62 lines
2.0 KiB
C
62 lines
2.0 KiB
C
/*
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* Copyright (c) 2011, 2012, 2013, 2014, 2015 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/ungetc_unlocked.c
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* Inserts data in front of the current read queue, allowing applications to
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* peek the incoming data and pretend they didn't.
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*/
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#include <errno.h>
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#include <stdio.h>
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#include <string.h>
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int ungetc_unlocked(int c, FILE* fp)
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{
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if ( c == EOF )
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return EOF;
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if ( !(fp->flags & _FILE_READABLE) )
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return errno = EBADF, fp->flags |= _FILE_STATUS_ERROR, EOF;
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if ( !(fp->flags & _FILE_BUFFER_MODE_SET) )
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setvbuf_unlocked(fp, NULL, fp->buffer_mode, 0);
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if ( fp->flags & _FILE_LAST_WRITE )
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fflush_stop_writing_unlocked(fp);
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fp->flags |= _FILE_LAST_READ;
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// TODO: Is this a bug that ungetc doesn't work for unbuffered files?
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if ( fp->buffer_mode == _IONBF )
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return errno = EBADF, fp->flags |= _FILE_STATUS_ERROR, EOF;
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if ( fp->offset_input_buffer == 0 )
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{
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size_t amount = fp->amount_input_buffered - fp->offset_input_buffer;
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size_t offset = BUFSIZ - amount;
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if ( !offset )
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return EOF;
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memmove(fp->buffer + offset, fp->buffer, sizeof(fp->buffer[0]) * amount);
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fp->offset_input_buffer = offset;
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fp->amount_input_buffered = offset + amount;
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}
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fp->buffer[--fp->offset_input_buffer] = c;
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fp->flags &= ~_FILE_STATUS_EOF;
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return c;
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}
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