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diff --git a/lib/ftello.c b/lib/ftello.c
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+/* An ftello() function that works around platform bugs.
+ Copyright (C) 2007, 2009-2022 Free Software Foundation, Inc.
+
+ This file is free software: you can redistribute it and/or modify
+ it under the terms of the GNU Lesser General Public License as
+ published by the Free Software Foundation; either version 2.1 of the
+ License, or (at your option) any later version.
+
+ This file is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public License
+ along with this program. If not, see <https://www.gnu.org/licenses/>. */
+
+#include <config.h>
+
+/* Specification. */
+#include <stdio.h>
+
+#include <errno.h>
+#include "intprops.h"
+
+/* Get lseek. */
+#include <unistd.h>
+
+#include "stdio-impl.h"
+
+off_t
+ftello (FILE *fp)
+#undef ftello
+#if !HAVE_FTELLO
+# undef ftell
+# define ftello ftell
+#endif
+#if _GL_WINDOWS_64_BIT_OFF_T
+# undef ftello
+# if HAVE__FTELLI64 /* msvc, mingw64 */
+# define ftello _ftelli64
+# else /* mingw */
+# define ftello ftello64
+# endif
+#endif
+{
+#if FTELLO_BROKEN_AFTER_UNGETC /* macOS >= 10.15 */
+ /* The system's ftello() is completely broken, because it calls __sflush,
+ which makes side effects on the stream. */
+
+ /* Handle non-seekable files first. */
+ if (fp->_file < 0 || fp->_seek == NULL)
+ {
+ errno = ESPIPE;
+ return -1;
+ }
+
+ /* Determine the current offset, ignoring buffered and pushed-back bytes. */
+ off_t pos;
+
+ if (fp->_flags & __SOFF)
+ pos = fp->_offset;
+ else
+ {
+ pos = fp->_seek (fp->_cookie, 0, SEEK_CUR);
+ if (pos < 0)
+ return -1;
+ if (fp->_flags & __SOPT)
+ {
+ fp->_offset = pos;
+ fp->_flags |= __SOFF;
+ }
+ }
+
+ if (fp->_flags & __SRD)
+ {
+ /* Now consider buffered and pushed-back bytes from ungetc. */
+ if (fp->_ub._base != NULL)
+ /* Considering the buffered bytes, we are at position
+ pos - fp->_ur.
+ Considering also the pushed-back bytes, we are at position
+ pos - fp->_ur - fp->_r. */
+ pos = pos - fp->_ur - fp->_r;
+ else
+ /* Considering the buffered bytes, we are at position
+ pos - fp->_r. */
+ pos = pos - fp->_r;
+ if (pos < 0)
+ {
+ errno = EIO;
+ return -1;
+ }
+ }
+ else if ((fp->_flags & __SWR) && fp->_p != NULL)
+ {
+ /* Consider the buffered bytes. */
+ off_t buffered = fp->_p - fp->_bf._base;
+
+ /* Compute pos + buffered, with overflow check. */
+ off_t sum;
+ if (! INT_ADD_OK (pos, buffered, &sum))
+ {
+ errno = EOVERFLOW;
+ return -1;
+ }
+ pos = sum;
+ }
+
+ return pos;
+
+#else
+
+# if LSEEK_PIPE_BROKEN
+ /* mingw gives bogus answers rather than failure on non-seekable files. */
+ if (lseek (fileno (fp), 0, SEEK_CUR) == -1)
+ return -1;
+# endif
+
+# if FTELLO_BROKEN_AFTER_SWITCHING_FROM_READ_TO_WRITE /* Solaris */
+ /* The Solaris stdio leaves the _IOREAD flag set after reading from a file
+ reaches EOF and the program then starts writing to the file. ftello
+ gets confused by this. */
+ if (fp_->_flag & _IOWRT)
+ {
+ off_t pos;
+
+ /* Call ftello nevertheless, for the side effects that it does on fp. */
+ ftello (fp);
+
+ /* Compute the file position ourselves. */
+ pos = lseek (fileno (fp), (off_t) 0, SEEK_CUR);
+ if (pos >= 0)
+ {
+ if ((fp_->_flag & _IONBF) == 0 && fp_->_base != NULL)
+ pos += fp_->_ptr - fp_->_base;
+ }
+ return pos;
+ }
+# endif
+
+# if defined __SL64 && defined __SCLE /* Cygwin */
+ if ((fp->_flags & __SL64) == 0)
+ {
+ /* Cygwin 1.5.0 through 1.5.24 failed to open stdin in 64-bit
+ mode; but has an ftello that requires 64-bit mode. */
+ FILE *tmp = fopen ("/dev/null", "r");
+ if (!tmp)
+ return -1;
+ fp->_flags |= __SL64;
+ fp->_seek64 = tmp->_seek64;
+ fclose (tmp);
+ }
+# endif
+
+ return ftello (fp);
+
+#endif
+}