src/libudev/libudev-util.c

   1 /* SPDX-License-Identifier: LGPL-2.1+ */
   2
   3 #include <ctype.h>
   4 #include <errno.h>
   5 #include <stddef.h>
   6 #include <stdlib.h>
   7 #include <string.h>
   8 #include <unistd.h>
   9
  10 #include "libudev.h"
  11
  12 #include "MurmurHash2.h"
  13 #include "device-nodes.h"
  14 #include "libudev-private.h"
  15 #include "syslog-util.h"
  16 #include "utf8.h"
  17
  18 /**
  19  * SECTION:libudev-util
  20  * @short_description: utils
  21  *
  22  * Utilities useful when dealing with devices and device node names.
  23  */
  24
  25 /* handle "[<SUBSYSTEM>/<KERNEL>]<attribute>" format */
  26 int util_resolve_subsys_kernel(struct udev *udev, const char *string,
  27                                char *result, size_t maxsize, int read_value)
  28 {
  29         char temp[UTIL_PATH_SIZE];
  30         char *subsys;
  31         char *sysname;
  32         struct udev_device *dev;
  33         char *attr;
  34
  35         if (string[0] != '[')
  36                 return -1;
  37
  38         strscpy(temp, sizeof(temp), string);
  39
  40         subsys = &temp[1];
  41
  42         sysname = strchr(subsys, '/');
  43         if (sysname == NULL)
  44                 return -1;
  45         sysname[0] = '\0';
  46         sysname = &sysname[1];
  47
  48         attr = strchr(sysname, ']');
  49         if (attr == NULL)
  50                 return -1;
  51         attr[0] = '\0';
  52         attr = &attr[1];
  53         if (attr[0] == '/')
  54                 attr = &attr[1];
  55         if (attr[0] == '\0')
  56                 attr = NULL;
  57
  58         if (read_value && attr == NULL)
  59                 return -1;
  60
  61         dev = udev_device_new_from_subsystem_sysname(udev, subsys, sysname);
  62         if (dev == NULL)
  63                 return -1;
  64
  65         if (read_value) {
  66                 const char *val;
  67
  68                 val = udev_device_get_sysattr_value(dev, attr);
  69                 if (val != NULL)
  70                         strscpy(result, maxsize, val);
  71                 else
  72                         result[0] = '\0';
  73                 log_debug("value '[%s/%s]%s' is '%s'", subsys, sysname, attr, result);
  74         } else {
  75                 size_t l;
  76                 char *s;
  77
  78                 s = result;
  79                 l = strpcpyl(&s, maxsize, udev_device_get_syspath(dev), NULL);
  80                 if (attr != NULL)
  81                         strpcpyl(&s, l, "/", attr, NULL);
  82                 log_debug("path '[%s/%s]%s' is '%s'", subsys, sysname, attr, result);
  83         }
  84         udev_device_unref(dev);
  85         return 0;
  86 }
  87
  88 int util_log_priority(const char *priority)
  89 {
  90         char *endptr;
  91         int prio;
  92
  93         prio = strtoul(priority, &endptr, 10);
  94         if (endptr[0] == '\0' || isspace(endptr[0])) {
  95                 if (prio >= 0 && prio <= 7)
  96                         return prio;
  97                 else
  98                         return -ERANGE;
  99         }
 100
 101         return log_level_from_string(priority);
 102 }
 103
 104 size_t util_path_encode(const char *src, char *dest, size_t size)
 105 {
 106         size_t i, j;
 107
 108         for (i = 0, j = 0; src[i] != '\0'; i++) {
 109                 if (src[i] == '/') {
 110                         if (j+4 >= size) {
 111                                 j = 0;
 112                                 break;
 113                         }
 114                         memcpy(&dest[j], "\\x2f", 4);
 115                         j += 4;
 116                 } else if (src[i] == '\\') {
 117                         if (j+4 >= size) {
 118                                 j = 0;
 119                                 break;
 120                         }
 121                         memcpy(&dest[j], "\\x5c", 4);
 122                         j += 4;
 123                 } else {
 124                         if (j+1 >= size) {
 125                                 j = 0;
 126                                 break;
 127                         }
 128                         dest[j] = src[i];
 129                         j++;
 130                 }
 131         }
 132         dest[j] = '\0';
 133         return j;
 134 }
 135
 136 /*
 137  * Copy from 'str' to 'to', while removing all leading and trailing whitespace,
 138  * and replacing each run of consecutive whitespace with a single underscore.
 139  * The chars from 'str' are copied up to the \0 at the end of the string, or
 140  * at most 'len' chars.  This appends \0 to 'to', at the end of the copied
 141  * characters.
 142  *
 143  * If 'len' chars are copied into 'to', the final \0 is placed at len+1
 144  * (i.e. 'to[len] = \0'), so the 'to' buffer must have at least len+1
 145  * chars available.
 146  *
 147  * Note this may be called with 'str' == 'to', i.e. to replace whitespace
 148  * in-place in a buffer.  This function can handle that situation.
 149  */
 150 int util_replace_whitespace(const char *str, char *to, size_t len)
 151 {
 152         size_t i, j;
 153
 154         /* strip trailing whitespace */
 155         len = strnlen(str, len);
 156         while (len && isspace(str[len-1]))
 157                 len--;
 158
 159         /* strip leading whitespace */
 160         i = 0;
 161         while ((i < len) && isspace(str[i]))
 162                 i++;
 163
 164         j = 0;
 165         while (i < len) {
 166                 /* substitute multiple whitespace with a single '_' */
 167                 if (isspace(str[i])) {
 168                         while (isspace(str[i]))
 169                                 i++;
 170                         to[j++] = '_';
 171                 }
 172                 to[j++] = str[i++];
 173         }
 174         to[j] = '\0';
 175         return j;
 176 }
 177
 178 /* allow chars in whitelist, plain ascii, hex-escaping and valid utf8 */
 179 int util_replace_chars(char *str, const char *white)
 180 {
 181         size_t i = 0;
 182         int replaced = 0;
 183
 184         while (str[i] != '\0') {
 185                 int len;
 186
 187                 if (whitelisted_char_for_devnode(str[i], white)) {
 188                         i++;
 189                         continue;
 190                 }
 191
 192                 /* accept hex encoding */
 193                 if (str[i] == '\\' && str[i+1] == 'x') {
 194                         i += 2;
 195                         continue;
 196                 }
 197
 198                 /* accept valid utf8 */
 199                 len = utf8_encoded_valid_unichar(&str[i]);
 200                 if (len > 1) {
 201                         i += len;
 202                         continue;
 203                 }
 204
 205                 /* if space is allowed, replace whitespace with ordinary space */
 206                 if (isspace(str[i]) && white != NULL && strchr(white, ' ') != NULL) {
 207                         str[i] = ' ';
 208                         i++;
 209                         replaced++;
 210                         continue;
 211                 }
 212
 213                 /* everything else is replaced with '_' */
 214                 str[i] = '_';
 215                 i++;
 216                 replaced++;
 217         }
 218         return replaced;
 219 }
 220
 221 /**
 222  * udev_util_encode_string:
 223  * @str: input string to be encoded
 224  * @str_enc: output string to store the encoded input string
 225  * @len: maximum size of the output string, which may be
 226  *       four times as long as the input string
 227  *
 228  * Encode all potentially unsafe characters of a string to the
 229  * corresponding 2 char hex value prefixed by '\x'.
 230  *
 231  * Returns: 0 if the entire string was copied, non-zero otherwise.
 232  **/
 233 _public_ int udev_util_encode_string(const char *str, char *str_enc, size_t len)
 234 {
 235         return encode_devnode_name(str, str_enc, len);
 236 }
 237
 238 unsigned int util_string_hash32(const char *str)
 239 {
 240         return MurmurHash2(str, strlen(str), 0);
 241 }
 242
 243 /* get a bunch of bit numbers out of the hash, and set the bits in our bit field */
 244 uint64_t util_string_bloom64(const char *str)
 245 {
 246         uint64_t bits = 0;
 247         unsigned int hash = util_string_hash32(str);
 248
 249         bits |= 1LLU << (hash & 63);
 250         bits |= 1LLU << ((hash >> 6) & 63);
 251         bits |= 1LLU << ((hash >> 12) & 63);
 252         bits |= 1LLU << ((hash >> 18) & 63);
 253         return bits;
 254 }