common/env_attr.c

   1 /*
   2  * (C) Copyright 2012
   3  * Joe Hershberger, National Instruments, [email protected]
   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))
  30 {
  31         const char *entry, *entry_end;
  32         char *name, *attributes;
  33
  34         if (!attr_list)
  35                 /* list not found */
  36                 return 1;
  37
  38         entry = attr_list;
  39         do {
  40                 char *entry_cpy = NULL;
  41
  42                 entry_end = strchr(entry, ENV_ATTR_LIST_DELIM);
  43                 /* check if this is the last entry in the list */
  44                 if (entry_end == NULL) {
  45                         int entry_len = strlen(entry);
  46
  47                         if (entry_len) {
  48                                 /*
  49                                  * allocate memory to copy the entry into since
  50                                  * we will need to inject '\0' chars and squash
  51                                  * white-space before calling the callback
  52                                  */
  53                                 entry_cpy = malloc(entry_len + 1);
  54                                 if (entry_cpy)
  55                                         /* copy the rest of the list */
  56                                         strcpy(entry_cpy, entry);
  57                                 else
  58                                         return -ENOMEM;
  59                         }
  60                 } else {
  61                         int entry_len = entry_end - entry;
  62
  63                         if (entry_len) {
  64                                 /*
  65                                  * allocate memory to copy the entry into since
  66                                  * we will need to inject '\0' chars and squash
  67                                  * white-space before calling the callback
  68                                  */
  69                                 entry_cpy = malloc(entry_len + 1);
  70                                 if (entry_cpy) {
  71                                         /* copy just this entry and null term */
  72                                         strncpy(entry_cpy, entry, entry_len);
  73                                         entry_cpy[entry_len] = '\0';
  74                                 } else
  75                                         return -ENOMEM;
  76                         }
  77                 }
  78
  79                 /* check if there is anything to process (e.g. not ",,,") */
  80                 if (entry_cpy != NULL) {
  81                         attributes = strchr(entry_cpy, ENV_ATTR_SEP);
  82                         /* check if there is a ':' */
  83                         if (attributes != NULL) {
  84                                 /* replace the ':' with '\0' to term name */
  85                                 *attributes++ = '\0';
  86                                 /* remove white-space from attributes */
  87                                 attributes = strim(attributes);
  88                         }
  89                         /* remove white-space from name */
  90                         name = strim(entry_cpy);
  91
  92                         /* only call the callback if there is a name */
  93                         if (strlen(name) != 0) {
  94                                 int retval = 0;
  95
  96                                 retval = callback(name, attributes);
  97                                 if (retval) {
  98                                         free(entry_cpy);
  99                                         return retval;
 100                                 }
 101                         }
 102                 }
 103
 104                 free(entry_cpy);
 105                 entry = entry_end + 1;
 106         } while (entry_end != NULL);
 107
 108         return 0;
 109 }
 110
 111 /*
 112  * Search for the last exactly matching name in an attribute list
 113  */
 114 static int reverse_name_search(const char *searched, const char *search_for,
 115         const char **result)
 116 {
 117         int result_size = 0;
 118         const char *cur_searched = searched;
 119
 120         if (result)
 121                 *result = NULL;
 122
 123         if (*search_for == '\0') {
 124                 if (result)
 125                         *result = searched;
 126                 return strlen(searched);
 127         }
 128
 129         for (;;) {
 130                 const char *match = strstr(cur_searched, search_for);
 131                 const char *prevch;
 132                 const char *nextch;
 133
 134                 /* Stop looking if no new match is found */
 135                 if (match == NULL)
 136                         break;
 137
 138                 prevch = match - 1;
 139                 nextch = match + strlen(search_for);
 140
 141                 /* Skip spaces */
 142                 while (*prevch == ' ' && prevch >= searched)
 143                         prevch--;
 144                 while (*nextch == ' ')
 145                         nextch++;
 146
 147                 /* Start looking past the current match so last is found */
 148                 cur_searched = match + 1;
 149                 /* Check for an exact match */
 150                 if (match != searched &&
 151                     *prevch != ENV_ATTR_LIST_DELIM &&
 152                     prevch != searched - 1)
 153                         continue;
 154                 if (*nextch != ENV_ATTR_SEP &&
 155                     *nextch != ENV_ATTR_LIST_DELIM &&
 156                     *nextch != '\0')
 157                         continue;
 158
 159                 if (result)
 160                         *result = match;
 161                 result_size = strlen(search_for);
 162         }
 163
 164         return result_size;
 165 }
 166
 167 /*
 168  * Retrieve the attributes string associated with a single name in the list
 169  * There is no protection on attributes being too small for the value
 170  */
 171 int env_attr_lookup(const char *attr_list, const char *name, char *attributes)
 172 {
 173         const char *entry = NULL;
 174         int entry_len;
 175
 176         if (!attributes)
 177                 /* bad parameter */
 178                 return -EINVAL;
 179         if (!attr_list)
 180                 /* list not found */
 181                 return -EINVAL;
 182
 183         entry_len = reverse_name_search(attr_list, name, &entry);
 184         if (entry != NULL) {
 185                 int len;
 186
 187                 /* skip the name */
 188                 entry += entry_len;
 189                 /* skip spaces */
 190                 while (*entry == ' ')
 191                         entry++;
 192                 if (*entry != ENV_ATTR_SEP)
 193                         len = 0;
 194                 else {
 195                         const char *delim;
 196                         static const char delims[] = {
 197                                 ENV_ATTR_LIST_DELIM, ' ', '\0'};
 198
 199                         /* skip the attr sep */
 200                         entry += 1;
 201                         /* skip spaces */
 202                         while (*entry == ' ')
 203                                 entry++;
 204
 205                         delim = strpbrk(entry, delims);
 206                         if (delim == NULL)
 207                                 len = strlen(entry);
 208                         else
 209                                 len = delim - entry;
 210                         memcpy(attributes, entry, len);
 211                 }
 212                 attributes[len] = '\0';
 213
 214                 /* success */
 215                 return 0;
 216         }
 217
 218         /* not found in list */
 219         return -ENOENT;
 220 }