1 files changed, 81 insertions, 0 deletions

diff --git a/gl/m4/fcntl-o.m4 b/gl/m4/fcntl-o.m4
new file mode 100644
index 00000000..d416a61c
--- /dev/null
+++ b/gl/m4/fcntl-o.m4
@@ -0,0 +1,81 @@
+# fcntl-o.m4 serial 1
+dnl Copyright (C) 2006, 2009-2010 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.
+
+dnl Written by Paul Eggert.
+
+# Test whether the flags O_NOATIME and O_NOFOLLOW actually work.
+# Define HAVE_WORKING_O_NOATIME to 1 if O_NOATIME works, or to 0 otherwise.
+# Define HAVE_WORKING_O_NOFOLLOW to 1 if O_NOFOLLOW works, or to 0 otherwise.
+AC_DEFUN([gl_FCNTL_O_FLAGS],
+[
+  dnl Persuade glibc <fcntl.h> to define O_NOATIME and O_NOFOLLOW.
+  AC_REQUIRE([AC_USE_SYSTEM_EXTENSIONS])
+  AC_CACHE_CHECK([for working fcntl.h], [gl_cv_header_working_fcntl_h],
+    [AC_RUN_IFELSE(
+       [AC_LANG_PROGRAM(
+          [[#include <sys/types.h>
+           #include <sys/stat.h>
+           #include <unistd.h>
+           #include <fcntl.h>
+           #ifndef O_NOATIME
+            #define O_NOATIME 0
+           #endif
+           #ifndef O_NOFOLLOW
+            #define O_NOFOLLOW 0
+           #endif
+           static int const constants[] =
+            {
+              O_CREAT, O_EXCL, O_NOCTTY, O_TRUNC, O_APPEND,
+              O_NONBLOCK, O_SYNC, O_ACCMODE, O_RDONLY, O_RDWR, O_WRONLY
+            };
+          ]],
+          [[
+            int status = !constants;
+            {
+              static char const sym[] = "conftest.sym";
+              if (symlink (".", sym) != 0
+                  || close (open (sym, O_RDONLY | O_NOFOLLOW)) == 0)
+                status |= 32;
+              unlink (sym);
+            }
+            {
+              static char const file[] = "confdefs.h";
+              int fd = open (file, O_RDONLY | O_NOATIME);
+              char c;
+              struct stat st0, st1;
+              if (fd < 0
+                  || fstat (fd, &st0) != 0
+                  || sleep (1) != 0
+                  || read (fd, &c, 1) != 1
+                  || close (fd) != 0
+                  || stat (file, &st1) != 0
+                  || st0.st_atime != st1.st_atime)
+                status |= 64;
+            }
+            return status;]])],
+       [gl_cv_header_working_fcntl_h=yes],
+       [case $? in #(
+        32) gl_cv_header_working_fcntl_h='no (bad O_NOFOLLOW)';; #(
+        64) gl_cv_header_working_fcntl_h='no (bad O_NOATIME)';; #(
+        96) gl_cv_header_working_fcntl_h='no (bad O_NOATIME, O_NOFOLLOW)';; #(
+         *) gl_cv_header_working_fcntl_h='no';;
+        esac],
+       [gl_cv_header_working_fcntl_h=cross-compiling])])
+
+  case $gl_cv_header_working_fcntl_h in #(
+  *O_NOATIME* | no | cross-compiling) ac_val=0;; #(
+  *) ac_val=1;;
+  esac
+  AC_DEFINE_UNQUOTED([HAVE_WORKING_O_NOATIME], [$ac_val],
+    [Define to 1 if O_NOATIME works.])
+
+  case $gl_cv_header_working_fcntl_h in #(
+  *O_NOFOLLOW* | no | cross-compiling) ac_val=0;; #(
+  *) ac_val=1;;
+  esac
+  AC_DEFINE_UNQUOTED([HAVE_WORKING_O_NOFOLLOW], [$ac_val],
+    [Define to 1 if O_NOFOLLOW works.])
+])