98 lines
2.5 KiB
C
98 lines
2.5 KiB
C
/*
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* Copyright (c) 1990 The Regents of the University of California.
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms are permitted
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* provided that the above copyright notice and this paragraph are
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* duplicated in all such forms and that any documentation,
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* advertising materials, and other materials related to such
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* distribution and use acknowledge that the software was developed
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* by the University of California, Berkeley. The name of the
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* University may not be used to endorse or promote products derived
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* from this software without specific prior written permission.
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* THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
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* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
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*/
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/*
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FUNCTION
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<<fread>>---read array elements from a file
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INDEX
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fread
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ANSI_SYNOPSIS
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#include <stdio.h>
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size_t fread(void *<[buf]>, size_t <[size]>, size_t <[count]>,
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FILE *<[fp]>);
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TRAD_SYNOPSIS
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#include <stdio.h>
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size_t fread(<[buf]>, <[size]>, <[count]>, <[fp]>)
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char *<[buf]>;
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size_t <[size]>;
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size_t <[count]>;
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FILE *<[fp]>;
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DESCRIPTION
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<<fread>> attempts to copy, from the file or stream identified by
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<[fp]>, <[count]> elements (each of size <[size]>) into memory,
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starting at <[buf]>. <<fread>> may copy fewer elements than
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<[count]> if an error, or end of file, intervenes.
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<<fread>> also advances the file position indicator (if any) for
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<[fp]> by the number of @emph{characters} actually read.
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RETURNS
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The result of <<fread>> is the number of elements it succeeded in
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reading.
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PORTABILITY
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ANSI C requires <<fread>>.
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Supporting OS subroutines required: <<close>>, <<fstat>>, <<isatty>>,
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<<lseek>>, <<read>>, <<sbrk>>, <<write>>.
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*/
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#include <stdio.h>
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#include <string.h>
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#include "local.h"
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size_t
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_DEFUN (fread, (buf, size, count, fp),
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_PTR buf _AND
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size_t size _AND
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size_t count _AND
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FILE * fp)
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{
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register size_t resid;
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register char *p;
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register int r;
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size_t total;
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if ((resid = count * size) == 0)
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return 0;
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if (fp->_r < 0)
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fp->_r = 0;
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total = resid;
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p = buf;
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while (resid > (r = fp->_r))
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{
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(void) memcpy ((void *) p, (void *) fp->_p, (size_t) r);
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fp->_p += r;
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/* fp->_r = 0 ... done in __srefill */
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p += r;
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resid -= r;
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if (__srefill (fp))
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{
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/* no more input: return partial result */
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return (total - resid) / size;
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}
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}
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(void) memcpy ((void *) p, (void *) fp->_p, resid);
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fp->_r -= resid;
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fp->_p += resid;
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return count;
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}
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