From e96957a78147c73e97a611e1c199fee02941b64f Mon Sep 17 00:00:00 2001
From: P. J. McDermott <pj@pehjota.net>
Date: Tue, 23 Mar 2021 16:23:43 -0400
Subject: db_base64_decode(): New function, from boukengine

---
(limited to 'src')

diff --git a/src/base64.c b/src/base64.c
new file mode 100644
index 0000000..dacd03e
--- /dev/null
+++ b/src/base64.c
@@ -0,0 +1,81 @@
+/*
+ * Copyright (C) 2013  P. J. McDermott
+ *
+ * This file is part of Dodge Balls
+ *
+ * Dodge Balls is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * Dodge Balls is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with Dodge Balls.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <stddef.h>
+#include "base64.h"
+
+static void
+_db_base64_decode_block(const char *src, char *dest)
+{
+	int i;
+	/* GCC's SSP won't wrap functions with arrays smaller than 8 bytes. */
+	char buf[8];
+
+	/* Convert base 64 characters into values. */
+	/* Supports ASCII and EBCDIC systems. */
+	for (i = 0; i < 4; ++i) {
+		if (src[i] >= 'A' && src[i] <= 'I') {
+			buf[i] = src[i] - 'A' + 0;
+		} else if (src[i] >= 'J' && src[i] <= 'R') {
+			buf[i] = src[i] - 'J' + 9;
+		} else if (src[i] >= 'S' && src[i] <= 'Z') {
+			buf[i] = src[i] - 'S' + 18;
+		} else if (src[i] >= 'a' && src[i] <= 'i') {
+			buf[i] = src[i] - 'a' + 26;
+		} else if (src[i] >= 'j' && src[i] <= 'r') {
+			buf[i] = src[i] - 'j' + 35;
+		} else if (src[i] >= 's' && src[i] <= 'z') {
+			buf[i] = src[i] - 's' + 44;
+		} else if (src[i] >= '0' && src[i] <= '9') {
+			buf[i] = src[i] - '0' + 52;
+		} else if (src[i] == '+') {
+			buf[i] = 62;
+		} else if (src[i] == '/') {
+			buf[i] = 63;
+		} else {
+			buf[i] = '\0';
+		}
+	}
+
+	/* Map four decoded value bytes into three output bytes. */
+	dest[0] = (buf[0] << 2) | (buf[1] >> 4);
+	dest[1] = (buf[1] << 4) | (buf[2] >> 2);
+	dest[2] = (buf[2] << 6) | (buf[3] >> 0);
+}
+	
+void
+db_base64_decode(const char *src, char *dest, size_t dest_len)
+{
+	size_t i;
+
+	/* Decode the input one entire block at a time. */
+	for (i = 0; i < (dest_len - 1) / 3; ++i) {
+		if (src[i * 4] == '\0' || 
+				src[i * 4 + 1] == '\0' || 
+				src[i * 4 + 2] == '\0' || 
+				src[i * 4 + 3] == '\0') {
+			dest[i * 3] = '\0';
+			break;
+		}
+		_db_base64_decode_block(src + i * 4, dest + i * 3);
+	}
+
+	/* Ensure NUL termination. */
+	dest[dest_len - 1] = '\0';
+}
diff --git a/src/base64.h b/src/base64.h
new file mode 100644
index 0000000..361a563
--- /dev/null
+++ b/src/base64.h
@@ -0,0 +1,27 @@
+/*
+ * Copyright (C) 2013  P. J. McDermott
+ *
+ * This file is part of Dodge Balls
+ *
+ * Dodge Balls is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * Dodge Balls is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with Dodge Balls.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef DB_BASE64_H_
+#define DB_BASE64_H_
+
+#include <stddef.h>
+
+void db_base64_decode(const char *src, char *dest, size_t dest_len);
+
+#endif  /* DB_BASE64_H_ */
diff --git a/src/local.mk b/src/local.mk
index c796ae7..4b6f55d 100644
--- a/src/local.mk
+++ b/src/local.mk
@@ -1,4 +1,6 @@
 dodge_balls_SOURCES += \
+	%reldir%/base64.c \
+	%reldir%/base64.h \
 	%reldir%/collision.c \
 	%reldir%/collision.h \
 	%reldir%/defs.h \
--
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