1 /*
2 * CDDL HEADER START
3 *
4 * The contents of this file are subject to the terms of the
5 * Common Development and Distribution License, Version 1.0 only
6 * (the "License"). You may not use this file except in compliance
7 * with the License.
8 *
9 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
10 * or http://www.opensolaris.org/os/licensing.
11 * See the License for the specific language governing permissions
12 * and limitations under the License.
13 *
14 * When distributing Covered Code, include this CDDL HEADER in each
15 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
16 * If applicable, add the following below this CDDL HEADER, with the
17 * fields enclosed by brackets "[]" replaced with your own identifying
18 * information: Portions Copyright [yyyy] [name of copyright owner]
19 *
20 * CDDL HEADER END
21 */
22 /*
23 * Copyright 2005 Sun Microsystems, Inc. All rights reserved.
24 * Use is subject to license terms.
25 */
26
27 #pragma ident "%Z%%M% %I% %E% SMI"
28
29 /*
30 * DTrace Memory Buffer Routines
31 *
32 * The routines in this file are used to create an automatically resizing
33 * memory buffer that can be written to like a file. Memory buffers are
34 * used to construct DOF to ioctl() to dtrace(7D), and provide semantics that
35 * simplify caller code. Specifically, any allocation errors result in an
36 * error code being set inside the buffer which is maintained persistently and
37 * propagates to another buffer if the buffer in error is concatenated. These
38 * semantics permit callers to execute a large series of writes without needing
39 * to check for errors and then perform a single check before using the buffer.
40 */
41
42 #include <sys/sysmacros.h>
43 #include <strings.h>
44
45 #include <dt_impl.h>
46 #include <dt_buf.h>
47
48 void
dt_buf_create(dtrace_hdl_t * dtp,dt_buf_t * bp,const char * name,size_t len)49 dt_buf_create(dtrace_hdl_t *dtp, dt_buf_t *bp, const char *name, size_t len)
50 {
51 if (len == 0)
52 len = _dtrace_bufsize;
53
54 bp->dbu_buf = bp->dbu_ptr = dt_zalloc(dtp, len);
55 bp->dbu_len = len;
56
57 if (bp->dbu_buf == NULL)
58 bp->dbu_err = dtrace_errno(dtp);
59 else
60 bp->dbu_err = 0;
61
62 bp->dbu_resizes = 0;
63 bp->dbu_name = name;
64 }
65
66 void
dt_buf_destroy(dtrace_hdl_t * dtp,dt_buf_t * bp)67 dt_buf_destroy(dtrace_hdl_t *dtp, dt_buf_t *bp)
68 {
69 dt_dprintf("dt_buf_destroy(%s): size=%lu resizes=%u\n",
70 bp->dbu_name, (ulong_t)bp->dbu_len, bp->dbu_resizes);
71
72 dt_free(dtp, bp->dbu_buf);
73 }
74
75 void
dt_buf_reset(dtrace_hdl_t * dtp,dt_buf_t * bp)76 dt_buf_reset(dtrace_hdl_t *dtp, dt_buf_t *bp)
77 {
78 if ((bp->dbu_ptr = bp->dbu_buf) != NULL)
79 bp->dbu_err = 0;
80 else
81 dt_buf_create(dtp, bp, bp->dbu_name, bp->dbu_len);
82 }
83
84 void
dt_buf_write(dtrace_hdl_t * dtp,dt_buf_t * bp,const void * buf,size_t len,size_t align)85 dt_buf_write(dtrace_hdl_t *dtp, dt_buf_t *bp,
86 const void *buf, size_t len, size_t align)
87 {
88 size_t off = (size_t)(bp->dbu_ptr - bp->dbu_buf);
89 size_t adj = roundup(off, align) - off;
90
91 if (bp->dbu_err != 0) {
92 (void) dt_set_errno(dtp, bp->dbu_err);
93 return; /* write silently fails */
94 }
95
96 if (bp->dbu_ptr + adj + len > bp->dbu_buf + bp->dbu_len) {
97 size_t new_len = bp->dbu_len * 2;
98 uchar_t *new_buf;
99 uint_t r = 1;
100
101 while (bp->dbu_ptr + adj + len > bp->dbu_buf + new_len) {
102 new_len *= 2;
103 r++;
104 }
105
106 if ((new_buf = dt_zalloc(dtp, new_len)) == NULL) {
107 bp->dbu_err = dtrace_errno(dtp);
108 return;
109 }
110
111 bcopy(bp->dbu_buf, new_buf, off);
112 dt_free(dtp, bp->dbu_buf);
113
114 bp->dbu_buf = new_buf;
115 bp->dbu_ptr = new_buf + off;
116 bp->dbu_len = new_len;
117 bp->dbu_resizes += r;
118 }
119
120 bp->dbu_ptr += adj;
121 bcopy(buf, bp->dbu_ptr, len);
122 bp->dbu_ptr += len;
123 }
124
125 void
dt_buf_concat(dtrace_hdl_t * dtp,dt_buf_t * dst,const dt_buf_t * src,size_t align)126 dt_buf_concat(dtrace_hdl_t *dtp, dt_buf_t *dst,
127 const dt_buf_t *src, size_t align)
128 {
129 if (dst->dbu_err == 0 && src->dbu_err != 0) {
130 (void) dt_set_errno(dtp, src->dbu_err);
131 dst->dbu_err = src->dbu_err;
132 } else {
133 dt_buf_write(dtp, dst, src->dbu_buf,
134 (size_t)(src->dbu_ptr - src->dbu_buf), align);
135 }
136 }
137
138 size_t
dt_buf_offset(const dt_buf_t * bp,size_t align)139 dt_buf_offset(const dt_buf_t *bp, size_t align)
140 {
141 size_t off = (size_t)(bp->dbu_ptr - bp->dbu_buf);
142 return (roundup(off, align));
143 }
144
145 size_t
dt_buf_len(const dt_buf_t * bp)146 dt_buf_len(const dt_buf_t *bp)
147 {
148 return (bp->dbu_ptr - bp->dbu_buf);
149 }
150
151 int
dt_buf_error(const dt_buf_t * bp)152 dt_buf_error(const dt_buf_t *bp)
153 {
154 return (bp->dbu_err);
155 }
156
157 void *
dt_buf_ptr(const dt_buf_t * bp)158 dt_buf_ptr(const dt_buf_t *bp)
159 {
160 return (bp->dbu_buf);
161 }
162
163 void *
dt_buf_claim(dtrace_hdl_t * dtp,dt_buf_t * bp)164 dt_buf_claim(dtrace_hdl_t *dtp, dt_buf_t *bp)
165 {
166 void *buf = bp->dbu_buf;
167
168 if (bp->dbu_err != 0) {
169 dt_free(dtp, buf);
170 buf = NULL;
171 }
172
173 bp->dbu_buf = bp->dbu_ptr = NULL;
174 bp->dbu_len = 0;
175
176 return (buf);
177 }
178