common/env_attr.c

   1 /*
   2  * (C) Copyright 2012
   3  * Joe Hershberger, National Instruments, joe.hershberger@ni.com
   4  *
   5  * SPDX-License-Identifier:     GPL-2.0+
   6  */
   7
   8 #ifdef USE_HOSTCC /* Eliminate "ANSI does not permit..." warnings */
   9 #include <stdint.h>
  10 #include <stdio.h>
  11 #include <linux/linux_string.h>
  12 #else
  13 #include <common.h>
  14 #include <slre.h>
  15 #endif
  16
  17 #include <env_attr.h>
  18 #include <errno.h>
  19 #include <linux/string.h>
  20 #include <malloc.h>
  21
  22 /*
  23  * Iterate through the whole list calling the callback for each found element.
  24  * "attr_list" takes the form:
  25  *      attributes = [^,:\s]*
  26  *      entry = name[:attributes]
  27  *      list = entry[,list]
  28  */
  29 int env_attr_walk(const char *attr_list,
  30         int (*callback)(const char *name, const char *attributes, void *priv),
  31         void *priv)
  32 {
  33         const char *entry, *entry_end;
  34         char *name, *attributes;
  35
  36         if (!attr_list)
  37                 /* list not found */
  38                 return 1;
  39
  40         entry = attr_list;
  41         do {
  42                 char *entry_cpy = NULL;
  43
  44                 entry_end = strchr(entry, ENV_ATTR_LIST_DELIM);
  45                 /* check if this is the last entry in the list */
  46                 if (entry_end == NULL) {
  47                         int entry_len = strlen(entry);
  48
  49                         if (entry_len) {
  50                                 /*
  51                                  * allocate memory to copy the entry into since
  52                                  * we will need to inject '\0' chars and squash
  53                                  * white-space before calling the callback
  54                                  */
  55                                 entry_cpy = malloc(entry_len + 1);
  56                                 if (entry_cpy)
  57                                         /* copy the rest of the list */
  58                                         strcpy(entry_cpy, entry);
  59                                 else
  60                                         return -ENOMEM;
  61                         }
  62                 } else {
  63                         int entry_len = entry_end - entry;
  64
  65                         if (entry_len) {
  66                                 /*
  67                                  * allocate memory to copy the entry into since
  68                                  * we will need to inject '\0' chars and squash
  69                                  * white-space before calling the callback
  70                                  */
  71                                 entry_cpy = malloc(entry_len + 1);
  72                                 if (entry_cpy) {
  73                                         /* copy just this entry and null term */
  74                                         strncpy(entry_cpy, entry, entry_len);
  75                                         entry_cpy[entry_len] = '\0';
  76                                 } else
  77                                         return -ENOMEM;
  78                         }
  79                 }
  80
  81                 /* check if there is anything to process (e.g. not ",,,") */
  82                 if (entry_cpy != NULL) {
  83                         attributes = strchr(entry_cpy, ENV_ATTR_SEP);
  84                         /* check if there is a ':' */
  85                         if (attributes != NULL) {
  86                                 /* replace the ':' with '\0' to term name */
  87                                 *attributes++ = '\0';
  88                                 /* remove white-space from attributes */
  89                                 attributes = strim(attributes);
  90                         }
  91                         /* remove white-space from name */
  92                         name = strim(entry_cpy);
  93
  94                         /* only call the callback if there is a name */
  95                         if (strlen(name) != 0) {
  96                                 int retval = 0;
  97
  98                                 retval = callback(name, attributes, priv);
  99                                 if (retval) {
 100                                         free(entry_cpy);
 101                                         return retval;
 102                                 }
 103                         }
 104                 }
 105
 106                 free(entry_cpy);
 107                 entry = entry_end + 1;
 108         } while (entry_end != NULL);
 109
 110         return 0;
 111 }
 112
 113 #if defined(CONFIG_REGEX)
 114 struct regex_callback_priv {
 115         const char *searched_for;
 116         char *regex;
 117         char *attributes;
 118 };
 119
 120 static int regex_callback(const char *name, const char *attributes, void *priv)
 121 {
 122         int retval = 0;
 123         struct regex_callback_priv *cbp = (struct regex_callback_priv *)priv;
 124         struct slre slre;
 125         char regex[strlen(name) + 3];
 126
 127         /* Require the whole string to be described by the regex */
 128         sprintf(regex, "^%s$", name);
 129         if (slre_compile(&slre, regex)) {
 130                 struct cap caps[slre.num_caps + 2];
 131
 132                 if (slre_match(&slre, cbp->searched_for,
 133                                strlen(cbp->searched_for), caps)) {
 134                         free(cbp->regex);
 135                         cbp->regex = malloc(strlen(regex) + 1);
 136                         if (cbp->regex) {
 137                                 strcpy(cbp->regex, regex);
 138                         } else {
 139                                 retval = -ENOMEM;
 140                                 goto done;
 141                         }
 142
 143                         free(cbp->attributes);
 144                         cbp->attributes = malloc(strlen(attributes) + 1);
 145                         if (cbp->attributes) {
 146                                 strcpy(cbp->attributes, attributes);
 147                         } else {
 148                                 retval = -ENOMEM;
 149                                 free(cbp->regex);
 150                                 cbp->regex = NULL;
 151                                 goto done;
 152                         }
 153                 }
 154         } else {
 155                 printf("Error compiling regex: %s\n", slre.err_str);
 156                 retval = EINVAL;
 157         }
 158 done:
 159         return retval;
 160 }
 161
 162 /*
 163  * Retrieve the attributes string associated with a single name in the list
 164  * There is no protection on attributes being too small for the value
 165  */
 166 int env_attr_lookup(const char *attr_list, const char *name, char *attributes)
 167 {
 168         if (!attributes)
 169                 /* bad parameter */
 170                 return -EINVAL;
 171         if (!attr_list)
 172                 /* list not found */
 173                 return -EINVAL;
 174
 175         struct regex_callback_priv priv;
 176         int retval;
 177
 178         priv.searched_for = name;
 179         priv.regex = NULL;
 180         priv.attributes = NULL;
 181         retval = env_attr_walk(attr_list, regex_callback, &priv);
 182         if (retval)
 183                 return retval; /* error */
 184
 185         if (priv.regex) {
 186                 strcpy(attributes, priv.attributes);
 187                 free(priv.attributes);
 188                 free(priv.regex);
 189                 /* success */
 190                 return 0;
 191         }
 192         return -ENOENT; /* not found in list */
 193 }
 194 #else
 195
 196 /*
 197  * Search for the last exactly matching name in an attribute list
 198  */
 199 static int reverse_name_search(const char *searched, const char *search_for,
 200         const char **result)
 201 {
 202         int result_size = 0;
 203         const char *cur_searched = searched;
 204
 205         if (result)
 206                 *result = NULL;
 207
 208         if (*search_for == '\0') {
 209                 if (result)
 210                         *result = searched;
 211                 return strlen(searched);
 212         }
 213
 214         for (;;) {
 215                 const char *match = strstr(cur_searched, search_for);
 216                 const char *prevch;
 217                 const char *nextch;
 218
 219                 /* Stop looking if no new match is found */
 220                 if (match == NULL)
 221                         break;
 222
 223                 prevch = match - 1;
 224                 nextch = match + strlen(search_for);
 225
 226                 /* Skip spaces */
 227                 while (*prevch == ' ' && prevch >= searched)
 228                         prevch--;
 229                 while (*nextch == ' ')
 230                         nextch++;
 231
 232                 /* Start looking past the current match so last is found */
 233                 cur_searched = match + 1;
 234                 /* Check for an exact match */
 235                 if (match != searched &&
 236                     *prevch != ENV_ATTR_LIST_DELIM &&
 237                     prevch != searched - 1)
 238                         continue;
 239                 if (*nextch != ENV_ATTR_SEP &&
 240                     *nextch != ENV_ATTR_LIST_DELIM &&
 241                     *nextch != '\0')
 242                         continue;
 243
 244                 if (result)
 245                         *result = match;
 246                 result_size = strlen(search_for);
 247         }
 248
 249         return result_size;
 250 }
 251
 252 /*
 253  * Retrieve the attributes string associated with a single name in the list
 254  * There is no protection on attributes being too small for the value
 255  */
 256 int env_attr_lookup(const char *attr_list, const char *name, char *attributes)
 257 {
 258         const char *entry = NULL;
 259         int entry_len;
 260
 261         if (!attributes)
 262                 /* bad parameter */
 263                 return -EINVAL;
 264         if (!attr_list)
 265                 /* list not found */
 266                 return -EINVAL;
 267
 268         entry_len = reverse_name_search(attr_list, name, &entry);
 269         if (entry != NULL) {
 270                 int len;
 271
 272                 /* skip the name */
 273                 entry += entry_len;
 274                 /* skip spaces */
 275                 while (*entry == ' ')
 276                         entry++;
 277                 if (*entry != ENV_ATTR_SEP)
 278                         len = 0;
 279                 else {
 280                         const char *delim;
 281                         static const char delims[] = {
 282                                 ENV_ATTR_LIST_DELIM, ' ', '\0'};
 283
 284                         /* skip the attr sep */
 285                         entry += 1;
 286                         /* skip spaces */
 287                         while (*entry == ' ')
 288                                 entry++;
 289
 290                         delim = strpbrk(entry, delims);
 291                         if (delim == NULL)
 292                                 len = strlen(entry);
 293                         else
 294                                 len = delim - entry;
 295                         memcpy(attributes, entry, len);
 296                 }
 297                 attributes[len] = '\0';
 298
 299                 /* success */
 300                 return 0;
 301         }
 302
 303         /* not found in list */
 304         return -ENOENT;
 305 }
 306 #endif