"crash" ping
============
This ping is captured after the main Firefox process crashes, whether or not the crash report is submitted to crash-stats.mozilla.org. It includes non-identifying metadata about the crash.
The environment block that is sent with this ping varies: if Firefox was running long enough to record the environment block before the crash, then the environment at the time of the crash will be recorded and ``hasCrashEnvironment`` will be true. If Firefox crashed before the environment was recorded, ``hasCrashEnvironment`` will be false and the recorded environment will be the environment at time of submission.
The client ID is submitted with this ping.
Structure:
.. code-block:: js
{
version: 1,
type: "crash",
... common ping data
clientId: <UUID>,
environment: { ... },
payload: {
crashDate: "YYYY-MM-DD",
sessionId: <UUID>, // may be missing for crashes that happen early
// in startup. Added in Firefox 48 with the
// intention of uplifting to Firefox 46
crashId: <UUID>, // Optional, ID of the associated crash
stackTraces: { ... }, // Optional, see below
metadata: { // Annotations saved while Firefox was running. See nsExceptionHandler.cpp for more information
ProductName: "Firefox",
ReleaseChannel: <channel>,
Version: <version number>,
BuildID: "YYYYMMDDHHMMSS",
AvailablePageFile: <size>, // Windows-only, available paging file
AvailablePhysicalMemory: <size>, // Windows-only, available physical memory
AvailableVirtualMemory: <size>, // Windows-only, available virtual memory
BlockedDllList: <list>, // Windows-only, see WindowsDllBlocklist.cpp for details
BlocklistInitFailed: 1, // Windows-only, present only if the DLL blocklist initialization failed
CrashTime: <time>, // Seconds since the Epoch
ContainsMemoryReport: 1, // Optional
EventLoopNestingLevel: <levels>, // Optional, present only if >0
IsGarbageCollecting: 1, // Optional, present only if set to 1
MozCrashReason: <reason>, // Optional, contains the string passed to MOZ_CRASH()
OOMAllocationSize: <size>, // Size of the allocation that caused an OOM
SecondsSinceLastCrash: <duration>, // Seconds elapsed since the last crash occurred
SystemMemoryUsePercentage: <percentage>, // Windows-only, percent of memory in use
TelemetrySessionId: <id>, // Active telemetry session ID when the crash was recorded
TextureUsage: <usage>, // Optional, usage of texture memory in bytes
TotalPageFile: <size>, // Windows-only, paging file in use
TotalPhysicalMemory: <size>, // Windows-only, physical memory in use
TotalVirtualMemory: <size>, // Windows-only, virtual memory in use
UptimeTS: <duration>, // Seconds since Firefox was started
User32BeforeBlocklist: 1, // Windows-only, present only if user32.dll was loaded before the DLL blocklist has been initialized
},
hasCrashEnvironment: bool
}
}
Stack Traces
------------
The crash ping may contain a ``stackTraces`` field which has been populated
with stack traces for all threads in the crashed process. The format of this
field is similar to the one used by Socorro for representing a crash. The main
differences are that redundant fields are not stored and that the module a
frame belongs to is referenced by index in the module array rather than by its
file name.
Note that this field does not contain data from the application; only bare
stack traces and module lists are stored.
.. code-block:: js
{
status: <string>, // Status of the analysis, "OK" or an error message
crash_info: { // Basic crash information
type: <string>, // Type of crash, SIGSEGV, assertion, etc...
address: <addr>, // Crash address crash, hex format, see the notes below
crashing_thread: <index> // Index in the thread array below
},
main_module: <index>, // Index of Firefox' executable in the module list
modules: [{
base_addr: <addr>, // Base address of the module, hex format
end_addr: <addr>, // End address of the module, hex format
code_id: <string>, // Unique ID of this module, see the notes below
debug_file: <string>, // Name of the file holding the debug information
debug_id: <string>, // ID or hash of the debug information file
filename: <string>, // File name
version: <string>, // Library/executable version
},
... // List of modules ordered by base memory address
],
threads: [{ // Stack traces for every thread
frames: [{
module_index: <index>, // Index of the module this frame belongs to
ip: <ip>, // Program counter, hex format
trust: <string> // Trust of this frame, see the notes below
},
... // List of frames, the first frame is the topmost
]
}]
}
Notes
~~~~~
Memory addresses and instruction pointers are always stored as strings in
hexadecimal format (e.g. "0x4000"). They can be made of up to 16 characters for
64-bit addresses.
The crash type is both OS and CPU dependent and can be either a descriptive
string (e.g. SIGSEGV, EXCEPTION_ACCESS_VIOLATION) or a raw numeric value. The
crash address meaning depends on the type of crash. In a segmentation fault the
crash address will be the memory address whose access caused the fault; in a
crash triggered by an illegal instruction exception the address will be the
instruction pointer where the invalid instruction resides.
See `breakpad <https://chromium.googlesource.com/breakpad/breakpad/+/c99d374dde62654a024840accfb357b2851daea0/src/processor/minidump_processor.cc#675>`_'s
relevant code for further information.
Since it's not always possible to establish with certainty the address of the
previous frame while walking the stack, every frame has a trust value that
represents how it was found and thus how certain we are that it's a real frame.
The trust levels are (from least trusted to most trusted):
+---------------+---------------------------------------------------+
| Trust | Description |
+===============+===================================================+
| context | Given as instruction pointer in a context |
+---------------+---------------------------------------------------+
| prewalked | Explicitly provided by some external stack walker |
+---------------+---------------------------------------------------+
| cfi | Derived from call frame info |
+---------------+---------------------------------------------------+
| frame_pointer | Derived from frame pointer |
+---------------+---------------------------------------------------+
| cfi_scan | Found while scanning stack using call frame info |
+---------------+---------------------------------------------------+
| scan | Scanned the stack, found this |
+---------------+---------------------------------------------------+
| none | Unknown, this is most likely not a valid frame |
+---------------+---------------------------------------------------+
The ``code_id`` field holds a unique ID used to distinguish between different
versions and builds of the same module. See `breakpad <https://chromium.googlesource.com/breakpad/breakpad/+/24f5931c5e0120982c0cbf1896641e3ef2bdd52f/src/google_breakpad/processor/code_module.h#60>`_'s
description for further information. This field is populated only on Windows.