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 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 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 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 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 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 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 144 dt_buf_len(const dt_buf_t *bp) 145 { 146 return (bp->dbu_ptr - bp->dbu_buf); 147 } 148 149 int 150 dt_buf_error(const dt_buf_t *bp) 151 { 152 return (bp->dbu_err); 153 } 154 155 void * 156 dt_buf_ptr(const dt_buf_t *bp) 157 { 158 return (bp->dbu_buf); 159 } 160 161 void * 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