dir API: add a generalized path_match_flags() function

Add a path_match_flags() function and have the two sets of
starts_with_dot_{,dot_}slash() functions added in
63e95beb085 (submodule: port resolve_relative_url from shell to C,
2016-04-15) and a2b26ffb1a8 (fsck: convert gitmodules url to URL
passed to curl, 2020-04-18) be thin wrappers for it.

As the latter of those notes the fsck version was copied from the
initial builtin/submodule--helper.c version.

Since the code added in a2b26ffb1a8 was doing really doing the same as
win32_is_dir_sep() added in 1cadad6f658 (git clone <url>
C:\cygwin\home\USER\repo' is working (again), 2018-12-15) let's move
the latter to git-compat-util.h is a is_xplatform_dir_sep(). We can
then call either it or the platform-specific is_dir_sep() from this
new function.

Let's likewise change code in various other places that was hardcoding
checks for "'/' || '\\'" with the new is_xplatform_dir_sep(). As can
be seen in those callers some of them still concern themselves with
':' (Mac OS classic?), but let's leave the question of whether that
should be consolidated for some other time.

As we expect to make wider use of the "native" case in the future,
define and use two starts_with_dot_{,dot_}slash_native() convenience
wrappers. This makes the diff in builtin/submodule--helper.c much
smaller.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Derrick Stolee <derrickstolee@github.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

2 files changed, 2 insertions, 6 deletions

diff --git a/compat/mingw.c b/compat/mingw.c
index 6fe80fdf01..b94b473d97 100644
--- a/compat/mingw.c
+++ b/compat/mingw.c
@@ -2830,7 +2830,7 @@ not_a_reserved_name:
 			}
 
 			c = path[i];
-			if (c && c != '.' && c != ':' && c != '/' && c != '\\')
+			if (c && c != '.' && c != ':' && !is_xplatform_dir_sep(c))
 				goto not_a_reserved_name;
 
 			/* contains reserved name */
diff --git a/compat/win32/path-utils.h b/compat/win32/path-utils.h
index bba2b64408..65fa3b9263 100644
--- a/compat/win32/path-utils.h
+++ b/compat/win32/path-utils.h
@@ -6,11 +6,7 @@ int win32_has_dos_drive_prefix(const char *path);
 
 int win32_skip_dos_drive_prefix(char **path);
 #define skip_dos_drive_prefix win32_skip_dos_drive_prefix
-static inline int win32_is_dir_sep(int c)
-{
-	return c == '/' || c == '\\';
-}
-#define is_dir_sep win32_is_dir_sep
+#define is_dir_sep is_xplatform_dir_sep
 static inline char *win32_find_last_dir_sep(const char *path)
 {
 	char *ret = NULL;