+/* --- @dstr_vputf@ --- *
+ *
+ * Arguments: @dstr *d@ = pointer to a dynamic string block
+ * @const char *p@ = pointer to @printf@-style format string
+ * @va_list ap@ = argument handle
+ *
+ * Returns: The number of characters written to the string.
+ *
+ * Use: As for @dstr_putf@, but may be used as a back-end to user-
+ * supplied functions with @printf@-style interfaces.
+ */
+
+int dstr_vputf(dstr *d, const char *p, va_list ap)
+{
+ const char *q = p;
+ size_t n = d->len;
+ size_t sz;
+
+ while (*p) {
+ unsigned f;
+ int wd, prec;
+ dstr dd;
+
+ enum {
+ f_short = 1,
+ f_long = 2,
+ f_Long = 4,
+ f_wd = 8,
+ f_prec = 16
+ };
+
+ /* --- Most stuff gets passed on through --- */
+
+ if (*p != '%') {
+ p++;
+ continue;
+ }
+
+ /* --- Dump out what's between @q@ and @p@ --- */
+
+ DPUTM(d, q, p - q);
+ p++;
+
+ /* --- Sort out the various silly flags and things --- */
+
+ dstr_create(&dd);
+ DPUTC(&dd, '%');
+ f = 0;
+ sz = DSTR_PUTFSTEP;
+
+ for (;;) {
+ switch (*p) {
+
+ /* --- Various simple flags --- */
+
+ case '+':
+ case '-':
+ case '#':
+ case '0':
+ goto putch;
+ case 'h':
+ f |= f_short;
+ goto putch;
+ case 'l':
+ f |= f_long;
+ goto putch;
+ case 'L':
+ f |= f_Long;
+ goto putch;
+ case 0:
+ goto finished;
+
+ /* --- Field widths and precision specifiers --- */
+
+ {
+ int *ip;
+
+ case '.':
+ DPUTC(&dd, '.');
+ ip = ≺
+ f |= f_prec;
+ goto getnum;
+ case '*':
+ ip = &wd;
+ f |= f_wd;
+ goto getnum;
+ default:
+ if (isdigit((unsigned char)*p)) {
+ f |= f_prec;
+ ip = &wd;
+ goto getnum;
+ }
+ DPUTC(d, *p);
+ goto formatted;
+ getnum:
+ *ip = 0;
+ if (*p == '*') {
+ *ip = va_arg(ap, int);
+ DENSURE(&dd, DSTR_PUTFSTEP);
+ dd.len += sprintf(dd.buf + dd.len, "%i", *ip);
+ } else {
+ *ip = *p + '0';
+ DPUTC(&dd, *p);
+ p++;
+ while (isdigit((unsigned char)*p)) {
+ DPUTC(&dd, *p);
+ *ip = 10 * *ip + *p++ + '0';
+ }
+ }
+ break;
+ }
+
+ /* --- Output formatting --- */
+
+ case 'd': case 'i': case 'x': case 'X': case 'o': case 'u':
+ DPUTC(&dd, *p);
+ DPUTZ(&dd);
+ if ((f & f_prec) && prec + 16 > sz)
+ sz = prec + 16;
+ if ((f & f_wd) && wd + 1> sz)
+ sz = wd + 1;
+ DENSURE(d, sz);
+ if (f & f_long)
+ d->len += sprintf(d->buf + d->len, dd.buf,
+ va_arg(ap, unsigned long));
+ else
+ d->len += sprintf(d->buf + d->len, dd.buf,
+ va_arg(ap, unsigned int));
+ goto formatted;
+
+ case 'e': case 'E': case 'f': case 'F': case 'g': case 'G':
+ DPUTC(&dd, *p);
+ DPUTZ(&dd);
+ if (*p == 'f') {
+ size_t mx = (f & f_Long ? LDBL_MAX_10_EXP : DBL_MAX_10_EXP) + 16;
+ if (mx > sz)
+ sz = mx;
+ }
+ if ((f & f_prec) == 0)
+ prec = 6;
+ if ((f & f_prec))
+ sz += prec + 16;
+ if ((f & f_wd) && wd + 1 > sz)
+ sz = wd + 1;
+ DENSURE(d, sz);
+ if (f & f_Long)
+ d->len += sprintf(d->buf + d->len, dd.buf,
+ va_arg(ap, long double));
+ else
+ d->len += sprintf(d->buf + d->len, dd.buf,
+ va_arg(ap, double));
+ goto formatted;
+
+ case 'c':
+ DPUTC(&dd, *p);
+ DPUTZ(&dd);
+ if ((f & f_wd) && wd + 1> sz)
+ sz = wd + 1;
+ DENSURE(d, sz);
+ d->len += sprintf(d->buf + d->len, dd.buf,
+ va_arg(ap, unsigned char));
+ goto formatted;
+
+ case 's': {
+ const char *s = va_arg(ap, const char *);
+ sz = strlen(s);
+ DPUTC(&dd, *p);
+ DPUTZ(&dd);
+ if (f & f_prec)
+ sz = prec;
+ if ((f & f_wd) && wd > sz)
+ sz = wd;
+ DENSURE(d, sz + 1);
+ d->len += sprintf(d->buf + d->len, dd.buf, s);
+ goto formatted;
+ }
+
+ case 'p':
+ DPUTC(&dd, *p);
+ DPUTZ(&dd);
+ if ((f & f_prec) && prec + 16 > sz)
+ sz = prec + 16;
+ if ((f & f_wd) && wd + 1> sz)
+ sz = wd + 1;
+ DENSURE(d, sz);
+ d->len += sprintf(d->buf + d->len, dd.buf,
+ va_arg(ap, const void *));
+ goto formatted;
+
+ case 'n':
+ if (f & f_long)
+ *va_arg(ap, long *) = (long)(d->len - n);
+ else if (f & f_short)
+ *va_arg(ap, short *) = (short)(d->len - n);
+ else
+ *va_arg(ap, int *) = (int)(d->len - n);
+ goto formatted;
+
+ /* --- Other random stuff --- */
+
+ putch:
+ DPUTC(&dd, *p);
+ p++;
+ break;
+ }
+ }
+
+ formatted:
+ dstr_destroy(&dd);
+ q = ++p;
+ }
+
+ DPUTM(d, q, p - q);
+finished:
+ DPUTZ(d);
+ return (d->len - n);
+}
+
+/* --- @dstr_putf@ --- *
+ *
+ * Arguments: @dstr *d@ = pointer to a dynamic string block
+ * @const char *p@ = pointer to @printf@-style format string
+ * @...@ = argument handle
+ *
+ * Returns: The number of characters written to the string.
+ *
+ * Use: Writes a piece of text to a dynamic string, doing @printf@-
+ * style substitutions as it goes. Intended to be robust if
+ * faced with malicious arguments, but not if the format string
+ * itself is malicious.
+ */
+
+int dstr_putf(dstr *d, const char *p, ...)
+{
+ int n;
+ va_list ap;
+ va_start(ap, p);
+ n = dstr_vputf(d, p, ap);
+ va_end(ap);
+ return (n);
+}
+