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>

1 files changed, 63 insertions, 0 deletions

diff --git a/dir.h b/dir.h
index 8e02dfb505..7bc862030c 100644
--- a/dir.h
+++ b/dir.h
@@ -578,4 +578,67 @@ void connect_work_tree_and_git_dir(const char *work_tree,
 void relocate_gitdir(const char *path,
 		     const char *old_git_dir,
 		     const char *new_git_dir);
+
+/**
+ * The "enum path_matches_kind" determines how path_match_flags() will
+ * behave. The flags come in sets, and one (and only one) must be
+ * provided out of each "set":
+ *
+ * PATH_MATCH_NATIVE:
+ *	Path separator is is_dir_sep()
+ * PATH_MATCH_XPLATFORM:
+ *	Path separator is is_xplatform_dir_sep()
+ *
+ * Do we use is_dir_sep() to check for a directory separator
+ * (*_NATIVE), or do we always check for '/' or '\' (*_XPLATFORM). The
+ * "*_NATIVE" version on Windows is the same as "*_XPLATFORM",
+ * everywhere else "*_NATIVE" means "only /".
+ *
+ * PATH_MATCH_STARTS_WITH_DOT_SLASH:
+ *	Match a path starting with "./"
+ * PATH_MATCH_STARTS_WITH_DOT_DOT_SLASH:
+ *	Match a path starting with "../"
+ *
+ * The "/" in the above is adjusted based on the "*_NATIVE" and
+ * "*_XPLATFORM" flags.
+ */
+enum path_match_flags {
+	PATH_MATCH_NATIVE = 1 << 0,
+	PATH_MATCH_XPLATFORM = 1 << 1,
+	PATH_MATCH_STARTS_WITH_DOT_SLASH = 1 << 2,
+	PATH_MATCH_STARTS_WITH_DOT_DOT_SLASH = 1 << 3,
+};
+#define PATH_MATCH_KINDS_MASK (PATH_MATCH_STARTS_WITH_DOT_SLASH | \
+	PATH_MATCH_STARTS_WITH_DOT_DOT_SLASH)
+#define PATH_MATCH_PLATFORM_MASK (PATH_MATCH_NATIVE | PATH_MATCH_XPLATFORM)
+
+/**
+ * path_match_flags() checks if a given "path" matches a given "enum
+ * path_match_flags" criteria.
+ */
+int path_match_flags(const char *const path, const enum path_match_flags f);
+
+/**
+ * starts_with_dot_slash_native(): convenience wrapper for
+ * path_match_flags() with PATH_MATCH_STARTS_WITH_DOT_SLASH and
+ * PATH_MATCH_NATIVE.
+ */
+static inline int starts_with_dot_slash_native(const char *const path)
+{
+	const enum path_match_flags what = PATH_MATCH_STARTS_WITH_DOT_SLASH;
+
+	return path_match_flags(path, what | PATH_MATCH_NATIVE);
+}
+
+/**
+ * starts_with_dot_slash_native(): convenience wrapper for
+ * path_match_flags() with PATH_MATCH_STARTS_WITH_DOT_DOT_SLASH and
+ * PATH_MATCH_NATIVE.
+ */
+static inline int starts_with_dot_dot_slash_native(const char *const path)
+{
+	const enum path_match_flags what = PATH_MATCH_STARTS_WITH_DOT_DOT_SLASH;
+
+	return path_match_flags(path, what | PATH_MATCH_NATIVE);
+}
 #endif