38 lines
1.4 KiB
C
38 lines
1.4 KiB
C
/*
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* Copyright (c) 2011, 2012, 2013, 2014 Jonas 'Sortie' Termansen.
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*
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* Permission to use, copy, modify, and distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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*
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* stdio/ftello_unlocked.c
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* Returns the current offset of a FILE.
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*/
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#include <sys/types.h>
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#include <errno.h>
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#include <stdio.h>
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off_t ftello_unlocked(FILE* fp)
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{
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if ( !fp->seek_func )
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return errno = EBADF, fp->flags |= _FILE_STATUS_ERROR, -1;
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off_t offset = fp->seek_func(fp->user, 0, SEEK_CUR);
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if ( offset < 0 )
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return -1;
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off_t read_ahead = fp->amount_input_buffered - fp->offset_input_buffer;
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off_t write_behind = fp->amount_output_buffered;
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if ( offset < read_ahead + write_behind ) // Too much ungetc'ing.
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return 0;
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return offset - read_ahead + write_behind;
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}
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