makebuf.c revision 302408 
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: makebuf.c,v 1.27 2013-11-22 20:51:43 ca Exp $")
17#include <stdlib.h>
18#include <unistd.h>
19#include <sys/types.h>
20#include <sys/stat.h>
21#include <sm/io.h>
22#include <sm/heap.h>
23#include <sm/conf.h>
24#include "local.h"
25
26/*
27**  SM_MAKEBUF -- make a buffer for the file
28**
29**	Parameters:
30**		fp -- the file to be buffered
31**
32**	Returns:
33**		nothing
34**
35**	Allocate a file buffer, or switch to unbuffered I/O.
36**	By default tty devices default to line buffered.
37*/
38
39void
40sm_makebuf(fp)
41	register SM_FILE_T *fp;
42{
43	register void *p;
44	register int flags;
45	size_t size;
46	int couldbetty;
47
48	if (fp->f_flags & SMNBF)
49	{
50		fp->f_bf.smb_base = fp->f_p = fp->f_nbuf;
51		fp->f_bf.smb_size = 1;
52		return;
53	}
54	flags = sm_whatbuf(fp, &size, &couldbetty);
55	if ((p = sm_malloc(size)) == NULL)
56	{
57		fp->f_flags |= SMNBF;
58		fp->f_bf.smb_base = fp->f_p = fp->f_nbuf;
59		fp->f_bf.smb_size = 1;
60		return;
61	}
62	if (!Sm_IO_DidInit)
63		sm_init();
64	flags |= SMMBF;
65	fp->f_bf.smb_base = fp->f_p = p;
66	fp->f_bf.smb_size = size;
67	if (couldbetty && isatty(fp->f_file))
68		flags |= SMLBF;
69	fp->f_flags |= flags;
70}
71
72/*
73**  SM_WHATBUF -- determine proper buffer for a file (internal)
74**
75**  Plus it fills in 'bufsize' for recommended buffer size and
76**  fills in flag to indicate if 'fp' could be a tty (nothing
77**  to do with "betty" :-) ).
78**
79**	Parameters:
80**		fp -- file pointer to be buffered
81**		bufsize -- new buffer size (a return)
82**		couldbetty -- could be a tty (returns)
83**
84**	Returns:
85**		Success:
86**		on error:
87**			SMNPT -- not seek opimized
88**			SMOPT -- seek opimized
89*/
90
91int
92sm_whatbuf(fp, bufsize, couldbetty)
93	register SM_FILE_T *fp;
94	size_t *bufsize;
95	int *couldbetty;
96{
97	struct stat st;
98
99	if (fp->f_file < 0 || fstat(fp->f_file, &st) < 0)
100	{
101		*couldbetty = 0;
102		*bufsize = SM_IO_BUFSIZ;
103		return SMNPT;
104	}
105
106	/* could be a tty iff it is a character device */
107	*couldbetty = S_ISCHR(st.st_mode);
108	if (st.st_blksize == 0)
109	{
110		*bufsize = SM_IO_BUFSIZ;
111		return SMNPT;
112	}
113
114#if SM_IO_MAX_BUF_FILE > 0
115	if (S_ISREG(st.st_mode) && st.st_blksize > SM_IO_MAX_BUF_FILE)
116		st.st_blksize = SM_IO_MAX_BUF_FILE;
117#endif /* SM_IO_MAX_BUF_FILE > 0 */
118
119#if SM_IO_MAX_BUF > 0 || SM_IO_MIN_BUF > 0
120	if (!S_ISREG(st.st_mode))
121	{
122# if SM_IO_MAX_BUF > 0
123		if (st.st_blksize > SM_IO_MAX_BUF)
124			st.st_blksize = SM_IO_MAX_BUF;
125#  if SM_IO_MIN_BUF > 0
126		else
127#  endif /* SM_IO_MIN_BUF > 0 */
128# endif /* SM_IO_MAX_BUF > 0 */
129# if SM_IO_MIN_BUF > 0
130		if (st.st_blksize < SM_IO_MIN_BUF)
131			st.st_blksize = SM_IO_MIN_BUF;
132# endif /* SM_IO_MIN_BUF > 0 */
133	}
134#endif /* SM_IO_MAX_BUF > 0 || SM_IO_MIN_BUF > 0 */
135
136	/*
137	**  Optimise fseek() only if it is a regular file.  (The test for
138	**  sm_std_seek is mainly paranoia.)  It is safe to set _blksize
139	**  unconditionally; it will only be used if SMOPT is also set.
140	*/
141
142	if ((fp->f_flags & SMSTR) == 0)
143	{
144		*bufsize = st.st_blksize;
145		fp->f_blksize = st.st_blksize;
146	}
147	else
148		*bufsize = SM_IO_BUFSIZ;
149	if ((st.st_mode & S_IFMT) == S_IFREG &&
150	    fp->f_seek == sm_stdseek)
151		return SMOPT;
152	else
153		return SMNPT;
154}
155