1 | /* |
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2 | * This file is part of libtrace |
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3 | * |
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4 | * Copyright (c) 2007,2008,2009,2010 The University of Waikato, Hamilton, |
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5 | * New Zealand. |
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6 | * |
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7 | * Authors: Daniel Lawson |
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8 | * Perry Lorier |
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9 | * Shane Alcock |
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10 | * |
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11 | * All rights reserved. |
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12 | * |
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13 | * This code has been developed by the University of Waikato WAND |
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14 | * research group. For further information please see http://www.wand.net.nz/ |
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15 | * |
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16 | * libtrace is free software; you can redistribute it and/or modify |
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17 | * it under the terms of the GNU General Public License as published by |
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18 | * the Free Software Foundation; either version 2 of the License, or |
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19 | * (at your option) any later version. |
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20 | * |
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21 | * libtrace is distributed in the hope that it will be useful, |
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22 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
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23 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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24 | * GNU General Public License for more details. |
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25 | * |
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26 | * You should have received a copy of the GNU General Public License |
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27 | * along with libtrace; if not, write to the Free Software |
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28 | * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA |
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29 | * |
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30 | * $Id$ |
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31 | * |
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32 | */ |
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33 | |
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34 | |
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35 | #define _GNU_SOURCE 1 |
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36 | #include "wandio.h" |
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37 | #include <sys/types.h> |
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38 | #include <sys/stat.h> |
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39 | #include <sys/uio.h> |
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40 | #include <fcntl.h> |
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41 | #include <stdlib.h> |
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42 | #include <unistd.h> |
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43 | #include <string.h> |
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44 | #include <assert.h> |
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45 | |
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46 | /* Libtrace IO module implementing a standard IO writer, i.e. no decompression |
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47 | */ |
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48 | |
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49 | enum { MIN_WRITE_SIZE = 4096 }; |
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50 | |
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51 | struct stdiow_t { |
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52 | char buffer[MIN_WRITE_SIZE]; |
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53 | int offset; |
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54 | int fd; |
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55 | }; |
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56 | |
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57 | extern iow_source_t stdio_wsource; |
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58 | |
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59 | #define DATA(iow) ((struct stdiow_t *)((iow)->data)) |
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60 | |
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61 | static int safe_open(const char *filename) |
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62 | { |
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63 | int fd; |
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64 | /* Try opening with O_DIRECT */ |
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65 | #ifdef O_DIRECT |
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66 | fd = open(filename, |
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67 | O_WRONLY |
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68 | |O_CREAT |
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69 | |O_TRUNC |
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70 | |(force_directio_write?O_DIRECT:0), |
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71 | 0666); |
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72 | if (fd != -1) |
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73 | return fd; |
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74 | #endif |
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75 | /* If that failed (or we don't support O_DIRECT) try opening without */ |
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76 | fd = open(filename, |
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77 | O_WRONLY |
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78 | |O_CREAT |
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79 | |O_TRUNC, |
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80 | 0666); |
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81 | if (fd != -1) |
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82 | return fd; |
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83 | return fd; |
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84 | } |
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85 | |
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86 | iow_t *stdio_wopen(const char *filename) |
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87 | { |
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88 | iow_t *iow = malloc(sizeof(iow_t)); |
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89 | iow->source = &stdio_wsource; |
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90 | iow->data = malloc(sizeof(struct stdiow_t)); |
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91 | |
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92 | if (strcmp(filename,"-") == 0) |
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93 | DATA(iow)->fd = 1; /* STDOUT */ |
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94 | else { |
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95 | DATA(iow)->fd = safe_open(filename); |
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96 | } |
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97 | |
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98 | if (DATA(iow)->fd == -1) { |
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99 | free(iow); |
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100 | return NULL; |
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101 | } |
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102 | |
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103 | DATA(iow)->offset = 0; |
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104 | |
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105 | return iow; |
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106 | } |
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107 | |
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108 | #define min(a,b) ((a)<(b) ? (a) : (b)) |
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109 | #define max(a,b) ((a)>(b) ? (a) : (b)) |
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110 | /* Round A Down to the nearest multiple of B */ |
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111 | #define rounddown(a,b) ((a)-((a)%b) |
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112 | |
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113 | /* When doing directio (O_DIRECT) we need to make sure that we write multiples of MIN_WRITE_SIZE. |
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114 | * So we accumulate data into DATA(iow)->buffer, and write it out when we get at least MIN_WRITE_SIZE. |
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115 | * |
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116 | * Since most writes are likely to be larger than MIN_WRITE_SIZE optimise for that case. |
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117 | */ |
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118 | static off_t stdio_wwrite(iow_t *iow, const char *buffer, off_t len) |
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119 | { |
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120 | struct iovec iov[2]; |
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121 | int err; |
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122 | /* Round down size to the nearest multiple of MIN_WRITE_SIZE */ |
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123 | |
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124 | assert(len >= 0); |
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125 | |
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126 | if (DATA(iow)->offset + len >= MIN_WRITE_SIZE) { |
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127 | int amount; |
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128 | iov[0].iov_base = DATA(iow)->buffer; |
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129 | iov[0].iov_len = DATA(iow)->offset; |
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130 | iov[1].iov_base = (void*)buffer; /* cast away constness, which is safe here */ |
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131 | iov[1].iov_len = len - (DATA(iow)->offset+len) % MIN_WRITE_SIZE; |
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132 | err=writev(DATA(iow)->fd, iov, 2); |
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133 | if (err==-1) |
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134 | return -1; |
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135 | /* Drop off "err" bytes from the beginning of the buffers */ |
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136 | amount = min(DATA(iow)->offset, err); |
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137 | DATA(iow)->offset -= amount; |
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138 | err -= amount; |
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139 | buffer += err; |
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140 | len -= err; |
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141 | } |
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142 | |
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143 | /* Make sure we're not going to overflow the buffer. The above writev should assure |
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144 | * that this is true |
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145 | */ |
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146 | assert(DATA(iow)->offset + len <= MIN_WRITE_SIZE); |
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147 | assert(len >= 0); |
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148 | |
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149 | /* Copy the remainder into the buffer to write next time. */ |
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150 | memcpy(DATA(iow)->buffer + DATA(iow)->offset, buffer, len); |
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151 | DATA(iow)->offset += len; |
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152 | |
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153 | return len; |
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154 | } |
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155 | |
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156 | static void stdio_wclose(iow_t *iow) |
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157 | { |
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158 | long err; |
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159 | /* Now, there might be some non multiple of the direct filesize left over, if so turn off |
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160 | * O_DIRECT and write the final chunk. |
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161 | */ |
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162 | #ifdef O_DIRECT |
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163 | err=fcntl(DATA(iow)->fd, F_GETFL); |
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164 | if (err != -1 && (err & O_DIRECT) != 0) { |
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165 | fcntl(DATA(iow)->fd,F_SETFL, err & ~O_DIRECT); |
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166 | } |
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167 | write(DATA(iow)->fd, DATA(iow)->buffer, DATA(iow)->offset); |
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168 | DATA(iow)->offset = 0; |
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169 | #endif |
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170 | close(DATA(iow)->fd); |
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171 | free(iow->data); |
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172 | free(iow); |
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173 | } |
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174 | |
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175 | iow_source_t stdio_wsource = { |
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176 | "stdiow", |
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177 | stdio_wwrite, |
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178 | stdio_wclose |
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179 | }; |
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