+/* find index of 'name' in environment envp */
+static int
+findenv(const char **envp, const char *name, size_t namelen)
+{
+ int i;
+
+ for (i = 0 ; envp[i] != NULL; i++) {
+ if (strlen(envp[i]) < namelen + 1)
+ continue;
+ if (strncmp(envp[i], name, namelen) == 0 &&
+ envp[i][namelen] == '=')
+ return i;
+ }
+ return -1;
+}
+
+/* merge rule->setenvlist into environment list; frees oldenvp */
+static char **
+dosetenv(char **oldenvp, struct rule *rule)
+{
+ size_t n, i, nset, nold;
+ char **envp, *cp, *cp2;
+ int found;
+
+ if (!(rule->options & SETENV))
+ return oldenvp;
+
+ nset = arraylen(rule->setenvlist);
+ nold = arraylen((const char**)oldenvp);
+
+ /* insert new variables */
+ n = 0;
+ envp = NULL;
+ for (i = 0; i < nset; i++) {
+ if ((cp = strchr(rule->setenvlist[i], '=')) == NULL)
+ errx(1, "invalid setenv"); /* shouldn't happen */
+ if (cp[1] == '\0' || cp - rule->setenvlist[i] > INT_MAX)
+ continue; /* skip variables with empty values */
+ if ((envp = reallocarray(envp, n + 2, sizeof(*envp))) == NULL)
+ errx(1, "reallocarray failed");
+ if (cp[1] == '$') {
+ /* FOO=$BAR: lookup and copy */
+ if ((cp2 = getenv(cp + 2)) == NULL)
+ continue; /* not found; skip */
+ if (asprintf(&(envp[n++]), "%.*s=%s",
+ (int)(cp - rule->setenvlist[i]),
+ rule->setenvlist[i], cp2) == -1)
+ errx(1, "asprintf failed");
+ continue;
+ } else {
+ /* plain setenv */
+ if ((envp[n++] = strdup(rule->setenvlist[i])) == NULL)
+ errx(1, "strdup failed");
+ }
+ }
+ /* move old variables, dropping ones already set */
+ for (i = 0; i < nold; i++) {
+ if ((cp = strchr(oldenvp[i], '=')) == NULL)
+ errx(1, "invalid env"); /* shouldn't happen */
+ found = findenv(rule->setenvlist, oldenvp[i], cp - oldenvp[i]);
+ if (found != -1)
+ free(oldenvp[i]); /* discard */
+ else {
+ if ((envp = reallocarray(envp, n + 2,
+ sizeof(*envp))) == NULL)
+ errx(1, "reallocarray failed");
+ envp[n++] = oldenvp[i]; /* move */
+ }
+ }
+ free(oldenvp);
+ if (n > 0)
+ envp[n] = NULL;
+ return envp;
+}
+