Imported Upstream version 1.4

[debian/gzip] / m4 / openat.m4

diff --git a/m4/openat.m4 b/m4/openat.m4
new file mode 100644 (file)
index 0000000..7975efb
--- /dev/null
+++ b/m4/openat.m4
@@ -0,0 +1,124 @@
+# serial 27
+# See if we need to use our replacement for Solaris' openat et al functions.
+
+dnl Copyright (C) 2004-2010 Free Software Foundation, Inc.
+dnl This file is free software; the Free Software Foundation
+dnl gives unlimited permission to copy and/or distribute it,
+dnl with or without modifications, as long as this notice is preserved.
+
+# Written by Jim Meyering.
+
+AC_DEFUN([gl_FUNC_OPENAT],
+[
+  AC_REQUIRE([gl_FCNTL_H_DEFAULTS])
+  GNULIB_OPENAT=1
+
+  AC_REQUIRE([gl_SYS_STAT_H_DEFAULTS])
+  GNULIB_FCHMODAT=1
+  GNULIB_FSTATAT=1
+  GNULIB_MKDIRAT=1
+
+  AC_REQUIRE([gl_UNISTD_H_DEFAULTS])
+  GNULIB_FCHOWNAT=1
+  GNULIB_UNLINKAT=1
+
+  AC_LIBOBJ([openat-proc])
+  AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS])
+  AC_CHECK_FUNCS_ONCE([lchmod])
+  AC_REPLACE_FUNCS([fchmodat fstatat mkdirat openat unlinkat])
+  AC_REQUIRE([AC_FUNC_LSTAT_FOLLOWS_SLASHED_SYMLINK])
+  AC_REQUIRE([gl_FUNC_UNLINK])
+  case $ac_cv_func_openat+$ac_cv_func_lstat_dereferences_slashed_symlink in
+  yes+yes)
+    # GNU/Hurd has unlinkat, but it has the same bug as unlink.
+    if test $REPLACE_UNLINK = 1; then
+      AC_LIBOBJ([unlinkat])
+      REPLACE_UNLINKAT=1
+    fi ;;
+  yes+*)
+    # Solaris 9 has *at functions, but uniformly mishandles trailing
+    # slash in all of them.
+    AC_LIBOBJ([openat])
+    REPLACE_OPENAT=1
+    AC_LIBOBJ([fstatat])
+    REPLACE_FSTATAT=1
+    AC_LIBOBJ([unlinkat])
+    REPLACE_UNLINKAT=1
+    ;;
+  *)
+    HAVE_OPENAT=0
+    HAVE_UNLINKAT=0 # No known system with unlinkat but not openat
+    HAVE_FSTATAT=0 # No known system with fstatat but not openat
+    gl_PREREQ_OPENAT;;
+  esac
+  if test $ac_cv_func_fchmodat != yes; then
+    HAVE_FCHMODAT=0
+  fi
+  if test $ac_cv_func_mkdirat != yes; then
+    HAVE_MKDIRAT=0
+  fi
+  gl_FUNC_FCHOWNAT
+])
+
+# gl_FUNC_FCHOWNAT_DEREF_BUG([ACTION-IF-BUGGY[, ACTION-IF-NOT_BUGGY]])
+AC_DEFUN([gl_FUNC_FCHOWNAT_DEREF_BUG],
+[
+  AC_CACHE_CHECK([whether fchownat works with AT_SYMLINK_NOFOLLOW],
+    gl_cv_func_fchownat_nofollow_works,
+    [
+     gl_dangle=conftest.dangle
+     # Remove any remnants of a previous test.
+     rm -f $gl_dangle
+     # Arrange for deletion of the temporary file this test creates.
+     ac_clean_files="$ac_clean_files $gl_dangle"
+     ln -s conftest.no-such $gl_dangle
+     AC_RUN_IFELSE(
+       [AC_LANG_SOURCE(
+          [[
+#include <fcntl.h>
+#include <unistd.h>
+#include <stdlib.h>
+#include <errno.h>
+#include <sys/types.h>
+int
+main ()
+{
+  return (fchownat (AT_FDCWD, "$gl_dangle", -1, getgid (),
+                    AT_SYMLINK_NOFOLLOW) != 0
+          && errno == ENOENT);
+}
+          ]])],
+    [gl_cv_func_fchownat_nofollow_works=yes],
+    [gl_cv_func_fchownat_nofollow_works=no],
+    [gl_cv_func_fchownat_nofollow_works=no],
+    )
+  ])
+  AS_IF([test $gl_cv_func_fchownat_nofollow_works = no], [$1], [$2])
+])
+
+# If we have the fchownat function, and it has the bug (in glibc-2.4)
+# that it dereferences symlinks even with AT_SYMLINK_NOFOLLOW, then
+# use the replacement function.
+# Also use the replacement function if fchownat is simply not available.
+AC_DEFUN([gl_FUNC_FCHOWNAT],
+[
+  AC_REQUIRE([gl_FUNC_CHOWN])
+  AC_CHECK_FUNC([fchownat],
+    [gl_FUNC_FCHOWNAT_DEREF_BUG([REPLACE_FCHOWNAT=1
+      AC_DEFINE([FCHOWNAT_NOFOLLOW_BUG], [1], [Define to 1 if your
+      platform has fchownat, but it cannot perform lchown tasks.])])],
+    [HAVE_FCHOWNAT=0])
+  if test $REPLACE_CHOWN = 1; then
+    REPLACE_FCHOWNAT=1
+  fi
+  if test $HAVE_FCHOWNAT = 0 || test $REPLACE_FCHOWNAT = 1; then
+    AC_LIBOBJ([fchownat])
+  fi
+])
+
+AC_DEFUN([gl_PREREQ_OPENAT],
+[
+  AC_REQUIRE([AC_C_INLINE])
+  AC_REQUIRE([gl_PROMOTED_TYPE_MODE_T])
+  :
+])