ardupilot/libraries/AP_Logger
Peter Barker ca4af94833 AP_Logger: prevent potential infinite recursion in log-open codepath
If anything in start_new_log did logging (for example, by sending a
statustext), we end up infinitely recursing.

With the patch:

diff --git a/libraries/AP_Logger/AP_Logger_File.cpp b/libraries/AP_Logger/AP_Logger_File.cpp
index 69b8ef0431..eb422d10f8 100644
--- a/libraries/AP_Logger/AP_Logger_File.cpp
+++ b/libraries/AP_Logger/AP_Logger_File.cpp
@@ -778,6 +778,7 @@ void AP_Logger_File::PrepForArming()
  */
 void AP_Logger_File::start_new_log(void)
 {
+    gcs().send_text(MAV_SEVERITY_WARNING, "Starting new log");
     stop_logging();

     start_new_log_reset_variables();
pbarker@bluebottle:~/rc/ardupilot(master)$

We see:

    at ../../libraries/AP_Logger/AP_Logger_File.cpp:781
    this=0x555555ad9d30, pBuffer=0x7fffff8209d0, size=75, is_critical=true)
    at ../../libraries/AP_Logger/AP_Logger_Backend.cpp:372
    this=0x555555ad9d30, pBuffer=0x7fffff8209d0, size=75)
    at ../../libraries/AP_Logger/AP_Logger_Backend.h:32
    this=0x555555ad9d30, message=0x7fffff820b10 "Starting new log")
    at ../../libraries/AP_Logger/LogFile.cpp:466
    this=0x555555a6d758 <copter+11384>,
    message=0x7fffff820b10 "Starting new log")
    at ../../libraries/AP_Logger/AP_Logger.cpp:752
    this=0x555555a6e708 <copter+15400>, severity=MAV_SEVERITY_WARNING,
    fmt=0x5555557d64d0 "Starting new log", arg_list=0x7fffff820be0,
    dest_bitmask=1 '\001') at ../../libraries/GCS_MAVLink/GCS_Common.cpp:1847
    this=0x555555a6e708 <copter+15400>, severity=MAV_SEVERITY_WARNING,
    fmt=0x5555557d64d0 "Starting new log", arg_list=0x7fffff820be0)
    at ../../libraries/GCS_MAVLink/GCS.cpp:53
    this=0x555555a6e708 <copter+15400>, severity=MAV_SEVERITY_WARNING,
    fmt=0x5555557d64d0 "Starting new log")
    at ../../libraries/GCS_MAVLink/GCS.cpp:60
    at ../../libraries/AP_Logger/AP_Logger_File.cpp:781
    this=0x555555ad9d30, pBuffer=0x7fffff820dc0, size=75, is_critical=true)
    at ../../libraries/AP_Logger/AP_Logger_Backend.cpp:372

I'm not aware of any instances in the code where this will actually
happen - but it could easily sneak in.
2020-05-11 15:12:36 +10:00
..
examples AP_Logger: fix examples 2020-04-23 11:33:41 +09:00
AP_Logger_Backend.cpp AP_Logger: create and use INTERNAL_ERROR macro so we get line numbers 2020-04-30 13:21:36 +10:00
AP_Logger_Backend.h AP_Logger: use existing LoggerMessageWriter to log uploaded missions 2020-04-15 16:24:40 +10:00
AP_Logger_Block.cpp AP_Logger: const extern hal reference 2020-04-07 20:45:51 +09:00
AP_Logger_Block.h AP_Logger: Change the type of a method 2020-01-22 12:45:27 +11:00
AP_Logger_DataFlash.cpp AP_Logger: mavlink backend needs to be the last backend 2020-01-02 18:18:04 +11:00
AP_Logger_DataFlash.h AP_Logger: mavlink backend needs to be the last backend 2020-01-02 18:18:04 +11:00
AP_Logger_File.cpp AP_Logger: prevent potential infinite recursion in log-open codepath 2020-05-11 15:12:36 +10:00
AP_Logger_File.h AP_Logger: Change the type of a method 2020-01-22 12:45:27 +11:00
AP_Logger_MAVLink.cpp AP_Logger: create and use INTERNAL_ERROR macro so we get line numbers 2020-04-30 13:21:36 +10:00
AP_Logger_MAVLink.h AP_Logger: Change the type of a method 2020-01-22 12:45:27 +11:00
AP_Logger_MAVLinkLogTransfer.cpp AP_Logger: mavlink backend needs to be the last backend 2020-01-02 18:18:04 +11:00
AP_Logger_SITL.cpp AP_Logger: mavlink backend needs to be the last backend 2020-01-02 18:18:04 +11:00
AP_Logger_SITL.h AP_Logger: mavlink backend needs to be the last backend 2020-01-02 18:18:04 +11:00
AP_Logger.cpp AP_Logger: create and use INTERNAL_ERROR macro so we get line numbers 2020-04-30 13:21:36 +10:00
AP_Logger.h AP_Logger: add message validation check against duplicate labels 2020-04-14 12:30:58 +10:00
LogFile.cpp AP_Logger: use existing LoggerMessageWriter to log uploaded missions 2020-04-15 16:24:40 +10:00
LoggerMessageWriter.cpp AP_Logger: remove unused FORMATS stage in DFLogStart messagewriter 2020-04-17 21:42:15 +10:00
LoggerMessageWriter.h AP_Logger: remove unused FORMATS stage in DFLogStart messagewriter 2020-04-17 21:42:15 +10:00
LogStructure.h AP_Logger: create and use INTERNAL_ERROR macro so we get line numbers 2020-04-30 13:21:36 +10:00
README.md AP_Logger: add a README.md to help locating units/mults/fieldtypes 2019-06-04 19:00:11 +10:00

Logger Notes

Format Types

The format type specifies the amount of storage required for the entry and how the content should be interpreted.

Char C Type
a int16_t[32]
b int8_t
B uint8_t
h int16_t
H uint16_t
i int32_t
I uint32_t
f float
d double
n char[4]
N char[16]
Z char[64]
L int32_t latitude/longitude (so -35.1332423 becomes -351332423)
M uint8_t flight mode
q int64_t
Q uint64_t

Legacy field types - do not use. These have been replaced by using the base C type and an appropriate multiplier column entry.

Char CType+Mult
c int16_t * 100
C uint16_t * 100
e int32_t * 100
E uint32_t * 100

Units

All units here should be base units This does mean battery capacity is here as "amp*second" Please keep the names consistent with Tools/autotest/param_metadata/param.py:33

Char Unit Abbrev. Description
'-' "" no units e.g. Pi
'?' "UNKNOWN" Units which haven't been worked out yet....
'A' "A" Ampere
'd' "deg" of the angular variety
'b' "B" bytes
'k' "deg/s" degrees per second. Degrees are NOT SI
'D' "deglatitude" degrees of latitude
'e' "deg/s/s" degrees per second per second. Degrees are NOT SI
'E' "rad/s" radians per second
'G' "Gauss" Gauss is not an SI unit
'h' "degheading" 0.? to 359.?
'i' "A.s" Ampere second
'J' "W.s" Joule (Watt second)
'l' "l" litres
'L' "rad/s/s" radians per second per second
'm' "m" metres
'n' "m/s" metres per second
'N' "N" Newton
'o' "m/s/s" metres per second per second
'O' "degC" degrees Celsius. Not SI
'%' "%" percent
'S' "satellites" number of satellites
's' "s" seconds
'q' "rpm" rounds per minute. Not SI
'r' "rad" radians
'U' "deglongitude" degrees of longitude
'u' "ppm" pulses per minute
'v' "V" Volt
'P' "Pa" Pascal
'w' "Ohm" Ohm
'Y' "us" pulse width modulation in microseconds
'z' "Hz" Hertz
'#' "instance" (e.g.)Sensor instance number

Multipliers

This multiplier information applies to the raw value present in the log. Any adjustment implied by the format field (e.g. the "centi" in "centidegrees" is IGNORED for the purposes of scaling. Essentially "format" simply tells you the C-type, and format-type h (int16_t) is equivalent to format-type c (int16_t*100) tl;dr a GCS shouldn't/mustn't infer any scaling from the unit name

Char Multiplier
'-' 0
'?' 1
'2' 1e2
'1' 1e1
'0' 1e0
'A' 1e-1
'B' 1e-2
'C' 1e-3
'D' 1e-4
'E' 1e-5
'F' 1e-6
'G' 1e-7
'!' 3.6
'/' 3600