2 files changed, 51 insertions, 0 deletions

diff --git a/m4/environ.m4 b/m4/environ.m4
new file mode 100644
index 00000000000..8eb57c9d999
--- /dev/null
+++ b/m4/environ.m4
@@ -0,0 +1,47 @@
+# environ.m4 serial 6
+dnl Copyright (C) 2001-2004, 2006-2012 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.
+
+AC_DEFUN_ONCE([gl_ENVIRON],
+[
+  AC_REQUIRE([gl_UNISTD_H_DEFAULTS])
+  dnl Persuade glibc <unistd.h> to declare environ.
+  AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS])
+
+  AC_CHECK_HEADERS_ONCE([unistd.h])
+  gt_CHECK_VAR_DECL(
+    [#if HAVE_UNISTD_H
+     #include <unistd.h>
+     #endif
+     /* mingw, BeOS, Haiku declare environ in <stdlib.h>, not in <unistd.h>.  */
+     #include <stdlib.h>
+    ],
+    [environ])
+  if test $gt_cv_var_environ_declaration != yes; then
+    HAVE_DECL_ENVIRON=0
+  fi
+])
+
+# Check if a variable is properly declared.
+# gt_CHECK_VAR_DECL(includes,variable)
+AC_DEFUN([gt_CHECK_VAR_DECL],
+[
+  define([gt_cv_var], [gt_cv_var_]$2[_declaration])
+  AC_MSG_CHECKING([if $2 is properly declared])
+  AC_CACHE_VAL([gt_cv_var], [
+    AC_COMPILE_IFELSE(
+      [AC_LANG_PROGRAM(
+         [[$1
+           extern struct { int foo; } $2;]],
+         [[$2.foo = 1;]])],
+      [gt_cv_var=no],
+      [gt_cv_var=yes])])
+  AC_MSG_RESULT([$gt_cv_var])
+  if test $gt_cv_var = yes; then
+    AC_DEFINE([HAVE_]m4_translit($2, [a-z], [A-Z])[_DECL], 1,
+              [Define if you have the declaration of $2.])
+  fi
+  undefine([gt_cv_var])
+])
diff --git a/m4/gnulib-comp.m4 b/m4/gnulib-comp.m4
index 754086ec2e7..b0cd185a2b5 100644
--- a/m4/gnulib-comp.m4
+++ b/m4/gnulib-comp.m4
@@ -52,6 +52,7 @@ AC_DEFUN([gl_EARLY],
   # Code from module dtoastr:
   # Code from module dtotimespec:
   # Code from module dup2:
+  # Code from module environ:
   # Code from module extensions:
   AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS])
   # Code from module filemode:
@@ -148,6 +149,8 @@ if test $HAVE_DUP2 = 0 || test $REPLACE_DUP2 = 1; then
   gl_PREREQ_DUP2
 fi
 gl_UNISTD_MODULE_INDICATOR([dup2])
+gl_ENVIRON
+gl_UNISTD_MODULE_INDICATOR([environ])
 gl_FILEMODE
 gl_GETLOADAVG
 if test $HAVE_GETLOADAVG = 0; then
@@ -598,6 +601,7 @@ AC_DEFUN([gl_FILE_LIST], [
   m4/c-strtod.m4
   m4/clock_time.m4
   m4/dup2.m4
+  m4/environ.m4
   m4/extensions.m4
   m4/filemode.m4
   m4/getloadavg.m4