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-rw-r--r--m4/environ.m446
1 files changed, 46 insertions, 0 deletions
diff --git a/m4/environ.m4 b/m4/environ.m4
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+++ b/m4/environ.m4
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+# environ.m4 serial 8
+dnl Copyright (C) 2001-2004, 2006-2022 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_CACHE_CHECK([if $2 is properly declared], [gt_cv_var],
+ [AC_COMPILE_IFELSE(
+ [AC_LANG_PROGRAM(
+ [[$1
+ typedef struct { int foo; } foo_t;
+ extern foo_t $2;]],
+ [[$2.foo = 1;]])],
+ [gt_cv_var=no],
+ [gt_cv_var=yes])])
+ 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])
+])