win32: share code to find root prefix of path

Move unc_root_len() from ash to mingw32.c and use it in the new
function root_len(), which can be used in make_directory().

This reduces changes to upstream code and saves a few bytes.

4 files changed, 42 insertions, 51 deletions

diff --git a/include/mingw.h b/include/mingw.h
index 36c2f6805..7c9423cad 100644
--- a/include/mingw.h
+++ b/include/mingw.h
@@ -522,3 +522,6 @@ ULONGLONG CompatGetTickCount64(void);
 ssize_t get_random_bytes(void *buf, ssize_t count);
 int enumerate_links(const char *file, char *name);
 void hide_console(void);
+
+int unc_root_len(const char *dir);
+int root_len(const char *path);
diff --git a/libbb/make_directory.c b/libbb/make_directory.c
index 9af5552d5..e0fd486d8 100644
--- a/libbb/make_directory.c
+++ b/libbb/make_directory.c
@@ -59,29 +59,8 @@ int FAST_FUNC bb_make_directory(char *path, long mode, int flags)
 
                 if (flags & FILEUTILS_RECUR) {  /* Get the parent */
 #if ENABLE_PLATFORM_MINGW32
-                        if (s == path && *s && s[1] == ':') {
-                                /* skip drive letter */
-                                s += 2;
-                        }
-                        else if (s == path && s[0] == '/' && s[1] == '/' ) {
-                                /* skip UNC server and share */
-                                int count = 0;
-                                s += 2;
-                                while (*s) {
-                                        if (*s == '/') {
-                                                do {
-                                                        ++s;
-                                                } while (*s == '/');
-                                                if (++count == 2) {
-                                                        --s;
-                                                        break;
-                                                }
-                                        }
-                                        else {
-                                                ++s;
-                                        }
-                                }
-                        }
+                        if (s == path)
+                                s += root_len(path);
 #endif
                         /* Bypass leading non-'/'s and then subsequent '/'s */
                         while (*s) {
diff --git a/shell/ash.c b/shell/ash.c
index cd6196640..34ddc14f1 100644
--- a/shell/ash.c
+++ b/shell/ash.c
@@ -2860,34 +2860,6 @@ cdopt(void)
         return flags;
 }
 
-#if ENABLE_PLATFORM_MINGW32
-#define is_path_sep(x) ((x) == '/' || (x) == '\\')
-#define is_unc_path(x) (is_path_sep(x[0]) && is_path_sep(x[1]))
-#define is_root(x) (is_path_sep(x[0]) && x[1] == '\0')
-
-/* Return the length of the root of a UNC path, i.e. the '//host/share'
- * component, or 0 if the path doesn't look like that. */
-static int
-unc_root_len(const char *dir)
-{
-        const char *s = dir + 2;
-        int len;
-
-        if (!is_unc_path(dir))
-                return 0;
-        len = strcspn(s, "/\\");
-        if (len == 0)
-                return 0;
-        s += len + 1;
-        len = strcspn(s, "/\\");
-        if (len == 0)
-                return 0;
-        s += len;
-
-        return s - dir;
-}
-#endif
-
 /*
  * Update curdir (the name of the current directory) in response to a
  * cd command.
@@ -2896,6 +2868,8 @@ static const char *
 updatepwd(const char *dir)
 {
 #if ENABLE_PLATFORM_MINGW32
+# define is_path_sep(x) ((x) == '/' || (x) == '\\')
+# define is_root(x) (is_path_sep(x[0]) && x[1] == '\0')
         /*
          * Due to Windows drive notion, getting pwd is a completely
          * different thing. Handle it in a separate routine
diff --git a/win32/mingw.c b/win32/mingw.c
index 0206f6dca..3ee1a2496 100644
--- a/win32/mingw.c
+++ b/win32/mingw.c
@@ -1609,3 +1609,38 @@ void hide_console(void)
         }
 }
 #endif
+
+#define is_path_sep(x) ((x) == '/' || (x) == '\\')
+#define is_unc_path(x) (is_path_sep(x[0]) && is_path_sep(x[1]))
+
+/* Return the length of the root of a UNC path, i.e. the '//host/share'
+ * component, or 0 if the path doesn't look like that. */
+int unc_root_len(const char *dir)
+{
+        const char *s = dir + 2;
+        int len;
+
+        if (!is_unc_path(dir))
+                return 0;
+        len = strcspn(s, "/\\");
+        if (len == 0)
+                return 0;
+        s += len + 1;
+        len = strcspn(s, "/\\");
+        if (len == 0)
+                return 0;
+        s += len;
+
+        return s - dir;
+}
+
+/* Return the length of the root of a path, i.e. either the drive or
+ * UNC '//host/share', or 0 if the path doesn't look like that. */
+int root_len(const char *path)
+{
+        if (path == NULL)
+                return 0;
+        if (isalpha(*path) && path[1] == ':')
+                return 2;
+        return unc_root_len(path);
+}