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# ftello.m4 serial 15
dnl Copyright (C) 2007-2023 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_FTELLO],
[
AC_REQUIRE([gl_STDIO_H_DEFAULTS])
AC_REQUIRE([AC_PROG_CC])
AC_REQUIRE([gl_STDIN_LARGE_OFFSET])
AC_REQUIRE([gl_SYS_TYPES_H])
dnl Persuade glibc <stdio.h> to declare ftello().
AC_REQUIRE([AC_USE_SYSTEM_EXTENSIONS])
AC_CHECK_DECLS_ONCE([ftello])
if test $ac_cv_have_decl_ftello = no; then
HAVE_DECL_FTELLO=0
fi
AC_CACHE_CHECK([for ftello], [gl_cv_func_ftello],
[
AC_LINK_IFELSE(
[AC_LANG_PROGRAM(
[[#include <stdio.h>]],
[[ftello (stdin);]])],
[gl_cv_func_ftello=yes],
[gl_cv_func_ftello=no])
])
if test $gl_cv_func_ftello = no; then
HAVE_FTELLO=0
else
if test $WINDOWS_64_BIT_OFF_T = 1; then
REPLACE_FTELLO=1
fi
if test $gl_cv_var_stdin_large_offset = no; then
REPLACE_FTELLO=1
fi
AC_REQUIRE([AC_CANONICAL_HOST])
if test $REPLACE_FTELLO = 0; then
dnl On native Windows, in some circumstances, ftell(), ftello(),
dnl fgetpos(), lseek(), _lseeki64() all succeed on devices of type
dnl FILE_TYPE_PIPE. However, to match POSIX behaviour, we want
dnl ftell(), ftello(), fgetpos(), lseek() to fail when the argument fd
dnl designates a pipe. See also
dnl https://github.com/python/cpython/issues/78961#issuecomment-1093800325
case "$host_os" in
mingw*) REPLACE_FTELLO=1 ;;
esac
fi
if test $REPLACE_FTELLO = 0; then
dnl Detect bug on Solaris.
dnl ftell and ftello produce incorrect results after putc that followed a
dnl getc call that reached EOF on Solaris. This is because the _IOREAD
dnl flag does not get cleared in this case, even though _IOWRT gets set,
dnl and ftell and ftello look whether the _IOREAD flag is set.
AC_CACHE_CHECK([whether ftello works],
[gl_cv_func_ftello_works],
[
dnl Initial guess, used when cross-compiling or when /dev/tty cannot
dnl be opened.
changequote(,)dnl
case "$host_os" in
# Guess no on Solaris.
solaris*) gl_cv_func_ftello_works="guessing no" ;;
# Guess yes on native Windows.
mingw*) gl_cv_func_ftello_works="guessing yes" ;;
# Guess yes otherwise.
*) gl_cv_func_ftello_works="guessing yes" ;;
esac
changequote([,])dnl
AC_RUN_IFELSE(
[AC_LANG_SOURCE([[
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define TESTFILE "conftest.tmp"
int
main (void)
{
FILE *fp;
/* Create a file with some contents. */
fp = fopen (TESTFILE, "w");
if (fp == NULL)
return 70;
if (fwrite ("foogarsh", 1, 8, fp) < 8)
{ fclose (fp); return 71; }
if (fclose (fp))
return 72;
/* The file's contents is now "foogarsh". */
/* Try writing after reading to EOF. */
fp = fopen (TESTFILE, "r+");
if (fp == NULL)
return 73;
if (fseek (fp, -1, SEEK_END))
{ fclose (fp); return 74; }
if (!(getc (fp) == 'h'))
{ fclose (fp); return 1; }
if (!(getc (fp) == EOF))
{ fclose (fp); return 2; }
if (!(ftell (fp) == 8))
{ fclose (fp); return 3; }
if (!(ftell (fp) == 8))
{ fclose (fp); return 4; }
if (!(putc ('!', fp) == '!'))
{ fclose (fp); return 5; }
if (!(ftell (fp) == 9))
{ fclose (fp); return 6; }
if (!(fclose (fp) == 0))
return 7;
fp = fopen (TESTFILE, "r");
if (fp == NULL)
return 75;
{
char buf[10];
if (!(fread (buf, 1, 10, fp) == 9))
{ fclose (fp); return 10; }
if (!(memcmp (buf, "foogarsh!", 9) == 0))
{ fclose (fp); return 11; }
}
if (!(fclose (fp) == 0))
return 12;
/* The file's contents is now "foogarsh!". */
return 0;
}]])],
[gl_cv_func_ftello_works=yes],
[gl_cv_func_ftello_works=no], [:])
])
case "$gl_cv_func_ftello_works" in
*yes) ;;
*)
REPLACE_FTELLO=1
AC_DEFINE([FTELLO_BROKEN_AFTER_SWITCHING_FROM_READ_TO_WRITE], [1],
[Define to 1 if the system's ftello function has the Solaris bug.])
;;
esac
fi
if test $REPLACE_FTELLO = 0; then
dnl Detect bug on macOS >= 10.15.
gl_FUNC_UNGETC_WORKS
if test $gl_ftello_broken_after_ungetc = yes; then
REPLACE_FTELLO=1
AC_DEFINE([FTELLO_BROKEN_AFTER_UNGETC], [1],
[Define to 1 if the system's ftello function has the macOS bug.])
fi
fi
fi
])
# Prerequisites of lib/ftello.c.
AC_DEFUN([gl_PREREQ_FTELLO],
[
dnl Native Windows has the function _ftelli64. mingw hides it, but mingw64
dnl makes it usable again.
AC_CHECK_FUNCS([_ftelli64])
])
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