util/envlist.c

   1 #include "qemu/osdep.h"
   2 #include "qemu/queue.h"
   3 #include "qemu/envlist.h"
   4
   5 struct envlist_entry {
   6         const char *ev_var;                     /* actual env value */
   7         QLIST_ENTRY(envlist_entry) ev_link;
   8 };
   9
  10 struct envlist {
  11         QLIST_HEAD(, envlist_entry) el_entries; /* actual entries */
  12         size_t el_count;                        /* number of entries */
  13 };
  14
  15 static int envlist_parse(envlist_t *envlist,
  16     const char *env, int (*)(envlist_t *, const char *));
  17
  18 /*
  19  * Allocates new envlist and returns pointer to it.
  20  */
  21 envlist_t *
  22 envlist_create(void)
  23 {
  24         envlist_t *envlist;
  25
  26         envlist = g_malloc(sizeof(*envlist));
  27
  28         QLIST_INIT(&envlist->el_entries);
  29         envlist->el_count = 0;
  30
  31         return (envlist);
  32 }
  33
  34 /*
  35  * Releases given envlist and its entries.
  36  */
  37 void
  38 envlist_free(envlist_t *envlist)
  39 {
  40         struct envlist_entry *entry;
  41
  42         assert(envlist != NULL);
  43
  44         while (envlist->el_entries.lh_first != NULL) {
  45                 entry = envlist->el_entries.lh_first;
  46                 QLIST_REMOVE(entry, ev_link);
  47
  48                 g_free((char *)entry->ev_var);
  49                 g_free(entry);
  50         }
  51         g_free(envlist);
  52 }
  53
  54 /*
  55  * Parses comma separated list of set/modify environment
  56  * variable entries and updates given enlist accordingly.
  57  *
  58  * For example:
  59  *     envlist_parse(el, "HOME=foo,SHELL=/bin/sh");
  60  *
  61  * inserts/sets environment variables HOME and SHELL.
  62  *
  63  * Returns 0 on success, errno otherwise.
  64  */
  65 int
  66 envlist_parse_set(envlist_t *envlist, const char *env)
  67 {
  68         return (envlist_parse(envlist, env, &envlist_setenv));
  69 }
  70
  71 /*
  72  * Parses comma separated list of unset environment variable
  73  * entries and removes given variables from given envlist.
  74  *
  75  * Returns 0 on success, errno otherwise.
  76  */
  77 int
  78 envlist_parse_unset(envlist_t *envlist, const char *env)
  79 {
  80         return (envlist_parse(envlist, env, &envlist_unsetenv));
  81 }
  82
  83 /*
  84  * Parses comma separated list of set, modify or unset entries
  85  * and calls given callback for each entry.
  86  *
  87  * Returns 0 in case of success, errno otherwise.
  88  */
  89 static int
  90 envlist_parse(envlist_t *envlist, const char *env,
  91     int (*callback)(envlist_t *, const char *))
  92 {
  93         char *tmpenv, *envvar;
  94         char *envsave = NULL;
  95     int ret = 0;
  96     assert(callback != NULL);
  97
  98         if ((envlist == NULL) || (env == NULL))
  99                 return (EINVAL);
 100
 101         tmpenv = g_strdup(env);
 102     envsave = tmpenv;
 103
 104     do {
 105         envvar = strchr(tmpenv, ',');
 106         if (envvar != NULL) {
 107             *envvar = '\0';
 108         }
 109         if ((*callback)(envlist, tmpenv) != 0) {
 110             ret = errno;
 111             break;
 112                 }
 113         tmpenv = envvar + 1;
 114     } while (envvar != NULL);
 115
 116     g_free(envsave);
 117     return ret;
 118 }
 119
 120 /*
 121  * Sets environment value to envlist in similar manner
 122  * than putenv(3).
 123  *
 124  * Returns 0 in success, errno otherwise.
 125  */
 126 int
 127 envlist_setenv(envlist_t *envlist, const char *env)
 128 {
 129         struct envlist_entry *entry = NULL;
 130         const char *eq_sign;
 131         size_t envname_len;
 132
 133         if ((envlist == NULL) || (env == NULL))
 134                 return (EINVAL);
 135
 136         /* find out first equals sign in given env */
 137         if ((eq_sign = strchr(env, '=')) == NULL)
 138                 return (EINVAL);
 139         envname_len = eq_sign - env + 1;
 140
 141         /*
 142          * If there already exists variable with given name
 143          * we remove and release it before allocating a whole
 144          * new entry.
 145          */
 146         for (entry = envlist->el_entries.lh_first; entry != NULL;
 147             entry = entry->ev_link.le_next) {
 148                 if (strncmp(entry->ev_var, env, envname_len) == 0)
 149                         break;
 150         }
 151
 152         if (entry != NULL) {
 153                 QLIST_REMOVE(entry, ev_link);
 154                 g_free((char *)entry->ev_var);
 155                 g_free(entry);
 156         } else {
 157                 envlist->el_count++;
 158         }
 159
 160         entry = g_malloc(sizeof(*entry));
 161         entry->ev_var = g_strdup(env);
 162         QLIST_INSERT_HEAD(&envlist->el_entries, entry, ev_link);
 163
 164         return (0);
 165 }
 166
 167 /*
 168  * Removes given env value from envlist in similar manner
 169  * than unsetenv(3).  Returns 0 in success, errno otherwise.
 170  */
 171 int
 172 envlist_unsetenv(envlist_t *envlist, const char *env)
 173 {
 174         struct envlist_entry *entry;
 175         size_t envname_len;
 176
 177         if ((envlist == NULL) || (env == NULL))
 178                 return (EINVAL);
 179
 180         /* env is not allowed to contain '=' */
 181         if (strchr(env, '=') != NULL)
 182                 return (EINVAL);
 183
 184         /*
 185          * Find out the requested entry and remove
 186          * it from the list.
 187          */
 188         envname_len = strlen(env);
 189         for (entry = envlist->el_entries.lh_first; entry != NULL;
 190             entry = entry->ev_link.le_next) {
 191                 if (strncmp(entry->ev_var, env, envname_len) == 0)
 192                         break;
 193         }
 194         if (entry != NULL) {
 195                 QLIST_REMOVE(entry, ev_link);
 196                 g_free((char *)entry->ev_var);
 197                 g_free(entry);
 198
 199                 envlist->el_count--;
 200         }
 201         return (0);
 202 }
 203
 204 /*
 205  * Returns given envlist as array of strings (in same form that
 206  * global variable environ is).  Caller must free returned memory
 207  * by calling g_free for each element and the array.
 208  * Returned array and given envlist are not related (no common
 209  * references).
 210  *
 211  * If caller provides count pointer, number of items in array is
 212  * stored there.
 213  */
 214 char **
 215 envlist_to_environ(const envlist_t *envlist, size_t *count)
 216 {
 217         struct envlist_entry *entry;
 218         char **env, **penv;
 219
 220         penv = env = g_new(char *, envlist->el_count + 1);
 221
 222         for (entry = envlist->el_entries.lh_first; entry != NULL;
 223             entry = entry->ev_link.le_next) {
 224                 *(penv++) = g_strdup(entry->ev_var);
 225         }
 226         *penv = NULL; /* NULL terminate the list */
 227
 228         if (count != NULL)
 229                 *count = envlist->el_count;
 230
 231         return (env);
 232 }