config: Check for extattr_{get,list}_{file,link}()

This lets us implement -xattr on DragonFly BSD.

7 files changed, 97 insertions, 11 deletions

diff --git a/config/extattr-get-file.c b/config/extattr-get-file.c
new file mode 100644
index 0000000..ac9cf96
--- /dev/null
+++ b/config/extattr-get-file.c
@@ -0,0 +1,10 @@
+// Copyright © Tavian Barnes <tavianator@tavianator.com>
+// SPDX-License-Identifier: 0BSD
+
+#include <stddef.h>
+#include <sys/types.h>
+#include <sys/extattr.h>
+
+int main(void) {
+	return extattr_get_file("file", EXTATTR_NAMESPACE_USER, "xattr", NULL, 0);
+}
diff --git a/config/extattr-get-link.c b/config/extattr-get-link.c
new file mode 100644
index 0000000..c35be5b
--- /dev/null
+++ b/config/extattr-get-link.c
@@ -0,0 +1,10 @@
+// Copyright © Tavian Barnes <tavianator@tavianator.com>
+// SPDX-License-Identifier: 0BSD
+
+#include <stddef.h>
+#include <sys/types.h>
+#include <sys/extattr.h>
+
+int main(void) {
+	return extattr_get_link("link", EXTATTR_NAMESPACE_USER, "xattr", NULL, 0);
+}
diff --git a/config/extattr-list-file.c b/config/extattr-list-file.c
new file mode 100644
index 0000000..e68a8bb
--- /dev/null
+++ b/config/extattr-list-file.c
@@ -0,0 +1,10 @@
+// Copyright © Tavian Barnes <tavianator@tavianator.com>
+// SPDX-License-Identifier: 0BSD
+
+#include <stddef.h>
+#include <sys/types.h>
+#include <sys/extattr.h>
+
+int main(void) {
+	return extattr_list_file("file", EXTATTR_NAMESPACE_USER, NULL, 0);
+}
diff --git a/config/extattr-list-link.c b/config/extattr-list-link.c
new file mode 100644
index 0000000..49f0ec2
--- /dev/null
+++ b/config/extattr-list-link.c
@@ -0,0 +1,10 @@
+// Copyright © Tavian Barnes <tavianator@tavianator.com>
+// SPDX-License-Identifier: 0BSD
+
+#include <stddef.h>
+#include <sys/types.h>
+#include <sys/extattr.h>
+
+int main(void) {
+	return extattr_list_link("link", EXTATTR_NAMESPACE_USER, NULL, 0);
+}
diff --git a/config/header.mk b/config/header.mk
index bba03ef..4da0fd2 100644
--- a/config/header.mk
+++ b/config/header.mk
@@ -12,6 +12,10 @@ HEADERS := \
     ${GEN}/acl-is-trivial-np.h \
     ${GEN}/aligned-alloc.h \
     ${GEN}/confstr.h \
+    ${GEN}/extattr-get-file.h \
+    ${GEN}/extattr-get-link.h \
+    ${GEN}/extattr-list-file.h \
+    ${GEN}/extattr-list-link.h \
     ${GEN}/fdclosedir.h \
     ${GEN}/getdents.h \
     ${GEN}/getdents64.h \
diff --git a/src/fsade.c b/src/fsade.c
index 51b629f..02b12d0 100644
--- a/src/fsade.c
+++ b/src/fsade.c
@@ -327,17 +327,62 @@ int bfs_check_capabilities(const struct BFTW *ftwbuf) {
 
 #if BFS_CAN_CHECK_XATTRS
 
+#if BFS_USE_SYS_EXTATTR_H
+
+/** Wrapper for extattr_list_{file,link}. */
+static ssize_t bfs_extattr_list(const char *path, enum bfs_type type, int namespace) {
+	if (type == BFS_LNK) {
+#if BFS_HAS_EXTATTR_LIST_LINK
+		return extattr_list_link(path, namespace, NULL, 0);
+#elif BFS_HAS_EXTATTR_GET_LINK
+		return extattr_get_link(path, namespace, "", NULL, 0);
+#else
+		return 0;
+#endif
+	}
+
+#if BFS_HAS_EXTATTR_LIST_FILE
+	return extattr_list_file(path, namespace, NULL, 0);
+#elif BFS_HAS_EXTATTR_GET_FILE
+	// From man extattr(2):
+	//
+	//     In earlier versions of this API, passing an empty string for the
+	//     attribute name to extattr_get_file() would return the list of attributes
+	//     defined for the target object.  This interface has been deprecated in
+	//     preference to using the explicit list API, and should not be used.
+	return extattr_get_file(path, namespace, "", NULL, 0);
+#else
+	return 0;
+#endif
+}
+
+/** Wrapper for extattr_get_{file,link}. */
+static ssize_t bfs_extattr_get(const char *path, enum bfs_type type, int namespace, const char *name) {
+	if (type == BFS_LNK) {
+#if BFS_HAS_EXTATTR_GET_LINK
+		return extattr_get_link(path, namespace, name, NULL, 0);
+#else
+		return 0;
+#endif
+	}
+
+#if BFS_HAS_EXTATTR_GET_FILE
+	return extattr_get_file(path, namespace, name, NULL, 0);
+#else
+	return 0;
+#endif
+}
+
+#endif // BFS_USE_SYS_EXTATTR_H
+
 int bfs_check_xattrs(const struct BFTW *ftwbuf) {
 	const char *path = fake_at(ftwbuf);
 	ssize_t len;
 
 #if BFS_USE_SYS_EXTATTR_H
-	ssize_t (*extattr_list)(const char *, int, void *, size_t) =
-		ftwbuf->type == BFS_LNK ? extattr_list_link : extattr_list_file;
-
-	len = extattr_list(path, EXTATTR_NAMESPACE_SYSTEM, NULL, 0);
+	len = bfs_extattr_list(path, ftwbuf->type, EXTATTR_NAMESPACE_SYSTEM);
 	if (len <= 0) {
-		len = extattr_list(path, EXTATTR_NAMESPACE_USER, NULL, 0);
+		len = bfs_extattr_list(path, ftwbuf->type, EXTATTR_NAMESPACE_USER);
 	}
 #elif __APPLE__
 	int options = ftwbuf->type == BFS_LNK ? XATTR_NOFOLLOW : 0;
@@ -371,12 +416,9 @@ int bfs_check_xattr_named(const struct BFTW *ftwbuf, const char *name) {
 	ssize_t len;
 
 #if BFS_USE_SYS_EXTATTR_H
-	ssize_t (*extattr_get)(const char *, int, const char *, void *, size_t) =
-		ftwbuf->type == BFS_LNK ? extattr_get_link : extattr_get_file;
-
-	len = extattr_get(path, EXTATTR_NAMESPACE_SYSTEM, name, NULL, 0);
+	len = bfs_extattr_get(path, ftwbuf->type, EXTATTR_NAMESPACE_SYSTEM, name);
 	if (len < 0) {
-		len = extattr_get(path, EXTATTR_NAMESPACE_USER, name, NULL, 0);
+		len = bfs_extattr_get(path, ftwbuf->type, EXTATTR_NAMESPACE_USER, name);
 	}
 #elif __APPLE__
 	int options = ftwbuf->type == BFS_LNK ? XATTR_NOFOLLOW : 0;
diff --git a/src/prelude.h b/src/prelude.h
index 390666b..9e64260 100644
--- a/src/prelude.h
+++ b/src/prelude.h
@@ -106,7 +106,7 @@ extern const char bfs_version[];
 #  define BFS_USE_SYS_CAPABILITY_H (BFS_HAS_SYS_CAPABILITY_H && !__FreeBSD__ && (!__linux__ || BFS_USE_LIBCAP))
 #endif
 #ifndef BFS_USE_SYS_EXTATTR_H
-#  define BFS_USE_SYS_EXTATTR_H (BFS_HAS_SYS_EXTATTR_H && !__DragonFly__)
+#  define BFS_USE_SYS_EXTATTR_H BFS_HAS_SYS_EXTATTR_H
 #endif
 #ifndef BFS_USE_SYS_MKDEV_H
 #  define BFS_USE_SYS_MKDEV_H BFS_HAS_SYS_MKDEV_H