dir: New DIR* facade

12 files changed, 473 insertions, 302 deletions

diff --git a/Makefile b/Makefile
index 5df2812..e78605e 100644
--- a/Makefile
+++ b/Makefile
@@ -142,6 +142,7 @@ bfs: \
     ctx.o \
     darray.o \
     diag.o \
+    dir.o \
     dstring.o \
     eval.o \
     exec.o \
diff --git a/bftw.c b/bftw.c
index aac6799..2e35594 100644
--- a/bftw.c
+++ b/bftw.c
@@ -33,13 +33,13 @@
  */
 
 #include "bftw.h"
+#include "dir.h"
 #include "dstring.h"
 #include "mtab.h"
 #include "stat.h"
 #include "trie.h"
 #include "util.h"
 #include <assert.h>
-#include <dirent.h>
 #include <errno.h>
 #include <fcntl.h>
 #include <stdbool.h>
@@ -70,7 +70,7 @@ struct bftw_file {
 	int fd;
 
 	/** This file's type, if known. */
-	enum bftw_type type;
+	enum bfs_type type;
 	/** The device number, for cycle detection. */
 	dev_t dev;
 	/** The inode number, for cycle detection. */
@@ -322,7 +322,7 @@ static struct bftw_file *bftw_file_new(struct bftw_cache *cache, struct bftw_fil
 	file->refcount = 1;
 	file->fd = -1;
 
-	file->type = BFTW_UNKNOWN;
+	file->type = BFS_UNKNOWN;
 	file->dev = -1;
 	file->ino = -1;
 
@@ -433,7 +433,7 @@ static int bftw_file_open(struct bftw_cache *cache, struct bftw_file *file, cons
 }
 
 /**
- * Open a DIR* for a bftw_file.
+ * Open a bftw_file as a directory.
  *
  * @param cache
  *         The cache to hold the file.
@@ -442,16 +442,16 @@ static int bftw_file_open(struct bftw_cache *cache, struct bftw_file *file, cons
  * @param path
  *         The full path to the directory.
  * @return
- *         The opened DIR *, or NULL on error.
+ *         The opened directory, or NULL on error.
  */
-static DIR *bftw_file_opendir(struct bftw_cache *cache, struct bftw_file *file, const char *path) {
+static struct bfs_dir *bftw_file_opendir(struct bftw_cache *cache, struct bftw_file *file, const char *path) {
 	int fd = bftw_file_open(cache, file, path);
 	if (fd < 0) {
 		return NULL;
 	}
 
 	// Now we dup() the fd and pass it to fdopendir().  This way we can
-	// close the DIR* as soon as we're done with it, reducing the memory
+	// close the bfs_dir as soon as we're done with it, reducing the memory
 	// footprint significantly, while keeping the fd around for future
 	// openat() calls.
 
@@ -467,7 +467,7 @@ static DIR *bftw_file_opendir(struct bftw_cache *cache, struct bftw_file *file,
 		return NULL;
 	}
 
-	DIR *ret = fdopendir(dfd);
+	struct bfs_dir *ret = bfs_opendir(dfd, NULL);
 	if (!ret) {
 		int error = errno;
 		close(dfd);
@@ -618,9 +618,11 @@ struct bftw_state {
 	struct bftw_file *previous;
 
 	/** The currently open directory. */
-	DIR *dir;
+	struct bfs_dir *dir;
 	/** The current directory entry. */
-	struct dirent *de;
+	struct bfs_dirent *de;
+	/** Storage for the directory entry. */
+	struct bfs_dirent de_storage;
 	/** Any error encountered while reading the directory. */
 	int direrror;
 
@@ -645,7 +647,7 @@ static int bftw_state_init(struct bftw_state *state, const struct bftw_args *arg
 		goto err;
 	}
 
-	// Reserve 1 fd for the open DIR *
+	// Reserve 1 fd for the open bfs_dir
 	if (bftw_cache_init(&state->cache, args->nopenfd - 1) != 0) {
 		goto err;
 	}
@@ -673,103 +675,6 @@ err:
 	return -1;
 }
 
-enum bftw_type bftw_mode_to_type(mode_t mode) {
-	switch (mode & S_IFMT) {
-#ifdef S_IFBLK
-	case S_IFBLK:
-		return BFTW_BLK;
-#endif
-#ifdef S_IFCHR
-	case S_IFCHR:
-		return BFTW_CHR;
-#endif
-#ifdef S_IFDIR
-	case S_IFDIR:
-		return BFTW_DIR;
-#endif
-#ifdef S_IFDOOR
-	case S_IFDOOR:
-		return BFTW_DOOR;
-#endif
-#ifdef S_IFIFO
-	case S_IFIFO:
-		return BFTW_FIFO;
-#endif
-#ifdef S_IFLNK
-	case S_IFLNK:
-		return BFTW_LNK;
-#endif
-#ifdef S_IFPORT
-	case S_IFPORT:
-		return BFTW_PORT;
-#endif
-#ifdef S_IFREG
-	case S_IFREG:
-		return BFTW_REG;
-#endif
-#ifdef S_IFSOCK
-	case S_IFSOCK:
-		return BFTW_SOCK;
-#endif
-#ifdef S_IFWHT
-	case S_IFWHT:
-		return BFTW_WHT;
-#endif
-
-	default:
-		return BFTW_UNKNOWN;
-	}
-}
-
-static enum bftw_type bftw_dirent_type(const struct dirent *de) {
-#if defined(_DIRENT_HAVE_D_TYPE) || defined(DT_UNKNOWN)
-	switch (de->d_type) {
-#ifdef DT_BLK
-	case DT_BLK:
-		return BFTW_BLK;
-#endif
-#ifdef DT_CHR
-	case DT_CHR:
-		return BFTW_CHR;
-#endif
-#ifdef DT_DIR
-	case DT_DIR:
-		return BFTW_DIR;
-#endif
-#ifdef DT_DOOR
-	case DT_DOOR:
-		return BFTW_DOOR;
-#endif
-#ifdef DT_FIFO
-	case DT_FIFO:
-		return BFTW_FIFO;
-#endif
-#ifdef DT_LNK
-	case DT_LNK:
-		return BFTW_LNK;
-#endif
-#ifdef DT_PORT
-	case DT_PORT:
-		return BFTW_PORT;
-#endif
-#ifdef DT_REG
-	case DT_REG:
-		return BFTW_REG;
-#endif
-#ifdef DT_SOCK
-	case DT_SOCK:
-		return BFTW_SOCK;
-#endif
-#ifdef DT_WHT
-	case DT_WHT:
-		return BFTW_WHT;
-#endif
-	}
-#endif
-
-	return BFTW_UNKNOWN;
-}
-
 /** Cached bfs_stat(). */
 static const struct bfs_stat *bftw_stat_impl(struct BFTW *ftwbuf, struct bftw_stat *cache, enum bfs_stat_flags flags) {
 	if (!cache->buf) {
@@ -817,20 +722,20 @@ const struct bfs_stat *bftw_cached_stat(const struct BFTW *ftwbuf, enum bfs_stat
 	}
 }
 
-enum bftw_type bftw_type(const struct BFTW *ftwbuf, enum bfs_stat_flags flags) {
+enum bfs_type bftw_type(const struct BFTW *ftwbuf, enum bfs_stat_flags flags) {
 	if (ftwbuf->stat_flags & BFS_STAT_NOFOLLOW) {
-		if ((flags & BFS_STAT_NOFOLLOW) || ftwbuf->type != BFTW_LNK) {
+		if ((flags & BFS_STAT_NOFOLLOW) || ftwbuf->type != BFS_LNK) {
 			return ftwbuf->type;
 		}
-	} else if ((flags & (BFS_STAT_NOFOLLOW | BFS_STAT_TRYFOLLOW)) == BFS_STAT_TRYFOLLOW || ftwbuf->type == BFTW_LNK) {
+	} else if ((flags & (BFS_STAT_NOFOLLOW | BFS_STAT_TRYFOLLOW)) == BFS_STAT_TRYFOLLOW || ftwbuf->type == BFS_LNK) {
 		return ftwbuf->type;
 	}
 
 	const struct bfs_stat *statbuf = bftw_stat(ftwbuf, flags);
 	if (statbuf) {
-		return bftw_mode_to_type(statbuf->mode);
+		return bfs_mode_to_type(statbuf->mode);
 	} else {
-		return BFTW_ERROR;
+		return BFS_ERROR;
 	}
 }
 
@@ -865,15 +770,15 @@ static bool bftw_need_stat(const struct bftw_state *state) {
 	}
 
 	const struct BFTW *ftwbuf = &state->ftwbuf;
-	if (ftwbuf->type == BFTW_UNKNOWN) {
+	if (ftwbuf->type == BFS_UNKNOWN) {
 		return true;
 	}
 
-	if (ftwbuf->type == BFTW_LNK && !(ftwbuf->stat_flags & BFS_STAT_NOFOLLOW)) {
+	if (ftwbuf->type == BFS_LNK && !(ftwbuf->stat_flags & BFS_STAT_NOFOLLOW)) {
 		return true;
 	}
 
-	if (ftwbuf->type == BFTW_DIR) {
+	if (ftwbuf->type == BFS_DIR) {
 		if (state->flags & (BFTW_DETECT_CYCLES | BFTW_SKIP_MOUNTS | BFTW_PRUNE_MOUNTS)) {
 			return true;
 		}
@@ -930,14 +835,14 @@ static int bftw_ensure_open(struct bftw_cache *cache, struct bftw_file *file, co
  */
 static void bftw_init_ftwbuf(struct bftw_state *state, enum bftw_visit visit) {
 	struct bftw_file *file = state->file;
-	const struct dirent *de = state->de;
+	const struct bfs_dirent *de = state->de;
 
 	struct BFTW *ftwbuf = &state->ftwbuf;
 	ftwbuf->path = state->path;
 	ftwbuf->root = file ? file->root->name : ftwbuf->path;
 	ftwbuf->depth = 0;
 	ftwbuf->visit = visit;
-	ftwbuf->type = BFTW_UNKNOWN;
+	ftwbuf->type = BFS_UNKNOWN;
 	ftwbuf->error = state->direrror;
 	ftwbuf->at_fd = AT_FDCWD;
 	ftwbuf->at_path = ftwbuf->path;
@@ -949,7 +854,7 @@ static void bftw_init_ftwbuf(struct bftw_state *state, enum bftw_visit visit) {
 	if (de) {
 		parent = file;
 		ftwbuf->depth = file->depth + 1;
-		ftwbuf->type = bftw_dirent_type(de);
+		ftwbuf->type = de->type;
 		ftwbuf->nameoff = bftw_child_nameoff(file);
 	} else if (file) {
 		parent = file->parent;
@@ -974,7 +879,7 @@ static void bftw_init_ftwbuf(struct bftw_state *state, enum bftw_visit visit) {
 	}
 
 	if (ftwbuf->error != 0) {
-		ftwbuf->type = BFTW_ERROR;
+		ftwbuf->type = BFS_ERROR;
 		return;
 	}
 
@@ -991,18 +896,18 @@ static void bftw_init_ftwbuf(struct bftw_state *state, enum bftw_visit visit) {
 	if (bftw_need_stat(state)) {
 		statbuf = bftw_stat(ftwbuf, ftwbuf->stat_flags);
 		if (statbuf) {
-			ftwbuf->type = bftw_mode_to_type(statbuf->mode);
+			ftwbuf->type = bfs_mode_to_type(statbuf->mode);
 		} else {
-			ftwbuf->type = BFTW_ERROR;
+			ftwbuf->type = BFS_ERROR;
 			ftwbuf->error = errno;
 			return;
 		}
 	}
 
-	if (ftwbuf->type == BFTW_DIR && (state->flags & BFTW_DETECT_CYCLES)) {
+	if (ftwbuf->type == BFS_DIR && (state->flags & BFTW_DETECT_CYCLES)) {
 		for (const struct bftw_file *ancestor = parent; ancestor; ancestor = ancestor->parent) {
 			if (ancestor->dev == statbuf->dev && ancestor->ino == statbuf->ino) {
-				ftwbuf->type = BFTW_ERROR;
+				ftwbuf->type = BFS_ERROR;
 				ftwbuf->error = ELOOP;
 				return;
 			}
@@ -1051,8 +956,8 @@ static enum bftw_action bftw_visit(struct bftw_state *state, const char *name, e
 	const struct BFTW *ftwbuf = &state->ftwbuf;
 	bftw_init_ftwbuf(state, visit);
 
-	// Never give the callback BFTW_ERROR unless BFTW_RECOVER is specified
-	if (ftwbuf->type == BFTW_ERROR && !(state->flags & BFTW_RECOVER)) {
+	// Never give the callback BFS_ERROR unless BFTW_RECOVER is specified
+	if (ftwbuf->type == BFS_ERROR && !(state->flags & BFTW_RECOVER)) {
 		state->error = ftwbuf->error;
 		return BFTW_STOP;
 	}
@@ -1073,7 +978,7 @@ static enum bftw_action bftw_visit(struct bftw_state *state, const char *name, e
 		return BFTW_STOP;
 	}
 
-	if (visit != BFTW_PRE || ftwbuf->type != BFTW_DIR) {
+	if (visit != BFTW_PRE || ftwbuf->type != BFS_DIR) {
 		ret = BFTW_PRUNE;
 		goto done;
 	}
@@ -1103,7 +1008,7 @@ static int bftw_push(struct bftw_state *state, const char *name, bool fill_id) {
 	}
 
 	if (state->de) {
-		file->type = bftw_dirent_type(state->de);
+		file->type = state->de->type;
 	}
 
 	if (fill_id) {
@@ -1190,14 +1095,17 @@ static int bftw_readdir(struct bftw_state *state) {
 		return -1;
 	}
 
-	if (xreaddir(state->dir, &state->de) != 0) {
-		state->direrror = errno;
-		return -1;
-	} else if (state->de) {
-		return 1;
+	int ret = bfs_readdir(state->dir, &state->de_storage);
+	if (ret > 0) {
+		state->de = &state->de_storage;
+	} else if (ret == 0) {
+		state->de = NULL;
 	} else {
-		return 0;
+		state->de = NULL;
+		state->direrror = errno;
 	}
+
+	return ret;
 }
 
 /**
@@ -1220,7 +1128,7 @@ enum bftw_release_flags {
 static enum bftw_action bftw_closedir(struct bftw_state *state, enum bftw_release_flags flags) {
 	enum bftw_action ret = BFTW_CONTINUE;
 
-	if (state->dir && closedir(state->dir) != 0) {
+	if (state->dir && bfs_closedir(state->dir) != 0) {
 		state->direrror = errno;
 	}
 	state->de = NULL;
@@ -1352,7 +1260,7 @@ static int bftw_stream(const struct bftw_args *args) {
 
 		bftw_batch_start(&state);
 		while (bftw_readdir(&state) > 0) {
-			const char *name = state.de->d_name;
+			const char *name = state.de->name;
 
 			switch (bftw_visit(&state, name, BFTW_PRE)) {
 			case BFTW_CONTINUE:
@@ -1415,7 +1323,7 @@ static int bftw_batch(const struct bftw_args *args) {
 
 		bftw_batch_start(&state);
 		while (bftw_readdir(&state) > 0) {
-			if (bftw_push(&state, state.de->d_name, false) != 0) {
+			if (bftw_push(&state, state.de->name, false) != 0) {
 				goto done;
 			}
 		}
@@ -1479,7 +1387,7 @@ static enum bftw_action bftw_ids_callback(const struct BFTW *ftwbuf, void *ptr)
 		mutbuf->visit = state->visit;
 	}
 
-	if (ftwbuf->type == BFTW_ERROR) {
+	if (ftwbuf->type == BFS_ERROR) {
 		if (ftwbuf->depth + 1 >= state->min_depth) {
 			return state->delegate(ftwbuf, state->ptr);
 		} else {
@@ -1506,13 +1414,13 @@ static enum bftw_action bftw_ids_callback(const struct BFTW *ftwbuf, void *ptr)
 
 	switch (ret) {
 	case BFTW_CONTINUE:
-		if (ftwbuf->type == BFTW_DIR && ftwbuf->depth + 1 >= state->max_depth) {
+		if (ftwbuf->type == BFS_DIR && ftwbuf->depth + 1 >= state->max_depth) {
 			state->bottom = false;
 			ret = BFTW_PRUNE;
 		}
 		break;
 	case BFTW_PRUNE:
-		if (ftwbuf->type == BFTW_DIR) {
+		if (ftwbuf->type == BFS_DIR) {
 			if (!trie_insert_str(&state->pruned, ftwbuf->path)) {
 				state->error = errno;
 				state->quit = true;
diff --git a/bftw.h b/bftw.h
index 098d12c..30fb39b 100644
--- a/bftw.h
+++ b/bftw.h
@@ -21,46 +21,12 @@
 #ifndef BFS_BFTW_H
 #define BFS_BFTW_H
 
+#include "dir.h"
 #include "stat.h"
 #include <stddef.h>
 #include <sys/types.h>
 
 /**
- * Possible file types.
- */
-enum bftw_type {
-	/** An error occurred for this file. */
-	BFTW_ERROR = -1,
-	/** Unknown type. */
-	BFTW_UNKNOWN,
-	/** Block device. */
-	BFTW_BLK,
-	/** Character device. */
-	BFTW_CHR,
-	/** Directory. */
-	BFTW_DIR,
-	/** Solaris door. */
-	BFTW_DOOR,
-	/** Pipe. */
-	BFTW_FIFO,
-	/** Symbolic link. */
-	BFTW_LNK,
-	/** Solaris event port. */
-	BFTW_PORT,
-	/** Regular file. */
-	BFTW_REG,
-	/** Socket. */
-	BFTW_SOCK,
-	/** BSD whiteout. */
-	BFTW_WHT,
-};
-
-/**
- * Convert a bfs_stat() mode to a bftw_type.
- */
-enum bftw_type bftw_mode_to_type(mode_t mode);
-
-/**
  * Possible visit occurrences.
  */
 enum bftw_visit {
@@ -99,7 +65,7 @@ struct BFTW {
 	enum bftw_visit visit;
 
 	/** The file type. */
-	enum bftw_type type;
+	enum bfs_type type;
 	/** The errno that occurred, if type == BFTW_ERROR. */
 	int error;
 
@@ -154,7 +120,7 @@ const struct bfs_stat *bftw_cached_stat(const struct BFTW *ftwbuf, enum bfs_stat
  * @return
  *         The type of the file, or BFTW_ERROR if an error occurred.
  */
-enum bftw_type bftw_type(const struct BFTW *ftwbuf, enum bfs_stat_flags flags);
+enum bfs_type bftw_type(const struct BFTW *ftwbuf, enum bfs_stat_flags flags);
 
 /**
  * Walk actions returned by the bftw() callback.
diff --git a/color.c b/color.c
index 1d06e51..cfedba1 100644
--- a/color.c
+++ b/color.c
@@ -16,6 +16,7 @@
 
 #include "color.h"
 #include "bftw.h"
+#include "dir.h"
 #include "dstring.h"
 #include "expr.h"
 #include "fsade.h"
@@ -581,8 +582,8 @@ static bool is_link_broken(const struct BFTW *ftwbuf) {
 
 /** Get the color for a file. */
 static const char *file_color(const struct colors *colors, const char *filename, const struct BFTW *ftwbuf, enum bfs_stat_flags flags) {
-	enum bftw_type type = bftw_type(ftwbuf, flags);
-	if (type == BFTW_ERROR) {
+	enum bfs_type type = bftw_type(ftwbuf, flags);
+	if (type == BFS_ERROR) {
 		goto error;
 	}
 
@@ -590,7 +591,7 @@ static const char *file_color(const struct colors *colors, const char *filename,
 	const char *color = NULL;
 
 	switch (type) {
-	case BFTW_REG:
+	case BFS_REG:
 		if (colors->setuid || colors->setgid || colors->executable || colors->multi_hard) {
 			statbuf = bftw_stat(ftwbuf, flags);
 			if (!statbuf) {
@@ -620,7 +621,7 @@ static const char *file_color(const struct colors *colors, const char *filename,
 
 		break;
 
-	case BFTW_DIR:
+	case BFS_DIR:
 		if (colors->sticky_other_writable || colors->other_writable || colors->sticky) {
 			statbuf = bftw_stat(ftwbuf, flags);
 			if (!statbuf) {
@@ -640,7 +641,7 @@ static const char *file_color(const struct colors *colors, const char *filename,
 
 		break;
 
-	case BFTW_LNK:
+	case BFS_LNK:
 		if (colors->orphan && is_link_broken(ftwbuf)) {
 			color = colors->orphan;
 		} else {
@@ -648,19 +649,19 @@ static const char *file_color(const struct colors *colors, const char *filename,
 		}
 		break;
 
-	case BFTW_BLK:
+	case BFS_BLK:
 		color = colors->blockdev;
 		break;
-	case BFTW_CHR:
+	case BFS_CHR:
 		color = colors->chardev;
 		break;
-	case BFTW_FIFO:
+	case BFS_FIFO:
 		color = colors->pipe;
 		break;
-	case BFTW_SOCK:
+	case BFS_SOCK:
 		color = colors->socket;
 		break;
-	case BFTW_DOOR:
+	case BFS_DOOR:
 		color = colors->door;
 		break;
 
@@ -733,7 +734,7 @@ static int print_colored(CFILE *cfile, const char *esc, const char *str, size_t
 static ssize_t first_broken_offset(const char *path, const struct BFTW *ftwbuf, enum bfs_stat_flags flags, size_t max) {
 	ssize_t ret = max;
 
-	if (bftw_type(ftwbuf, flags) != BFTW_ERROR) {
+	if (bftw_type(ftwbuf, flags) != BFS_ERROR) {
 		goto out;
 	}
 
@@ -840,7 +841,7 @@ static int print_path(CFILE *cfile, const struct BFTW *ftwbuf) {
 	}
 
 	enum bfs_stat_flags flags = ftwbuf->stat_flags;
-	if (colors && colors->link_as_target && ftwbuf->type == BFTW_LNK) {
+	if (colors && colors->link_as_target && ftwbuf->type == BFS_LNK) {
 		flags = BFS_STAT_TRYFOLLOW;
 	}
 
diff --git a/dir.c b/dir.c
new file mode 100644
index 0000000..23aa62d
--- /dev/null
+++ b/dir.c
@@ -0,0 +1,200 @@
+/****************************************************************************
+ * bfs                                                                      *
+ * Copyright (C) 2021 Tavian Barnes <tavianator@tavianator.com>             *
+ *                                                                          *
+ * Permission to use, copy, modify, and/or distribute this software for any *
+ * purpose with or without fee is hereby granted.                           *
+ *                                                                          *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES *
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF         *
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR  *
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES   *
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN    *
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF  *
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.           *
+ ****************************************************************************/
+
+#include "dir.h"
+#include "util.h"
+#include <dirent.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <stdbool.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+enum bfs_type bfs_mode_to_type(mode_t mode) {
+	switch (mode & S_IFMT) {
+#ifdef S_IFBLK
+	case S_IFBLK:
+		return BFS_BLK;
+#endif
+#ifdef S_IFCHR
+	case S_IFCHR:
+		return BFS_CHR;
+#endif
+#ifdef S_IFDIR
+	case S_IFDIR:
+		return BFS_DIR;
+#endif
+#ifdef S_IFDOOR
+	case S_IFDOOR:
+		return BFS_DOOR;
+#endif
+#ifdef S_IFIFO
+	case S_IFIFO:
+		return BFS_FIFO;
+#endif
+#ifdef S_IFLNK
+	case S_IFLNK:
+		return BFS_LNK;
+#endif
+#ifdef S_IFPORT
+	case S_IFPORT:
+		return BFS_PORT;
+#endif
+#ifdef S_IFREG
+	case S_IFREG:
+		return BFS_REG;
+#endif
+#ifdef S_IFSOCK
+	case S_IFSOCK:
+		return BFS_SOCK;
+#endif
+#ifdef S_IFWHT
+	case S_IFWHT:
+		return BFS_WHT;
+#endif
+
+	default:
+		return BFS_UNKNOWN;
+	}
+}
+
+struct bfs_dir {
+	DIR *dir;
+	struct dirent *ent;
+};
+
+struct bfs_dir *bfs_opendir(int at_fd, const char *at_path) {
+	struct bfs_dir *dir = malloc(sizeof(*dir));
+	if (!dir) {
+		return NULL;
+	}
+
+	int fd;
+	if (at_path) {
+		fd = openat(at_fd, at_path, O_RDONLY | O_CLOEXEC | O_DIRECTORY);
+	} else if (at_fd >= 0) {
+		fd = at_fd;
+	} else {
+		free(dir);
+		errno = EBADF;
+		return NULL;
+	}
+
+	if (fd < 0) {
+		free(dir);
+		return NULL;
+	}
+
+	dir->dir = fdopendir(fd);
+	if (!dir->dir) {
+		int error = errno;
+		close(fd);
+		free(dir);
+		errno = error;
+		return NULL;
+	}
+
+	dir->ent = NULL;
+
+	return dir;
+}
+
+int bfs_dirfd(const struct bfs_dir *dir) {
+	return dirfd(dir->dir);
+}
+
+static enum bfs_type dirent_type(const struct dirent *de) {
+#if defined(_DIRENT_HAVE_D_TYPE) || defined(DT_UNKNOWN)
+	switch (de->d_type) {
+#ifdef DT_BLK
+	case DT_BLK:
+		return BFS_BLK;
+#endif
+#ifdef DT_CHR
+	case DT_CHR:
+		return BFS_CHR;
+#endif
+#ifdef DT_DIR
+	case DT_DIR:
+		return BFS_DIR;
+#endif
+#ifdef DT_DOOR
+	case DT_DOOR:
+		return BFS_DOOR;
+#endif
+#ifdef DT_FIFO
+	case DT_FIFO:
+		return BFS_FIFO;
+#endif
+#ifdef DT_LNK
+	case DT_LNK:
+		return BFS_LNK;
+#endif
+#ifdef DT_PORT
+	case DT_PORT:
+		return BFS_PORT;
+#endif
+#ifdef DT_REG
+	case DT_REG:
+		return BFS_REG;
+#endif
+#ifdef DT_SOCK
+	case DT_SOCK:
+		return BFS_SOCK;
+#endif
+#ifdef DT_WHT
+	case DT_WHT:
+		return BFS_WHT;
+#endif
+	}
+#endif
+
+	return BFS_UNKNOWN;
+}
+
+int bfs_readdir(struct bfs_dir *dir, struct bfs_dirent *dirent) {
+	while (true) {
+		errno = 0;
+		dir->ent = readdir(dir->dir);
+		if (dir->ent) {
+			const char *name = dir->ent->d_name;
+			if (name[0] == '.' && (name[1] == '\0' || (name[1] == '.' && name[2] == '\0'))) {
+				continue;
+			}
+			if (dirent) {
+				dirent->type = dirent_type(dir->ent);
+				dirent->name = name;
+			}
+			return 1;
+		} else if (errno != 0) {
+			return -1;
+		} else {
+			return 0;
+		}
+	}
+}
+
+int bfs_closedir(struct bfs_dir *dir) {
+	int ret = closedir(dir->dir);
+	free(dir);
+	return ret;
+}
+
+int bfs_freedir(struct bfs_dir *dir) {
+	int ret = dup_cloexec(dirfd(dir->dir));
+	bfs_closedir(dir);
+	return ret;
+}
diff --git a/dir.h b/dir.h
new file mode 100644
index 0000000..5817013
--- /dev/null
+++ b/dir.h
@@ -0,0 +1,124 @@
+/****************************************************************************
+ * bfs                                                                      *
+ * Copyright (C) 2021 Tavian Barnes <tavianator@tavianator.com>             *
+ *                                                                          *
+ * Permission to use, copy, modify, and/or distribute this software for any *
+ * purpose with or without fee is hereby granted.                           *
+ *                                                                          *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES *
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF         *
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR  *
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES   *
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN    *
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF  *
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.           *
+ ****************************************************************************/
+
+/**
+ * Directories and their contents.
+ */
+
+#ifndef BFS_DIR_H
+#define BFS_DIR_H
+
+#include <sys/types.h>
+
+/**
+ * A directory.
+ */
+struct bfs_dir;
+
+/**
+ * File types.
+ */
+enum bfs_type {
+	/** An error occurred for this file. */
+	BFS_ERROR = -1,
+	/** Unknown type. */
+	BFS_UNKNOWN,
+	/** Block device. */
+	BFS_BLK,
+	/** Character device. */
+	BFS_CHR,
+	/** Directory. */
+	BFS_DIR,
+	/** Solaris door. */
+	BFS_DOOR,
+	/** Pipe. */
+	BFS_FIFO,
+	/** Symbolic link. */
+	BFS_LNK,
+	/** Solaris event port. */
+	BFS_PORT,
+	/** Regular file. */
+	BFS_REG,
+	/** Socket. */
+	BFS_SOCK,
+	/** BSD whiteout. */
+	BFS_WHT,
+};
+
+/**
+ * Convert a bfs_stat() mode to a bfs_type.
+ */
+enum bfs_type bfs_mode_to_type(mode_t mode);
+
+/**
+ * A directory entry.
+ */
+struct bfs_dirent {
+	/** The type of this file (possibly unknown). */
+	enum bfs_type type;
+	/** The name of this file. */
+	const char *name;
+};
+
+/**
+ * Open a directory.
+ *
+ * @param at_fd
+ *         The base directory for path resolution.
+ * @param at_path
+ *         The path of the directory to open, relative to at_fd.  Pass NULL to
+ *         open at_fd itself.
+ * @return
+ *         The opened directory, or NULL on failure.
+ */
+struct bfs_dir *bfs_opendir(int at_fd, const char *at_path);
+
+/**
+ * Get the file descriptor for a directory.
+ */
+int bfs_dirfd(const struct bfs_dir *dir);
+
+/**
+ * Read a directory entry.
+ *
+ * @param dir
+ *         The directory to read.
+ * @param[out] dirent
+ *         The directory entry to populate.
+ * @return
+ *         1 on success, 0 on EOF, or -1 on failure.
+ */
+int bfs_readdir(struct bfs_dir *dir, struct bfs_dirent *dirent);
+
+/**
+ * Close a directory.
+ *
+ * @return
+ *         0 on success, -1 on failure.
+ */
+int bfs_closedir(struct bfs_dir *dir);
+
+/**
+ * Free a directory, keeping an open file descriptor to it.
+ *
+ * @param dir
+ *         The directory to free.
+ * @return
+ *         The file descriptor on success, or -1 on failure.
+ */
+int bfs_freedir(struct bfs_dir *dir);
+
+#endif // BFS_DIR_H
diff --git a/eval.c b/eval.c
index 2bcfa8a..9e8b0b6 100644
--- a/eval.c
+++ b/eval.c
@@ -25,6 +25,7 @@
 #include "ctx.h"
 #include "darray.h"
 #include "diag.h"
+#include "dir.h"
 #include "dstring.h"
 #include "exec.h"
 #include "expr.h"
@@ -37,7 +38,6 @@
 #include "trie.h"
 #include "util.h"
 #include <assert.h>
-#include <dirent.h>
 #include <errno.h>
 #include <fcntl.h>
 #include <fnmatch.h>
@@ -345,10 +345,10 @@ bool eval_delete(const struct expr *expr, struct eval_state *state) {
 	int flag = 0;
 
 	// We need to know the actual type of the path, not what it points to
-	enum bftw_type type = bftw_type(ftwbuf, BFS_STAT_NOFOLLOW);
-	if (type == BFTW_DIR) {
+	enum bfs_type type = bftw_type(ftwbuf, BFS_STAT_NOFOLLOW);
+	if (type == BFS_DIR) {
 		flag |= AT_REMOVEDIR;
-	} else if (type == BFTW_ERROR) {
+	} else if (type == BFS_ERROR) {
 		eval_report_error(state);
 		return false;
 	}
@@ -415,29 +415,22 @@ bool eval_empty(const struct expr *expr, struct eval_state *state) {
 	bool ret = false;
 	const struct BFTW *ftwbuf = state->ftwbuf;
 
-	if (ftwbuf->type == BFTW_DIR) {
-		int dfd = openat(ftwbuf->at_fd, ftwbuf->at_path, O_RDONLY | O_CLOEXEC | O_DIRECTORY);
-		if (dfd < 0) {
-			eval_report_error(state);
-			goto done;
-		}
-
-		DIR *dir = fdopendir(dfd);
+	if (ftwbuf->type == BFS_DIR) {
+		struct bfs_dir *dir = bfs_opendir(ftwbuf->at_fd, ftwbuf->at_path);
 		if (!dir) {
 			eval_report_error(state);
-			close(dfd);
 			goto done;
 		}
 
-		struct dirent *de;
-		if (xreaddir(dir, &de) == 0) {
-			ret = !de;
-		} else {
+		int did_read = bfs_readdir(dir, NULL);
+		if (did_read < 0) {
 			eval_report_error(state);
+		} else {
+			ret = !did_read;
 		}
 
-		closedir(dir);
-	} else if (ftwbuf->type == BFTW_REG) {
+		bfs_closedir(dir);
+	} else if (ftwbuf->type == BFS_REG) {
 		const struct bfs_stat *statbuf = eval_stat(state);
 		if (statbuf) {
 			ret = statbuf->size == 0;
@@ -514,7 +507,7 @@ bool eval_lname(const struct expr *expr, struct eval_state *state) {
 	char *name = NULL;
 
 	const struct BFTW *ftwbuf = state->ftwbuf;
-	if (ftwbuf->type != BFTW_LNK) {
+	if (ftwbuf->type != BFS_LNK) {
 		goto done;
 	}
 
@@ -580,7 +573,7 @@ bool eval_perm(const struct expr *expr, struct eval_state *state) {
 
 	mode_t mode = statbuf->mode;
 	mode_t target;
-	if (state->ftwbuf->type == BFTW_DIR) {
+	if (state->ftwbuf->type == BFS_DIR) {
 		target = expr->dir_mode;
 	} else {
 		target = expr->file_mode;
@@ -648,7 +641,7 @@ bool eval_fls(const struct expr *expr, struct eval_state *state) {
 		}
 	}
 
-	if (ftwbuf->type == BFTW_BLK || ftwbuf->type == BFTW_CHR) {
+	if (ftwbuf->type == BFS_BLK || ftwbuf->type == BFS_CHR) {
 		int ma = bfs_major(statbuf->rdev);
 		int mi = bfs_minor(statbuf->rdev);
 		if (fprintf(file, " %3d, %3d", ma, mi) < 0) {
@@ -686,7 +679,7 @@ bool eval_fls(const struct expr *expr, struct eval_state *state) {
 		goto error;
 	}
 
-	if (ftwbuf->type == BFTW_LNK) {
+	if (ftwbuf->type == BFS_LNK) {
 		if (cfprintf(cfile, " -> %pL", ftwbuf) < 0) {
 			goto error;
 		}
@@ -914,8 +907,8 @@ bool eval_xattrname(const struct expr *expr, struct eval_state *state) {
 bool eval_xtype(const struct expr *expr, struct eval_state *state) {
 	const struct BFTW *ftwbuf = state->ftwbuf;
 	enum bfs_stat_flags flags = ftwbuf->stat_flags ^ (BFS_STAT_NOFOLLOW | BFS_STAT_TRYFOLLOW);
-	enum bftw_type type = bftw_type(ftwbuf, flags);
-	if (type == BFTW_ERROR) {
+	enum bfs_type type = bftw_type(ftwbuf, flags);
+	if (type == BFS_ERROR) {
 		eval_report_error(state);
 		return false;
 	} else {
@@ -1236,28 +1229,28 @@ static void debug_stats(const struct bfs_ctx *ctx, const struct BFTW *ftwbuf) {
 	}
 }
 
-#define DUMP_BFTW_MAP(value) [value] = #value
+#define DUMP_MAP(value) [value] = #value
 
 /**
- * Dump the bftw_type for -D search.
+ * Dump the bfs_type for -D search.
  */
-static const char *dump_bftw_type(enum bftw_type type) {
+static const char *dump_bfs_type(enum bfs_type type) {
 	static const char *types[] = {
-		DUMP_BFTW_MAP(BFTW_UNKNOWN),
-		DUMP_BFTW_MAP(BFTW_BLK),
-		DUMP_BFTW_MAP(BFTW_CHR),
-		DUMP_BFTW_MAP(BFTW_DIR),
-		DUMP_BFTW_MAP(BFTW_DOOR),
-		DUMP_BFTW_MAP(BFTW_FIFO),
-		DUMP_BFTW_MAP(BFTW_LNK),
-		DUMP_BFTW_MAP(BFTW_PORT),
-		DUMP_BFTW_MAP(BFTW_REG),
-		DUMP_BFTW_MAP(BFTW_SOCK),
-		DUMP_BFTW_MAP(BFTW_WHT),
+		DUMP_MAP(BFS_UNKNOWN),
+		DUMP_MAP(BFS_BLK),
+		DUMP_MAP(BFS_CHR),
+		DUMP_MAP(BFS_DIR),
+		DUMP_MAP(BFS_DOOR),
+		DUMP_MAP(BFS_FIFO),
+		DUMP_MAP(BFS_LNK),
+		DUMP_MAP(BFS_PORT),
+		DUMP_MAP(BFS_REG),
+		DUMP_MAP(BFS_SOCK),
+		DUMP_MAP(BFS_WHT),
 	};
 
-	if (type == BFTW_ERROR) {
-		return "BFTW_ERROR";
+	if (type == BFS_ERROR) {
+		return "BFS_ERROR";
 	} else {
 		return types[type];
 	}
@@ -1268,8 +1261,8 @@ static const char *dump_bftw_type(enum bftw_type type) {
  */
 static const char *dump_bftw_visit(enum bftw_visit visit) {
 	static const char *visits[] = {
-		DUMP_BFTW_MAP(BFTW_PRE),
-		DUMP_BFTW_MAP(BFTW_POST),
+		DUMP_MAP(BFTW_PRE),
+		DUMP_MAP(BFTW_POST),
 	};
 	return visits[visit];
 }
@@ -1279,9 +1272,9 @@ static const char *dump_bftw_visit(enum bftw_visit visit) {
  */
 static const char *dump_bftw_action(enum bftw_action action) {
 	static const char *actions[] = {
-		DUMP_BFTW_MAP(BFTW_CONTINUE),
-		DUMP_BFTW_MAP(BFTW_PRUNE),
-		DUMP_BFTW_MAP(BFTW_STOP),
+		DUMP_MAP(BFTW_CONTINUE),
+		DUMP_MAP(BFTW_PRUNE),
+		DUMP_MAP(BFTW_STOP),
 	};
 	return actions[action];
 }
@@ -1327,7 +1320,7 @@ static enum bftw_action eval_callback(const struct BFTW *ftwbuf, void *ptr) {