+
+static int env_append(char **r, char ***k, char **a) {
+ assert(r);
+ assert(k);
+ assert(a);
+
+ /* Add the entries of a to *k unless they already exist in *r
+ * in which case they are overriden instead. This assumes
+ * there is enough space in the r */
+
+ for (; *a; a++) {
+ char **j;
+ size_t n = strcspn(*a, "=") + 1;
+
+ for (j = r; j < *k; j++)
+ if (strncmp(*j, *a, n) == 0)
+ break;
+
+ if (j >= *k)
+ (*k)++;
+ else
+ free(*j);
+
+ if (!(*j = strdup(*a)))
+ return -ENOMEM;
+ }
+
+ return 0;
+}
+
+char **strv_env_merge(char **x, ...) {
+ size_t n = 0;
+ char **l, **k, **r;
+ va_list ap;
+
+ /* Merges an arbitrary number of environment sets */
+
+ if (x) {
+ n += strv_length(x);
+
+ va_start(ap, x);
+ while ((l = va_arg(ap, char**)))
+ n += strv_length(l);
+ va_end(ap);
+ }
+
+
+ if (!(r = new(char*, n+1)))
+ return NULL;
+
+ k = r;
+
+ if (x) {
+ if (env_append(r, &k, x) < 0)
+ goto fail;
+
+ va_start(ap, x);
+ while ((l = va_arg(ap, char**)))
+ if (env_append(r, &k, l) < 0)
+ goto fail;
+ va_end(ap);
+ }
+
+ *k = NULL;
+
+ return r;
+
+fail:
+ for (k--; k >= r; k--)
+ free(*k);
+
+ free(r);
+
+ return NULL;
+}
+
+static bool env_match(const char *t, const char *pattern) {
+ assert(t);
+ assert(pattern);
+
+ /* pattern a matches string a
+ * a matches a=
+ * a matches a=b
+ * a= matches a=
+ * a=b matches a=b
+ * a= does not match a
+ * a=b does not match a=
+ * a=b does not match a
+ * a=b does not match a=c */
+
+ if (streq(t, pattern))
+ return true;
+
+ if (!strchr(pattern, '=')) {
+ size_t l = strlen(pattern);
+
+ return strncmp(t, pattern, l) == 0 && t[l] == '=';
+ }
+
+ return false;
+}
+
+char **strv_env_delete(char **x, ...) {
+ size_t n = 0, i = 0;
+ char **l, **k, **r, **j;
+ va_list ap;
+
+ /* Deletes every entry fromx that is mentioned in the other
+ * string lists */
+
+ n = strv_length(x);
+
+ if (!(r = new(char*, n+1)))
+ return NULL;
+
+ STRV_FOREACH(k, x) {
+ va_start(ap, x);
+
+ while ((l = va_arg(ap, char**)))
+ STRV_FOREACH(j, l)
+ if (env_match(*k, *j))
+ goto delete;
+
+ va_end(ap);
+
+ if (!(r[i++] = strdup(*k))) {
+ strv_free(r);
+ return NULL;
+ }
+
+ continue;
+
+ delete:
+ va_end(ap);
+ }
+
+ r[i] = NULL;
+
+ assert(i <= n);
+
+ return r;
+}