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-rw-r--r--configure.in31
1 files changed, 31 insertions, 0 deletions
diff --git a/configure.in b/configure.in
index 3b1d49e4..50c149a8 100644
--- a/configure.in
+++ b/configure.in
@@ -784,6 +784,37 @@ AC_PROG_CC
AM_PROG_CC_C_O
AC_PROG_RANLIB
+# Look for environ alternatives. Possibility #1: is environ in unistd.h?
+AC_MSG_CHECKING([for environ in unistd.h])
+AC_COMPILE_IFELSE([
+#define _GNU_SOURCE
+#include <unistd.h>
+int main(int argc, char **argv) { char **ep = environ; }
+ ], [
+ AC_MSG_RESULT([yes])
+ has_environ=yes
+ ], [
+ AC_MSG_RESULT([no])
+
+ # Possibility #2: can environ be found in an available library?
+ AC_MSG_CHECKING([for extern environ])
+ AC_LINK_IFELSE([
+extern char **environ;
+int main(int argc, char **argv) { char **ep = environ; }
+ ], [
+ AC_DEFINE(NEED_ENVIRON_EXTERN, [1], [Must declare 'environ' to use it.])
+ has_environ=yes
+ ], [
+ has_environ=no
+ ])
+ AC_MSG_RESULT([${has_environ}])
+ ])
+
+if test "${has_environ}" != "yes" ; then
+ AC_MSG_FAILURE([Could find 'environ' in unistd.h or available libraries.])
+fi
+
+
# set default gcc warnings
GCC_WARNINGS="-Wall -Wstrict-prototypes -Wformat-security"
if test "${gcc_wextra}" = yes; then