ref: ff4daa7e93f4ea09506276ecdb69fa1cca19a7a7
dir: /sys/src/ape/lib/fmt/werrstr.c/
#include <stdarg.h>
#include <errno.h>
#include "fmt.h"
extern char _plan9err[128];
void
werrstr(const char *fmt, ...)
{
va_list arg;
va_start(arg, fmt);
snprint(_plan9err, sizeof _plan9err, fmt, arg);
va_end(arg);
errno = EPLAN9;
}