fcntl_h.m4

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Author : Bruno Haible
Date : 2009-10-18 17:30:55
Hash : 8a7fc3c7
Message : Avoid symlink attack in localcharset module. Use fcntl_h.m4 from gnulib.
libcharset/m4/fcntl_h.m4
# serial 6
# Configure fcntl.h.
dnl Copyright (C) 2006, 2007, 2009 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.

AC_DEFUN([gl_FCNTL_H],
[
  AC_REQUIRE([gl_FCNTL_H_DEFAULTS])
  AC_REQUIRE([gl_FCNTL_O_FLAGS])
  gl_CHECK_NEXT_HEADERS([fcntl.h])
  FCNTL_H='fcntl.h'
  AC_SUBST([FCNTL_H])
])

# 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.])
])

AC_DEFUN([gl_FCNTL_MODULE_INDICATOR],
[
  dnl Use AC_REQUIRE here, so that the default settings are expanded once only.
  AC_REQUIRE([gl_FCNTL_H_DEFAULTS])
  GNULIB_[]m4_translit([$1],[abcdefghijklmnopqrstuvwxyz./-],[ABCDEFGHIJKLMNOPQRSTUVWXYZ___])=1
])

AC_DEFUN([gl_FCNTL_H_DEFAULTS],
[
  GNULIB_OPEN=0;    AC_SUBST([GNULIB_OPEN])
  GNULIB_OPENAT=0;  AC_SUBST([GNULIB_OPENAT])
  dnl Assume proper GNU behavior unless another module says otherwise.
  HAVE_OPENAT=1;    AC_SUBST([HAVE_OPENAT])
  REPLACE_OPEN=0;   AC_SUBST([REPLACE_OPEN])
  REPLACE_OPENAT=0; AC_SUBST([REPLACE_OPENAT])
])
thodg/libiconv/libcharset/m4/fcntl_h.m4

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thodg/libiconv /libcharset/m4/fcntl_h.m4
