--- a/lib/acl.c
+++ b/lib/acl.c
@@ -16,48 +16,394 @@
    along with this program; if not, write to the Free Software Foundation,
    Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 
-   Written by Paul Eggert.  */
+   Written by Paul Eggert and Andreas Gruenbacher.  */
 
 #ifdef HAVE_CONFIG_H
 # include <config.h>
 #endif
 
+#include <stdbool.h>
+#include <stdlib.h>
+#include <string.h>
 #include <sys/types.h>
 #include <sys/stat.h>
 #ifndef S_ISLNK
 # define S_ISLNK(Mode) 0
 #endif
 
+#ifdef HAVE_ACL_LIBACL_H
+# include <acl/libacl.h>
+#endif
+
 #include "acl.h"
+#include "error.h"
+#include "quote.h"
 
 #include <errno.h>
 #ifndef ENOSYS
 # define ENOSYS (-1)
 #endif
+#ifndef ENOTSUP
+# define ENOTSUP (-1)
+#endif
 
-#ifndef MIN_ACL_ENTRIES
-# define MIN_ACL_ENTRIES 4
+#if ENABLE_NLS
+# include <libintl.h>
+# define _(Text) gettext (Text)
+#else
+# define _(Text) Text
+#endif
+
+#ifndef HAVE_FCHMOD
+# define HAVE_FCHMOD false
+# define fchmod(fd, mode) (-1)
+#endif
+
+/* POSIX 1003.1e (draft 17) */
+#ifndef HAVE_ACL_GET_FD
+# define HAVE_ACL_GET_FD false
+# define acl_get_fd(fd) (NULL)
+#endif
+
+/* POSIX 1003.1e (draft 17) */
+#ifndef HAVE_ACL_SET_FD
+# define HAVE_ACL_SET_FD false
+# define acl_set_fd(fd, acl) (-1)
+#endif
+
+/* Linux-specific */
+#ifndef HAVE_ACL_EXTENDED_FILE
+# define HAVE_ACL_EXTENDED_FILE false
+# define acl_extended_file(name) (-1)
 #endif
 
-/* Return 1 if FILE has a nontrivial access control list, 0 if not,
-   and -1 (setting errno) if an error is encountered.  */
+/* Linux-specific */
+#ifndef HAVE_ACL_FROM_MODE
+# define HAVE_ACL_FROM_MODE false
+# define acl_from_mode(mode) (NULL)
+#endif
+
+/* We detect presence of POSIX 1003.1e (draft 17 -- abandoned) support
+   by checking for HAVE_ACL_GET_FILE, HAVE_ACL_SET_FILE, and HAVE_ACL_FREE.
+   Systems that have acl_get_file, acl_set_file, and acl_free must also
+   have acl_to_text, acl_from_text, and acl_delete_def_file (all defined
+   in the draft); systems that don't would hit #error statements here.  */
+
+#if USE_ACL && HAVE_ACL_GET_FILE && !HAVE_ACL_ENTRIES
+# ifndef HAVE_ACL_TO_TEXT
+#  error Must have acl_to_text (see POSIX 1003.1e draft 17).
+# endif
+
+/* Return the number of entries in ACL. Linux implements acl_entries
+   as a more efficient extension than using this workaround.  */
+
+static int
+acl_entries (acl_t acl)
+{
+  char *text = acl_to_text (acl, NULL), *t;
+  int entries;
+  if (text == NULL)
+    return -1;
+  for (entries = 0, t = text; ; t++, entries++) {
+    t = strchr (t, '\n');
+    if (t == NULL)
+      break;
+  }
+  acl_free (text);
+  return entries;
+}
+#endif
+
+/* If DESC is a valid file descriptor use fchmod to change the
+   file's mode to MODE on systems that have fchown. On systems
+   that don't have fchown and if DESC is invalid, use chown on
+   NAME instead.  */
 
 int
-file_has_acl (char const *file, struct stat const *filestat)
+chmod_or_fchmod (const char *name, int desc, mode_t mode)
+{
+  if (HAVE_FCHMOD && desc != -1)
+    return fchmod (desc, mode);
+  else
+    return chmod (name, mode);
+}
+
+/* Return 1 if NAME has a nontrivial access control list, 0 if
+   NAME only has no or a base access control list, and -1 on
+   error.  SB must be set to the stat buffer of FILE.  */
+
+int
+file_has_acl (char const *name, struct stat const *sb)
 {
-  /* FIXME: This implementation should work on recent-enough versions
-     of HP-UX, Solaris, and Unixware, but it simply returns 0 with
-     POSIX 1003.1e (draft 17 -- abandoned), AIX, GNU/Linux, Irix, and
-     Tru64.  Please see Samba's source/lib/sysacls.c file for
-     fix-related ideas.  */
+#if USE_ACL && HAVE_ACL && defined GETACLCNT
+  /* This implementation should work on recent-enough versions of HP-UX,
+     Solaris, and Unixware.  */
+
+# ifndef MIN_ACL_ENTRIES
+#  define MIN_ACL_ENTRIES 4
+# endif
+
+  if (! S_ISLNK (sb->st_mode))
+    {
+      int n = acl (name, GETACLCNT, 0, NULL);
+      return n < 0 ? (errno == ENOSYS ? 0 : -1) : (MIN_ACL_ENTRIES < n);
+    }
+#elif USE_ACL && HAVE_ACL_GET_FILE && HAVE_ACL_FREE
+  /* POSIX 1003.1e (draft 17 -- abandoned) specific version.  */
+
+  if (! S_ISLNK (sb->st_mode))
+    {
+      int ret;
 
-#if HAVE_ACL && defined GETACLCNT
-  if (! S_ISLNK (filestat->st_mode))
-    {
-      int n = acl (file, GETACLCNT, 0, NULL);
-      return n < 0 ? (errno == ENOSYS ? 0 : -1) : (MIN_ACL_ENTRIES < n);
+      if (HAVE_ACL_EXTENDED_FILE)
+	ret = acl_extended_file (name);
+      else
+	{
+	  acl_t acl = acl_get_file (name, ACL_TYPE_ACCESS);
+	  if (acl)
+	    {
+	      ret = (3 < acl_entries (acl));
+	      acl_free (acl);
+	      if (ret == 0 && S_ISDIR (sb->st_mode))
+		{
+		  acl = acl_get_file (name, ACL_TYPE_DEFAULT);
+		  if (acl)
+		    {
+		      ret = (0 < acl_entries (acl));
+		      acl_free (acl);
+		    }
+		  else
+		    ret = -1;
+		}
+	    }
+	  else
+	    ret = -1;
+	}
+      if (ret < 0)
+	return (errno == ENOSYS || errno == ENOTSUP) ? 0 : -1;
+      return ret;
     }
 #endif
 
+  /* FIXME: Add support for AIX, Irix, and Tru64.  Please see Samba's
+     source/lib/sysacls.c file for fix-related ideas.  */
+
   return 0;
 }
+
+/* Copy access control lists from one file to another. If SOURCE_DESC is
+   a valid file descriptor, use file descriptor operations, else use
+   filename based operations on SRC_NAME. Likewise for DEST_DESC and
+   DEST_NAME.
+   If access control lists are not available, fchmod the target file to
+   MODE.  Also sets the non-permission bits of the destination file
+   (S_ISUID, S_ISGID, S_ISVTX) to those from MODE if any are set.
+   System call return value semantics.  */
+
+int
+copy_acl (const char *src_name, int source_desc, const char *dst_name,
+	  int dest_desc, mode_t mode)
+{
+  int ret;
+
+#if USE_ACL && HAVE_ACL_GET_FILE && HAVE_ACL_SET_FILE && HAVE_ACL_FREE
+  /* POSIX 1003.1e (draft 17 -- abandoned) specific version.  */
+
+  acl_t acl;
+  if (HAVE_ACL_GET_FD && source_desc != -1)
+    acl = acl_get_fd (source_desc);
+  else
+    acl = acl_get_file (src_name, ACL_TYPE_ACCESS);
+  if (acl == NULL)
+    {
+      if (errno == ENOSYS || errno == ENOTSUP)
+	return set_acl (dst_name, dest_desc, mode);
+      else
+        {
+	  error (0, errno, "%s", quote (src_name));
+	  return -1;
+	}
+    }
+
+  if (HAVE_ACL_SET_FD && dest_desc != -1)
+    ret = acl_set_fd (dest_desc, acl);
+  else
+    ret = acl_set_file (dst_name, ACL_TYPE_ACCESS, acl);
+  if (ret != 0)
+    {
+      int saved_errno = errno;
+
+      if (errno == ENOSYS || errno == ENOTSUP)
+        {
+	  int n = acl_entries (acl);
+
+	  acl_free (acl);
+	  if (n == 3)
+	    {
+	      if (chmod_or_fchmod (dst_name, dest_desc, mode) != 0)
+		saved_errno = errno;
+	      else
+		return 0;
+	    }
+	  else
+	    chmod_or_fchmod (dst_name, dest_desc, mode);
+	}
+      else
+	{
+	  acl_free (acl);
+	  chmod_or_fchmod (dst_name, dest_desc, mode);
+	}
+      error (0, saved_errno, _("preserving permissions for %s"),
+	     quote (dst_name));
+      return -1;
+    }
+  else
+    acl_free (acl);
+
+  if (mode & (S_ISUID | S_ISGID | S_ISVTX))
+    {
+      /* We did not call chmod so far, so the special bits have not yet
+         been set.  */
+
+      if (chmod_or_fchmod (dst_name, dest_desc, mode) != 0)
+	{
+	  error (0, errno, _("preserving permissions for %s"),
+		 quote (dst_name));
+	  return -1;
+	}
+    }
+
+  if (S_ISDIR (mode))
+    {
+      acl = acl_get_file (src_name, ACL_TYPE_DEFAULT);
+      if (acl == NULL)
+	{
+	  error (0, errno, "%s", quote (src_name));
+	  return -1;
+	}
+
+      if (acl_set_file (dst_name, ACL_TYPE_DEFAULT, acl))
+	{
+	  error (0, errno, _("preserving permissions for %s"),
+		 quote (dst_name));
+	  acl_free (acl);
+	  return -1;
+	}
+      else
+        acl_free (acl);
+    }
+  return 0;
+#else
+  ret = chmod_or_fchmod (dst_name, dest_desc, mode);
+  if (ret != 0)
+    error (0, errno, _("preserving permissions for %s"), quote (dst_name));
+  return ret;
+#endif
+}
+
+/* Set the access control lists of a file. If DESC is a valid file
+   descriptor, use file descriptor operations where available, else use
+   filename based operations on NAME.  If access control lists are not
+   available, fchmod the target file to MODE.  Also sets the
+   non-permission bits of the destination file (S_ISUID, S_ISGID, S_ISVTX)
+   to those from MODE if any are set.  System call return value
+   semantics.  */
+
+int
+set_acl (char const *name, int desc, mode_t mode)
+{
+#if USE_ACL && HAVE_ACL_SET_FILE && HAVE_ACL_FREE
+  /* POSIX 1003.1e draft 17 (abandoned) specific version.  */
+
+  /* We must also have have_acl_from_text and acl_delete_def_file.
+     (acl_delete_def_file could be emulated with acl_init followed
+      by acl_set_file, but acl_set_file with an empty acl is
+      unspecified.)  */
+
+# ifndef HAVE_ACL_FROM_TEXT
+#  error Must have acl_from_text (see POSIX 1003.1e draft 17).
+# endif
+# ifndef HAVE_ACL_DELETE_DEF_FILE
+#  error Must have acl_delete_def_file (see POSIX 1003.1e draft 17).
+# endif
+
+  acl_t acl;
+  int ret;
+
+  if (HAVE_ACL_FROM_MODE)
+    {
+      acl = acl_from_mode (mode);
+      if (!acl)
+	{
+	  error (0, errno, "%s", quote (name));
+	  return -1;
+	}
+    }
+  else
+    {
+      char acl_text[] = "u::---,g::---,o::---";
+
+      if (mode & S_IRUSR) acl_text[ 3] = 'r';
+      if (mode & S_IWUSR) acl_text[ 4] = 'w';
+      if (mode & S_IXUSR) acl_text[ 5] = 'x';
+      if (mode & S_IRGRP) acl_text[10] = 'r';
+      if (mode & S_IWGRP) acl_text[11] = 'w';
+      if (mode & S_IXGRP) acl_text[12] = 'x';
+      if (mode & S_IROTH) acl_text[17] = 'r';
+      if (mode & S_IWOTH) acl_text[18] = 'w';
+      if (mode & S_IXOTH) acl_text[19] = 'x';
+
+      acl = acl_from_text (acl_text);
+      if (!acl)
+	{
+	  error (0, errno, "%s", quote (name));
+	  return -1;
+	}
+    }
+  if (HAVE_ACL_SET_FD && desc != -1)
+    ret = acl_set_fd (desc, acl);
+  else
+    ret = acl_set_file (name, ACL_TYPE_ACCESS, acl);
+  if (ret != 0)
+    {
+      int saved_errno = errno;
+      acl_free (acl);
+
+      if (errno == ENOTSUP || errno == ENOSYS)
+	{
+	  if (chmod_or_fchmod (name, desc, mode) != 0)
+	    saved_errno = errno;
+	  else
+	    return 0;
+	}
+      error (0, saved_errno, _("setting permissions for %s"), quote (name));
+      return -1;
+    }
+  else
+    acl_free (acl);
+
+  if (S_ISDIR (mode) && acl_delete_def_file (name))
+    {
+      error (0, errno, _("setting permissions for %s"), quote (name));
+      return -1;
+    }
+
+  if (mode & (S_ISUID | S_ISGID | S_ISVTX))
+    {
+      /* We did not call chmod so far, so the special bits have not yet
+         been set.  */
+
+      if (chmod_or_fchmod (name, desc, mode))
+	{
+	  error (0, errno, _("preserving permissions for %s"), quote (name));
+	  return -1;
+	}
+    }
+  return 0;
+#else
+   int ret = chmod_or_fchmod (name, desc, mode);
+   if (ret)
+     error (0, errno, _("setting permissions for %s"), quote (name));
+   return ret;
+#endif
+}