1 files changed, 151 insertions, 0 deletions

diff --git a/gl/m4/ftello.m4 b/gl/m4/ftello.m4
new file mode 100644
index 00000000..919f39d8
--- /dev/null
+++ b/gl/m4/ftello.m4
@@ -0,0 +1,151 @@
+# ftello.m4 serial 14
+dnl Copyright (C) 2007-2022 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_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
+    if test $REPLACE_FTELLO = 0; then
+      dnl Detect bug on Solaris.
+      dnl ftell and ftello produce incorrect results after putc that followed a
+      dnl getc call that reached EOF on Solaris. This is because the _IOREAD
+      dnl flag does not get cleared in this case, even though _IOWRT gets set,
+      dnl and ftell and ftello look whether the _IOREAD flag is set.
+      AC_REQUIRE([AC_CANONICAL_HOST])
+      AC_CACHE_CHECK([whether ftello works],
+        [gl_cv_func_ftello_works],
+        [
+          dnl Initial guess, used when cross-compiling or when /dev/tty cannot
+          dnl be opened.
+changequote(,)dnl
+          case "$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])
+])