Feature request: allow logging to syslog from hostapd during startup

[Max Zhao]

Hi,

Currently, hostapd does not log any messages generated during startup
to syslog. This is because these startup messages are logged using
wpa_printf, which currently only writes to stdout, and is not
configurable. logger_syslog and logger_syslog_level do not apply to
wpa_printf.

To capture these messages through syslog, sysadmins will need to run
hostapd as `stdbuf -oL hostapd | logger -t ...` or similar. This seems
a suboptimal solution for a daemon like hostapd.

Would it be possible to add something similar to the `-s` flag of
wpa_supplicant to hostapd? The flag should simply trigger a call to
wpa_debug_open_syslog and forward anything logged by wpa_printf to
syslog.

Alternatively, make logger_syslog control the output of wpa_printf as
well, which would make it more consistent.

See https://dev.openwrt.org/ticket/20623 for a related OpenWrt bug report.

-- 
Yichen Zhao