patch for string_builder_vsprintf

[Arne Goedeke]

Hello,

I noticed that only %f is supported in string_builder_vsprintf(). I
would like to use something else in JSON2, so it would be nice if
someone could review this and maybe commit.

arne

diff --git a/src/stralloc.c b/src/stralloc.c
index eb60b8b..e75d45b 100644
--- a/src/stralloc.c
+++ b/src/stralloc.c
@@ -2945,13 +2945,17 @@ PMOD_EXPORT void string_builder_vsprintf(struct 
string_builder *s,
                                        flags, min_width, precision);
          break;
 
-         /* FIMXE: TODO: Doubles (ie 'a', 'e', 'E', 'g', 'G'). */
-
          /* %f used in modules/Image/colors.c. */
+       case 'a':
+       case 'g':
+       case 'G':
+       case 'e':
+       case 'E':
        case 'f':
          {
            double val = va_arg(args, double);
            size_t bytes;
+           char nfmt[] = { '%', *(fmt-1), 0 };
 
            if (PIKE_ISNAN(val)) {
              /* NaN */
@@ -2974,9 +2978,9 @@ PMOD_EXPORT void string_builder_vsprintf(struct 
string_builder *s,
              break;
            }
            /* FIXME: Field lengths and precision. */
-           if ((bytes = SNPRINTF(NULL, 0, "%f", val))) {
+           if ((bytes = SNPRINTF(NULL, 0, nfmt, val))) {
              p_wchar0 *p = string_builder_allocate(s, bytes, 0);
-             size_t check = SNPRINTF((char*)p, bytes+1, "%f", val);
+             size_t check = SNPRINTF((char*)p, bytes+1, nfmt, val);
              if (check != bytes) {
                Pike_fatal("string_builder_vsprintf(): snprintf(%f) is not "
                           "trustworthy: %"PRINTSIZET"u != %"PRINTSIZET"u\n",