reencode_string(): introduce and use same_encoding()

Callers of reencode_string() that re-encodes a string from one
encoding to another all used ad-hoc way to bypass the case where the
input and the output encodings are the same.  Some did strcmp(),
some did strcasecmp(), yet some others when converting to UTF-8 used
is_encoding_utf8().

Introduce same_encoding() helper function to make these callers use
the same logic.  Notably, is_encoding_utf8() has a work-around for
common misconfiguration to use "utf8" to name UTF-8 encoding, which
does not match "UTF-8" hence strcasecmp() would not consider the
same.  Make use of it in this helper function.

Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/utf8.h b/utf8.h
index 3c0ae76..93ef600 100644
--- a/utf8.h
+++ b/utf8.h
@@ -7,6 +7,7 @@ int utf8_width(const char **start, size_t *remainder_p);
 int utf8_strwidth(const char *string);
 int is_utf8(const char *text);
 int is_encoding_utf8(const char *name);
+int same_encoding(const char *, const char *);
 
 int strbuf_add_wrapped_text(struct strbuf *buf,
 		const char *text, int indent, int indent2, int width);