Merge GDB 7.5.1

gdb/gnulib/import/m4/fcntl-o.m4

+# fcntl-o.m4 serial 4
+dnl Copyright (C) 2006, 2009-2012 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.
+  dnl AC_USE_SYSTEM_EXTENSIONS was introduced in autoconf 2.60 and obsoletes
+  dnl AC_GNU_SOURCE.
+  m4_ifdef([AC_USE_SYSTEM_EXTENSIONS],
+    [AC_REQUIRE([AC_USE_SYSTEM_EXTENSIONS])],
+    [AC_REQUIRE([AC_GNU_SOURCE])])
+
+  AC_CHECK_HEADERS_ONCE([unistd.h])
+  AC_CHECK_FUNCS_ONCE([symlink])
+  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>
+           #if HAVE_UNISTD_H
+           # include <unistd.h>
+           #else /* on Windows with MSVC */
+           # include <io.h>
+           # include <stdlib.h>
+           # defined sleep(n) _sleep ((n) * 1000)
+           #endif
+           #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 result = !constants;
+            #if HAVE_SYMLINK
+            {
+              static char const sym[] = "conftest.sym";
+              if (symlink (".", sym) != 0)
+                result |= 2;
+              else
+                {
+                  int fd = open (sym, O_RDONLY | O_NOFOLLOW);
+                  if (fd >= 0)
+                    {
+                      close (fd);
+                      result |= 4;
+                    }
+                }
+              unlink (sym);
+            }
+            #endif
+            {
+              static char const file[] = "confdefs.h";
+              int fd = open (file, O_RDONLY | O_NOATIME);
+              if (fd < 0)
+                result |= 8;
+              else
+                {
+                  struct stat st0;
+                  if (fstat (fd, &st0) != 0)
+                    result |= 16;
+                  else
+                    {
+                      char c;
+                      sleep (1);
+                      if (read (fd, &c, 1) != 1)
+                        result |= 24;
+                      else
+                        {
+                          if (close (fd) != 0)
+                            result |= 32;
+                          else
+                            {
+                              struct stat st1;
+                              if (stat (file, &st1) != 0)
+                                result |= 40;
+                              else
+                                if (st0.st_atime != st1.st_atime)
+                                  result |= 64;
+                            }
+                        }
+                    }
+                }
+            }
+            return result;]])],
+       [gl_cv_header_working_fcntl_h=yes],
+       [case $? in #(
+        4) gl_cv_header_working_fcntl_h='no (bad O_NOFOLLOW)';; #(
+        64) gl_cv_header_working_fcntl_h='no (bad O_NOATIME)';; #(
+        68) 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.])
+])