3f5e3f5d06
This is a variant of fgets which fails with ERANGE if the buffer is too small, and the buffer length is given as an argument of type size_t. This function will be useful for implementing NSS file reading operations. Compared to a direct implementation using the public API, it avoids an lseek system call in case the line terminator can be found in the internal read buffer.
71 lines
2.2 KiB
C
71 lines
2.2 KiB
C
/* Copyright (C) 1993-2018 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<http://www.gnu.org/licenses/>.
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As a special exception, if you link the code in this file with
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files compiled with a GNU compiler to produce an executable,
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that does not cause the resulting executable to be covered by
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the GNU Lesser General Public License. This exception does not
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however invalidate any other reasons why the executable file
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might be covered by the GNU Lesser General Public License.
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This exception applies to code released by its copyright holders
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in files containing the exception. */
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/* We need to disable the redirect for __ftello64 for the alias
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definitions below to work. */
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#define __ftello64 __ftello64_disable
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#include <stdio.h>
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#include <stdlib.h>
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#include <libioP.h>
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#include <errno.h>
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off_t
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__ftello (FILE *fp)
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{
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off64_t pos;
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CHECK_FILE (fp, -1L);
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_IO_acquire_lock (fp);
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pos = _IO_seekoff_unlocked (fp, 0, _IO_seek_cur, 0);
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if (_IO_in_backup (fp) && pos != _IO_pos_BAD)
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{
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if (fp->_mode <= 0)
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pos -= fp->_IO_save_end - fp->_IO_save_base;
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}
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_IO_release_lock (fp);
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if (pos == _IO_pos_BAD)
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{
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if (errno == 0)
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__set_errno (EIO);
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return -1L;
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}
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if ((off64_t) (off_t) pos != pos)
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{
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__set_errno (EOVERFLOW);
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return -1L;
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}
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return pos;
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}
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libc_hidden_def (__ftello)
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weak_alias (__ftello, ftello)
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#ifdef __OFF_T_MATCHES_OFF64_T
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weak_alias (__ftello, ftello64)
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# undef __ftello64
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strong_alias (__ftello, __ftello64)
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libc_hidden_ver (__ftello, __ftello64)
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#endif
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