1 files changed, 117 insertions, 0 deletions
diff --git a/gl/m4/select.m4 b/gl/m4/select.m4
new file mode 100644
index 0000000..163f8fb
--- /dev/null
+++ b/gl/m4/select.m4
@@ -0,0 +1,117 @@
+# select.m4 serial 13
+dnl Copyright (C) 2009-2022 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([gl_FUNC_SELECT],
+[
+  AC_REQUIRE([gl_SYS_SELECT_H])
+  AC_REQUIRE([AC_C_RESTRICT])
+  AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
+  AC_REQUIRE([gl_SOCKETS])
+  if test "$ac_cv_header_winsock2_h" = yes; then
+    REPLACE_SELECT=1
+  else
+    dnl On Interix 3.5, select(0, NULL, NULL, NULL, timeout) fails with error
+    dnl EFAULT.
+    AC_CHECK_HEADERS_ONCE([sys/select.h])
+    AC_CACHE_CHECK([whether select supports a 0 argument],
+      [gl_cv_func_select_supports0],
+      [
+        AC_RUN_IFELSE([AC_LANG_SOURCE([[
+#include <sys/types.h>
+#include <sys/time.h>
+#if HAVE_SYS_SELECT_H
+#include <sys/select.h>
+#endif
+int main ()
+{
+  struct timeval timeout;
+  timeout.tv_sec = 0;
+  timeout.tv_usec = 5;
+  return select (0, (fd_set *)0, (fd_set *)0, (fd_set *)0, &timeout) < 0;
+}]])], [gl_cv_func_select_supports0=yes], [gl_cv_func_select_supports0=no],
+          [
+changequote(,)dnl
+           case "$host_os" in
+                       # Guess no on Interix.
+             interix*) gl_cv_func_select_supports0="guessing no";;
+                       # Guess yes otherwise.
+             *)        gl_cv_func_select_supports0="guessing yes";;
+           esac
+changequote([,])dnl
+          ])
+      ])
+    case "$gl_cv_func_select_supports0" in
+      *yes) ;;
+      *) REPLACE_SELECT=1 ;;
+    esac
+
+    dnl On FreeBSD 8.2, select() doesn't always reject bad fds.
+    AC_CACHE_CHECK([whether select detects invalid fds],
+      [gl_cv_func_select_detects_ebadf],
+      [
+        AC_RUN_IFELSE([AC_LANG_PROGRAM([[
+#include <sys/types.h>
+#include <sys/time.h>
+#if HAVE_SYS_SELECT_H
+# include <sys/select.h>
+#endif
+#include <unistd.h>
+#include <errno.h>
+]GL_MDA_DEFINES],
+[[
+  fd_set set;
+  dup2(0, 16);
+  FD_ZERO(&set);
+  FD_SET(16, &set);
+  close(16);
+  struct timeval timeout;
+  timeout.tv_sec = 0;
+  timeout.tv_usec = 5;
+  return select (17, &set, NULL, NULL, &timeout) != -1 || errno != EBADF;
+]])], [gl_cv_func_select_detects_ebadf=yes],
+      [gl_cv_func_select_detects_ebadf=no],
+          [
+           case "$host_os" in
+                             # Guess yes on Linux systems.
+            linux-* | linux) gl_cv_func_select_detects_ebadf="guessing yes" ;;
+                             # Guess yes on glibc systems.
+            *-gnu* | gnu*)   gl_cv_func_select_detects_ebadf="guessing yes" ;;
+                             # If we don't know, obey --enable-cross-guesses.
+            *)               gl_cv_func_select_detects_ebadf="$gl_cross_guess_normal" ;;
+           esac
+          ])
+      ])
+    case $gl_cv_func_select_detects_ebadf in
+      *yes) ;;
+      *) REPLACE_SELECT=1 ;;
+    esac
+  fi
+
+  dnl Determine the needed libraries.
+  LIB_SELECT="$LIBSOCKET"
+  if test $REPLACE_SELECT = 1; then
+    case "$host_os" in
+      mingw*)
+        dnl On the MSVC platform, the function MsgWaitForMultipleObjects
+        dnl (used in lib/select.c) requires linking with -luser32. On mingw,
+        dnl it is implicit.
+        AC_LINK_IFELSE(
+          [AC_LANG_SOURCE([[
+#define WIN32_LEAN_AND_MEAN
+#include <windows.h>
+int
+main ()
+{
+  MsgWaitForMultipleObjects (0, NULL, 0, 0, 0);
+  return 0;
+}]])],
+          [],
+          [LIB_SELECT="$LIB_SELECT -luser32"])
+        ;;
+    esac
+  fi
+  AC_SUBST([LIB_SELECT])
+])