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Diffstat (limited to '')
| -rw-r--r-- | lib/freadahead.c | 103 |
1 files changed, 103 insertions, 0 deletions
diff --git a/lib/freadahead.c b/lib/freadahead.c new file mode 100644 index 0000000..829d03b --- /dev/null +++ b/lib/freadahead.c @@ -0,0 +1,103 @@ +/* Retrieve information about a FILE stream. + 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 "freadahead.h" + +#include <stdlib.h> +#include "stdio-impl.h" + +#if defined __DragonFly__ +/* Defined in libc, but not declared in <stdio.h>. */ +extern size_t __sreadahead (FILE *); +#endif + +/* This file is not used on systems that have the __freadahead function, + namely musl libc. */ + +size_t +freadahead (FILE *fp) +{ +#if defined _IO_EOF_SEEN || defined _IO_ftrylockfile || __GNU_LIBRARY__ == 1 + /* GNU libc, BeOS, Haiku, Linux libc5 */ + if (fp->_IO_write_ptr > fp->_IO_write_base) + return 0; + return (fp->_IO_read_end - fp->_IO_read_ptr) + + (fp->_flags & _IO_IN_BACKUP ? fp->_IO_save_end - fp->_IO_save_base : + 0); +#elif defined __sferror || defined __DragonFly__ || defined __ANDROID__ + /* FreeBSD, NetBSD, OpenBSD, DragonFly, Mac OS X, Cygwin, Minix 3, Android */ + if ((fp_->_flags & __SWR) != 0 || fp_->_r < 0) + return 0; +# if defined __DragonFly__ + return __sreadahead (fp); +# else + return fp_->_r + + (HASUB (fp) ? fp_->_ur : 0); +# endif +#elif defined __EMX__ /* emx+gcc */ + if ((fp->_flags & _IOWRT) != 0) + return 0; + /* Note: fp->_ungetc_count > 0 implies fp->_rcount <= 0, + fp->_ungetc_count = 0 implies fp->_rcount >= 0. */ + /* equivalent to + (fp->_ungetc_count == 0 ? fp->_rcount : fp->_ungetc_count - fp->_rcount) */ + return (fp->_rcount > 0 ? fp->_rcount : fp->_ungetc_count - fp->_rcount); +#elif defined __minix /* Minix */ + if ((fp_->_flags & _IOWRITING) != 0) + return 0; + return fp_->_count; +#elif defined _IOERR /* AIX, HP-UX, IRIX, OSF/1, Solaris, OpenServer, UnixWare, mingw, MSVC, NonStop Kernel, OpenVMS */ + if ((fp_->_flag & _IOWRT) != 0) + return 0; + return fp_->_cnt; +#elif defined __UCLIBC__ /* uClibc */ +# ifdef __STDIO_BUFFERS + if (fp->__modeflags & __FLAG_WRITING) + return 0; + return (fp->__bufread - fp->__bufpos) + + (fp->__modeflags & __FLAG_UNGOT ? 1 : 0); +# else + return 0; +# endif +#elif defined __QNX__ /* QNX */ + if ((fp->_Mode & 0x2000 /* _MWRITE */) != 0) + return 0; + /* fp->_Buf <= fp->_Next <= fp->_Rend, + and fp->_Rend may be overridden by fp->_Rsave. */ + return ((fp->_Rsave ? fp->_Rsave : fp->_Rend) - fp->_Next) + + (fp->_Mode & 0x4000 /* _MBYTE */ + ? (fp->_Back + sizeof (fp->_Back)) - fp->_Rback + : 0); +#elif defined __MINT__ /* Atari FreeMiNT */ + if (!fp->__mode.__read) + return 0; + return (fp->__pushed_back + ? fp->__get_limit - fp->__pushback_bufp + 1 + : fp->__get_limit - fp->__bufp); +#elif defined EPLAN9 /* Plan9 */ + if (fp->state == 4 /* WR */ || fp->rp >= fp->wp) + return 0; + return fp->wp - fp->rp; +#elif defined SLOW_BUT_NO_HACKS /* users can define this */ + abort (); + return 0; +#else + #error "Please port gnulib freadahead.c to your platform! Look at the definition of fflush, fread, ungetc on your system, then report this to bug-gnulib." +#endif +} |