62 lines
3.0 KiB
Markdown
62 lines
3.0 KiB
Markdown
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# crash_reporter
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`crash_reporter` is a deamon running on the device that saves the call stack of
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crashing programs. It makes use of the
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[Breakpad](https://chromium.googlesource.com/breakpad/breakpad/) library.
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During a build, Breakpad symbol files are generated for all binaries. They are
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packaged into a zip file when running `m dist`, so that a developer can upload
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them to the crash server.
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On a device, if the user has opted in to metrics and crash reporting, a
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Breakpad minidump is generated when an executable crashes, which is then
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uploaded to the crash server.
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On the crash server, it compares the minidump's signature to the symbol files
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that the developer has uploaded, and extracts and symbolizes the stack trace
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from the minidump.
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## SELinux policies
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In order to correctly generate a minidump, `crash_reporter` needs to be given
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the proper SELinux permissions for accessing the domain of the crashing
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executable. By default, `crash_reporter` has only been given access to a select
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number of system domains, such as `metricsd`, `weave`, and `update_engine`. If
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a developer wants their executable's crashes to be caught by `crash_reporter`,
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they will have to set their SELinux policies in their .te file to allow
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`crash_reporter` access to their domain. This can be done through a simple
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[macro](https://android.googlesource.com/device/generic/brillo/+/master/sepolicy/te_macros):
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allow_crash_reporter(domain_name)
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Replace *domain_name* with whatever domain is assigned to the executable in
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the `file_contexts` file.
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## Configuration
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`crash_reporter` has a few different configuration options that have to be set.
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- Crashes are only handled and uploaded if analytics reporting is enabled,
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either via the weave call to set `_metrics.enableAnalyticsReporting` or by
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manually creating the file `/data/misc/metrics/enabled` (for testing only).
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- The `BRILLO_CRASH_SERVER` make variable should be set in the `product.mk`
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file to the URL of the crash server. For Brillo builds, it is set
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automatically through the product configuration. Setting this variable will
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populate the `/etc/os-release.d/crash_server` file on the device, which is
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read by `crash_sender`.
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- The `BRILLO_PRODUCT_ID` make variable should be set in the `product.mk` file
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to the product's ID. For Brillo builds, it is set automatically through the
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product configuration. Setting this variable will populate the
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`/etc/os-release.d/product_id`, which is read by `crash_sender`.
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## Uploading crash reports in *eng* builds
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By default, crash reports are only uploaded to the server for production
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*user* and *userdebug* images. In *eng* builds, with crash reporting enabled
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the device will generate minidumps for any crashing executables but will not
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send them to the crash server. If a developer does want to force an upload,
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they can do so by issuing the command `SECONDS_SEND_SPREAD=5 FORCE_OFFICIAL=1
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crash_sender` from an ADB shell. This will send the report to the server, with
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the *image_type* field set to *force-official* so that these reports can be
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differentiated from normal reports.
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