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-rw-r--r--lib/fseeko.c164
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diff --git a/lib/fseeko.c b/lib/fseeko.c
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--- /dev/null
+++ b/lib/fseeko.c
@@ -0,0 +1,164 @@
+/* An fseeko() function that, together with fflush(), is POSIX compliant.
+ Copyright (C) 2007-2022 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>
+
+/* Get off_t, lseek, _POSIX_VERSION. */
+#include <unistd.h>
+
+#include "stdio-impl.h"
+
+int
+fseeko (FILE *fp, off_t offset, int whence)
+#undef fseeko
+#if !HAVE_FSEEKO
+# undef fseek
+# define fseeko fseek
+#endif
+#if _GL_WINDOWS_64_BIT_OFF_T
+# undef fseeko
+# if HAVE__FSEEKI64 && HAVE_DECL__FSEEKI64 /* msvc, mingw since msvcrt8.0, mingw64 */
+# define fseeko _fseeki64
+# else /* mingw before msvcrt8.0 */
+# define fseeko fseeko64
+# endif
+#endif
+{
+#if LSEEK_PIPE_BROKEN
+ /* mingw gives bogus answers rather than failure on non-seekable files. */
+ if (lseek (fileno (fp), 0, SEEK_CUR) == -1)
+ return EOF;
+#endif
+
+ /* These tests are based on fpurge.c. */
+#if defined _IO_EOF_SEEN || defined _IO_ftrylockfile || __GNU_LIBRARY__ == 1
+ /* GNU libc, BeOS, Haiku, Linux libc5 */
+ if (fp->_IO_read_end == fp->_IO_read_ptr
+ && fp->_IO_write_ptr == fp->_IO_write_base
+ && fp->_IO_save_base == NULL)
+#elif defined __sferror || defined __DragonFly__ || defined __ANDROID__
+ /* FreeBSD, NetBSD, OpenBSD, DragonFly, Mac OS X, Cygwin, Minix 3, Android */
+# 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 fseeko 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
+ if (fp_->_p == fp_->_bf._base
+ && fp_->_r == 0
+ && fp_->_w == ((fp_->_flags & (__SLBF | __SNBF | __SRD)) == 0 /* fully buffered and not currently reading? */
+ ? fp_->_bf._size
+ : 0)
+ && fp_ub._base == NULL)
+#elif defined __EMX__ /* emx+gcc */
+ if (fp->_ptr == fp->_buffer
+ && fp->_rcount == 0
+ && fp->_wcount == 0
+ && fp->_ungetc_count == 0)
+#elif defined __minix /* Minix */
+ if (fp_->_ptr == fp_->_buf
+ && (fp_->_ptr == NULL || fp_->_count == 0))
+#elif defined _IOERR /* AIX, HP-UX, IRIX, OSF/1, Solaris, OpenServer, UnixWare, mingw, MSVC, NonStop Kernel, OpenVMS */
+ if (fp_->_ptr == fp_->_base
+ && (fp_->_ptr == NULL || fp_->_cnt == 0))
+#elif defined __UCLIBC__ /* uClibc */
+ if (((fp->__modeflags & __FLAG_WRITING) == 0
+ || fp->__bufpos == fp->__bufstart)
+ && ((fp->__modeflags & (__FLAG_READONLY | __FLAG_READING)) == 0
+ || fp->__bufpos == fp->__bufread))
+#elif defined __QNX__ /* QNX */
+ if ((fp->_Mode & 0x2000 /* _MWRITE */ ? fp->_Next == fp->_Buf : fp->_Next == fp->_Rend)
+ && fp->_Rback == fp->_Back + sizeof (fp->_Back)
+ && fp->_Rsave == NULL)
+#elif defined __MINT__ /* Atari FreeMiNT */
+ if (fp->__bufp == fp->__buffer
+ && fp->__get_limit == fp->__bufp
+ && fp->__put_limit == fp->__bufp
+ && !fp->__pushed_back)
+#elif defined EPLAN9 /* Plan9 */
+ if (fp->rp == fp->buf
+ && fp->wp == fp->buf)
+#elif FUNC_FFLUSH_STDIN < 0 && 200809 <= _POSIX_VERSION
+ /* Cross-compiling to some other system advertising conformance to
+ POSIX.1-2008 or later. Assume fseeko and fflush work as advertised.
+ If this assumption is incorrect, please report the bug to
+ bug-gnulib. */
+ if (0)
+#else
+ #error "Please port gnulib fseeko.c to your platform! Look at the code in fseeko.c, then report this to bug-gnulib."
+#endif
+ {
+ /* We get here when an fflush() call immediately preceded this one (or
+ if ftell() has created buffers but no I/O has occurred on a
+ newly-opened stream). We know there are no buffers. */
+ off_t pos = lseek (fileno (fp), offset, whence);
+ if (pos == -1)
+ {
+#if defined __sferror || defined __DragonFly__ || defined __ANDROID__
+ /* FreeBSD, NetBSD, OpenBSD, DragonFly, Mac OS X, Cygwin, Minix 3, Android */
+ fp_->_flags &= ~__SOFF;
+#endif
+ return -1;
+ }
+
+#if defined _IO_EOF_SEEN || defined _IO_ftrylockfile || __GNU_LIBRARY__ == 1
+ /* GNU libc, BeOS, Haiku, Linux libc5 */
+ fp->_flags &= ~_IO_EOF_SEEN;
+ fp->_offset = pos;
+#elif defined __sferror || defined __DragonFly__ || defined __ANDROID__
+ /* FreeBSD, NetBSD, OpenBSD, DragonFly, Mac OS X, Cygwin, Minix 3, Android */
+# if defined __CYGWIN__ || (defined __NetBSD__ && __NetBSD_Version__ >= 600000000) || defined __minix
+ /* fp_->_offset is typed as an integer. */
+ fp_->_offset = pos;
+# else
+ /* fp_->_offset is an fpos_t. */
+ {
+ /* Use a union, since on NetBSD, the compilation flags
+ determine whether fpos_t is typedef'd to off_t or a struct
+ containing a single off_t member. */
+ union
+ {
+ fpos_t f;
+ off_t o;
+ } u;
+ u.o = pos;
+ fp_->_offset = u.f;
+ }
+# endif
+ fp_->_flags |= __SOFF;
+ fp_->_flags &= ~__SEOF;
+#elif defined __EMX__ /* emx+gcc */
+ fp->_flags &= ~_IOEOF;
+#elif defined _IOERR /* AIX, HP-UX, IRIX, OSF/1, Solaris, OpenServer, UnixWare, mingw, MSVC, NonStop Kernel, OpenVMS */
+ fp_->_flag &= ~_IOEOF;
+#elif defined __MINT__ /* Atari FreeMiNT */
+ fp->__offset = pos;
+ fp->__eof = 0;
+#endif
+ return 0;
+ }
+ return fseeko (fp, offset, whence);
+}