Refactor skipping DOS drive prefixes

Junio noticed that there is an implicit assumption in pretty much
all the code calling has_dos_drive_prefix(): it forces all of its
callsites to hardcode the knowledge that the DOS drive prefix is
always two bytes long.

While this assumption is pretty safe, we can still make the code
more readable and less error-prone by introducing a function that
skips the DOS drive prefix safely.

While at it, we change the has_dos_drive_prefix() return value: it
now returns the number of bytes to be skipped if there is a DOS
drive prefix.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 5 insertions, 9 deletions

diff --git a/path.c b/path.c
index 38f2ebd..747d6da 100644
--- a/path.c
+++ b/path.c
@@ -544,13 +544,10 @@ const char *relative_path(const char *in, const char *prefix,
 	else if (!prefix_len)
 		return in;
 
-	if (have_same_root(in, prefix)) {
+	if (have_same_root(in, prefix))
 		/* bypass dos_drive, for "c:" is identical to "C:" */
-		if (has_dos_drive_prefix(in)) {
-			i = 2;
-			j = 2;
-		}
-	} else {
+		i = j = has_dos_drive_prefix(in);
+	else {
 		return in;
 	}
 
@@ -703,11 +700,10 @@ const char *remove_leading_path(const char *in, const char *prefix)
 int normalize_path_copy_len(char *dst, const char *src, int *prefix_len)
 {
 	char *dst0;
+	int i;
 
-	if (has_dos_drive_prefix(src)) {
+	for (i = has_dos_drive_prefix(src); i > 0; i--)
 		*dst++ = *src++;
-		*dst++ = *src++;
-	}
 	dst0 = dst;
 
 	if (is_dir_sep(*src)) {