1 | /* vi:set ts=4:
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2 | *
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3 | * mdev - Mini udev for busybox
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4 | *
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5 | * Copyright 2005 Rob Landley <rob@landley.net>
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6 | * Copyright 2005 Frank Sorenson <frank@tuxrocks.com>
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7 | *
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8 | * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
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9 | */
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10 |
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11 | #include "busybox.h"
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12 | #include <ctype.h>
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13 | #include <errno.h>
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14 | #include <sys/mman.h>
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15 | #include <sys/sysmacros.h>
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16 | #include "xregex.h"
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17 |
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18 | #define DEV_PATH "/dev"
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19 |
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20 | struct mdev_globals
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21 | {
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22 | int root_major, root_minor;
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23 | } mdev_globals;
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24 |
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25 | #define bbg mdev_globals
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26 |
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27 | /* mknod in /dev based on a path like "/sys/block/hda/hda1" */
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28 | static void make_device(char *path, int delete)
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29 | {
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30 | char *device_name;
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31 | int major, minor, type, len, fd;
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32 | int mode = 0660;
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33 | uid_t uid = 0;
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34 | gid_t gid = 0;
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35 | char *temp = path + strlen(path);
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36 | char *command = NULL;
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37 |
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38 | /* Try to read major/minor string. Note that the kernel puts \n after
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39 | * the data, so we don't need to worry about null terminating the string
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40 | * because sscanf() will stop at the first nondigit, which \n is. We
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41 | * also depend on path having writeable space after it. */
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42 |
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43 | strcat(path, "/dev");
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44 | fd = open(path, O_RDONLY);
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45 | len = read(fd, temp + 1, 64);
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46 | *temp++ = 0;
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47 | close(fd);
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48 | if (len < 1) return;
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49 |
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50 | /* Determine device name, type, major and minor */
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51 |
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52 | device_name = strrchr(path, '/') + 1;
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53 | type = path[5]=='c' ? S_IFCHR : S_IFBLK;
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54 | if (sscanf(temp, "%d:%d", &major, &minor) != 2) return;
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55 |
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56 | /* If we have a config file, look up permissions for this device */
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57 |
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58 | if (ENABLE_FEATURE_MDEV_CONF) {
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59 | char *conf, *pos, *end;
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60 |
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61 | /* mmap the config file */
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62 | if (-1 != (fd=open("/etc/mdev.conf",O_RDONLY))) {
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63 | len = lseek(fd, 0, SEEK_END);
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64 | conf = mmap(NULL, len, PROT_READ, MAP_PRIVATE, fd, 0);
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65 | if (conf) {
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66 | int line = 0;
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67 |
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68 | /* Loop through lines in mmaped file*/
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69 | for (pos=conf; pos-conf<len;) {
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70 | int field;
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71 | char *end2;
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72 |
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73 | line++;
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74 | /* find end of this line */
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75 | for(end=pos; end-conf<len && *end!='\n'; end++)
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76 | ;
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77 |
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78 | /* Three fields: regex, uid:gid, mode */
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79 | for (field=0; field < (3 + ENABLE_FEATURE_MDEV_EXEC);
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80 | field++)
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81 | {
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82 | /* Skip whitespace */
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83 | while (pos<end && isspace(*pos)) pos++;
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84 | if (pos==end || *pos=='#') break;
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85 | for (end2=pos;
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86 | end2<end && !isspace(*end2) && *end2!='#'; end2++)
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87 | ;
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88 |
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89 | if (!field) {
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90 | /* Regex to match this device */
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91 |
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92 | char *regex = strndupa(pos, end2-pos);
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93 | regex_t match;
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94 | regmatch_t off;
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95 | int result;
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96 |
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97 | /* Is this it? */
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98 | xregcomp(&match,regex, REG_EXTENDED);
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99 | result = regexec(&match, device_name, 1, &off, 0);
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100 | regfree(&match);
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101 |
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102 | /* If not this device, skip rest of line */
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103 | if (result || off.rm_so
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104 | || off.rm_eo != strlen(device_name))
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105 | break;
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106 |
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107 | } else if (field == 1) {
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108 | /* uid:gid */
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109 |
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110 | char *s, *s2;
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111 |
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112 | /* Find : */
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113 | for(s=pos; s<end2 && *s!=':'; s++)
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114 | ;
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115 | if (s == end2) break;
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116 |
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117 | /* Parse UID */
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118 | uid = strtoul(pos,&s2,10);
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119 | if (s != s2) {
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120 | struct passwd *pass;
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121 | pass = getpwnam(strndupa(pos, s-pos));
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122 | if (!pass) break;
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123 | uid = pass->pw_uid;
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124 | }
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125 | s++;
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126 | /* parse GID */
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127 | gid = strtoul(s, &s2, 10);
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128 | if (end2 != s2) {
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129 | struct group *grp;
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130 | grp = getgrnam(strndupa(s, end2-s));
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131 | if (!grp) break;
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132 | gid = grp->gr_gid;
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133 | }
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134 | } else if (field == 2) {
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135 | /* mode */
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136 |
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137 | mode = strtoul(pos, &pos, 8);
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138 | if (pos != end2) break;
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139 | } else if (ENABLE_FEATURE_MDEV_EXEC && field == 3) {
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140 | // Command to run
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141 | char *s = "@$*", *s2;
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142 | if (!(s2 = strchr(s, *pos++))) {
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143 | // Force error
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144 | field = 1;
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145 | break;
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146 | }
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147 | if ((s2-s+1) & (1<<delete))
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148 | command = bb_xstrndup(pos, end-pos);
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149 | }
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150 |
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151 | pos = end2;
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152 | }
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153 |
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154 | /* Did everything parse happily? */
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155 |
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156 | if (field > 2) break;
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157 | if (field) bb_error_msg_and_die("Bad line %d",line);
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158 |
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159 | /* Next line */
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160 | pos = ++end;
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161 | }
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162 | munmap(conf, len);
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163 | }
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164 | close(fd);
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165 | }
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166 | }
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167 |
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168 | umask(0);
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169 | if (!delete) {
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170 | if (mknod(device_name, mode | type, makedev(major, minor)) && errno != EEXIST)
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171 | bb_perror_msg_and_die("mknod %s failed", device_name);
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172 |
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173 | if (major == bbg.root_major && minor == bbg.root_minor)
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174 | symlink(device_name, "root");
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175 |
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176 | if (ENABLE_FEATURE_MDEV_CONF) chown(device_name, uid, gid);
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177 | }
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178 | if (command) {
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179 | int rc;
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180 | char *s;
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181 |
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182 | s=bb_xasprintf("MDEV=%s",device_name);
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183 | putenv(s);
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184 | rc = system(command);
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185 | s[4]=0;
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186 | putenv(s);
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187 | free(s);
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188 | free(command);
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189 | if (rc == -1) bb_perror_msg_and_die("Couldn't run %s", command);
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190 | }
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191 | if (delete) unlink(device_name);
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192 | }
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193 |
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194 | /* Recursive search of /sys/block or /sys/class. path must be a writeable
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195 | * buffer of size PATH_MAX containing the directory string to start at. */
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196 |
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197 | static void find_dev(char *path)
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198 | {
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199 | DIR *dir;
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200 | size_t len = strlen(path);
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201 | struct dirent *entry;
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202 |
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203 | if ((dir = opendir(path)) == NULL)
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204 | return;
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205 |
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206 | while ((entry = readdir(dir)) != NULL) {
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207 | struct stat st;
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208 |
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209 | /* Skip "." and ".." (also skips hidden files, which is ok) */
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210 |
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211 | if (entry->d_name[0] == '.')
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212 | continue;
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213 |
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214 | // uClibc doesn't fill out entry->d_type reliably. so we use lstat().
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215 |
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216 | snprintf(path+len, PATH_MAX-len, "/%s", entry->d_name);
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217 | if (!lstat(path, &st) && S_ISDIR(st.st_mode)) find_dev(path);
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218 | path[len] = 0;
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219 |
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220 | /* If there's a dev entry, mknod it */
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221 |
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222 | if (!strcmp(entry->d_name, "dev")) make_device(path, 0);
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223 | }
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224 |
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225 | closedir(dir);
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226 | }
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227 |
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228 | int mdev_main(int argc, char *argv[])
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229 | {
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230 | char *action;
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231 | char *env_path;
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232 | RESERVE_CONFIG_BUFFER(temp,PATH_MAX);
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233 |
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234 | bb_xchdir(DEV_PATH);
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235 |
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236 | /* Scan */
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237 |
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238 | if (argc == 2 && !strcmp(argv[1],"-s")) {
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239 | struct stat st;
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240 |
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241 | stat("/", &st); // If this fails, we have bigger problems.
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242 | bbg.root_major=major(st.st_dev);
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243 | bbg.root_minor=minor(st.st_dev);
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244 | strcpy(temp,"/sys/block");
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245 | find_dev(temp);
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246 | strcpy(temp,"/sys/class");
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247 | find_dev(temp);
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248 |
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249 | /* Hotplug */
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250 |
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251 | } else {
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252 | action = getenv("ACTION");
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253 | env_path = getenv("DEVPATH");
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254 | if (!action || !env_path)
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255 | bb_show_usage();
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256 |
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257 | sprintf(temp, "/sys%s", env_path);
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258 | if (!strcmp(action, "add")) make_device(temp,0);
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259 | else if (!strcmp(action, "remove")) make_device(temp,1);
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260 | }
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261 |
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262 | if (ENABLE_FEATURE_CLEAN_UP) RELEASE_CONFIG_BUFFER(temp);
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263 | return 0;
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264 | }
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