+/*
+ * mkdir_check - helper for mkdir_recursive, creates a directory
+ * but do not error on EEXIST if and only if entry is a directory
+ * The caller must check for errno == ENOENT if appropriate.
+ */
+static int
+mkdir_check(const char *path)
+{
+ struct stat statbuf;
+
+ if (mkdir(path, 0755) >= 0)
+ return 0;
+
+ if (errno == EEXIST) {
+ if (stat(path, &statbuf) < 0)
+ /* got raced? */
+ return -1;
+
+ if ((statbuf.st_mode & S_IFMT) == S_IFDIR)
+ return 0;
+
+ /* already exists but not a dir, treat as failure */
+ errno = EEXIST;
+ return -1;
+ }
+
+ return -1;
+}
+
+/*
+ * mkdir_parent - helper for mkdir_recursive, modifies the string in place
+ * Assumes mkdir(path) already failed, so it first creates the parent then
+ * full path again.
+ */
+static int
+mkdir_parent(char *path)
+{
+ char *slash;
+ int rc;
+
+ slash = strrchr(path, '/');
+ if (!slash)
+ return -1;
+
+ *slash = 0;
+ if (mkdir_check(path) < 0) {
+ if (errno != ENOENT) {
+ *slash = '/';
+ return -1;
+ }
+ if (mkdir_parent(path) < 0) {
+ *slash = '/';
+ return -1;
+ }
+ }
+ *slash = '/';
+
+ return mkdir_check(path);
+}
+
+/*
+ * mkdir_recursive - recursively create directory if it didn't exist
+ */
+int
+mkdir_recursive(const char *path)
+{
+ char *copy;
+ int rc;
+
+ // optimistically try on full path first to avoid allocation
+ if (mkdir_check(path) == 0)
+ return 0;
+
+ copy = strdup(path);
+ if (!copy)
+ return -1;
+
+ rc = mkdir_parent(copy);
+ free(copy);
+ return rc;
+}
+