nmea: parse $GPZDA sentences for date/time

Some GPS receivers only send $GPZDA sentence for date/time. Parse it
and refactor NMEA-0138 code to avoid code duplication.

Signed-off-by: Daniel Golle <daniel@makrotopia.org>

ugps: fix 64-bit time_t

The abs function takes a 32-bit int, which can cause truncation. Fixes
compilation error:

error: absolute value function 'abs' given an argu>
if ((sec < 0) || (abs(cur.tv_sec - tv.tv_sec) > MAX_TIME_OFFSET)) {

Signed-off-by: Rosen Penev <rosenp@gmail.com>

nmea: make sure date is valid

GPS time without date was previously used to set system date:
Tue Oct 10 11:48:21 2000 user.info kernel: [  108.786639] ugps: system time differs from GPS time by more than 5 seconds. Using 2000-10-10T10:48:21 UTC as the new time
Tue Oct 10 11:49:27 2000 user.info kernel: [  174.794699] ugps: system time differs from GPS time by more than 5 seconds. Using 2020-05-26T10:49:27 UTC as the new time

Fix this by ignoring incomplete dates and wait for complete time
information before adjusting system date/time.

Signed-off-by: Daniel Golle <daniel@makrotopia.org>

nmea: fix time comparision

Code introduced by commit b88037b ("check timegm return code") compares
GPS-time with tv_sec of freshly zero-initialized struct timeval tv.
Compare with current time instead.

Fixes: b88037b ("check timegm return code")
Signed-off-by: Daniel Golle <daniel@makrotopia.org>

ugps: Fix compilation under 64-bit

strlen returns size_t, not int.

Signed-off-by: Rosen Penev <rosenp@gmail.com>

Fix build error caused by enabled extra compiler warnings

 nmea.c:257:16: error: comparison between signed and
     unsigned integer expressions [-Werror=sign-compare]

Signed-off-by: Petr Štetiar <ynezz@true.cz>

Enable extra compiler warnings

Signed-off-by: Petr Štetiar <ynezz@true.cz>

nmea.c: set _BSD_SOURCE to have timegm() & stime() on musl

musl doesn't know _DEFAULT_SOURCE which is used by glibc >= 2.19
to enable timegm() and stime().

Signed-off-by: Alexander Couzens <lynxis@fe80.eu>

check timegm return code

Signed-off-by: John Crispin <john@phrozen.org>

nmea.c: Add null byte to nmea fields

Either the main.c treat them as non-null terminated strings or
nmea adds a null byte to the fields.

Found-by: Coverity
Fixes CID 1431321 1431098

remove deprication warning

In file included from /usr/include/time.h:27:0,
from /src/projects/ugps/nmea.c:21:
/usr/include/features.h:148:3: error: #warning "_BSD_SOURCE and _SVID_SOURCE are deprecated, use _DEFAULT_SOURCE" [-Werror=cpp]

Signed-off-by: John Crispin <john@phrozen.org>

ugps: Only convert lat and lon to negative after parsing

This is a bugfix for package ugps.

Current code parses following GPRMC

$GPRMC,185834.0,A,2335.766399,S,04635.923564,W,0.0,,191017,0.0,E,A*20

as

position: -22.929440 -45.932056

with this fix it's being parsed correctly as

position: -23.596106 -46.598721

Signed-off-by: Giovani Milanez Espindola <gespindola@advantech-bb.com>
>From 092b311a3c8911ce9da3f913787b77397e88b4a8 Mon Sep 17 00:00:00 2001
From: Giovani Espindola <gespindola@advantech-bb.com>
Date: Thu, 19 Oct 2017 15:54:05 -0200
Subject: [PATCH] Only convert lat and lon to negative after parsing

link libm to fix build error

Signed-off-by: Felix Fietkau <nbd@nbd.name>

Switched from strptime to sscanf, added command line switch to set system clock and fixed typo

Signed-off-by: Thomas Hogge <thomas@hoogi.de>

ugps: Simplify and fix position computation from GPRMC sentence

Current code parses following GPRMC

  $GPRMC,071305.0,A,5207.76855,N,02104.022546,E,0.0,,270816,0.0,E,A*18

as

  position: 52.117947 21.67042

with this fix it's being parsed correctly as

  position: 52.129475 21.067041

Fixes https://github.com/lede-project/source/issues/279

Signed-off-by: Petr Štetiar <ynezz@true.cz>
Tested-by: Cezary Jackiewicz <cezary@eko.one.pl>

fix ms->deg conversion

Signed-off-by: John Crispin <john@phrozen.org>

fix reading of speed

Signed-off-by: John Crispin <john@phrozen.org>

Allow bigger lat/lng numbers in RMC message

It works now with following message:

  $GPRMC,122536.0,A,4350.237769,N,01826.423315

Signed-off-by: Petr Štetiar <ynezz@true.cz>

Show more useful error message if we can't open GPS device

Signed-off-by: Petr Štetiar <ynezz@true.cz>

Fix typo in error message

Signed-off-by: Petr Štetiar <ynezz@true.cz>

Use strsep for NMEA message tokenization

strtok doesn't parse correctly following message:

  $GPGSA,A,1,,,,,,,,,,,,,,,*1E

Resulting in "datagram has wrong parameter count".

Signed-off-by: Petr Štetiar <ynezz@true.cz>

Bail out if we can't find GPS device

Signed-off-by: Petr Štetiar <ynezz@true.cz>

Switch to ulog for logging and add few commandline params

Signed-off-by: Petr Štetiar <ynezz@true.cz>

cmake: Add proper library and include files search logic for dependecies

Signed-off-by: Petr Štetiar <ynezz@true.cz>

lat/lng format when printing is incorrect

Signed-off-by: Maurice-Jörg Nießen <post@mjniessen.com>

typo fix

Signed-off-by: Maurice-Jörg Nießen <post@mjniessen.com>

Import