PW_MAX_SHELL
if (left < PW_MAX_SHELL + 1)
len = fs_read_attr(fd, B_PW_SHELL, B_STRING_TYPE, 0LL, buf, PW_MAX_SHELL);
#define PWBUFFSZ (PW_MAX_NAME + PW_MAX_DIR + PW_MAX_GECOS + PW_MAX_PASSWD + PW_MAX_SHELL + 4)