setvbuf.c revision 266692 
1/*
2 * Copyright (c) 2000-2001 Proofpoint, 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#include <sm/gen.h>
16SM_RCSID("@(#)$Id: setvbuf.c,v 1.33 2013-11-22 20:51:43 ca Exp $")
17#include <stdlib.h>
18#include <errno.h>
19#include <fcntl.h>
20#include <sm/io.h>
21#include <sm/heap.h>
22#include <sm/assert.h>
23#include <sm/conf.h>
24#include "local.h"
25
26/*
27**  SM_IO_SETVBUF -- set the buffering type for a file
28**
29**  Set one of the different kinds of buffering, optionally including
30**  a buffer.
31**  If 'size' is == 0 then an "optimal" size will be selected.
32**  If 'buf' is == NULL then space will be allocated at 'size'.
33**
34**	Parameters:
35**		fp -- the file that buffering is to be changed for
36**		timeout -- time allowed for completing the function
37**		buf -- buffer to use
38**		mode -- buffering method to use
39**		size -- size of 'buf'
40**
41**	Returns:
42**		Failure: SM_IO_EOF
43**		Success: 0 (zero)
44*/
45
46int
47sm_io_setvbuf(fp, timeout, buf, mode, size)
48	SM_FILE_T *fp;
49	int timeout;
50	char *buf;
51	int mode;
52	size_t size;
53{
54	int ret, flags;
55	size_t iosize;
56	int ttyflag;
57	int fd;
58	struct timeval to;
59
60	SM_REQUIRE_ISA(fp, SmFileMagic);
61
62	/*
63	**  Verify arguments.  The `int' limit on `size' is due to this
64	**  particular implementation.  Note, buf and size are ignored
65	**  when setting SM_IO_NBF.
66	*/
67
68	if (mode != SM_IO_NBF)
69		if ((mode != SM_IO_FBF && mode != SM_IO_LBF &&
70		    mode != SM_IO_NOW) || (int) size < 0)
71			return SM_IO_EOF;
72
73	/*
74	**  Write current buffer, if any.  Discard unread input (including
75	**  ungetc data), cancel line buffering, and free old buffer if
76	**  malloc()ed.  We also clear any eof condition, as if this were
77	**  a seek.
78	*/
79
80	ret = 0;
81	SM_CONVERT_TIME(fp, fd, timeout, &to);
82	(void) sm_flush(fp, &timeout);
83	if (HASUB(fp))
84		FREEUB(fp);
85	fp->f_r = fp->f_lbfsize = 0;
86	flags = fp->f_flags;
87	if (flags & SMMBF)
88	{
89		sm_free((void *) fp->f_bf.smb_base);
90		fp->f_bf.smb_base = NULL;
91	}
92	flags &= ~(SMLBF | SMNBF | SMMBF | SMOPT | SMNPT | SMFEOF | SMNOW |
93		   SMFBF);
94
95	/* If setting unbuffered mode, skip all the hard work. */
96	if (mode == SM_IO_NBF)
97		goto nbf;
98
99	/*
100	**  Find optimal I/O size for seek optimization.  This also returns
101	**  a `tty flag' to suggest that we check isatty(fd), but we do not
102	**  care since our caller told us how to buffer.
103	*/
104
105	flags |= sm_whatbuf(fp, &iosize, &ttyflag);
106	if (size == 0)
107	{
108		buf = NULL;	/* force local allocation */
109		size = iosize;
110	}
111
112	/* Allocate buffer if needed. */
113	if (buf == NULL)
114	{
115		if ((buf = sm_malloc(size)) == NULL)
116		{
117			/*
118			**  Unable to honor user's request.  We will return
119			**  failure, but try again with file system size.
120			*/
121
122			ret = SM_IO_EOF;
123			if (size != iosize)
124			{
125				size = iosize;
126				buf = sm_malloc(size);
127			}
128		}
129		if (buf == NULL)
130		{
131			/* No luck; switch to unbuffered I/O. */
132nbf:
133			fp->f_flags = flags | SMNBF;
134			fp->f_w = 0;
135			fp->f_bf.smb_base = fp->f_p = fp->f_nbuf;
136			fp->f_bf.smb_size = 1;
137			return ret;
138		}
139		flags |= SMMBF;
140	}
141
142	/*
143	**  Kill any seek optimization if the buffer is not the
144	**  right size.
145	**
146	**  SHOULD WE ALLOW MULTIPLES HERE (i.e., ok iff (size % iosize) == 0)?
147	*/
148
149	if (size != iosize)
150		flags |= SMNPT;
151
152	/*
153	**  Fix up the SM_FILE_T fields, and set sm_cleanup for output flush on
154	**  exit (since we are buffered in some way).
155	*/
156
157	if (mode == SM_IO_LBF)
158		flags |= SMLBF;
159	else if (mode == SM_IO_NOW)
160		flags |= SMNOW;
161	else if (mode == SM_IO_FBF)
162		flags |= SMFBF;
163	fp->f_flags = flags;
164	fp->f_bf.smb_base = fp->f_p = (unsigned char *)buf;
165	fp->f_bf.smb_size = size;
166	/* fp->f_lbfsize is still 0 */
167	if (flags & SMWR)
168	{
169		/*
170		**  Begin or continue writing: see sm_wsetup().  Note
171		**  that SMNBF is impossible (it was handled earlier).
172		*/
173
174		if (flags & SMLBF)
175		{
176			fp->f_w = 0;
177			fp->f_lbfsize = -fp->f_bf.smb_size;
178		}
179		else
180			fp->f_w = size;
181	}
182	else
183	{
184		/* begin/continue reading, or stay in intermediate state */
185		fp->f_w = 0;
186	}
187
188	atexit(sm_cleanup);
189	return ret;
190}
191