Add function to get the byte length of n characters in a utf8 string.

2 files changed, 19 insertions, 0 deletions

diff --git a/utils/utf8.c b/utils/utf8.c
index b4e308044..885ca94ee 100644
--- a/utils/utf8.c
+++ b/utils/utf8.c
@@ -118,6 +118,24 @@ size_t utf8_bounded_length(const char *s, size_t l)
 }
 
 /**
+ * Calculate the length (in bytes) of a bounded UTF-8 string
+ *
+ * \param s  The string
+ * \param l  Maximum length of input (in bytes)
+ * \param c  Maximum number of characters to measure
+ * \return Length of string, in bytes
+ */
+size_t utf8_bounded_byte_length(const char *s, size_t l, size_t c)
+{
+	size_t len = 0;
+
+	while (len < l && c-- > 0)
+		len = utf8_next(s, l, len);
+
+	return len;
+}
+
+/**
  * Calculate the length (in bytes) of a UTF-8 character
  *
  * \param s  Pointer to start of character
diff --git a/utils/utf8.h b/utils/utf8.h
index 26234f6c0..eb043c227 100644
--- a/utils/utf8.h
+++ b/utils/utf8.h
@@ -37,6 +37,7 @@ size_t utf8_from_ucs4(uint32_t c, char *s);
 
 size_t utf8_length(const char *s);
 size_t utf8_bounded_length(const char *s, size_t l);
+size_t utf8_bounded_byte_length(const char *s, size_t l, size_t c);
 
 size_t utf8_char_byte_length(const char *s);