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 #endif
  15
  16 #include <env_attr.h>
  17 #include <errno.h>
  18 #include <linux/string.h>
  19 #include <malloc.h>
  20
  21 /*
  22  * Iterate through the whole list calling the callback for each found element.
  23  * "attr_list" takes the form:
  24  *      attributes = [^,:\s]*
  25  *      entry = name[:attributes]
  26  *      list = entry[,list]
  27  */
  28 int env_attr_walk(const char *attr_list,
  29         int (*callback)(const char *name, const char *attributes, void *priv),
  30         void *priv)
  31 {
  32         const char *entry, *entry_end;
  33         char *name, *attributes;
  34
  35         if (!attr_list)
  36                 /* list not found */
  37                 return 1;
  38
  39         entry = attr_list;
  40         do {
  41                 char *entry_cpy = NULL;
  42
  43                 entry_end = strchr(entry, ENV_ATTR_LIST_DELIM);
  44                 /* check if this is the last entry in the list */
  45                 if (entry_end == NULL) {
  46                         int entry_len = strlen(entry);
  47
  48                         if (entry_len) {
  49                                 /*
  50                                  * allocate memory to copy the entry into since
  51                                  * we will need to inject '\0' chars and squash
  52                                  * white-space before calling the callback
  53                                  */
  54                                 entry_cpy = malloc(entry_len + 1);
  55                                 if (entry_cpy)
  56                                         /* copy the rest of the list */
  57                                         strcpy(entry_cpy, entry);
  58                                 else
  59                                         return -ENOMEM;
  60                         }
  61                 } else {
  62                         int entry_len = entry_end - entry;
  63
  64                         if (entry_len) {
  65                                 /*
  66                                  * allocate memory to copy the entry into since
  67                                  * we will need to inject '\0' chars and squash
  68                                  * white-space before calling the callback
  69                                  */
  70                                 entry_cpy = malloc(entry_len + 1);
  71                                 if (entry_cpy) {
  72                                         /* copy just this entry and null term */
  73                                         strncpy(entry_cpy, entry, entry_len);
  74                                         entry_cpy[entry_len] = '\0';
  75                                 } else
  76                                         return -ENOMEM;
  77                         }
  78                 }
  79
  80                 /* check if there is anything to process (e.g. not ",,,") */
  81                 if (entry_cpy != NULL) {
  82                         attributes = strchr(entry_cpy, ENV_ATTR_SEP);
  83                         /* check if there is a ':' */
  84                         if (attributes != NULL) {
  85                                 /* replace the ':' with '\0' to term name */
  86                                 *attributes++ = '\0';
  87                                 /* remove white-space from attributes */
  88                                 attributes = strim(attributes);
  89                         }
  90                         /* remove white-space from name */
  91                         name = strim(entry_cpy);
  92
  93                         /* only call the callback if there is a name */
  94                         if (strlen(name) != 0) {
  95                                 int retval = 0;
  96
  97                                 retval = callback(name, attributes, priv);
  98                                 if (retval) {
  99                                         free(entry_cpy);
 100                                         return retval;
 101                                 }
 102                         }
 103                 }
 104
 105                 free(entry_cpy);
 106                 entry = entry_end + 1;
 107         } while (entry_end != NULL);
 108
 109         return 0;
 110 }
 111
 112 /*
 113  * Search for the last exactly matching name in an attribute list
 114  */
 115 static int reverse_name_search(const char *searched, const char *search_for,
 116         const char **result)
 117 {
 118         int result_size = 0;
 119         const char *cur_searched = searched;
 120
 121         if (result)
 122                 *result = NULL;
 123
 124         if (*search_for == '\0') {
 125                 if (result)
 126                         *result = searched;
 127                 return strlen(searched);
 128         }
 129
 130         for (;;) {
 131                 const char *match = strstr(cur_searched, search_for);
 132                 const char *prevch;
 133                 const char *nextch;
 134
 135                 /* Stop looking if no new match is found */
 136                 if (match == NULL)
 137                         break;
 138
 139                 prevch = match - 1;
 140                 nextch = match + strlen(search_for);
 141
 142                 /* Skip spaces */
 143                 while (*prevch == ' ' && prevch >= searched)
 144                         prevch--;
 145                 while (*nextch == ' ')
 146                         nextch++;
 147
 148                 /* Start looking past the current match so last is found */
 149                 cur_searched = match + 1;
 150                 /* Check for an exact match */
 151                 if (match != searched &&
 152                     *prevch != ENV_ATTR_LIST_DELIM &&
 153                     prevch != searched - 1)
 154                         continue;
 155                 if (*nextch != ENV_ATTR_SEP &&
 156                     *nextch != ENV_ATTR_LIST_DELIM &&
 157                     *nextch != '\0')
 158                         continue;
 159
 160                 if (result)
 161                         *result = match;
 162                 result_size = strlen(search_for);
 163         }
 164
 165         return result_size;
 166 }
 167
 168 /*
 169  * Retrieve the attributes string associated with a single name in the list
 170  * There is no protection on attributes being too small for the value
 171  */
 172 int env_attr_lookup(const char *attr_list, const char *name, char *attributes)
 173 {
 174         const char *entry = NULL;
 175         int entry_len;
 176
 177         if (!attributes)
 178                 /* bad parameter */
 179                 return -EINVAL;
 180         if (!attr_list)
 181                 /* list not found */
 182                 return -EINVAL;
 183
 184         entry_len = reverse_name_search(attr_list, name, &entry);
 185         if (entry != NULL) {
 186                 int len;
 187
 188                 /* skip the name */
 189                 entry += entry_len;
 190                 /* skip spaces */
 191                 while (*entry == ' ')
 192                         entry++;
 193                 if (*entry != ENV_ATTR_SEP)
 194                         len = 0;
 195                 else {
 196                         const char *delim;
 197                         static const char delims[] = {
 198                                 ENV_ATTR_LIST_DELIM, ' ', '\0'};
 199
 200                         /* skip the attr sep */
 201                         entry += 1;
 202                         /* skip spaces */
 203                         while (*entry == ' ')
 204                                 entry++;
 205
 206                         delim = strpbrk(entry, delims);
 207                         if (delim == NULL)
 208                                 len = strlen(entry);
 209                         else
 210                                 len = delim - entry;
 211                         memcpy(attributes, entry, len);
 212                 }
 213                 attributes[len] = '\0';
 214
 215                 /* success */
 216                 return 0;
 217         }
 218
 219         /* not found in list */
 220         return -ENOENT;
 221 }