- It is not possible to code this function in a "natural" way, using
- a loop, because of the braindeadness of the varargs API.
- Specifically, each call to vsnprintf() must be preceded by va_start
- and followed by va_end. And this is possible only in the function
- that contains the `...' declaration. The alternative would be to
- use va_copy, but that's not portable. */
+ Normally we'd want this function to loop around vsnprintf until
+ sufficient room is allocated, as the Linux man page recommends.
+ However each call to vsnprintf() must be preceded by va_start and
+ followed by va_end. Since calling va_start/va_end is possible only
+ in the function that contains the `...' declaration, we cannot call
+ vsnprintf more than once. Therefore this function saves its state
+ to logvprintf_state and signals the parent to call it again.
+
+ (An alternative approach would be to use va_copy, but that's not
+ portable.) */