1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
|
/*
* Copyright (c) 1990 The Regents of the University of California.
* All rights reserved.
*
* Redistribution and use in source and binary forms are permitted
* provided that the above copyright notice and this paragraph are
* duplicated in all such forms and that any documentation,
* advertising materials, and other materials related to such
* distribution and use acknowledge that the software was developed
* by the University of California, Berkeley. The name of the
* University may not be used to endorse or promote products derived
* from this software without specific prior written permission.
* THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
*/
/*
FUNCTION
<<fread>>---read array elements from a file
INDEX
fread
ANSI_SYNOPSIS
#include <stdio.h>
size_t fread(void *<[buf]>, size_t <[size]>, size_t <[count]>,
FILE *<[fp]>);
TRAD_SYNOPSIS
#include <stdio.h>
size_t fread(<[buf]>, <[size]>, <[count]>, <[fp]>)
char *<[buf]>;
size_t <[size]>;
size_t <[count]>;
FILE *<[fp]>;
DESCRIPTION
<<fread>> attempts to copy, from the file or stream identified by
<[fp]>, <[count]> elements (each of size <[size]>) into memory,
starting at <[buf]>. <<fread>> may copy fewer elements than
<[count]> if an error, or end of file, intervenes.
<<fread>> also advances the file position indicator (if any) for
<[fp]> by the number of @emph{characters} actually read.
RETURNS
The result of <<fread>> is the number of elements it succeeded in
reading.
PORTABILITY
ANSI C requires <<fread>>.
Supporting OS subroutines required: <<close>>, <<fstat>>, <<isatty>>,
<<lseek>>, <<read>>, <<sbrk>>, <<write>>.
*/
#include <stdio.h>
#include <string.h>
#include "local.h"
size_t
_DEFUN (fread, (buf, size, count, fp),
_PTR buf _AND
size_t size _AND
size_t count _AND
FILE * fp)
{
register size_t resid;
register char *p;
register int r;
size_t total;
if ((resid = count * size) == 0)
return 0;
if (fp->_r < 0)
fp->_r = 0;
total = resid;
p = buf;
while (resid > (r = fp->_r))
{
(void) memcpy ((void *) p, (void *) fp->_p, (size_t) r);
fp->_p += r;
/* fp->_r = 0 ... done in __srefill */
p += r;
resid -= r;
if (__srefill (fp))
{
/* no more input: return partial result */
return (total - resid) / size;
}
}
(void) memcpy ((void *) p, (void *) fp->_p, resid);
fp->_r -= resid;
fp->_p += resid;
return count;
}
|
