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 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 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 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 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 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 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 146 dt_buf_len(const dt_buf_t *bp) 147 { 148 return (bp->dbu_ptr - bp->dbu_buf); 149 } 150 151 int 152 dt_buf_error(const dt_buf_t *bp) 153 { 154 return (bp->dbu_err); 155 } 156 157 void * 158 dt_buf_ptr(const dt_buf_t *bp) 159 { 160 return (bp->dbu_buf); 161 } 162 163 void * 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