1# fpurge.m4 serial 8
2dnl Copyright (C) 2007, 2009-2018 Free Software Foundation, Inc.
3dnl This file is free software; the Free Software Foundation
4dnl gives unlimited permission to copy and/or distribute it,
5dnl with or without modifications, as long as this notice is preserved.
6
7AC_DEFUN([gl_FUNC_FPURGE],
8[
9  AC_REQUIRE([gl_STDIO_H_DEFAULTS])
10  AC_CHECK_FUNCS_ONCE([fpurge])
11  AC_CHECK_FUNCS_ONCE([__fpurge])
12  AC_CHECK_DECLS([fpurge], , , [[#include <stdio.h>]])
13  if test "x$ac_cv_func_fpurge" = xyes; then
14    HAVE_FPURGE=1
15    # Detect BSD bug.  Only cygwin 1.7 is known to be immune.
16    AC_CACHE_CHECK([whether fpurge works], [gl_cv_func_fpurge_works],
17      [AC_RUN_IFELSE(
18         [AC_LANG_PROGRAM(
19            [[#include <stdio.h>
20]],
21            [FILE *f = fopen ("conftest.txt", "w+");
22             if (!f)
23               return 1;
24             if (fputc ('a', f) != 'a')
25               { fclose (f); return 2; }
26             rewind (f);
27             if (fgetc (f) != 'a')
28               { fclose (f); return 3; }
29             if (fgetc (f) != EOF)
30               { fclose (f); return 4; }
31             if (fpurge (f) != 0)
32               { fclose (f); return 5; }
33             if (putc ('b', f) != 'b')
34               { fclose (f); return 6; }
35             if (fclose (f) != 0)
36               return 7;
37             if ((f = fopen ("conftest.txt", "r")) == NULL)
38               return 8;
39             if (fgetc (f) != 'a')
40               { fclose (f); return 9; }
41             if (fgetc (f) != 'b')
42               { fclose (f); return 10; }
43             if (fgetc (f) != EOF)
44               { fclose (f); return 11; }
45             if (fclose (f) != 0)
46               return 12;
47             if (remove ("conftest.txt") != 0)
48               return 13;
49             return 0;
50            ])],
51      [gl_cv_func_fpurge_works=yes], [gl_cv_func_fpurge_works=no],
52      [gl_cv_func_fpurge_works='guessing no'])])
53    if test "x$gl_cv_func_fpurge_works" != xyes; then
54      REPLACE_FPURGE=1
55    fi
56  else
57    HAVE_FPURGE=0
58  fi
59  if test "x$ac_cv_have_decl_fpurge" = xno; then
60    HAVE_DECL_FPURGE=0
61  fi
62])
63