ref: ada54defbcb037f8858b475f90ef215b7d1b44a6
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; }