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 /*
28 * DTrace Memory Buffer Routines
29 *
30 * The routines in this file are used to create an automatically resizing
31 * memory buffer that can be written to like a file. Memory buffers are
32 * used to construct DOF to ioctl() to dtrace(4D), and provide semantics that
33 * simplify caller code. Specifically, any allocation errors result in an
34 * error code being set inside the buffer which is maintained persistently and
35 * propagates to another buffer if the buffer in error is concatenated. These
36 * semantics permit callers to execute a large series of writes without needing
37 * to check for errors and then perform a single check before using the buffer.
38 */
39
40 #include <sys/sysmacros.h>
41 #include <strings.h>
42
43 #include <dt_impl.h>
44 #include <dt_buf.h>
45
46 void
dt_buf_create(dtrace_hdl_t * dtp,dt_buf_t * bp,const char * name,size_t len)47 dt_buf_create(dtrace_hdl_t *dtp, dt_buf_t *bp, const char *name, size_t len)
48 {
49 if (len == 0)
50 len = _dtrace_bufsize;
51
52 bp->dbu_buf = bp->dbu_ptr = dt_zalloc(dtp, len);
53 bp->dbu_len = len;
54
55 if (bp->dbu_buf == NULL)
56 bp->dbu_err = dtrace_errno(dtp);
57 else
58 bp->dbu_err = 0;
59
60 bp->dbu_resizes = 0;
61 bp->dbu_name = name;
62 }
63
64 void
dt_buf_destroy(dtrace_hdl_t * dtp,dt_buf_t * bp)65 dt_buf_destroy(dtrace_hdl_t *dtp, dt_buf_t *bp)
66 {
67 dt_dprintf("dt_buf_destroy(%s): size=%lu resizes=%u\n",
68 bp->dbu_name, (ulong_t)bp->dbu_len, bp->dbu_resizes);
69
70 dt_free(dtp, bp->dbu_buf);
71 }
72
73 void
dt_buf_reset(dtrace_hdl_t * dtp,dt_buf_t * bp)74 dt_buf_reset(dtrace_hdl_t *dtp, dt_buf_t *bp)
75 {
76 if ((bp->dbu_ptr = bp->dbu_buf) != NULL)
77 bp->dbu_err = 0;
78 else
79 dt_buf_create(dtp, bp, bp->dbu_name, bp->dbu_len);
80 }
81
82 void
dt_buf_write(dtrace_hdl_t * dtp,dt_buf_t * bp,const void * buf,size_t len,size_t align)83 dt_buf_write(dtrace_hdl_t *dtp, dt_buf_t *bp,
84 const void *buf, size_t len, size_t align)
85 {
86 size_t off = (size_t)(bp->dbu_ptr - bp->dbu_buf);
87 size_t adj = roundup(off, align) - off;
88
89 if (bp->dbu_err != 0) {
90 (void) dt_set_errno(dtp, bp->dbu_err);
91 return; /* write silently fails */
92 }
93
94 if (bp->dbu_ptr + adj + len > bp->dbu_buf + bp->dbu_len) {
95 size_t new_len = bp->dbu_len * 2;
96 uchar_t *new_buf;
97 uint_t r = 1;
98
99 while (bp->dbu_ptr + adj + len > bp->dbu_buf + new_len) {
100 new_len *= 2;
101 r++;
102 }
103
104 if ((new_buf = dt_zalloc(dtp, new_len)) == NULL) {
105 bp->dbu_err = dtrace_errno(dtp);
106 return;
107 }
108
109 bcopy(bp->dbu_buf, new_buf, off);
110 dt_free(dtp, bp->dbu_buf);
111
112 bp->dbu_buf = new_buf;
113 bp->dbu_ptr = new_buf + off;
114 bp->dbu_len = new_len;
115 bp->dbu_resizes += r;
116 }
117
118 bp->dbu_ptr += adj;
119 bcopy(buf, bp->dbu_ptr, len);
120 bp->dbu_ptr += len;
121 }
122
123 void
dt_buf_concat(dtrace_hdl_t * dtp,dt_buf_t * dst,const dt_buf_t * src,size_t align)124 dt_buf_concat(dtrace_hdl_t *dtp, dt_buf_t *dst,
125 const dt_buf_t *src, size_t align)
126 {
127 if (dst->dbu_err == 0 && src->dbu_err != 0) {
128 (void) dt_set_errno(dtp, src->dbu_err);
129 dst->dbu_err = src->dbu_err;
130 } else {
131 dt_buf_write(dtp, dst, src->dbu_buf,
132 (size_t)(src->dbu_ptr - src->dbu_buf), align);
133 }
134 }
135
136 size_t
dt_buf_offset(const dt_buf_t * bp,size_t align)137 dt_buf_offset(const dt_buf_t *bp, size_t align)
138 {
139 size_t off = (size_t)(bp->dbu_ptr - bp->dbu_buf);
140 return (roundup(off, align));
141 }
142
143 size_t
dt_buf_len(const dt_buf_t * bp)144 dt_buf_len(const dt_buf_t *bp)
145 {
146 return (bp->dbu_ptr - bp->dbu_buf);
147 }
148
149 int
dt_buf_error(const dt_buf_t * bp)150 dt_buf_error(const dt_buf_t *bp)
151 {
152 return (bp->dbu_err);
153 }
154
155 void *
dt_buf_ptr(const dt_buf_t * bp)156 dt_buf_ptr(const dt_buf_t *bp)
157 {
158 return (bp->dbu_buf);
159 }
160
161 void *
dt_buf_claim(dtrace_hdl_t * dtp,dt_buf_t * bp)162 dt_buf_claim(dtrace_hdl_t *dtp, dt_buf_t *bp)
163 {
164 void *buf = bp->dbu_buf;
165
166 if (bp->dbu_err != 0) {
167 dt_free(dtp, buf);
168 buf = NULL;
169 }
170
171 bp->dbu_buf = bp->dbu_ptr = NULL;
172 bp->dbu_len = 0;
173
174 return (buf);
175 }
176