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: setvbuf.c,v 1.30 2001/02/28 20:25:18 rodney Exp $")
19#include <stdlib.h>
20#include <errno.h>
21#include <fcntl.h>
22#include <sm/io.h>
23#include <sm/heap.h>
24#include <sm/assert.h>
25#include <sm/conf.h>
26#include "local.h"
27
28/*
29**  SM_IO_SETVBUF -- set the buffering type for a file
30**
31**  Set one of the different kinds of buffering, optionally including
32**  a buffer.
33**  If 'size' is == 0 then an "optimal" size will be selected.
34**  If 'buf' is == NULL then space will be allocated at 'size'.
35**
36**	Parameters:
37**		fp -- the file that buffering is to be changed for
38**		timeout -- time allowed for completing the function
39**		buf -- buffer to use
40**		mode -- buffering method to use
41**		size -- size of 'buf'
42**
43**	Returns:
44**		Failure: SM_IO_EOF
45**		Success: 0 (zero)
46*/
47
48int
49sm_io_setvbuf(fp, timeout, buf, mode, size)
50	SM_FILE_T *fp;
51	int timeout;
52	char *buf;
53	int mode;
54	size_t size;
55{
56	int ret, flags;
57	size_t iosize;
58	int ttyflag;
59	int fd;
60	struct timeval to;
61
62	SM_REQUIRE_ISA(fp, SmFileMagic);
63
64	/*
65	**  Verify arguments.  The `int' limit on `size' is due to this
66	**  particular implementation.  Note, buf and size are ignored
67	**  when setting SM_IO_NBF.
68	*/
69
70	if (mode != SM_IO_NBF)
71		if ((mode != SM_IO_FBF && mode != SM_IO_LBF &&
72		    mode != SM_IO_NOW) || (int) size < 0)
73			return SM_IO_EOF;
74
75	/*
76	**  Write current buffer, if any.  Discard unread input (including
77	**  ungetc data), cancel line buffering, and free old buffer if
78	**  malloc()ed.  We also clear any eof condition, as if this were
79	**  a seek.
80	*/
81
82	ret = 0;
83	SM_CONVERT_TIME(fp, fd, timeout, &to);
84	(void) sm_flush(fp, &timeout);
85	if (HASUB(fp))
86		FREEUB(fp);
87	fp->f_r = fp->f_lbfsize = 0;
88	flags = fp->f_flags;
89	if (flags & SMMBF)
90	{
91		sm_free((void *) fp->f_bf.smb_base);
92		fp->f_bf.smb_base = NULL;
93	}
94	flags &= ~(SMLBF | SMNBF | SMMBF | SMOPT | SMNPT | SMFEOF | SMNOW |
95		   SMFBF);
96
97	/* If setting unbuffered mode, skip all the hard work. */
98	if (mode == SM_IO_NBF)
99		goto nbf;
100
101	/*
102	**  Find optimal I/O size for seek optimization.  This also returns
103	**  a `tty flag' to suggest that we check isatty(fd), but we do not
104	**  care since our caller told us how to buffer.
105	*/
106
107	flags |= sm_whatbuf(fp, &iosize, &ttyflag);
108	if (size == 0)
109	{
110		buf = NULL;	/* force local allocation */
111		size = iosize;
112	}
113
114	/* Allocate buffer if needed. */
115	if (buf == NULL)
116	{
117		if ((buf = sm_malloc(size)) == NULL)
118		{
119			/*
120			**  Unable to honor user's request.  We will return
121			**  failure, but try again with file system size.
122			*/
123
124			ret = SM_IO_EOF;
125			if (size != iosize)
126			{
127				size = iosize;
128				buf = sm_malloc(size);
129			}
130		}
131		if (buf == NULL)
132		{
133			/* No luck; switch to unbuffered I/O. */
134nbf:
135			fp->f_flags = flags | SMNBF;
136			fp->f_w = 0;
137			fp->f_bf.smb_base = fp->f_p = fp->f_nbuf;
138			fp->f_bf.smb_size = 1;
139			return ret;
140		}
141		flags |= SMMBF;
142	}
143
144	/*
145	**  Kill any seek optimization if the buffer is not the
146	**  right size.
147	**
148	**  SHOULD WE ALLOW MULTIPLES HERE (i.e., ok iff (size % iosize) == 0)?
149	*/
150
151	if (size != iosize)
152		flags |= SMNPT;
153
154	/*
155	**  Fix up the SM_FILE_T fields, and set sm_cleanup for output flush on
156	**  exit (since we are buffered in some way).
157	*/
158
159	if (mode == SM_IO_LBF)
160		flags |= SMLBF;
161	else if (mode == SM_IO_NOW)
162		flags |= SMNOW;
163	else if (mode == SM_IO_FBF)
164		flags |= SMFBF;
165	fp->f_flags = flags;
166	fp->f_bf.smb_base = fp->f_p = (unsigned char *)buf;
167	fp->f_bf.smb_size = size;
168	/* fp->f_lbfsize is still 0 */
169	if (flags & SMWR)
170	{
171		/*
172		**  Begin or continue writing: see sm_wsetup().  Note
173		**  that SMNBF is impossible (it was handled earlier).
174		*/
175
176		if (flags & SMLBF)
177		{
178			fp->f_w = 0;
179			fp->f_lbfsize = -fp->f_bf.smb_size;
180		}
181		else
182			fp->f_w = size;
183	}
184	else
185	{
186		/* begin/continue reading, or stay in intermediate state */
187		fp->f_w = 0;
188	}
189
190	atexit(sm_cleanup);
191	return ret;
192}
193