strbuf: add a case insensitive starts_with()

Check in a case insensitive manner if one string is a prefix of another
string.

This function is used in a subsequent commit.

Signed-off-by: Lars Schneider <larsxschneider@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 9 insertions, 0 deletions

diff --git a/strbuf.c b/strbuf.c
index a20af696bc..0a24c3dd76 100644
--- a/strbuf.c
+++ b/strbuf.c
@@ -11,6 +11,15 @@ int starts_with(const char *str, const char *prefix)
 			return 0;
 }
 
+int istarts_with(const char *str, const char *prefix)
+{
+	for (; ; str++, prefix++)
+		if (!*prefix)
+			return 1;
+		else if (tolower(*str) != tolower(*prefix))
+			return 0;
+}
+
 int skip_to_optional_arg_default(const char *str, const char *prefix,
 				 const char **arg, const char *def)
 {