ref: e81e1a4aeddad2bc612c9c5243573250b6ff33a4
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; }