1 files changed, 73 insertions, 0 deletions

diff --git a/gl/m4/fpurge.m4 b/gl/m4/fpurge.m4
new file mode 100644
index 00000000..b365409d
--- /dev/null
+++ b/gl/m4/fpurge.m4
@@ -0,0 +1,73 @@
+# fpurge.m4 serial 12
+dnl Copyright (C) 2007, 2009-2023 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_FPURGE],
+[
+  AC_REQUIRE([gl_STDIO_H_DEFAULTS])
+  AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
+  AC_CHECK_HEADERS_ONCE([stdio_ext.h])
+  AC_CHECK_FUNCS_ONCE([fpurge])
+  AC_CHECK_FUNCS_ONCE([__fpurge])
+  AC_CHECK_DECLS([fpurge], , , [[#include <stdio.h>]])
+  if test "x$ac_cv_func_fpurge" = xyes; then
+    HAVE_FPURGE=1
+    # Detect BSD bug.  Only cygwin 1.7 and musl are known to be immune.
+    AC_CACHE_CHECK([whether fpurge works], [gl_cv_func_fpurge_works],
+      [AC_RUN_IFELSE(
+         [AC_LANG_PROGRAM(
+            [[#include <stdio.h>
+]],
+            [[FILE *f = fopen ("conftest.txt", "w+");
+              if (!f)
+                return 1;
+              if (fputc ('a', f) != 'a')
+                { fclose (f); return 2; }
+              rewind (f);
+              if (fgetc (f) != 'a')
+                { fclose (f); return 3; }
+              if (fgetc (f) != EOF)
+                { fclose (f); return 4; }
+              if (fpurge (f) != 0)
+                { fclose (f); return 5; }
+              if (putc ('b', f) != 'b')
+                { fclose (f); return 6; }
+              if (fclose (f) != 0)
+                return 7;
+              if ((f = fopen ("conftest.txt", "r")) == NULL)
+                return 8;
+              if (fgetc (f) != 'a')
+                { fclose (f); return 9; }
+              if (fgetc (f) != 'b')
+                { fclose (f); return 10; }
+              if (fgetc (f) != EOF)
+                { fclose (f); return 11; }
+              if (fclose (f) != 0)
+                return 12;
+              if (remove ("conftest.txt") != 0)
+                return 13;
+              return 0;
+            ]])],
+         [gl_cv_func_fpurge_works=yes],
+         [gl_cv_func_fpurge_works=no],
+         [case "$host_os" in
+                     # Guess yes on musl systems.
+            *-musl*) gl_cv_func_fpurge_works="guessing yes" ;;
+                     # Otherwise obey --enable-cross-guesses.
+            *)       gl_cv_func_fpurge_works="$gl_cross_guess_normal" ;;
+          esac
+         ])
+      ])
+    case "$gl_cv_func_fpurge_works" in
+      *yes) ;;
+      *) REPLACE_FPURGE=1 ;;
+    esac
+  else
+    HAVE_FPURGE=0
+  fi
+  if test "x$ac_cv_have_decl_fpurge" = xno; then
+    HAVE_DECL_FPURGE=0
+  fi
+])