1/*
2 * Copyright (c) 2000-2001 Sendmail, Inc. and its suppliers.
3 *      All rights reserved.
4 * Copyright (c) 1990, 1993
5 *	The Regents of the University of California.  All rights reserved.
6 *
7 * This code is derived from software contributed to Berkeley by
8 * Chris Torek.
9 *
10 * By using this file, you agree to the terms and conditions set
11 * forth in the LICENSE file which can be found at the top level of
12 * the sendmail distribution.
13 */
14
15#pragma ident	"%Z%%M%	%I%	%E% SMI"
16
17#include <sm/gen.h>
18SM_RCSID("@(#)$Id: fread.c,v 1.26 2001/02/28 20:54:03 ca Exp $")
19#include <string.h>
20#include <errno.h>
21#include <sm/io.h>
22#include <sm/assert.h>
23#include "local.h"
24
25/*
26**  SM_IO_READ -- read data from the file pointer
27**
28**	Parameters:
29**		fp -- file pointer to read from
30**		timeout -- time to complete the read
31**		buf -- location to place read data
32**		size -- size of each chunk of data
33**
34**	Returns:
35**		Failure: returns 0 (zero) _and_ sets errno
36**		Success: returns the number of whole chunks read.
37**
38**	A read returning 0 (zero) is only an indication of error when errno
39**	has been set.
40*/
41
42size_t
43sm_io_read(fp, timeout, buf, size)
44	SM_FILE_T *fp;
45	int timeout;
46	void *buf;
47	size_t size;
48{
49	register size_t resid = size;
50	register char *p;
51	register int r;
52
53	SM_REQUIRE_ISA(fp, SmFileMagic);
54
55	if (fp->f_read == NULL)
56	{
57		errno = ENODEV;
58		return 0;
59	}
60
61	/*
62	**  The ANSI standard requires a return value of 0 for a count
63	**  or a size of 0.  Peculiarily, it imposes no such requirements
64	**  on fwrite; it only requires read to be broken.
65	*/
66
67	if (resid == 0)
68		return 0;
69	if (fp->f_r < 0)
70		fp->f_r = 0;
71	p = buf;
72	while ((int) resid > (r = fp->f_r))
73	{
74		(void) memcpy((void *) p, (void *) fp->f_p, (size_t) r);
75		fp->f_p += r;
76		/* fp->f_r = 0 ... done in sm_refill */
77		p += r;
78		resid -= r;
79		if ((fp->f_flags & SMNOW) != 0 && r > 0)
80		{
81			/*
82			**  Take whatever we have available. Spend no more time
83			**  trying to get all that has been requested.
84			**  This is needed on some file types (such as
85			**  SASL) that would jam when given extra, untimely
86			**  reads.
87			*/
88
89			fp->f_r -= r;
90			return size - resid;
91		}
92		if (sm_refill(fp, timeout) != 0)
93		{
94			/* no more input: return partial result */
95			return size - resid;
96		}
97	}
98	(void) memcpy((void *) p, (void *) fp->f_p, resid);
99	fp->f_r -= resid;
100	fp->f_p += resid;
101	return size;
102}
103