deal in the Software without restriction,
+ * including without limitation the rights to use, copy, modify, merge,
+ * publish, distribute, sublicense, and/or sell copies of the Software,
+ * and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT.  IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+ * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+ * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+#ifndef CYTOPLASM_BASE64_H
+#define CYTOPLASM_BASE64_H
+
+/***
+ * @Nm Base64
+ * @Nd A simple base64 encoder/decoder with unpadded base64 support.
+ * @Dd September 30 2022
+ * @Xr Sha2
+ *
+ * This is an efficient yet simple base64 encoding and decoding API
+ * that supports regular base64, as well as the Matrix specification's
+ * extension to base64, called ``unpadded base64.'' This API provides
+ * the ability to convert between the two, instead of just implementing
+ * unpadded base64.
+ */
+
+#include <stddef.h>
+
+/**
+ * This function computes the amount of bytes needed to store a message
+ * of the specified number of bytes as base64.
+ */
+extern size_t
+ Base64EncodedSize(size_t);
+
+/**
+ * This function computes the amount of bytes needed to store a decoded
+ * representation of the encoded message. It takes a pointer to the
+ * encoded string because it must read a few bytes off the end in order
+ * to accurately compute the size.
+ */
+extern size_t
+ Base64DecodedSize(const char *, size_t);
+
+/**
+ * Encode the specified number of bytes from the specified buffer as
+ * base64. This function returns a string on the heap that should be
+ * freed with
+ * .Fn Free ,
+ * or NULL if a memory allocation error ocurred.
+ */
+extern char *
+ Base64Encode(const char *, size_t);
+
+/**
+ * Decode the specified number of bytes from the specified buffer of
+ * base64. This function returns a string on the heap that should be
+ * freed with
+ * .Fn Free ,
+ * or NULL if a memory allocation error occured.
+ */
+extern char *
+ Base64Decode(const char *, size_t);
+
+/**
+ * Remove the padding from a specified base64 string. This function
+ * modifies the specified string in place. It thus has no return value
+ * because it cannot fail. If the passed pointer is invalid, the
+ * behavior is undefined.
+ */
+extern void
+ Base64Unpad(char *, size_t);
+
+/**
+ * Add padding to an unpadded base64 string. This function takes a
+ * pointer to a pointer because it may be necessary to grow the memory
+ * allocated to the string. This function returns a boolean value
+ * indicating whether the pad operation was successful. In practice,
+ * this means it will only fail if a bigger string is necessary, but it
+ * could not be automatically allocated on the heap.
+ */
+extern int
+ Base64Pad(char **, size_t);
+
+#endif                             /* CYTOPLASM_BASE64_H */