tal/str: add tal_append_fmt() and tal_append_vfmt() helpers.

[ccan] / ccan / tal / str / str.c

diff --git a/ccan/tal/str/str.c b/ccan/tal/str/str.c
index 771c07c24ee69ddd2bac49c408f62766768f4c67..15aa0c046883633d956eb8abbf50c48e9e362c5e 100644 (file)
--- a/ccan/tal/str/str.c
+++ b/ccan/tal/str/str.c
@@ -52,35 +52,71 @@ char *tal_fmt(const tal_t *ctx, const char *fmt, ...)
        return ret;
 }
 
        return ret;
 }
 

-char *tal_vfmt(const tal_t *ctx, const char *fmt, va_list ap)
+static bool do_vfmt(char **buf, size_t off, const char *fmt, va_list ap)

 {
 {

-       size_t max;
-       char *buf;
-       int ret;
-
-       if (!fmt && taken(fmt))
-               return NULL;
-

        /* A decent guess to start. */
        /* A decent guess to start. */

-       max = strlen(fmt) * 2;
-       buf = tal_arr(ctx, char, max);
-       while (buf) {
+       size_t max = strlen(fmt) * 2;
+       bool ok;
+
+       for (;;) {

                va_list ap2;
                va_list ap2;

+               int ret;
+
+               if (!tal_resize(buf, off + max)) {
+                       ok = false;
+                       break;
+               }

 
                va_copy(ap2, ap);
 
                va_copy(ap2, ap);

-               ret = vsnprintf(buf, max, fmt, ap2);
+               ret = vsnprintf(*buf + off, max, fmt, ap2);

                va_end(ap2);
 
                va_end(ap2);
 

-               if (ret < max)
+               if (ret < max) {
+                       ok = true;

                        break;
                        break;

-               if (!tal_resize(&buf, max *= 2))
-                       buf = tal_free(buf);
+               }
+               max *= 2;

        }
        }

+

        if (taken(fmt))
                tal_free(fmt);
        if (taken(fmt))
                tal_free(fmt);

+       return ok;
+}
+
+char *tal_vfmt(const tal_t *ctx, const char *fmt, va_list ap)
+{
+       char *buf;
+
+       if (!fmt && taken(fmt))
+               return NULL;
+
+       /* A decent guess to start. */
+       buf = tal_arr(ctx, char, strlen(fmt) * 2);
+       if (!do_vfmt(&buf, 0, fmt, ap))
+               buf = tal_free(buf);

        return buf;
 }
 
        return buf;
 }
 

+bool tal_append_vfmt(char **baseptr, const char *fmt, va_list ap)
+{
+       if (!fmt && taken(fmt))
+               return false;
+
+       return do_vfmt(baseptr, strlen(*baseptr), fmt, ap);
+}
+
+bool tal_append_fmt(char **baseptr, const char *fmt, ...)
+{
+       va_list ap;
+       bool ret;
+
+       va_start(ap, fmt);
+       ret = tal_append_vfmt(baseptr, fmt, ap);
+       va_end(ap);
+
+       return ret;
+}
+

 char *tal_strcat(const tal_t *ctx, const char *s1, const char *s2)
 {
        size_t len1, len2;
 char *tal_strcat(const tal_t *ctx, const char *s1, const char *s2)
 {
        size_t len1, len2;