[PATCH] libfrog: emulate deprecated attrlist functionality in libattr

[PATCH] libfrog: emulate deprecated attrlist functionality in libattr

[Darrick J. Wong]

From: Darrick J. Wong <djwong@kernel.org>

Break our dependence on the (deprecated) libattr by emulating the
necessary pieces in libfrog.  It's a little sketchy to open-code these
symbols, but they're originally from XFS so we trust ourselves.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
---
 configure.ac          |    2 --
 debian/control        |    2 +-
 include/builddefs.in  |    1 -
 libfrog/Makefile      |    8 +++-----
 libfrog/fakelibattr.h |   34 ++++++++++++++++++++++++++++++++++
 libfrog/fsprops.c     |   17 +++++++++--------
 m4/package_attr.m4    |   25 -------------------------
 scrub/Makefile        |    4 ----
 scrub/phase5.c        |   28 +++++++++++-----------------
 9 files changed, 58 insertions(+), 63 deletions(-)
 create mode 100644 libfrog/fakelibattr.h
 delete mode 100644 m4/package_attr.m4

diff --git a/configure.ac b/configure.ac
index 33b01399ae3b..d021c519d538 100644
--- a/configure.ac
+++ b/configure.ac
@@ -152,8 +152,6 @@ AC_HAVE_DEVMAPPER
 AC_HAVE_MALLINFO
 AC_HAVE_MALLINFO2
 AC_HAVE_MEMFD_CREATE
-AC_PACKAGE_WANT_ATTRIBUTES_H
-AC_HAVE_LIBATTR
 if test "$enable_scrub" = "yes"; then
         if test "$enable_libicu" = "yes" || test "$enable_libicu" = "probe"; then
                 AC_HAVE_LIBICU
diff --git a/debian/control b/debian/control
index 3f05d4e3797c..66b0a47a36ee 100644
--- a/debian/control
+++ b/debian/control
@@ -3,7 +3,7 @@ Section: admin
 Priority: optional
 Maintainer: XFS Development Team <linux-xfs@vger.kernel.org>
 Uploaders: Nathan Scott <nathans@debian.org>, Anibal Monsalve Salazar <anibal@debian.org>, Bastian Germann <bage@debian.org>
-Build-Depends: libinih-dev (>= 53), uuid-dev, debhelper (>= 12), gettext, libtool, libedit-dev, libblkid-dev (>= 2.17), linux-libc-dev, libdevmapper-dev, libattr1-dev, libicu-dev, pkg-config, liburcu-dev, systemd-dev | systemd (<< 253-2~)
+Build-Depends: libinih-dev (>= 53), uuid-dev, debhelper (>= 12), gettext, libtool, libedit-dev, libblkid-dev (>= 2.17), linux-libc-dev, libdevmapper-dev, libicu-dev, pkg-config, liburcu-dev, systemd-dev | systemd (<< 253-2~)
 Standards-Version: 4.0.0
 Homepage: https://xfs.wiki.kernel.org/
 
diff --git a/include/builddefs.in b/include/builddefs.in
index 9900a0f858ad..57fa527b60ae 100644
--- a/include/builddefs.in
+++ b/include/builddefs.in
@@ -175,7 +175,6 @@ HAVE_DEVMAPPER = @have_devmapper@
 HAVE_MALLINFO = @have_mallinfo@
 HAVE_MALLINFO2 = @have_mallinfo2@
 HAVE_MEMFD_CREATE = @have_memfd_create@
-HAVE_LIBATTR = @have_libattr@
 HAVE_LIBICU = @have_libicu@
 HAVE_SYSTEMD = @have_systemd@
 SYSTEMD_SYSTEM_UNIT_DIR = @systemd_system_unit_dir@
diff --git a/libfrog/Makefile b/libfrog/Makefile
index acddc894ee93..4da427789411 100644
--- a/libfrog/Makefile
+++ b/libfrog/Makefile
@@ -21,6 +21,7 @@ crc32.c \
 file_exchange.c \
 fsgeom.c \
 fsproperties.c \
+fsprops.c \
 getparents.c \
 histogram.c \
 list_sort.c \
@@ -46,9 +47,11 @@ crc32defs.h \
 crc32table.h \
 dahashselftest.h \
 div64.h \
+fakelibattr.h \
 file_exchange.h \
 fsgeom.h \
 fsproperties.h \
+fsprops.h \
 getparents.h \
 histogram.h \
 logging.h \
@@ -62,11 +65,6 @@ workqueue.h
 
 LSRCFILES += gen_crc32table.c
 
-ifeq ($(HAVE_LIBATTR),yes)
-CFILES+=fsprops.c
-HFILES+=fsprops.h
-endif
-
 LDIRT = gen_crc32table crc32table.h
 
 default: ltdepend $(LTLIBRARY)
diff --git a/libfrog/fakelibattr.h b/libfrog/fakelibattr.h
new file mode 100644
index 000000000000..82b5c8a34d1a
--- /dev/null
+++ b/libfrog/fakelibattr.h
@@ -0,0 +1,34 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * Copyright (c) 2024 Oracle.  All Rights Reserved.
+ * Author: Darrick J. Wong <djwong@kernel.org>
+ */
+#ifndef __LIBFROG_FAKELIBATTR_H__
+#define __LIBFROG_FAKELIBATTR_H__
+
+struct attrlist_cursor;
+
+static inline struct xfs_attrlist_ent *
+libfrog_attr_entry(
+	struct xfs_attrlist	*list,
+	unsigned int		index)
+{
+	char			*buffer = (char *)list;
+
+	return (struct xfs_attrlist_ent *)&buffer[list->al_offset[index]];
+}
+
+static inline int
+libfrog_attr_list_by_handle(
+	void				*hanp,
+	size_t				hlen,
+	void				*buf,
+	size_t				bufsize,
+	int				flags,
+	struct xfs_attrlist_cursor	*cursor)
+{
+	return attr_list_by_handle(hanp, hlen, buf, bufsize, flags,
+			(struct attrlist_cursor *)cursor);
+}
+
+#endif /* __LIBFROG_FAKELIBATTR_H__ */
diff --git a/libfrog/fsprops.c b/libfrog/fsprops.c
index 88046b7a0738..eb15c3b9792c 100644
--- a/libfrog/fsprops.c
+++ b/libfrog/fsprops.c
@@ -10,8 +10,7 @@
 #include "libfrog/bulkstat.h"
 #include "libfrog/fsprops.h"
 #include "libfrog/fsproperties.h"
-
-#include <attr/attributes.h>
+#include "libfrog/fakelibattr.h"
 
 /*
  * Given an xfd and a mount table path, get us the handle for the root dir so
@@ -68,20 +67,22 @@ fsprops_walk_names(
 	fsprops_name_walk_fn	walk_fn,
 	void			*priv)
 {
-	struct attrlist_cursor	cur = { };
-	char			attrbuf[XFS_XATTR_LIST_MAX];
-	struct attrlist		*attrlist = (struct attrlist *)attrbuf;
-	int			ret;
+	struct xfs_attrlist_cursor	cur = { };
+	char				attrbuf[XFS_XATTR_LIST_MAX];
+	struct xfs_attrlist		*attrlist =
+				(struct xfs_attrlist *)attrbuf;
+	int				ret;
 
 	memset(attrbuf, 0, XFS_XATTR_LIST_MAX);
 
-	while ((ret = attr_list_by_handle(fph->hanp, fph->hlen, attrbuf,
+	while ((ret = libfrog_attr_list_by_handle(fph->hanp, fph->hlen, attrbuf,
 				XFS_XATTR_LIST_MAX, XFS_IOC_ATTR_ROOT,
 				&cur)) == 0) {
 		unsigned int	i;
 
 		for (i = 0; i < attrlist->al_count; i++) {
-			struct attrlist_ent	*ent = ATTR_ENTRY(attrlist, i);
+			struct xfs_attrlist_ent	*ent =
+				libfrog_attr_entry(attrlist, i);
 			const char		*p =
 				attr_name_to_fsprop_name(ent->a_name);
 
diff --git a/m4/package_attr.m4 b/m4/package_attr.m4
deleted file mode 100644
index 05e02b38fb5a..000000000000
--- a/m4/package_attr.m4
+++ /dev/null
@@ -1,25 +0,0 @@
-AC_DEFUN([AC_PACKAGE_WANT_ATTRIBUTES_H],
-  [
-    AC_CHECK_HEADERS(attr/attributes.h)
-  ])
-
-#
-# Check if we have a ATTR_ROOT flag and libattr structures
-#
-AC_DEFUN([AC_HAVE_LIBATTR],
-  [ AC_MSG_CHECKING([for struct attrlist_cursor])
-    AC_COMPILE_IFELSE(
-    [	AC_LANG_PROGRAM([[
-#include <sys/types.h>
-#include <attr/attributes.h>
-	]], [[
-struct attrlist_cursor *cur;
-struct attrlist *list;
-struct attrlist_ent *ent;
-int flags = ATTR_ROOT;
-	]])
-    ], have_libattr=yes
-          AC_MSG_RESULT(yes),
-          AC_MSG_RESULT(no))
-    AC_SUBST(have_libattr)
-  ])
diff --git a/scrub/Makefile b/scrub/Makefile
index 53e8cb02a926..1e1109048c2a 100644
--- a/scrub/Makefile
+++ b/scrub/Makefile
@@ -100,10 +100,6 @@ ifeq ($(HAVE_MALLINFO2),yes)
 LCFLAGS += -DHAVE_MALLINFO2
 endif
 
-ifeq ($(HAVE_LIBATTR),yes)
-LCFLAGS += -DHAVE_LIBATTR
-endif
-
 ifeq ($(HAVE_LIBICU),yes)
 CFILES += unicrash.c
 LCFLAGS += -DHAVE_LIBICU $(LIBICU_CFLAGS)
diff --git a/scrub/phase5.c b/scrub/phase5.c
index f6c295c64ada..0f8dc2de01ba 100644
--- a/scrub/phase5.c
+++ b/scrub/phase5.c
@@ -8,9 +8,6 @@
 #include <dirent.h>
 #include <sys/types.h>
 #include <sys/statvfs.h>
-#ifdef HAVE_LIBATTR
-# include <attr/attributes.h>
-#endif
 #include <linux/fs.h>
 #include "handle.h"
 #include "list.h"
@@ -20,6 +17,7 @@
 #include "libfrog/scrub.h"
 #include "libfrog/bitmap.h"
 #include "libfrog/bulkstat.h"
+#include "libfrog/fakelibattr.h"
 #include "xfs_scrub.h"
 #include "common.h"
 #include "inodes.h"
@@ -164,7 +162,6 @@ check_dirent_names(
 	return ret;
 }
 
-#ifdef HAVE_LIBATTR
 /* Routines to scan all of an inode's xattrs for name problems. */
 struct attrns_decode {
 	int			flags;
@@ -173,8 +170,8 @@ struct attrns_decode {
 
 static const struct attrns_decode attr_ns[] = {
 	{0,			"user"},
-	{ATTR_ROOT,		"system"},
-	{ATTR_SECURE,		"secure"},
+	{XFS_IOC_ATTR_ROOT,	"system"},
+	{XFS_IOC_ATTR_SECURE,	"secure"},
 	{0, NULL},
 };
 
@@ -190,11 +187,11 @@ check_xattr_ns_names(
 	struct xfs_bulkstat		*bstat,
 	const struct attrns_decode	*attr_ns)
 {
-	struct attrlist_cursor		cur;
+	struct xfs_attrlist_cursor	cur = { };
 	char				attrbuf[XFS_XATTR_LIST_MAX];
 	char				keybuf[XATTR_NAME_MAX + 1];
-	struct attrlist			*attrlist = (struct attrlist *)attrbuf;
-	struct attrlist_ent		*ent;
+	struct xfs_attrlist		*attrlist = (struct xfs_attrlist *)attrbuf;
+	struct xfs_attrlist_ent		*ent;
 	struct unicrash			*uc = NULL;
 	int				i;
 	int				error;
@@ -206,14 +203,13 @@ check_xattr_ns_names(
 	}
 
 	memset(attrbuf, 0, XFS_XATTR_LIST_MAX);
-	memset(&cur, 0, sizeof(cur));
 	memset(keybuf, 0, XATTR_NAME_MAX + 1);
-	error = attr_list_by_handle(handle, sizeof(*handle), attrbuf,
+	error = libfrog_attr_list_by_handle(handle, sizeof(*handle), attrbuf,
 			XFS_XATTR_LIST_MAX, attr_ns->flags, &cur);
 	while (!error) {
 		/* Examine the xattrs. */
 		for (i = 0; i < attrlist->al_count; i++) {
-			ent = ATTR_ENTRY(attrlist, i);
+			ent = libfrog_attr_entry(attrlist, i);
 			snprintf(keybuf, XATTR_NAME_MAX, "%s.%s", attr_ns->name,
 					ent->a_name);
 			if (uc)
@@ -231,8 +227,9 @@ check_xattr_ns_names(
 
 		if (!attrlist->al_more)
 			break;
-		error = attr_list_by_handle(handle, sizeof(*handle), attrbuf,
-				XFS_XATTR_LIST_MAX, attr_ns->flags, &cur);
+		error = libfrog_attr_list_by_handle(handle, sizeof(*handle),
+				attrbuf, XFS_XATTR_LIST_MAX, attr_ns->flags,
+				&cur);
 	}
 	if (error) {
 		if (errno == ESTALE)
@@ -267,9 +264,6 @@ check_xattr_names(
 	}
 	return ret;
 }
-#else
-# define check_xattr_names(c, d, h, b)	(0)
-#endif /* HAVE_LIBATTR */
 
 static int
 render_ino_from_handle(

Re: [PATCH] libfrog: emulate deprecated attrlist functionality in libattr

[Christoph Hellwig]

> @@ -0,0 +1,34 @@
> +/* SPDX-License-Identifier: GPL-2.0-or-later */
> +/*
> + * Copyright (c) 2024 Oracle.  All Rights Reserved.
> + * Author: Darrick J. Wong <djwong@kernel.org>
> + */
> +#ifndef __LIBFROG_FAKELIBATTR_H__
> +#define __LIBFROG_FAKELIBATTR_H__
> +
> +struct attrlist_cursor;

Maybe this file could use a common that it emulates libattr APIs /
helpers?

> +	struct xfs_attrlist_cursor	cur = { };
>  	char				attrbuf[XFS_XATTR_LIST_MAX];
>  	char				keybuf[XATTR_NAME_MAX + 1];
> -	struct attrlist			*attrlist = (struct attrlist *)attrbuf;
> -	struct attrlist_ent		*ent;
> +	struct xfs_attrlist		*attrlist = (struct xfs_attrlist *)attrbuf;

Overly long line.  And as mentioned in reply to Carlos version of this
we're probably better of just dynamically allocating the buffer here and
do away with the casting.

The rest looks good to me.

Re: [PATCH] libfrog: emulate deprecated attrlist functionality in libattr

[Darrick J. Wong]

On Thu, Sep 19, 2024 at 07:00:39AM -0700, Christoph Hellwig wrote:
> > @@ -0,0 +1,34 @@
> > +/* SPDX-License-Identifier: GPL-2.0-or-later */
> > +/*
> > + * Copyright (c) 2024 Oracle.  All Rights Reserved.
> > + * Author: Darrick J. Wong <djwong@kernel.org>
> > + */
> > +#ifndef __LIBFROG_FAKELIBATTR_H__
> > +#define __LIBFROG_FAKELIBATTR_H__
> > +
> > +struct attrlist_cursor;
> 
> Maybe this file could use a common that it emulates libattr APIs /
> helpers?

/* This file emulates APIs from the deprecated libattr. */

> > +	struct xfs_attrlist_cursor	cur = { };
> >  	char				attrbuf[XFS_XATTR_LIST_MAX];
> >  	char				keybuf[XATTR_NAME_MAX + 1];
> > -	struct attrlist			*attrlist = (struct attrlist *)attrbuf;
> > -	struct attrlist_ent		*ent;
> > +	struct xfs_attrlist		*attrlist = (struct xfs_attrlist *)attrbuf;
> 
> Overly long line.  And as mentioned in reply to Carlos version of this
> we're probably better of just dynamically allocating the buffer here and
> do away with the casting.

I'll make a prep patch that turns all those into dynamic allocations.

> The rest looks good to me.

<nod>

--D