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+#ifndef DIR_ITERATOR_H
+#define DIR_ITERATOR_H
+
+#include "strbuf.h"
+
+/*
+ * Iterate over a directory tree.
+ *
+ * Iterate over a directory tree, recursively, including paths of all
+ * types and hidden paths. Skip "." and ".." entries and don't follow
+ * symlinks except for the original path. Note that the original path
+ * is not included in the iteration.
+ *
+ * Every time dir_iterator_advance() is called, update the members of
+ * the dir_iterator structure to reflect the next path in the
+ * iteration. The order that paths are iterated over within a
+ * directory is undefined, directory paths are always given before
+ * their contents.
+ *
+ * A typical iteration looks like this:
+ *
+ * int ok;
+ * unsigned int flags = DIR_ITERATOR_PEDANTIC;
+ * struct dir_iterator *iter = dir_iterator_begin(path, flags);
+ *
+ * if (!iter)
+ * goto error_handler;
+ *
+ * while ((ok = dir_iterator_advance(iter)) == ITER_OK) {
+ * if (want_to_stop_iteration()) {
+ * ok = dir_iterator_abort(iter);
+ * break;
+ * }
+ *
+ * // Access information about the current path:
+ * if (S_ISDIR(iter->st.st_mode))
+ * printf("%s is a directory\n", iter->relative_path);
+ * }
+ *
+ * if (ok != ITER_DONE)
+ * handle_error();
+ *
+ * Callers are allowed to modify iter->path while they are working,
+ * but they must restore it to its original contents before calling
+ * dir_iterator_advance() again.
+ */
+
+/*
+ * Flags for dir_iterator_begin:
+ *
+ * - DIR_ITERATOR_PEDANTIC: override dir-iterator's default behavior
+ * in case of an error at dir_iterator_advance(), which is to keep
+ * looking for a next valid entry. With this flag, resources are freed
+ * and ITER_ERROR is returned immediately. In both cases, a meaningful
+ * warning is emitted. Note: ENOENT errors are always ignored so that
+ * the API users may remove files during iteration.
+ *
+ * - DIR_ITERATOR_FOLLOW_SYMLINKS: make dir-iterator follow symlinks.
+ * i.e., linked directories' contents will be iterated over and
+ * iter->base.st will contain information on the referred files,
+ * not the symlinks themselves, which is the default behavior. Broken
+ * symlinks are ignored.
+ *
+ * Note: setting DIR_ITERATOR_FOLLOW_SYMLINKS affects resolving the
+ * starting path as well (e.g., attempting to iterate starting at a
+ * symbolic link pointing to a directory without FOLLOW_SYMLINKS will
+ * result in an error).
+ *
+ * Warning: circular symlinks are also followed when
+ * DIR_ITERATOR_FOLLOW_SYMLINKS is set. The iteration may end up with
+ * an ELOOP if they happen and DIR_ITERATOR_PEDANTIC is set.
+ */
+#define DIR_ITERATOR_PEDANTIC (1 << 0)
+#define DIR_ITERATOR_FOLLOW_SYMLINKS (1 << 1)
+
+struct dir_iterator {
+ /* The current path: */
+ struct strbuf path;
+
+ /*
+ * The current path relative to the starting path. This part
+ * of the path always uses "/" characters to separate path
+ * components:
+ */
+ const char *relative_path;
+
+ /* The current basename: */
+ const char *basename;
+
+ /*
+ * The result of calling lstat() on path; or stat(), if the
+ * DIR_ITERATOR_FOLLOW_SYMLINKS flag was set at
+ * dir_iterator's initialization.
+ */
+ struct stat st;
+};
+
+/*
+ * Start a directory iteration over path with the combination of
+ * options specified by flags. On success, return a dir_iterator
+ * that holds the internal state of the iteration. In case of
+ * failure, return NULL and set errno accordingly.
+ *
+ * The iteration includes all paths under path, not including path
+ * itself and not including "." or ".." entries.
+ *
+ * Parameters are:
+ * - path is the starting directory. An internal copy will be made.
+ * - flags is a combination of the possible flags to initialize a
+ * dir-iterator or 0 for default behavior.
+ */
+struct dir_iterator *dir_iterator_begin(const char *path, unsigned int flags);
+
+/*
+ * Advance the iterator to the first or next item and return ITER_OK.
+ * If the iteration is exhausted, free the dir_iterator and any
+ * resources associated with it and return ITER_DONE.
+ *
+ * It is a bug to use iterator or call this function again after it
+ * has returned ITER_DONE or ITER_ERROR (which may be returned iff
+ * the DIR_ITERATOR_PEDANTIC flag was set).
+ */
+int dir_iterator_advance(struct dir_iterator *iterator);
+
+/*
+ * End the iteration before it has been exhausted. Free the
+ * dir_iterator and any associated resources and return ITER_DONE. On
+ * error, free the dir_iterator and return ITER_ERROR.
+ */
+int dir_iterator_abort(struct dir_iterator *iterator);
+
+#endif