1 | /* vi: set sw=4 ts=4: */
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2 | /*
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3 | * read.c - read the blkid cache from disk, to avoid scanning all devices
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4 | *
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5 | * Copyright (C) 2001, 2003 Theodore Y. Ts'o
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6 | * Copyright (C) 2001 Andreas Dilger
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7 | *
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8 | * %Begin-Header%
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9 | * This file may be redistributed under the terms of the
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10 | * GNU Lesser General Public License.
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11 | * %End-Header%
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12 | */
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13 |
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14 | #include <stdio.h>
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15 | #include <ctype.h>
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16 | #include <string.h>
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17 | #include <time.h>
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18 | #include <sys/types.h>
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19 | #include <sys/stat.h>
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20 | #include <fcntl.h>
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21 | #include <unistd.h>
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22 | #include <errno.h>
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23 |
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24 | #include "blkidP.h"
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25 | #include "../uuid/uuid.h"
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26 |
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27 | #ifdef HAVE_STRTOULL
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28 | #define __USE_ISOC9X
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29 | #define STRTOULL strtoull /* defined in stdlib.h if you try hard enough */
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30 | #else
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31 | /* FIXME: need to support real strtoull here */
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32 | #define STRTOULL strtoul
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33 | #endif
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34 |
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35 | #include <stdlib.h>
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36 |
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37 | #ifdef TEST_PROGRAM
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38 | #define blkid_debug_dump_dev(dev) (debug_dump_dev(dev))
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39 | static void debug_dump_dev(blkid_dev dev);
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40 | #endif
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41 |
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42 | /*
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43 | * File format:
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44 | *
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45 | * <device [<NAME="value"> ...]>device_name</device>
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46 | *
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47 | * The following tags are required for each entry:
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48 | * <ID="id"> unique (within this file) ID number of this device
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49 | * <TIME="time"> (ascii time_t) time this entry was last read from disk
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50 | * <TYPE="type"> (detected) type of filesystem/data for this partition
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51 | *
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52 | * The following tags may be present, depending on the device contents
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53 | * <LABEL="label"> (user supplied) label (volume name, etc)
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54 | * <UUID="uuid"> (generated) universally unique identifier (serial no)
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55 | */
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56 |
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57 | static char *skip_over_blank(char *cp)
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58 | {
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59 | while (*cp && isspace(*cp))
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60 | cp++;
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61 | return cp;
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62 | }
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63 |
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64 | static char *skip_over_word(char *cp)
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65 | {
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66 | char ch;
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67 |
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68 | while ((ch = *cp)) {
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69 | /* If we see a backslash, skip the next character */
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70 | if (ch == '\\') {
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71 | cp++;
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72 | if (*cp == '\0')
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73 | break;
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74 | cp++;
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75 | continue;
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76 | }
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77 | if (isspace(ch) || ch == '<' || ch == '>')
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78 | break;
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79 | cp++;
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80 | }
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81 | return cp;
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82 | }
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83 |
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84 | static char *strip_line(char *line)
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85 | {
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86 | char *p;
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87 |
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88 | line = skip_over_blank(line);
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89 |
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90 | p = line + strlen(line) - 1;
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91 |
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92 | while (*line) {
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93 | if (isspace(*p))
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94 | *p-- = '\0';
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95 | else
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96 | break;
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97 | }
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98 |
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99 | return line;
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100 | }
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101 |
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102 | /*
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103 | * Start parsing a new line from the cache.
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104 | *
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105 | * line starts with "<device" return 1 -> continue parsing line
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106 | * line starts with "<foo", empty, or # return 0 -> skip line
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107 | * line starts with other, return -BLKID_ERR_CACHE -> error
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108 | */
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109 | static int parse_start(char **cp)
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110 | {
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111 | char *p;
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112 |
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113 | p = strip_line(*cp);
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114 |
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115 | /* Skip comment or blank lines. We can't just NUL the first '#' char,
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116 | * in case it is inside quotes, or escaped.
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117 | */
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118 | if (*p == '\0' || *p == '#')
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119 | return 0;
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120 |
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121 | if (!strncmp(p, "<device", 7)) {
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122 | DBG(DEBUG_READ, printf("found device header: %8s\n", p));
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123 | p += 7;
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124 |
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125 | *cp = p;
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126 | return 1;
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127 | }
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128 |
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129 | if (*p == '<')
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130 | return 0;
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131 |
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132 | return -BLKID_ERR_CACHE;
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133 | }
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134 |
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135 | /* Consume the remaining XML on the line (cosmetic only) */
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136 | static int parse_end(char **cp)
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137 | {
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138 | *cp = skip_over_blank(*cp);
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139 |
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140 | if (!strncmp(*cp, "</device>", 9)) {
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141 | DBG(DEBUG_READ, printf("found device trailer %9s\n", *cp));
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142 | *cp += 9;
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143 | return 0;
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144 | }
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145 |
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146 | return -BLKID_ERR_CACHE;
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147 | }
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148 |
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149 | /*
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150 | * Allocate a new device struct with device name filled in. Will handle
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151 | * finding the device on lines of the form:
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152 | * <device foo=bar>devname</device>
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153 | * <device>devname<foo>bar</foo></device>
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154 | */
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155 | static int parse_dev(blkid_cache cache, blkid_dev *dev, char **cp)
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156 | {
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157 | char *start, *tmp, *end, *name;
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158 | int ret;
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159 |
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160 | if ((ret = parse_start(cp)) <= 0)
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161 | return ret;
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162 |
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163 | start = tmp = strchr(*cp, '>');
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164 | if (!start) {
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165 | DBG(DEBUG_READ,
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166 | printf("blkid: short line parsing dev: %s\n", *cp));
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167 | return -BLKID_ERR_CACHE;
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168 | }
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169 | start = skip_over_blank(start + 1);
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170 | end = skip_over_word(start);
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171 |
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172 | DBG(DEBUG_READ, printf("device should be %*s\n", end - start, start));
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173 |
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174 | if (**cp == '>')
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175 | *cp = end;
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176 | else
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177 | (*cp)++;
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178 |
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179 | *tmp = '\0';
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180 |
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181 | if (!(tmp = strrchr(end, '<')) || parse_end(&tmp) < 0) {
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182 | DBG(DEBUG_READ,
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183 | printf("blkid: missing </device> ending: %s\n", end));
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184 | } else if (tmp)
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185 | *tmp = '\0';
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186 |
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187 | if (end - start <= 1) {
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188 | DBG(DEBUG_READ, printf("blkid: empty device name: %s\n", *cp));
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189 | return -BLKID_ERR_CACHE;
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190 | }
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191 |
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192 | name = blkid_strndup(start, end-start);
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193 | if (name == NULL)
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194 | return -BLKID_ERR_MEM;
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195 |
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196 | DBG(DEBUG_READ, printf("found dev %s\n", name));
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197 |
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198 | if (!(*dev = blkid_get_dev(cache, name, BLKID_DEV_CREATE)))
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199 | return -BLKID_ERR_MEM;
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200 |
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201 | free(name);
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202 | return 1;
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203 | }
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204 |
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205 | /*
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206 | * Extract a tag of the form NAME="value" from the line.
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207 | */
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208 | static int parse_token(char **name, char **value, char **cp)
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209 | {
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210 | char *end;
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211 |
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212 | if (!name || !value || !cp)
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213 | return -BLKID_ERR_PARAM;
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214 |
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215 | if (!(*value = strchr(*cp, '=')))
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216 | return 0;
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217 |
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218 | **value = '\0';
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219 | *name = strip_line(*cp);
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220 | *value = skip_over_blank(*value + 1);
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221 |
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222 | if (**value == '"') {
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223 | end = strchr(*value + 1, '"');
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224 | if (!end) {
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225 | DBG(DEBUG_READ,
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226 | printf("unbalanced quotes at: %s\n", *value));
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227 | *cp = *value;
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228 | return -BLKID_ERR_CACHE;
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229 | }
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230 | (*value)++;
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231 | *end = '\0';
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232 | end++;
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233 | } else {
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234 | end = skip_over_word(*value);
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235 | if (*end) {
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236 | *end = '\0';
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237 | end++;
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238 | }
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239 | }
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240 | *cp = end;
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241 |
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242 | return 1;
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243 | }
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244 |
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245 | /*
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246 | * Extract a tag of the form <NAME>value</NAME> from the line.
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247 | */
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248 | /*
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249 | static int parse_xml(char **name, char **value, char **cp)
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250 | {
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251 | char *end;
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252 |
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253 | if (!name || !value || !cp)
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254 | return -BLKID_ERR_PARAM;
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255 |
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256 | *name = strip_line(*cp);
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257 |
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258 | if ((*name)[0] != '<' || (*name)[1] == '/')
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259 | return 0;
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260 |
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261 | FIXME: finish this.
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262 | }
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263 | */
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264 |
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265 | /*
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266 | * Extract a tag from the line.
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267 | *
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268 | * Return 1 if a valid tag was found.
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269 | * Return 0 if no tag found.
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270 | * Return -ve error code.
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271 | */
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272 | static int parse_tag(blkid_cache cache, blkid_dev dev, char **cp)
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273 | {
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274 | char *name;
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275 | char *value;
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276 | int ret;
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277 |
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278 | if (!cache || !dev)
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279 | return -BLKID_ERR_PARAM;
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280 |
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281 | if ((ret = parse_token(&name, &value, cp)) <= 0 /* &&
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282 | (ret = parse_xml(&name, &value, cp)) <= 0 */)
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283 | return ret;
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284 |
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285 | /* Some tags are stored directly in the device struct */
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286 | if (!strcmp(name, "DEVNO"))
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287 | dev->bid_devno = STRTOULL(value, 0, 0);
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288 | else if (!strcmp(name, "PRI"))
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289 | dev->bid_pri = strtol(value, 0, 0);
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290 | else if (!strcmp(name, "TIME"))
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291 | /* FIXME: need to parse a long long eventually */
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292 | dev->bid_time = strtol(value, 0, 0);
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293 | else
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294 | ret = blkid_set_tag(dev, name, value, strlen(value));
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295 |
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296 | DBG(DEBUG_READ, printf(" tag: %s=\"%s\"\n", name, value));
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297 |
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298 | return ret < 0 ? ret : 1;
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299 | }
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300 |
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301 | /*
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302 | * Parse a single line of data, and return a newly allocated dev struct.
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303 | * Add the new device to the cache struct, if one was read.
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304 | *
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305 | * Lines are of the form <device [TAG="value" ...]>/dev/foo</device>
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306 | *
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307 | * Returns -ve value on error.
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308 | * Returns 0 otherwise.
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309 | * If a valid device was read, *dev_p is non-NULL, otherwise it is NULL
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310 | * (e.g. comment lines, unknown XML content, etc).
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311 | */
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312 | static int blkid_parse_line(blkid_cache cache, blkid_dev *dev_p, char *cp)
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313 | {
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314 | blkid_dev dev;
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315 | int ret;
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316 |
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317 | if (!cache || !dev_p)
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318 | return -BLKID_ERR_PARAM;
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319 |
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320 | *dev_p = NULL;
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321 |
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322 | DBG(DEBUG_READ, printf("line: %s\n", cp));
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323 |
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324 | if ((ret = parse_dev(cache, dev_p, &cp)) <= 0)
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325 | return ret;
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326 |
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327 | dev = *dev_p;
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328 |
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329 | while ((ret = parse_tag(cache, dev, &cp)) > 0) {
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330 | ;
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331 | }
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332 |
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333 | if (dev->bid_type == NULL) {
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334 | DBG(DEBUG_READ,
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335 | printf("blkid: device %s has no TYPE\n",dev->bid_name));
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336 | blkid_free_dev(dev);
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337 | }
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338 |
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339 | DBG(DEBUG_READ, blkid_debug_dump_dev(dev));
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340 |
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341 | return ret;
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342 | }
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343 |
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344 | /*
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345 | * Parse the specified filename, and return the data in the supplied or
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346 | * a newly allocated cache struct. If the file doesn't exist, return a
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347 | * new empty cache struct.
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348 | */
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349 | void blkid_read_cache(blkid_cache cache)
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350 | {
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351 | FILE *file;
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352 | char buf[4096];
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353 | int fd, lineno = 0;
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354 | struct stat st;
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355 |
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356 | if (!cache)
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357 | return;
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358 |
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359 | /*
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360 | * If the file doesn't exist, then we just return an empty
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361 | * struct so that the cache can be populated.
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362 | */
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363 | if ((fd = open(cache->bic_filename, O_RDONLY)) < 0)
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364 | return;
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365 | if (fstat(fd, &st) < 0)
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366 | goto errout;
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367 | if ((st.st_mtime == cache->bic_ftime) ||
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368 | (cache->bic_flags & BLKID_BIC_FL_CHANGED)) {
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369 | DBG(DEBUG_CACHE, printf("skipping re-read of %s\n",
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370 | cache->bic_filename));
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371 | goto errout;
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372 | }
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373 |
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374 | DBG(DEBUG_CACHE, printf("reading cache file %s\n",
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375 | cache->bic_filename));
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376 |
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377 | file = fdopen(fd, "r");
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378 | if (!file)
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379 | goto errout;
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380 |
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381 | while (fgets(buf, sizeof(buf), file)) {
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382 | blkid_dev dev;
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383 | unsigned int end;
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384 |
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385 | lineno++;
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386 | if (buf[0] == 0)
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387 | continue;
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388 | end = strlen(buf) - 1;
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389 | /* Continue reading next line if it ends with a backslash */
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390 | while (buf[end] == '\\' && end < sizeof(buf) - 2 &&
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391 | fgets(buf + end, sizeof(buf) - end, file)) {
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392 | end = strlen(buf) - 1;
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393 | lineno++;
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394 | }
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395 |
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396 | if (blkid_parse_line(cache, &dev, buf) < 0) {
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397 | DBG(DEBUG_READ,
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398 | printf("blkid: bad format on line %d\n", lineno));
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399 | continue;
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400 | }
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401 | }
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402 | fclose(file);
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403 |
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404 | /*
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405 | * Initially we do not need to write out the cache file.
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406 | */
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407 | cache->bic_flags &= ~BLKID_BIC_FL_CHANGED;
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408 | cache->bic_ftime = st.st_mtime;
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409 |
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410 | return;
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411 | errout:
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412 | close(fd);
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413 | }
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414 |
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415 | #ifdef TEST_PROGRAM
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416 | static void debug_dump_dev(blkid_dev dev)
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417 | {
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418 | struct list_head *p;
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419 |
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420 | if (!dev) {
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421 | printf(" dev: NULL\n");
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422 | return;
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423 | }
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424 |
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425 | printf(" dev: name = %s\n", dev->bid_name);
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426 | printf(" dev: DEVNO=\"0x%0llx\"\n", dev->bid_devno);
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427 | printf(" dev: TIME=\"%lu\"\n", dev->bid_time);
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428 | printf(" dev: PRI=\"%d\"\n", dev->bid_pri);
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429 | printf(" dev: flags = 0x%08X\n", dev->bid_flags);
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430 |
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431 | list_for_each(p, &dev->bid_tags) {
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432 | blkid_tag tag = list_entry(p, struct blkid_struct_tag, bit_tags);
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433 | if (tag)
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434 | printf(" tag: %s=\"%s\"\n", tag->bit_name,
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435 | tag->bit_val);
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436 | else
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437 | printf(" tag: NULL\n");
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438 | }
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439 | puts("");
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440 | }
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441 |
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442 | int main(int argc, char**argv)
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443 | {
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444 | blkid_cache cache = NULL;
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445 | int ret;
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446 |
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447 | blkid_debug_mask = DEBUG_ALL;
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448 | if (argc > 2) {
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449 | fprintf(stderr, "Usage: %s [filename]\n"
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450 | "Test parsing of the cache (filename)\n", argv[0]);
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451 | exit(1);
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452 | }
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453 | if ((ret = blkid_get_cache(&cache, argv[1])) < 0)
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454 | fprintf(stderr, "error %d reading cache file %s\n", ret,
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455 | argv[1] ? argv[1] : BLKID_CACHE_FILE);
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456 |
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457 | blkid_put_cache(cache);
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458 |
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459 | return ret;
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460 | }
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461 | #endif
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