1 | /* |
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2 | * devno.c - find a particular device by its device number (major/minor) |
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3 | * |
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4 | * Copyright (C) 2000, 2001, 2003 Theodore Ts'o |
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5 | * Copyright (C) 2001 Andreas Dilger |
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6 | * |
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7 | * %Begin-Header% |
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8 | * This file may be redistributed under the terms of the |
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9 | * GNU Lesser General Public License. |
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10 | * %End-Header% |
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11 | */ |
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12 | |
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13 | #include <stdio.h> |
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14 | #include <string.h> |
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15 | #if HAVE_UNISTD_H |
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16 | #include <unistd.h> |
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17 | #endif |
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18 | #include <stdlib.h> |
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19 | #include <string.h> |
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20 | #if HAVE_SYS_TYPES_H |
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21 | #include <sys/types.h> |
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22 | #endif |
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23 | #if HAVE_SYS_STAT_H |
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24 | #include <sys/stat.h> |
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25 | #endif |
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26 | #include <dirent.h> |
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27 | #if HAVE_ERRNO_H |
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28 | #include <errno.h> |
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29 | #endif |
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30 | #if HAVE_SYS_MKDEV_H |
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31 | #include <sys/mkdev.h> |
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32 | #endif |
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33 | |
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34 | #include "blkidP.h" |
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35 | |
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36 | struct dir_list { |
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37 | char *name; |
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38 | struct dir_list *next; |
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39 | }; |
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40 | |
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41 | char *blkid_strndup(const char *s, int length) |
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42 | { |
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43 | char *ret; |
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44 | |
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45 | if (!s) |
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46 | return NULL; |
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47 | |
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48 | if (!length) |
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49 | length = strlen(s); |
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50 | |
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51 | ret = xmalloc(length + 1); |
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52 | strncpy(ret, s, length); |
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53 | ret[length] = '\0'; |
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54 | return ret; |
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55 | } |
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56 | |
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57 | char *blkid_strdup(const char *s) |
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58 | { |
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59 | return blkid_strndup(s, 0); |
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60 | } |
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61 | |
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62 | /* |
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63 | * This function adds an entry to the directory list |
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64 | */ |
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65 | static void add_to_dirlist(const char *name, struct dir_list **list) |
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66 | { |
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67 | struct dir_list *dp; |
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68 | |
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69 | dp = xmalloc(sizeof(struct dir_list)); |
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70 | dp->name = blkid_strdup(name); |
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71 | dp->next = *list; |
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72 | *list = dp; |
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73 | } |
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74 | |
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75 | /* |
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76 | * This function frees a directory list |
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77 | */ |
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78 | static void free_dirlist(struct dir_list **list) |
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79 | { |
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80 | struct dir_list *dp, *next; |
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81 | |
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82 | for (dp = *list; dp; dp = next) { |
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83 | next = dp->next; |
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84 | free(dp->name); |
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85 | free(dp); |
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86 | } |
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87 | *list = NULL; |
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88 | } |
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89 | |
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90 | static void scan_dir(char *dir_name, dev_t devno, struct dir_list **list, |
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91 | char **devname) |
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92 | { |
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93 | DIR *dir; |
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94 | struct dirent *dp; |
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95 | char path[1024]; |
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96 | int dirlen; |
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97 | struct stat st; |
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98 | |
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99 | if ((dir = opendir(dir_name)) == NULL) |
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100 | return; |
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101 | dirlen = strlen(dir_name) + 2; |
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102 | while ((dp = readdir(dir)) != 0) { |
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103 | if (dirlen + strlen(dp->d_name) >= sizeof(path)) |
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104 | continue; |
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105 | |
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106 | if (dp->d_name[0] == '.' && |
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107 | ((dp->d_name[1] == 0) || |
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108 | ((dp->d_name[1] == '.') && (dp->d_name[2] == 0)))) |
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109 | continue; |
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110 | |
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111 | sprintf(path, "%s/%s", dir_name, dp->d_name); |
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112 | if (stat(path, &st) < 0) |
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113 | continue; |
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114 | |
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115 | if (S_ISDIR(st.st_mode)) |
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116 | add_to_dirlist(path, list); |
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117 | else if (S_ISBLK(st.st_mode) && st.st_rdev == devno) { |
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118 | *devname = blkid_strdup(path); |
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119 | DBG(DEBUG_DEVNO, |
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120 | printf("found 0x%llx at %s (%p)\n", devno, |
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121 | path, *devname)); |
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122 | break; |
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123 | } |
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124 | } |
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125 | closedir(dir); |
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126 | return; |
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127 | } |
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128 | |
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129 | /* Directories where we will try to search for device numbers */ |
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130 | const char *blkid_devdirs[] = { "/devices", "/devfs", "/dev", NULL }; |
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131 | |
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132 | /* |
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133 | * This function finds the pathname to a block device with a given |
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134 | * device number. It returns a pointer to allocated memory to the |
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135 | * pathname on success, and NULL on failure. |
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136 | */ |
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137 | char *blkid_devno_to_devname(dev_t devno) |
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138 | { |
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139 | struct dir_list *list = NULL, *new_list = NULL; |
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140 | char *devname = NULL; |
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141 | const char **dir; |
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142 | |
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143 | /* |
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144 | * Add the starting directories to search in reverse order of |
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145 | * importance, since we are using a stack... |
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146 | */ |
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147 | for (dir = blkid_devdirs; *dir; dir++) |
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148 | add_to_dirlist(*dir, &list); |
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149 | |
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150 | while (list) { |
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151 | struct dir_list *current = list; |
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152 | |
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153 | list = list->next; |
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154 | DBG(DEBUG_DEVNO, printf("directory %s\n", current->name)); |
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155 | scan_dir(current->name, devno, &new_list, &devname); |
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156 | free(current->name); |
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157 | free(current); |
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158 | if (devname) |
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159 | break; |
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160 | /* |
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161 | * If we're done checking at this level, descend to |
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162 | * the next level of subdirectories. (breadth-first) |
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163 | */ |
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164 | if (list == NULL) { |
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165 | list = new_list; |
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166 | new_list = NULL; |
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167 | } |
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168 | } |
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169 | free_dirlist(&list); |
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170 | free_dirlist(&new_list); |
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171 | |
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172 | if (!devname) { |
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173 | DBG(DEBUG_DEVNO, |
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174 | printf("blkid: couldn't find devno 0x%04lx\n", |
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175 | (unsigned long) devno)); |
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176 | } else { |
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177 | DBG(DEBUG_DEVNO, |
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178 | printf("found devno 0x%04llx as %s\n", devno, devname)); |
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179 | } |
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180 | |
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181 | |
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182 | return devname; |
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183 | } |
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184 | |
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185 | #ifdef TEST_PROGRAM |
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186 | int main(int argc, char** argv) |
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187 | { |
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188 | char *devname, *tmp; |
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189 | int major, minor; |
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190 | dev_t devno; |
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191 | const char *errmsg = "Couldn't parse %s: %s\n"; |
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192 | |
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193 | blkid_debug_mask = DEBUG_ALL; |
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194 | if ((argc != 2) && (argc != 3)) { |
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195 | fprintf(stderr, "Usage:\t%s device_number\n\t%s major minor\n" |
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196 | "Resolve a device number to a device name\n", |
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197 | argv[0], argv[0]); |
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198 | exit(1); |
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199 | } |
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200 | if (argc == 2) { |
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201 | devno = strtoul(argv[1], &tmp, 0); |
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202 | if (*tmp) { |
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203 | fprintf(stderr, errmsg, "device number", argv[1]); |
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204 | exit(1); |
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205 | } |
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206 | } else { |
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207 | major = strtoul(argv[1], &tmp, 0); |
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208 | if (*tmp) { |
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209 | fprintf(stderr, errmsg, "major number", argv[1]); |
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210 | exit(1); |
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211 | } |
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212 | minor = strtoul(argv[2], &tmp, 0); |
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213 | if (*tmp) { |
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214 | fprintf(stderr, errmsg, "minor number", argv[2]); |
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215 | exit(1); |
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216 | } |
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217 | devno = makedev(major, minor); |
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218 | } |
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219 | printf("Looking for device 0x%04Lx\n", devno); |
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220 | devname = blkid_devno_to_devname(devno); |
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221 | free(devname); |
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222 | return 0; |
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223 | } |
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224 | #endif |
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