1 files changed, 94 insertions, 0 deletions
diff --git a/lib/libcfg/unescape.c b/lib/libcfg/unescape.c
new file mode 100644
index 0000000..e2b450c
--- /dev/null
+++ b/lib/libcfg/unescape.c
@@ -0,0 +1,94 @@
+/* SPDX-License-Identifier: GPL-3.0-or-later */
+/*
+ * Copyright (C) 2018 - David Oberhollenzer
+ *
+ * This program 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.
+ *
+ * This program 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 this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+#include <stdlib.h>
+#include <ctype.h>
+#include <errno.h>
+
+#include "libcfg.h"
+
+static int xdigit(int x)
+{
+	if (isupper(x))
+		return x - 'A' + 0x0A;
+	if (islower(x))
+		return x - 'a' + 0x0A;
+	return x - '0';
+}
+
+int unescape(char *src)
+{
+	char *dst = src;
+	int c;
+
+	for (;;) {
+		while (*src != '"' && *src != '\0')
+			*(dst++) = *(src++);
+
+		if (*src == '\0')
+			break;
+
+		++src;
+
+		while ((c = *(src++)) != '"') {
+			if (c == '\0')
+				return -1;
+
+			if (c == '\\') {
+				c = *(src++);
+
+				switch (c) {
+				case 'a': c = '\a'; break;
+				case 'b': c = '\b'; break;
+				case 'f': c = '\f'; break;
+				case 'n': c = '\n'; break;
+				case 't': c = '\t'; break;
+				case '\\':
+				case '"':
+				case '%':
+					break;
+				case 'x':
+					c = 0;
+					if (isxdigit(*src))
+						c = (c<<4) | xdigit(*(src++));
+					if (isxdigit(*src))
+						c = (c<<4) | xdigit(*(src++));
+					break;
+				case '0':
+					c = 0;
+					if (isdigit(*src) && *src < '8')
+						c = (c<<3) | (*(src++) - '0');
+					if (isdigit(*src) && *src < '8')
+						c = (c<<3) | (*(src++) - '0');
+					if (isdigit(*src) && *src < '8')
+						c = (c<<3) | (*(src++) - '0');
+					break;
+				default:
+					return -1;
+				}
+
+				if (c == 0)
+					return -1;
+			}
+
+			*(dst++) = c;
+		}
+	}
+
+	*(dst++) = '\0';
+	return 0;
+}