Use Gnulib ACL implementation, for benefit of Solaris etc.

* configure.ac: Remove -with-acl option, since Gnulib does that for
us now.
(LIBACL_LIBS): Remove; no longer needed.
* lib/Makefile.am (CLEANFILES, SUFFIXES): New (empty) macros,
for the benefit of the new ACL implementation.
* lib/makefile.w32-in (GNULIBOBJS): Add $(BLD)/acl-errno-valid.$(O).
($(BLD)/acl-errno-valid.$(O)): New rule.
* lib/acl-errno-valid.c, lib/acl-internal.h, lib/acl.h:
* lib/acl_entries.c, lib/errno.in.h, lib/file-has-acl.c:
* lib/qcopy-acl.c, lib/qset-acl.c, m4/acl.m4, m4/errno_h.m4:
New files, taken from gnulib.
* lib/gnulib.mk, m4/gnulib-comp.m4: Regenerate.
* admin/merge-gnulib (GNULIB_MODULES): Add qacl.
(GNULIB_TOOL_FLAGS): Do not avoid errno.
* etc/NEWS: Emacs is no longer limited to POSIX ACLs.  --disable-acl,
not --without-acl, since we're now using Gnulib's implementation.
* nt/config.nt (HAVE_ACL_SET_FILE): Rename from HAVE_POSIX_ACL.
* nt/inc/ms-w32.h (EOPNOTSUPP): New macro.
* src/Makefile.in (LIB_ACL): New macro.
(LIBACL_LIBS): Remove.
(LIBES): Use LIB_ACL, not LIBACL_LIBS.
* src/fileio.c: Include <acl.h>.
Use HAVE_ACL_SET_FILE rather than HAVE_POSIX_ACL.
(ACL_NOT_WELL_SUPPORTED): Remove.  All uses replaced by
!acl_errno_valid.
(Fcopy_file) [!WINDOWSNT]: Use qcopy_acl instead of rolling
it ourselves.

Fixes: debbugs:14295

1 files changed, 918 insertions, 0 deletions

diff --git a/lib/file-has-acl.c b/lib/file-has-acl.c
new file mode 100644
index 00000000000..bb8bae12861
--- /dev/null
+++ b/lib/file-has-acl.c
@@ -0,0 +1,918 @@
+/* Test whether a file has a nontrivial access control list.
+
+   Copyright (C) 2002-2003, 2005-2013 Free Software Foundation, 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 3 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, see <http://www.gnu.org/licenses/>.
+
+   Written by Paul Eggert, Andreas Grünbacher, and Bruno Haible.  */
+
+/* Without this pragma, gcc 4.7.0 20120126 may suggest that the
+   file_has_acl function might be candidate for attribute 'const'  */
+#if (__GNUC__ == 4 && 6 <= __GNUC_MINOR__) || 4 < __GNUC__
+# pragma GCC diagnostic ignored "-Wsuggest-attribute=const"
+#endif
+
+#include <config.h>
+
+#include "acl.h"
+
+#include "acl-internal.h"
+
+
+#if USE_ACL && HAVE_ACL_GET_FILE
+
+# if HAVE_ACL_TYPE_EXTENDED /* Mac OS X */
+
+/* ACL is an ACL, from a file, stored as type ACL_TYPE_EXTENDED.
+   Return 1 if the given ACL is non-trivial.
+   Return 0 if it is trivial.  */
+int
+acl_extended_nontrivial (acl_t acl)
+{
+  /* acl is non-trivial if it is non-empty.  */
+  return (acl_entries (acl) > 0);
+}
+
+# else /* Linux, FreeBSD, IRIX, Tru64 */
+
+/* ACL is an ACL, from a file, stored as type ACL_TYPE_ACCESS.
+   Return 1 if the given ACL is non-trivial.
+   Return 0 if it is trivial, i.e. equivalent to a simple stat() mode.
+   Return -1 and set errno upon failure to determine it.  */
+int
+acl_access_nontrivial (acl_t acl)
+{
+  /* acl is non-trivial if it has some entries other than for "user::",
+     "group::", and "other::".  Normally these three should be present
+     at least, allowing us to write
+        return (3 < acl_entries (acl));
+     but the following code is more robust.  */
+#  if HAVE_ACL_FIRST_ENTRY /* Linux, FreeBSD */
+
+  acl_entry_t ace;
+  int got_one;
+
+  for (got_one = acl_get_entry (acl, ACL_FIRST_ENTRY, &ace);
+       got_one > 0;
+       got_one = acl_get_entry (acl, ACL_NEXT_ENTRY, &ace))
+    {
+      acl_tag_t tag;
+      if (acl_get_tag_type (ace, &tag) < 0)
+        return -1;
+      if (!(tag == ACL_USER_OBJ || tag == ACL_GROUP_OBJ || tag == ACL_OTHER))
+        return 1;
+    }
+  return got_one;
+
+#  else /* IRIX, Tru64 */
+#   if HAVE_ACL_TO_SHORT_TEXT /* IRIX */
+  /* Don't use acl_get_entry: it is undocumented.  */
+
+  int count = acl->acl_cnt;
+  int i;
+
+  for (i = 0; i < count; i++)
+    {
+      acl_entry_t ace = &acl->acl_entry[i];
+      acl_tag_t tag = ace->ae_tag;
+
+      if (!(tag == ACL_USER_OBJ || tag == ACL_GROUP_OBJ
+            || tag == ACL_OTHER_OBJ))
+        return 1;
+    }
+  return 0;
+
+#   endif
+#   if HAVE_ACL_FREE_TEXT /* Tru64 */
+  /* Don't use acl_get_entry: it takes only one argument and does not work.  */
+
+  int count = acl->acl_num;
+  acl_entry_t ace;
+
+  for (ace = acl->acl_first; count > 0; ace = ace->next, count--)
+    {
+      acl_tag_t tag;
+      acl_perm_t perm;
+
+      tag = ace->entry->acl_type;
+      if (!(tag == ACL_USER_OBJ || tag == ACL_GROUP_OBJ || tag == ACL_OTHER))
+        return 1;
+
+      perm = ace->entry->acl_perm;
+      /* On Tru64, perm can also contain non-standard bits such as
+         PERM_INSERT, PERM_DELETE, PERM_MODIFY, PERM_LOOKUP, ... */
+      if ((perm & ~(ACL_READ | ACL_WRITE | ACL_EXECUTE)) != 0)
+        return 1;
+    }
+  return 0;
+
+#   endif
+#  endif
+}
+
+# endif
+
+
+#elif USE_ACL && HAVE_FACL && defined GETACL /* Solaris, Cygwin, not HP-UX */
+
+/* Test an ACL retrieved with GETACL.
+   Return 1 if the given ACL, consisting of COUNT entries, is non-trivial.
+   Return 0 if it is trivial, i.e. equivalent to a simple stat() mode.  */
+int
+acl_nontrivial (int count, aclent_t *entries)
+{
+  int i;
+
+  for (i = 0; i < count; i++)
+    {
+      aclent_t *ace = &entries[i];
+
+      /* Note: If ace->a_type = USER_OBJ, ace->a_id is the st_uid from stat().
+         If ace->a_type = GROUP_OBJ, ace->a_id is the st_gid from stat().
+         We don't need to check ace->a_id in these cases.  */
+      if (!(ace->a_type == USER_OBJ
+            || ace->a_type == GROUP_OBJ
+            || ace->a_type == OTHER_OBJ
+            /* Note: Cygwin does not return a CLASS_OBJ ("mask:") entry
+               sometimes.  */
+            || ace->a_type == CLASS_OBJ))
+        return 1;
+    }
+  return 0;
+}
+
+# ifdef ACE_GETACL
+
+/* A shortcut for a bitmask.  */
+#  define NEW_ACE_WRITEA_DATA (NEW_ACE_WRITE_DATA | NEW_ACE_APPEND_DATA)
+
+/* Test an ACL retrieved with ACE_GETACL.
+   Return 1 if the given ACL, consisting of COUNT entries, is non-trivial.
+   Return 0 if it is trivial, i.e. equivalent to a simple stat() mode.  */
+int
+acl_ace_nontrivial (int count, ace_t *entries)
+{
+  int i;
+
+  /* The flags in the ace_t structure changed in a binary incompatible way
+     when ACL_NO_TRIVIAL etc. were introduced in <sys/acl.h> version 1.15.
+     How to distinguish the two conventions at runtime?
+     In the old convention, usually three ACEs have a_flags = ACE_OWNER /
+     ACE_GROUP / ACE_OTHER, in the range 0x0100..0x0400.  In the new
+     convention, these values are not used.  */
+  int old_convention = 0;
+
+  for (i = 0; i < count; i++)
+    if (entries[i].a_flags & (OLD_ACE_OWNER | OLD_ACE_GROUP | OLD_ACE_OTHER))
+      {
+        old_convention = 1;
+        break;
+      }
+
+  if (old_convention)
+    /* Running on Solaris 10.  */
+    for (i = 0; i < count; i++)
+      {
+        ace_t *ace = &entries[i];
+
+        /* Note:
+           If ace->a_flags = ACE_OWNER, ace->a_who is the st_uid from stat().
+           If ace->a_flags = ACE_GROUP, ace->a_who is the st_gid from stat().
+           We don't need to check ace->a_who in these cases.  */
+        if (!(ace->a_type == OLD_ALLOW
+              && (ace->a_flags == OLD_ACE_OWNER
+                  || ace->a_flags == OLD_ACE_GROUP
+                  || ace->a_flags == OLD_ACE_OTHER)))
+          return 1;
+      }
+  else
+    {
+      /* Running on Solaris 10 (newer version) or Solaris 11.  */
+      unsigned int access_masks[6] =
+        {
+          0, /* owner@ deny */
+          0, /* owner@ allow */
+          0, /* group@ deny */
+          0, /* group@ allow */
+          0, /* everyone@ deny */
+          0  /* everyone@ allow */
+        };
+
+      for (i = 0; i < count; i++)
+        {
+          ace_t *ace = &entries[i];
+          unsigned int index1;
+          unsigned int index2;
+
+          if (ace->a_type == NEW_ACE_ACCESS_ALLOWED_ACE_TYPE)
+            index1 = 1;
+          else if (ace->a_type == NEW_ACE_ACCESS_DENIED_ACE_TYPE)
+            index1 = 0;
+          else
+            return 1;
+
+          if (ace->a_flags == NEW_ACE_OWNER)
+            index2 = 0;
+          else if (ace->a_flags == (NEW_ACE_GROUP | NEW_ACE_IDENTIFIER_GROUP))
+            index2 = 2;
+          else if (ace->a_flags == NEW_ACE_EVERYONE)
+            index2 = 4;
+          else
+            return 1;
+
+          access_masks[index1 + index2] |= ace->a_access_mask;
+        }
+
+      /* The same bit shouldn't be both allowed and denied.  */
+      if (access_masks[0] & access_masks[1])
+        return 1;
+      if (access_masks[2] & access_masks[3])
+        return 1;
+      if (access_masks[4] & access_masks[5])
+        return 1;
+
+      /* Check minimum masks.  */
+      if ((NEW_ACE_WRITE_NAMED_ATTRS
+           | NEW_ACE_WRITE_ATTRIBUTES
+           | NEW_ACE_WRITE_ACL
+           | NEW_ACE_WRITE_OWNER)
+          & ~ access_masks[1])
+        return 1;
+      access_masks[1] &= ~(NEW_ACE_WRITE_NAMED_ATTRS
+                           | NEW_ACE_WRITE_ATTRIBUTES
+                           | NEW_ACE_WRITE_ACL
+                           | NEW_ACE_WRITE_OWNER);
+      if ((NEW_ACE_READ_NAMED_ATTRS
+           | NEW_ACE_READ_ATTRIBUTES
+           | NEW_ACE_READ_ACL
+           | NEW_ACE_SYNCHRONIZE)
+          & ~ access_masks[5])
+        return 1;
+      access_masks[5] &= ~(NEW_ACE_READ_NAMED_ATTRS
+                           | NEW_ACE_READ_ATTRIBUTES
+                           | NEW_ACE_READ_ACL
+                           | NEW_ACE_SYNCHRONIZE);
+
+      /* Check the allowed or denied bits.  */
+      switch ((access_masks[0] | access_masks[1])
+              & ~(NEW_ACE_READ_NAMED_ATTRS
+                  | NEW_ACE_READ_ATTRIBUTES
+                  | NEW_ACE_READ_ACL
+                  | NEW_ACE_SYNCHRONIZE))
+        {
+        case 0:
+        case NEW_ACE_READ_DATA:
+        case                     NEW_ACE_WRITEA_DATA:
+        case NEW_ACE_READ_DATA | NEW_ACE_WRITEA_DATA:
+        case                                           NEW_ACE_EXECUTE:
+        case NEW_ACE_READ_DATA |                       NEW_ACE_EXECUTE:
+        case                     NEW_ACE_WRITEA_DATA | NEW_ACE_EXECUTE:
+        case NEW_ACE_READ_DATA | NEW_ACE_WRITEA_DATA | NEW_ACE_EXECUTE:
+          break;
+        default:
+          return 1;
+        }
+      switch ((access_masks[2] | access_masks[3])
+              & ~(NEW_ACE_READ_NAMED_ATTRS
+                  | NEW_ACE_READ_ATTRIBUTES
+                  | NEW_ACE_READ_ACL
+                  | NEW_ACE_SYNCHRONIZE))
+        {
+        case 0:
+        case NEW_ACE_READ_DATA:
+        case                     NEW_ACE_WRITEA_DATA:
+        case NEW_ACE_READ_DATA | NEW_ACE_WRITEA_DATA:
+        case                                           NEW_ACE_EXECUTE:
+        case NEW_ACE_READ_DATA |                       NEW_ACE_EXECUTE:
+        case                     NEW_ACE_WRITEA_DATA | NEW_ACE_EXECUTE:
+        case NEW_ACE_READ_DATA | NEW_ACE_WRITEA_DATA | NEW_ACE_EXECUTE:
+          break;
+        default:
+          return 1;
+        }
+      switch ((access_masks[4] | access_masks[5])
+              & ~(NEW_ACE_WRITE_NAMED_ATTRS
+                  | NEW_ACE_WRITE_ATTRIBUTES
+                  | NEW_ACE_WRITE_ACL
+                  | NEW_ACE_WRITE_OWNER))
+        {
+        case 0:
+        case NEW_ACE_READ_DATA:
+        case                     NEW_ACE_WRITEA_DATA:
+        case NEW_ACE_READ_DATA | NEW_ACE_WRITEA_DATA:
+        case                                           NEW_ACE_EXECUTE:
+        case NEW_ACE_READ_DATA |                       NEW_ACE_EXECUTE:
+        case                     NEW_ACE_WRITEA_DATA | NEW_ACE_EXECUTE:
+        case NEW_ACE_READ_DATA | NEW_ACE_WRITEA_DATA | NEW_ACE_EXECUTE:
+          break;
+        default:
+          return 1;
+        }
+
+      /* Check that the NEW_ACE_WRITE_DATA and NEW_ACE_APPEND_DATA bits are
+         either both allowed or both denied.  */
+      if (((access_masks[0] & NEW_ACE_WRITE_DATA) != 0)
+          != ((access_masks[0] & NEW_ACE_APPEND_DATA) != 0))
+        return 1;
+      if (((access_masks[2] & NEW_ACE_WRITE_DATA) != 0)
+          != ((access_masks[2] & NEW_ACE_APPEND_DATA) != 0))
+        return 1;
+      if (((access_masks[4] & NEW_ACE_WRITE_DATA) != 0)
+          != ((access_masks[4] & NEW_ACE_APPEND_DATA) != 0))
+        return 1;
+    }
+
+  return 0;
+}
+
+# endif
+
+#elif USE_ACL && HAVE_GETACL /* HP-UX */
+
+/* Return 1 if the given ACL is non-trivial.
+   Return 0 if it is trivial, i.e. equivalent to a simple stat() mode.  */
+int
+acl_nontrivial (int count, struct acl_entry *entries, struct stat *sb)
+{
+  int i;
+
+  for (i = 0; i < count; i++)
+    {
+      struct acl_entry *ace = &entries[i];
+
+      if (!((ace->uid == sb->st_uid && ace->gid == ACL_NSGROUP)
+            || (ace->uid == ACL_NSUSER && ace->gid == sb->st_gid)
+            || (ace->uid == ACL_NSUSER && ace->gid == ACL_NSGROUP)))
+        return 1;
+    }
+  return 0;
+}
+
+# if HAVE_ACLV_H /* HP-UX >= 11.11 */
+
+/* Return 1 if the given ACL is non-trivial.
+   Return 0 if it is trivial, i.e. equivalent to a simple stat() mode.  */
+int
+aclv_nontrivial (int count, struct acl *entries)
+{
+  int i;
+
+  for (i = 0; i < count; i++)
+    {
+      struct acl *ace = &entries[i];
+
+      /* Note: If ace->a_type = USER_OBJ, ace->a_id is the st_uid from stat().
+         If ace->a_type = GROUP_OBJ, ace->a_id is the st_gid from stat().
+         We don't need to check ace->a_id in these cases.  */
+      if (!(ace->a_type == USER_OBJ /* no need to check ace->a_id here */
+            || ace->a_type == GROUP_OBJ /* no need to check ace->a_id here */
+            || ace->a_type == CLASS_OBJ
+            || ace->a_type == OTHER_OBJ))
+        return 1;
+    }
+  return 0;
+}
+
+# endif
+
+#elif USE_ACL && (HAVE_ACLX_GET || HAVE_STATACL) /* AIX */
+
+/* Return 1 if the given ACL is non-trivial.
+   Return 0 if it is trivial, i.e. equivalent to a simple stat() mode.  */
+int
+acl_nontrivial (struct acl *a)
+{
+  /* The normal way to iterate through an ACL is like this:
+       struct acl_entry *ace;
+       for (ace = a->acl_ext; ace != acl_last (a); ace = acl_nxt (ace))
+         {
+           struct ace_id *aei;
+           switch (ace->ace_type)
+             {
+             case ACC_PERMIT:
+             case ACC_DENY:
+             case ACC_SPECIFY:
+               ...;
+             }
+           for (aei = ace->ace_id; aei != id_last (ace); aei = id_nxt (aei))
+             ...
+         }
+   */
+  return (acl_last (a) != a->acl_ext ? 1 : 0);
+}
+
+# if HAVE_ACLX_GET && defined ACL_AIX_WIP /* newer AIX */
+
+/* Return 1 if the given ACL is non-trivial.
+   Return 0 if it is trivial, i.e. equivalent to a simple stat() mode.  */
+int
+acl_nfs4_nontrivial (nfs4_acl_int_t *a)
+{
+#  if 1 /* let's try this first */
+  return (a->aclEntryN > 0 ? 1 : 0);
+#  else
+  int count = a->aclEntryN;
+  int i;
+
+  for (i = 0; i < count; i++)
+    {
+      nfs4_ace_int_t *ace = &a->aclEntry[i];
+
+      if (!((ace->flags & ACE4_ID_SPECIAL) != 0
+            && (ace->aceWho.special_whoid == ACE4_WHO_OWNER
+                || ace->aceWho.special_whoid == ACE4_WHO_GROUP
+                || ace->aceWho.special_whoid == ACE4_WHO_EVERYONE)
+            && ace->aceType == ACE4_ACCESS_ALLOWED_ACE_TYPE
+            && ace->aceFlags == 0
+            && (ace->aceMask & ~(ACE4_READ_DATA | ACE4_LIST_DIRECTORY
+                                 | ACE4_WRITE_DATA | ACE4_ADD_FILE
+                                 | ACE4_EXECUTE)) == 0))
+        return 1;
+    }
+  return 0;
+#  endif
+}
+
+# endif
+
+#elif USE_ACL && HAVE_ACLSORT /* NonStop Kernel */
+
+/* Test an ACL retrieved with ACL_GET.
+   Return 1 if the given ACL, consisting of COUNT entries, is non-trivial.
+   Return 0 if it is trivial, i.e. equivalent to a simple stat() mode.  */
+int
+acl_nontrivial (int count, struct acl *entries)
+{
+  int i;
+
+  for (i = 0; i < count; i++)
+    {
+      struct acl *ace = &entries[i];
+
+      /* Note: If ace->a_type = USER_OBJ, ace->a_id is the st_uid from stat().
+         If ace->a_type = GROUP_OBJ, ace->a_id is the st_gid from stat().
+         We don't need to check ace->a_id in these cases.  */
+      if (!(ace->a_type == USER_OBJ /* no need to check ace->a_id here */
+            || ace->a_type == GROUP_OBJ /* no need to check ace->a_id here */
+            || ace->a_type == CLASS_OBJ
+            || ace->a_type == OTHER_OBJ))
+        return 1;
+    }
+  return 0;
+}
+
+#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)
+   on error.  SB must be set to the stat buffer of NAME, obtained
+   through stat() or lstat().  */
+
+int
+file_has_acl (char const *name, struct stat const *sb)
+{
+#if USE_ACL
+  if (! S_ISLNK (sb->st_mode))
+    {
+# if HAVE_ACL_GET_FILE
+
+      /* POSIX 1003.1e (draft 17 -- abandoned) specific version.  */
+      /* Linux, FreeBSD, Mac OS X, IRIX, Tru64 */
+      int ret;
+
+      if (HAVE_ACL_EXTENDED_FILE) /* Linux */
+        {
+          /* On Linux, acl_extended_file is an optimized function: It only
+             makes two calls to getxattr(), one for ACL_TYPE_ACCESS, one for
+             ACL_TYPE_DEFAULT.  */
+          ret = acl_extended_file (name);
+        }
+      else /* FreeBSD, Mac OS X, IRIX, Tru64 */
+        {
+#  if HAVE_ACL_TYPE_EXTENDED /* Mac OS X */
+          /* On Mac OS X, acl_get_file (name, ACL_TYPE_ACCESS)
+             and acl_get_file (name, ACL_TYPE_DEFAULT)
+             always return NULL / EINVAL.  There is no point in making
+             these two useless calls.  The real ACL is retrieved through
+             acl_get_file (name, ACL_TYPE_EXTENDED).  */
+          acl_t acl = acl_get_file (name, ACL_TYPE_EXTENDED);
+          if (acl)
+            {
+              ret = acl_extended_nontrivial (acl);
+              acl_free (acl);
+            }
+          else
+            ret = -1;
+#  else /* FreeBSD, IRIX, Tru64 */
+          acl_t acl = acl_get_file (name, ACL_TYPE_ACCESS);
+          if (acl)
+            {
+              int saved_errno;
+
+              ret = acl_access_nontrivial (acl);
+              saved_errno = errno;
+              acl_free (acl);
+              errno = saved_errno;
+#   if HAVE_ACL_FREE_TEXT /* Tru64 */
+              /* On OSF/1, acl_get_file (name, ACL_TYPE_DEFAULT) always
+                 returns NULL with errno not set.  There is no point in
+                 making this call.  */
+#   else /* FreeBSD, IRIX */
+              /* On Linux, FreeBSD, IRIX, acl_get_file (name, ACL_TYPE_ACCESS)
+                 and acl_get_file (name, ACL_TYPE_DEFAULT) on a directory
+                 either both succeed or both fail; it depends on the
+                 file system.  Therefore there is no point in making the second
+                 call if the first one already failed.  */
+              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;
+                }
+#   endif
+            }
+          else
+            ret = -1;
+#  endif
+        }
+      if (ret < 0)
+        return - acl_errno_valid (errno);
+      return ret;
+
+# elif HAVE_FACL && defined GETACL /* Solaris, Cygwin, not HP-UX */
+
+#  if defined ACL_NO_TRIVIAL
+
+      /* Solaris 10 (newer version), which has additional API declared in
+         <sys/acl.h> (acl_t) and implemented in libsec (acl_set, acl_trivial,
+         acl_fromtext, ...).  */
+      return acl_trivial (name);
+
+#  else /* Solaris, Cygwin, general case */
+
+      /* Solaris 2.5 through Solaris 10, Cygwin, and contemporaneous versions
+         of Unixware.  The acl() call returns the access and default ACL both
+         at once.  */
+      {
+        /* Initially, try to read the entries into a stack-allocated buffer.
+           Use malloc if it does not fit.  */
+        enum
+          {
+            alloc_init = 4000 / sizeof (aclent_t), /* >= 3 */
+            alloc_max = MIN (INT_MAX, SIZE_MAX / sizeof (aclent_t))
+          };
+        aclent_t buf[alloc_init];
+        size_t alloc = alloc_init;
+        aclent_t *entries = buf;
+        aclent_t *malloced = NULL;
+        int count;
+
+        for (;;)
+          {
+            count = acl (name, GETACL, alloc, entries);
+            if (count < 0 && errno == ENOSPC)
+              {
+                /* Increase the size of the buffer.  */
+                free (malloced);
+                if (alloc > alloc_max / 2)
+                  {
+                    errno = ENOMEM;
+                    return -1;
+                  }
+                alloc = 2 * alloc; /* <= alloc_max */
+                entries = malloced =
+                  (aclent_t *) malloc (alloc * sizeof (aclent_t));
+                if (entries == NULL)
+                  {
+                    errno = ENOMEM;
+                    return -1;
+                  }
+                continue;
+              }
+            break;
+          }
+        if (count < 0)
+          {
+            if (errno == ENOSYS || errno == ENOTSUP)
+              ;
+            else
+              {
+                int saved_errno = errno;
+                free (malloced);
+                errno = saved_errno;
+                return -1;
+              }
+          }
+        else if (count == 0)
+          ;
+        else
+          {
+            /* Don't use MIN_ACL_ENTRIES:  It's set to 4 on Cygwin, but Cygwin
+               returns only 3 entries for files with no ACL.  But this is safe:
+               If there are more than 4 entries, there cannot be only the
+               "user::", "group::", "other:", and "mask:" entries.  */
+            if (count > 4)
+              {
+                free (malloced);
+                return 1;
+              }
+
+            if (acl_nontrivial (count, entries))
+              {
+                free (malloced);
+                return 1;
+              }
+          }
+        free (malloced);
+      }
+
+#   ifdef ACE_GETACL
+      /* Solaris also has a different variant of ACLs, used in ZFS and NFSv4
+         file systems (whereas the other ones are used in UFS file systems).  */
+      {
+        /* Initially, try to read the entries into a stack-allocated buffer.
+           Use malloc if it does not fit.  */
+        enum
+          {
+            alloc_init = 4000 / sizeof (ace_t), /* >= 3 */
+            alloc_max = MIN (INT_MAX, SIZE_MAX / sizeof (ace_t))
+          };
+        ace_t buf[alloc_init];
+        size_t alloc = alloc_init;
+        ace_t *entries = buf;
+        ace_t *malloced = NULL;
+        int count;
+
+        for (;;)
+          {
+            count = acl (name, ACE_GETACL, alloc, entries);
+            if (count < 0 && errno == ENOSPC)
+              {
+                /* Increase the size of the buffer.  */
+                free (malloced);
+                if (alloc > alloc_max / 2)
+                  {
+                    errno = ENOMEM;
+                    return -1;
+                  }
+                alloc = 2 * alloc; /* <= alloc_max */
+                entries = malloced = (ace_t *) malloc (alloc * sizeof (ace_t));
+                if (entries == NULL)
+                  {
+                    errno = ENOMEM;
+                    return -1;
+                  }
+                continue;
+              }
+            break;
+          }
+        if (count < 0)
+          {
+            if (errno == ENOSYS || errno == EINVAL)
+              ;
+            else
+              {
+                int saved_errno = errno;
+                free (malloced);
+                errno = saved_errno;
+                return -1;
+              }
+          }
+        else if (count == 0)
+          ;
+        else
+          {
+            /* In the old (original Solaris 10) convention:
+               If there are more than 3 entries, there cannot be only the
+               ACE_OWNER, ACE_GROUP, ACE_OTHER entries.
+               In the newer Solaris 10 and Solaris 11 convention:
+               If there are more than 6 entries, there cannot be only the
+               ACE_OWNER, ACE_GROUP, ACE_EVERYONE entries, each once with
+               NEW_ACE_ACCESS_ALLOWED_ACE_TYPE and once with
+               NEW_ACE_ACCESS_DENIED_ACE_TYPE.  */
+            if (count > 6)
+              {
+                free (malloced);
+                return 1;
+              }
+
+            if (acl_ace_nontrivial (count, entries))
+              {
+                free (malloced);
+                return 1;
+              }
+          }
+        free (malloced);
+      }
+#   endif
+
+      return 0;
+#  endif
+
+# elif HAVE_GETACL /* HP-UX */
+
+      {
+        struct acl_entry entries[NACLENTRIES];
+        int count;
+
+        count = getacl (name, NACLENTRIES, entries);
+
+        if (count < 0)
+          {
+            /* ENOSYS is seen on newer HP-UX versions.
+               EOPNOTSUPP is typically seen on NFS mounts.
+               ENOTSUP was seen on Quantum StorNext file systems (cvfs).  */
+            if (errno == ENOSYS || errno == EOPNOTSUPP || errno == ENOTSUP)
+              ;
+            else
+              return -1;
+          }
+        else if (count == 0)
+          return 0;
+        else /* count > 0 */
+          {
+            if (count > NACLENTRIES)
+              /* If NACLENTRIES cannot be trusted, use dynamic memory
+                 allocation.  */
+              abort ();
+
+            /* If there are more than 3 entries, there cannot be only the
+               (uid,%), (%,gid), (%,%) entries.  */
+            if (count > 3)
+              return 1;
+
+            {
+              struct stat statbuf;
+
+              if (stat (name, &statbuf) < 0)
+                return -1;
+
+              return acl_nontrivial (count, entries, &statbuf);
+            }
+          }
+      }
+
+#  if HAVE_ACLV_H /* HP-UX >= 11.11 */
+
+      {
+        struct acl entries[NACLVENTRIES];
+        int count;
+
+        count = acl ((char *) name, ACL_GET, NACLVENTRIES, entries);
+
+        if (count < 0)
+          {
+            /* EOPNOTSUPP is seen on NFS in HP-UX 11.11, 11.23.
+               EINVAL is seen on NFS in HP-UX 11.31.  */
+            if (errno == ENOSYS || errno == EOPNOTSUPP || errno == EINVAL)
+              ;
+            else
+              return -1;
+          }
+        else if (count == 0)
+          return 0;
+        else /* count > 0 */
+          {
+            if (count > NACLVENTRIES)
+              /* If NACLVENTRIES cannot be trusted, use dynamic memory
+                 allocation.  */
+              abort ();
+
+            /* If there are more than 4 entries, there cannot be only the
+               four base ACL entries.  */
+            if (count > 4)
+              return 1;
+
+            return aclv_nontrivial (count, entries);
+          }
+      }
+
+#  endif
+
+# elif HAVE_ACLX_GET && defined ACL_AIX_WIP /* AIX */
+
+      acl_type_t type;
+      char aclbuf[1024];
+      void *acl = aclbuf;
+      size_t aclsize = sizeof (aclbuf);
+      mode_t mode;
+
+      for (;;)
+        {
+          /* The docs say that type being 0 is equivalent to ACL_ANY, but it
+             is not true, in AIX 5.3.  */
+          type.u64 = ACL_ANY;
+          if (aclx_get (name, 0, &type, aclbuf, &aclsize, &mode) >= 0)
+            break;
+          if (errno == ENOSYS)
+            return 0;
+          if (errno != ENOSPC)
+            {
+              if (acl != aclbuf)
+                {
+                  int saved_errno = errno;
+                  free (acl);
+                  errno = saved_errno;
+                }
+              return -1;
+            }
+          aclsize = 2 * aclsize;
+          if (acl != aclbuf)
+            free (acl);
+          acl = malloc (aclsize);
+          if (acl == NULL)
+            {
+              errno = ENOMEM;
+              return -1;
+            }
+        }
+
+      if (type.u64 == ACL_AIXC)
+        {
+          int result = acl_nontrivial ((struct acl *) acl);
+          if (acl != aclbuf)
+            free (acl);
+          return result;
+        }
+      else if (type.u64 == ACL_NFS4)
+        {
+          int result = acl_nfs4_nontrivial ((nfs4_acl_int_t *) acl);
+          if (acl != aclbuf)
+            free (acl);
+          return result;
+        }
+      else
+        {
+          /* A newer type of ACL has been introduced in the system.
+             We should better support it.  */
+          if (acl != aclbuf)
+            free (acl);
+          errno = EINVAL;
+          return -1;
+        }
+
+# elif HAVE_STATACL /* older AIX */
+
+      union { struct acl a; char room[4096]; } u;
+
+      if (statacl (name, STX_NORMAL, &u.a, sizeof (u)) < 0)
+        return -1;
+
+      return acl_nontrivial (&u.a);
+
+# elif HAVE_ACLSORT /* NonStop Kernel */
+
+      {
+        struct acl entries[NACLENTRIES];
+        int count;
+
+        count = acl ((char *) name, ACL_GET, NACLENTRIES, entries);
+
+        if (count < 0)
+          {
+            if (errno == ENOSYS || errno == ENOTSUP)
+              ;
+            else
+              return -1;
+          }
+        else if (count == 0)
+          return 0;
+        else /* count > 0 */
+          {
+            if (count > NACLENTRIES)
+              /* If NACLENTRIES cannot be trusted, use dynamic memory
+                 allocation.  */
+              abort ();
+
+            /* If there are more than 4 entries, there cannot be only the
+               four base ACL entries.  */
+            if (count > 4)
+              return 1;
+
+            return acl_nontrivial (count, entries);
+          }
+      }
+
+# endif
+    }
+#endif
+
+  return 0;
+}