libbb: introduce last_char_is_dir_sep()

Add a convenience function to determine if the last character of
a string is a directory separator.

Adds 16-32 bytes.

2 files changed, 13 insertions, 2 deletions

diff --git a/libbb/concat_path_file.c b/libbb/concat_path_file.c
index 81c7481ca..3afb0e3a4 100644
--- a/libbb/concat_path_file.c
+++ b/libbb/concat_path_file.c
@@ -22,8 +22,8 @@ char* FAST_FUNC concat_path_file(const char *path, const char *filename)
         if (!path)
                 path = "";
 #if ENABLE_PLATFORM_MINGW32
-        lc = last_char_is(path, '/') ?: last_char_is(path, '\\');
-        while (*filename == '/' || *filename == '\\')
+        lc = last_char_is_dir_sep(path);
+        while (is_dir_sep(*filename))
                 filename++;
 #else
         lc = last_char_is(path, '/');
diff --git a/libbb/last_char_is.c b/libbb/last_char_is.c
index fba05f974..c2cd92174 100644
--- a/libbb/last_char_is.c
+++ b/libbb/last_char_is.c
@@ -17,3 +17,14 @@ char* FAST_FUNC last_char_is(const char *s, int c)
                 s++;
         return (*s == (char)c) ? (char *) s : NULL;
 }
+
+#if ENABLE_PLATFORM_MINGW32
+char* FAST_FUNC last_char_is_dir_sep(const char *s)
+{
+        if (!s[0])
+                return NULL;
+        while (s[1])
+                s++;
+        return is_dir_sep(*s)? (char *) s : NULL;
+}
+#endif