90 lines
3.6 KiB
ReStructuredText
90 lines
3.6 KiB
ReStructuredText
.. _usercrash_doc:
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Usercrash
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#########
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Description
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***********
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The ``usercrash`` tool gets the crash information for the crashing process in
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user space. The collected information is saved as usercrash_xx under
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``/var/log/usercrashes/``.
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Design
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******
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``usercrash`` is designed using a client/server model. The server is
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autostarted at boot. The client is configured in ``core_pattern``, which
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will be triggered when a crash occurs in user space. The client then
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sends the crash event to the server. The server checks the files under
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``/var/log/usercrashes/`` and creates a file usercrash_xx (xx means
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the index of the crash file). Then it sends the file descriptor (fd) to
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the client. The client collects the crash information
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and saves it in the crash file. After the saving work is done, the
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client notifies the server. The server cleans up.
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The workflow diagram:
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::
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+--------------------------------------------------+
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| Server Client |
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| + + |
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| | Send crash event | |
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| | <-----------------------+ |
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| | | |
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| Create usercrash_xx | |
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| | Send usercrash_xx fd | |
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| +-----------------------> | |
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| | Fill usercrash_xx |
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| | Notify completion | |
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| | <-----------------------+ |
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| Clean up | |
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| v v |
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+--------------------------------------------------+
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Usage
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*****
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- The server is launched automatically at boot after this tool is enabled with
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instruction ``sudo crashlogctl enable``, and the client is configured in
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``usercrash-wrapper``, which is set as the app of ``core_pattern``. In
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``usercrash-wrapper``, it will collect and reorder the parameters of the
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client and default app. Once a crash occurs in user space, the client and
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default app will be invoked separately.
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- The ``debugger`` is an independent tool to dump the debugging information of the
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specific process, including backtrace, stack, opened files, register values,
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and memory content around registers.
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.. code-block:: none
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$ debugger <pid>
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.. note::
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You need to be ``root`` to use the ``debugger``.
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Source Code
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***********
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- client.c : This file is the implementation for the client of ``usercrash``.
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The client is responsible for delivering the ``usercrash`` event to the
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server, and collecting crash information and saving it to the crash file.
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- crash_dump.c : This file is the implementation for dumping the crash
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information, including backtrace stack, opened files, register values, and
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memory content around registers.
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- debugger.c : This file implements a tool, which runs in command line to
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dump the process information listed above.
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- protocol.c : This file is the socket protocol implementation file.
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- server.c : This file is the implementation file for the server of
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``usercrash``. The server is responsible for creating the crash file and
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handling the events from the client.
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