Support for Linux extended attributes.

This commit adds six calls to support Linux extended attributes.
They are:
  getxattrs     list all extended attributes for a file or directory
  setxattr      add/replace an extended attribute
  removexattr   remove an extended attribute
  lgetxattrs    \
  lsetxattr     (same as above, but operate on symbolic links)
  lremovexattr  /

See attr(5) for more information.

This also adds support for the FBuffer field type, which maps to
an XDR opaque<> or a C (int, char *) pair.

3 files changed, 289 insertions, 1 deletions

diff --git a/daemon/Makefile.am b/daemon/Makefile.am
index 846a95c7..7b8a87ee 100644
--- a/daemon/Makefile.am
+++ b/daemon/Makefile.am
@@ -65,6 +65,7 @@ guestfsd_SOURCES = \
 	umask.c \
 	upload.c \
 	wc.c \
+	xattr.c \
 	zero.c \
 	zerofree.c \
 	$(top_builddir)/../src/guestfs_protocol.h \
diff --git a/daemon/configure.ac b/daemon/configure.ac
index 238532ea..2fd1ae93 100644
--- a/daemon/configure.ac
+++ b/daemon/configure.ac
@@ -63,7 +63,10 @@ AC_CHECK_LIB([portablexdr],[xdrmem_create],[],[
 	])
 
 dnl Functions which may not be available in older distributions.
-AC_CHECK_FUNCS([futimens])
+AC_CHECK_FUNCS([futimens listxattr llistxattr getxattr lgetxattr setxattr lsetxattr removexattr lremovexattr])
+
+dnl Headers.
+AC_CHECK_HEADERS([attr/xattr.h])
 
 dnl Produce output files.
 AC_CONFIG_HEADERS([config.h])
diff --git a/daemon/xattr.c b/daemon/xattr.c
new file mode 100644
index 00000000..76f44bbf
--- /dev/null
+++ b/daemon/xattr.c
@@ -0,0 +1,284 @@
+/* libguestfs - the guestfsd daemon
+ * Copyright (C) 2009 Red Hat Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+#include <config.h>
+
+#include <stdio.h>
+#include <unistd.h>
+
+#ifdef HAVE_ATTR_XATTR_H
+#include <attr/xattr.h>
+
+#include "../src/guestfs_protocol.h"
+#include "daemon.h"
+#include "actions.h"
+
+static guestfs_int_xattr_list *getxattrs (char *path, ssize_t (*listxattr) (const char *path, char *list, size_t size), ssize_t (*getxattr) (const char *path, const char *name, void *value, size_t size));
+static int _setxattr (char *xattr, char *val, int vallen, char *path, int (*setxattr) (const char *path, const char *name, const void *value, size_t size, int flags));
+static int _removexattr (char *xattr, char *path, int (*removexattr) (const char *path, const char *name));
+
+guestfs_int_xattr_list *
+do_getxattrs (char *path)
+{
+#if defined(HAVE_LISTXATTR) && defined(HAVE_GETXATTR)
+  return getxattrs (path, listxattr, getxattr);
+#else
+  reply_with_error ("getxattrs: no support for listxattr and getxattr");
+  return NULL;
+#endif
+}
+
+guestfs_int_xattr_list *
+do_lgetxattrs (char *path)
+{
+#if defined(HAVE_LLISTXATTR) && defined(HAVE_LGETXATTR)
+  return getxattrs (path, llistxattr, lgetxattr);
+#else
+  reply_with_error ("lgetxattrs: no support for llistxattr and lgetxattr");
+  return NULL;
+#endif
+}
+
+int
+do_setxattr (char *xattr, char *val, int vallen, char *path)
+{
+#if defined(HAVE_SETXATTR)
+  return _setxattr (xattr, val, vallen, path, setxattr);
+#else
+  reply_with_error ("setxattr: no support for setxattr");
+  return -1;
+#endif
+}
+
+int
+do_lsetxattr (char *xattr, char *val, int vallen, char *path)
+{
+#if defined(HAVE_LSETXATTR)
+  return _setxattr (xattr, val, vallen, path, lsetxattr);
+#else
+  reply_with_error ("lsetxattr: no support for lsetxattr");
+  return -1;
+#endif
+}
+
+int
+do_removexattr (char *xattr, char *path)
+{
+#if defined(HAVE_REMOVEXATTR)
+  return _removexattr (xattr, path, removexattr);
+#else
+  reply_with_error ("removexattr: no support for removexattr");
+  return -1;
+#endif
+}
+
+int
+do_lremovexattr (char *xattr, char *path)
+{
+#if defined(HAVE_LREMOVEXATTR)
+  return _removexattr (xattr, path, lremovexattr);
+#else
+  reply_with_error ("lremovexattr: no support for lremovexattr");
+  return -1;
+#endif
+}
+
+static guestfs_int_xattr_list *
+getxattrs (char *path,
+	   ssize_t (*listxattr) (const char *path, char *list, size_t size),
+	   ssize_t (*getxattr) (const char *path, const char *name,
+				void *value, size_t size))
+{
+  ssize_t len, vlen;
+  char *buf = NULL;
+  int i, j;
+  guestfs_int_xattr_list *r = NULL;
+
+  NEED_ROOT (NULL);
+  ABS_PATH (path, NULL);
+
+  CHROOT_IN;
+  len = listxattr (path, NULL, 0);
+  CHROOT_OUT;
+  if (len == -1) {
+    reply_with_perror ("listxattr");
+    goto error;
+  }
+
+  buf = malloc (len);
+  if (buf == NULL) {
+    reply_with_perror ("malloc");
+    goto error;
+  }
+
+  CHROOT_IN;
+  len = listxattr (path, buf, len);
+  CHROOT_OUT;
+  if (len == -1) {
+    reply_with_perror ("listxattr");
+    goto error;
+  }
+
+  r = calloc (1, sizeof (*r));
+  if (r == NULL) {
+    reply_with_perror ("malloc");
+    goto error;
+  }
+
+  /* What we get from the kernel is a string "foo\0bar\0baz" of length
+   * len.  First count the strings.
+   */
+  r->guestfs_int_xattr_list_len = 0;
+  for (i = 0; i < len; i += strlen (&buf[i]) + 1)
+    r->guestfs_int_xattr_list_len++;
+
+  r->guestfs_int_xattr_list_val =
+    calloc (r->guestfs_int_xattr_list_len, sizeof (guestfs_int_xattr));
+  if (r->guestfs_int_xattr_list_val == NULL) {
+    reply_with_perror ("calloc");
+    goto error;
+  }
+
+  for (i = 0, j = 0; i < len; i += strlen (&buf[i]) + 1, ++j) {
+    CHROOT_IN;
+    vlen = getxattr (path, &buf[i], NULL, 0);
+    CHROOT_OUT;
+    if (vlen == -1) {
+      reply_with_perror ("getxattr");
+      goto error;
+    }
+
+    r->guestfs_int_xattr_list_val[j].attrname = strdup (&buf[i]);
+    r->guestfs_int_xattr_list_val[j].attrval.attrval_val = malloc (vlen);
+    r->guestfs_int_xattr_list_val[j].attrval.attrval_len = vlen;
+
+    if (r->guestfs_int_xattr_list_val[j].attrname == NULL ||
+	r->guestfs_int_xattr_list_val[j].attrval.attrval_val == NULL) {
+      reply_with_perror ("malloc");
+      goto error;
+    }
+
+    CHROOT_IN;
+    vlen = getxattr (path, &buf[i],
+		     r->guestfs_int_xattr_list_val[j].attrval.attrval_val,
+		     vlen);
+    CHROOT_OUT;
+    if (vlen == -1) {
+      reply_with_perror ("getxattr");
+      goto error;
+    }
+  }
+
+  free (buf);
+
+  return r;
+
+ error:
+  free (buf);
+  if (r) {
+    if (r->guestfs_int_xattr_list_val)
+      for (i = 0; i < r->guestfs_int_xattr_list_len; ++i) {
+	free (r->guestfs_int_xattr_list_val[i].attrname);
+	free (r->guestfs_int_xattr_list_val[i].attrval.attrval_val);
+      }
+    free (r->guestfs_int_xattr_list_val);
+  }
+  free (r);
+  return NULL;
+}
+
+static int
+_setxattr (char *xattr, char *val, int vallen, char *path,
+	   int (*setxattr) (const char *path, const char *name,
+			    const void *value, size_t size, int flags))
+{
+  int r;
+
+  CHROOT_IN;
+  r = setxattr (path, xattr, val, vallen, 0);
+  CHROOT_OUT;
+  if (r == -1) {
+    reply_with_perror ("setxattr");
+    return -1;
+  }
+
+  return 0;
+}
+
+static int
+_removexattr (char *xattr, char *path,
+	      int (*removexattr) (const char *path, const char *name))
+{
+  int r;
+
+  CHROOT_IN;
+  r = removexattr (path, xattr);
+  CHROOT_OUT;
+  if (r == -1) {
+    reply_with_perror ("removexattr");
+    return -1;
+  }
+
+  return 0;
+}
+
+#else /* !HAVE_ATTR_XATTR_H */
+
+guestfs_int_xattr_list *
+do_getxattrs (char *path)
+{
+  reply_with_error ("getxattrs: no support for xattrs");
+  return NULL;
+}
+
+guestfs_int_xattr_list *
+do_lgetxattrs (char *path)
+{
+  reply_with_error ("lgetxattrs: no support for xattrs");
+  return NULL;
+}
+
+int
+do_setxattr (char *xattr, char *val, int vallen, char *path)
+{
+  reply_with_error ("setxattr: no support for xattrs");
+  return -1;
+}
+
+int
+do_lsetxattr (char *xattr, char *val, int vallen, char *path)
+{
+  reply_with_error ("lsetxattr: no support for xattrs");
+  return -1;
+}
+
+int
+do_removexattr (char *xattr, char *path)
+{
+  reply_with_error ("removexattr: no support for xattrs");
+  return -1;
+}
+
+int
+do_lremovexattr (char *xattr, char *path)
+{
+  reply_with_error ("lremovexattr: no support for xattrs");
+  return -1;
+}
+
+#endif /* !HAVE_ATTR_XATTR_H */