acl: On Linux, check for acls without libacl

On Linux, use the getxattr syscall instead of the acl_extended_file libacl
library function to check for the presence of acls, avoiding a library
dependency.

* lib/file-has-acl.c: Include xattr headers if we have them.
(file_has_acl): On Linux, use getxattr().
* m4/acl.m4 (gl_FUNC_ACL): Define LIB_HAS_ACL as the libraries to link with for
file_has_acl(). Check for xattr headers and getxattr().
* modules/acl: Add a dep on the stdbool module which was already needed.
Add the new reduced dependency LIB_HAS_ACL reference.

1 files changed, 34 insertions, 1 deletions

diff --git a/lib/file-has-acl.c b/lib/file-has-acl.c
index de89a75918..5dfe9a8510 100644
--- a/lib/file-has-acl.c
+++ b/lib/file-has-acl.c
@@ -29,6 +29,13 @@
 
 #include "acl-internal.h"
 
+#if HAVE_SYS_XATTR_H
+# include <sys/xattr.h>
+#endif
+
+#if HAVE_LINUX_XATTR_H
+# include <linux/xattr.h>
+#endif
 
 /* Return 1 if NAME has a nontrivial access control list, 0 if NAME
    only has no or a base access control list, and -1 (setting errno)
@@ -41,7 +48,33 @@ file_has_acl (char const *name, struct stat const *sb)
 #if USE_ACL
   if (! S_ISLNK (sb->st_mode))
     {
-# if HAVE_ACL_GET_FILE
+
+# if HAVE_GETXATTR && defined XATTR_NAME_POSIX_ACL_ACCESS && defined XATTR_NAME_POSIX_ACL_DEFAULT
+
+      ssize_t ret;
+
+      ret = getxattr (name, XATTR_NAME_POSIX_ACL_ACCESS, NULL, 0);
+      if (ret < 0)
+	{
+	  if (errno != ENODATA)
+	    return -1;
+	}
+      else if (ret > 0)
+	return 1;
+      if (S_ISDIR (sb->st_mode))
+	{
+	  ret = getxattr (name, XATTR_NAME_POSIX_ACL_DEFAULT, NULL, 0);
+	  if (ret < 0)
+	    {
+	      if (errno != ENODATA)
+		return -1;
+	    }
+	  else if (ret > 0)
+	    return 1;
+	}
+      return 0;
+
+# elif HAVE_ACL_GET_FILE
 
       /* POSIX 1003.1e (draft 17 -- abandoned) specific version.  */
       /* Linux, FreeBSD, Mac OS X, IRIX, Tru64 */