+
+#ifndef HAVE_SNPRINTF
+/* Approximate snprintf as best we can on ancient hosts that lack it. */
+int
+snprintf (char *buf, size_t bufsize, char const *format, ...)
+{
+ ptrdiff_t size = min (bufsize, PTRDIFF_MAX);
+ ptrdiff_t nbytes = size - 1;
+ va_list ap;
+
+ if (size)
+ {
+ va_start (ap, format);
+ nbytes = doprnt (buf, size, format, 0, ap);
+ va_end (ap);
+ }
+
+ if (nbytes == size - 1)
+ {
+ /* Calculate the length of the string that would have been created
+ had the buffer been large enough. */
+ char stackbuf[4000];
+ char *b = stackbuf;
+ ptrdiff_t bsize = sizeof stackbuf;
+ va_start (ap, format);
+ nbytes = evxprintf (&b, &bsize, stackbuf, -1, format, ap);
+ va_end (ap);
+ if (b != stackbuf)
+ xfree (b);
+ }
+
+ if (INT_MAX < nbytes)
+ {
+ errno = EOVERFLOW;
+ return -1;
+ }
+ return nbytes;
+}
+#endif