path: export the dotgit-checking functions

These checks are preformed by libgit2 on checkout, but they're also useful for
performing checks in applications which do not involve checkout.

Expose them under `sys/` as it's still fairly in the weeds even for this
library.

include/git2/sys/path.h

+/*
+ * Copyright (C) the libgit2 contributors. All rights reserved.
+ *
+ * This file is part of libgit2, distributed under the GNU GPL v2 with
+ * a Linking Exception. For full terms see the included COPYING file.
+ */
+
+#ifndef INCLUDE_sys_git_path_h__
+#define INCLUDE_sys_git_path_h__
+
+#include "git2/common.h"
+
+GIT_BEGIN_DECL
+
+/**
+ * The kinds of git-specific files we know about.
+ *
+ * The order needs to stay the same to not break the `gitfiles`
+ * array in path.c
+ */
+typedef enum {
+	/** Check for the .gitignore file */
+	GIT_PATH_GITFILE_GITIGNORE,
+	/** Check for the .gitmodules file */
+	GIT_PATH_GITFILE_GITMODULES,
+	/** Check for the .gitattributes file */
+	GIT_PATH_GITFILE_GITATTRIBUTES
+} git_path_gitfile;
+
+/**
+ * The kinds of checks to perform according to which filesystem we are trying to
+ * protect.
+ */
+typedef enum {
+	/** Do both NTFS- and HFS-specific checks */
+	GIT_PATH_FS_GENERIC,
+	/** Do NTFS-specific checks only */
+	GIT_PATH_FS_NTFS,
+	/** Do HFS-specific checks only */
+	GIT_PATH_FS_HFS
+} git_path_fs;
+
+/**
+ * Check whether a path component corresponds to a .git$SUFFIX
+ * file.
+ *
+ * As some filesystems do special things to filenames when
+ * writing files to disk, you cannot always do a plain string
+ * comparison to verify whether a file name matches an expected
+ * path or not. This function can do the comparison for you,
+ * depending on the filesystem you're on.
+ *
+ * @param path the path component to check
+ * @param pathlen the length of `path` that is to be checked
+ * @param gitfile which file to check against
+ * @param fs which filesystem-specific checks to use
+ * @return 0 in case the file does not match, a positive value if
+ *         it does; -1 in case of an error
+ */
+GIT_EXTERN(int) git_path_is_gitfile(const char *path, size_t pathlen, git_path_gitfile gitfile, git_path_fs fs);
+
+GIT_END_DECL
+
+#endif	/* INCLUDE_sys_git_path */

src/path.h

@@ -13,6 +13,8 @@
 #include "buffer.h"
 #include "vector.h"
 
+#include "git2/sys/path.h"
+
 /**
  * Path manipulation utils
  *
@@ -645,42 +647,4 @@ extern bool git_path_isvalid(
  */
 int git_path_normalize_slashes(git_buf *out, const char *path);
 
-/*
- * The order needs to stay the same to not break the `gitfiles`
- * array in path.c
- */
-typedef enum {
-	GIT_PATH_GITFILE_GITIGNORE,
-	GIT_PATH_GITFILE_GITMODULES,
-	GIT_PATH_GITFILE_GITATTRIBUTES
-} git_path_gitfile;
-
-typedef enum {
-	/* Do both NTFS- and HFS-specific checks */
-	GIT_PATH_FS_GENERIC,
-	/* Do NTFS-specific checks only */
-	GIT_PATH_FS_NTFS,
-	/* Do HFS-specific checks only */
-	GIT_PATH_FS_HFS
-} git_path_fs;
-
-/**
- * Check whether a path component corresponds to a .git$SUFFIX
- * file.
- *
- * As some filesystems do special things to filenames when
- * writing files to disk, you cannot always do a plain string
- * comparison to verify whether a file name matches an expected
- * path or not. This function can do the comparison for you,
- * depending on the filesystem you're on.
- *
- * @param path the path component to check
- * @param pathlen the length of `path` that is to be checked
- * @param gitfile which file to check against
- * @param fs which filesystem-specific checks to use
- * @return 0 in case the file does not match, a positive value if
- *         it does; -1 in case of an error
- */
-extern int git_path_is_gitfile(const char *path, size_t pathlen, git_path_gitfile gitfile, git_path_fs fs);
-
 #endif