1 files changed, 89 insertions, 0 deletions
diff --git a/libbb/process_escape_sequence.c b/libbb/process_escape_sequence.c
new file mode 100644
index 0000000..138e751
--- /dev/null
+++ b/libbb/process_escape_sequence.c
@@ -0,0 +1,89 @@
+/* vi: set sw=4 ts=4: */
+/*
+ * Utility routines.
+ *
+ * Copyright (C) Manuel Novoa III <mjn3@codepoet.org>
+ * and Vladimir Oleynik <dzo@simtreas.ru>
+ *
+ * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
+ */
+
+#include <stdio.h>
+#include <limits.h>
+#include <ctype.h>
+#include "libbb.h"
+
+#define WANT_HEX_ESCAPES 1
+
+/* Usual "this only works for ascii compatible encodings" disclaimer. */
+#undef _tolower
+#define _tolower(X) ((X)|((char) 0x20))
+
+char bb_process_escape_sequence(const char **ptr)
+{
+	static const char charmap[] = {
+		'a',  'b',  'f',  'n',  'r',  't',  'v',  '\\', 0,
+		'\a', '\b', '\f', '\n', '\r', '\t', '\v', '\\', '\\' };
+
+	const char *p;
+	const char *q;
+	unsigned int num_digits;
+	unsigned int r;
+	unsigned int n;
+	unsigned int d;
+	unsigned int base;
+
+	num_digits = n = 0;
+	base = 8;
+	q = *ptr;
+
+#ifdef WANT_HEX_ESCAPES
+	if (*q == 'x') {
+		++q;
+		base = 16;
+		++num_digits;
+	}
+#endif
+
+	do {
+		d = (unsigned int)(*q - '0');
+#ifdef WANT_HEX_ESCAPES
+		if (d >= 10) {
+			d = ((unsigned int)(_tolower(*q) - 'a')) + 10;
+		}
+#endif
+
+		if (d >= base) {
+#ifdef WANT_HEX_ESCAPES
+			if ((base == 16) && (!--num_digits)) {
+/*				return '\\'; */
+				--q;
+			}
+#endif
+			break;
+		}
+
+		r = n * base + d;
+		if (r > UCHAR_MAX) {
+			break;
+		}
+
+		n = r;
+		++q;
+	} while (++num_digits < 3);
+
+	if (num_digits == 0) {	/* mnemonic escape sequence? */
+		p = charmap;
+		do {
+			if (*p == *q) {
+				q++;
+				break;
+			}
+		} while (*++p);
+		n = *(p+(sizeof(charmap)/2));
+	}
+
+	*ptr = q;
+
+	return (char) n;
+}