+static void *format_specfile(const struct commit *commit, const char *format,
+ unsigned long *sizep)
+{
+ unsigned long len = *sizep, result_len = 0;
+ const char *a = format;
+ char *result = NULL;
+
+ for (;;) {
+ const char *b, *c;
+ char *fmt, *formatted = NULL;
+ unsigned long a_len, fmt_len, formatted_len, allocated = 0;
+
+ b = memmem(a, len, "$Format:", 8);
+ if (!b || a + len < b + 9)
+ break;
+ c = memchr(b + 8, '$', len - 8);
+ if (!c)
+ break;
+
+ a_len = b - a;
+ fmt_len = c - b - 8;
+ fmt = xmalloc(fmt_len + 1);
+ memcpy(fmt, b + 8, fmt_len);
+ fmt[fmt_len] = '\0';
+
+ formatted_len = format_commit_message(commit, fmt, &formatted,
+ &allocated);
+ result = xrealloc(result, result_len + a_len + formatted_len);
+ memcpy(result + result_len, a, a_len);
+ memcpy(result + result_len + a_len, formatted, formatted_len);
+ result_len += a_len + formatted_len;
+ len -= c + 1 - a;
+ a = c + 1;
+ }
+
+ if (result && len) {
+ result = xrealloc(result, result_len + len);
+ memcpy(result + result_len, a, len);
+ result_len += len;
+ }
+
+ *sizep = result_len;
+
+ return result;
+}
+