+/* return true if 'path' exists, false otherwise */
+static bool is_present(const char *path)
+{
+ struct stat st;
+
+ return !stat(path, &st);
+}
+
+/* return true if 'path' exists and it is a directory, false otherwise */
+static bool is_dir(const char *path)
+{
+ struct stat st;
+
+ if (stat(path, &st))
+ return 0;
+
+ return S_ISDIR(st.st_mode);
+}
+
+/*
+ * Create the parent directory of the given path.
+ *
+ * For example, if 'include/config/auto.conf' is given, create 'include/config'.
+ */
+static int make_parent_dir(const char *path)
+{
+ char tmp[PATH_MAX + 1];
+ char *p;
+
+ strncpy(tmp, path, sizeof(tmp));
+ tmp[sizeof(tmp) - 1] = 0;
+
+ /* Remove the base name. Just return if nothing is left */
+ p = strrchr(tmp, '/');
+ if (!p)
+ return 0;
+ *(p + 1) = 0;
+
+ /* Just in case it is an absolute path */
+ p = tmp;
+ while (*p == '/')
+ p++;
+
+ while ((p = strchr(p, '/'))) {
+ *p = 0;
+
+ /* skip if the directory exists */
+ if (!is_dir(tmp) && mkdir(tmp, 0755))
+ return -1;
+
+ *p = '/';
+ while (*p == '/')
+ p++;
+ }
+
+ return 0;
+}
+
+static char depfile_path[PATH_MAX];
+static size_t depfile_prefix_len;
+
+/* touch depfile for symbol 'name' */
+static int conf_touch_dep(const char *name)
+{
+ int fd, ret;
+ const char *s;
+ char *d, c;
+
+ /* check overflow: prefix + name + ".h" + '\0' must fit in buffer. */
+ if (depfile_prefix_len + strlen(name) + 3 > sizeof(depfile_path))
+ return -1;
+
+ d = depfile_path + depfile_prefix_len;
+ s = name;
+
+ while ((c = *s++))
+ *d++ = (c == '_') ? '/' : tolower(c);
+ strcpy(d, ".h");
+
+ /* Assume directory path already exists. */
+ fd = open(depfile_path, O_WRONLY | O_CREAT | O_TRUNC, 0644);
+ if (fd == -1) {
+ if (errno != ENOENT)
+ return -1;
+
+ ret = make_parent_dir(depfile_path);
+ if (ret)
+ return ret;
+
+ /* Try it again. */
+ fd = open(depfile_path, O_WRONLY | O_CREAT | O_TRUNC, 0644);
+ if (fd == -1)
+ return -1;
+ }
+ close(fd);
+
+ return 0;
+}
+