xref: /illumos-gate/usr/src/cmd/sendmail/libsm/makebuf.c (revision 2a8bcb4efb45d99ac41c94a75c396b362c414f7f)
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 #include <sm/gen.h>
16 SM_RCSID("@(#)$Id: makebuf.c,v 1.26 2001/10/31 16:04:08 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 
39 void
40 sm_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 
91 int
sm_whatbuf(fp,bufsize,couldbetty)92 sm_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