README.md

   1 ![Icon made by Freepik from www.flaticon.com](https://lttng.org/blog/images/barectf.png)
   2
   3 [![](https://img.shields.io/pypi/v/barectf.svg)](https://pypi.python.org/pypi/barectf)
   4 [![Jenkins](https://img.shields.io/jenkins/s/https/ci.lttng.org/barectf.svg)](https://ci.lttng.org/job/barectf)
   5
   6 **barectf** is a command-line utility which generates C99
   7 code that is able to write native [Common Trace Format](http://diamon.org/ctf)
   8 (CTF) binary streams.
   9
  10 You will find barectf interesting if:
  11
  12   1. You need to trace an application.
  13   2. You need tracing to be efficient, yet flexible:
  14      record integers of custom sizes, custom floating point numbers,
  15      enumerations supported by a specific integer type, and
  16      null-terminated UTF-8/ASCII strings (C strings).
  17   3. You need to be able to convert the recorded binary events to
  18      human-readable text, as well as analyze them with Python scripts
  19      ([Babeltrace](http://diamon.org/babeltrace/) does all that,
  20      given a CTF input).
  21   4. You _cannot_ use [LTTng](http://lttng.org/), an efficient tracing
  22      framework for the Linux kernel and Linux/BSD user applications, which
  23      also outputs CTF.
  24
  25 The target audience of barectf is developers who need to trace bare metal
  26 systems (without an operating system). The code produced by barectf
  27 is pure C99 and can be lightweight enough to fit on a tiny microcontroller.
  28
  29 **Key features**:
  30
  31   * Single input: easy-to-write [YAML configuration
  32     file](https://github.com/efficios/barectf/wiki/Writing-the-YAML-configuration-file)
  33   * 1-to-1 mapping from tracing function parameters to event fields
  34   * Custom and bundled
  35     [_platforms_](https://github.com/efficios/barectf/wiki/barectf-platform)
  36     hiding the details of opening/closing packets and writing them to a
  37     back-end (continuous tracing), getting the clock values, etc.:
  38     * _linux-fs_: basic Linux application tracing writing stream files to
  39       the file system for demonstration purposes
  40     * _parallella_: Adapteva Epiphany/[Parallella](http://parallella.org/)
  41       with host-side consumer
  42   * CTF metadata generated by the command-line tool (automatic trace UUID,
  43     stream IDs, and event IDs)
  44   * All basic CTF types are supported: integers, floating point numbers,
  45     enumerations, and null-terminated strings (C strings)
  46   * Binary streams produced by the generated C code and metadata file
  47     produced by barectf are CTF 1.8-compliant
  48   * Human-readable error reporting
  49
  50 **Current limitations**:
  51
  52 As of this version:
  53
  54   * All the generated tracing C functions, for a given barectf
  55     stream-specific context, need to be called from the same thread, and cannot
  56     be called from an interrupt handler, unless a user-provided
  57     synchronization mechanism is used.
  58   * CTF compound types (array, sequence, structure, variant) are not supported
  59     yet, except at some very specific locations in the metadata.
  60   * The current generated C code is not strictly C99 compliant:
  61     [statement expressions](https://gcc.gnu.org/onlinedocs/gcc/Statement-Exprs.html)
  62     and the
  63     [`typeof` keyword](https://gcc.gnu.org/onlinedocs/gcc/Typeof.html)
  64     GCC extensions are used in the generated bitfield macros. The
  65     generated C code is known to be compiled with no warnings using
  66     both GCC and Clang.
  67
  68 barectf is written in Python 3.
  69
  70
  71 ## Installing
  72
  73 Make sure you have Python 3 and `pip` for Python 3 installed, then
  74 install barectf.
  75
  76 Note that you may pass the `--user` argument to
  77 `pip install` to install the tool in your home directory (instead of
  78 installing globally).
  79
  80 **Latest Ubuntu**:
  81
  82     sudo apt-get install python3-pip
  83     sudo pip3 install barectf
  84
  85 **Ubuntu 12.04 and lower**:
  86
  87     sudo apt-get install python3-setuptools
  88     sudo easy_install3 pip
  89     sudo pip3 install barectf
  90
  91 **Debian**:
  92
  93     sudo apt-get install python3-pip
  94     sudo pip3 install barectf
  95
  96 **Fedora 20 and up**:
  97
  98     sudo yum install python3-pip
  99     sudo pip3 install barectf
 100
 101 **Arch Linux**:
 102
 103     sudo pacman -S python-pip
 104     sudo pip install barectf
 105
 106 **OS X**
 107
 108 With [Homebrew](http://brew.sh/):
 109
 110     brew install python3
 111     pip3 install barectf
 112
 113
 114 ## What is CTF?
 115
 116 See the [CTF in a nutshell](http://diamon.org/ctf/#ctf-in-a-nutshell)
 117 section of CTF's website to understand the basics of this
 118 trace format.
 119
 120 The most important thing to understand about CTF, for barectf use
 121 cases, is the layout of a binary stream packet:
 122
 123   * Packet header (defined at the trace level)
 124   * Packet context (defined at the stream level)
 125   * Sequence of events (defined at the stream level):
 126     * Event header (defined at the stream level)
 127     * Stream event context (defined at the stream level)
 128     * Event context (defined at the event level)
 129     * Event payload (defined at the event level)
 130
 131 The following diagram, stolen without remorse from CTF's website, shows
 132 said packet layout:
 133
 134 ![](http://diamon.org/ctf/img/ctf-stream-packet.png)
 135
 136 Any of those six dynamic scopes, if defined at all, has an associated
 137 CTF type. barectf requires them to be structure types.
 138
 139
 140 ## Using
 141
 142 See the [project's wiki](https://github.com/efficios/barectf/wiki) which
 143 contains all the information needed to use barectf.
 144
 145
 146 ## Testing
 147
 148 Bash is required for testing barectf.
 149
 150 The barectf tests execute the `barectf` command available in your
 151 `$PATH`. The best way to test a specific version of barectf is to create
 152 a Python 3 [virtual environment](https://virtualenv.pypa.io/en/latest/),
 153 install the appropriate version, and then run the tests.
 154
 155 In the barectf source tree root, do:
 156
 157     virtualenv --python=python3 virt
 158     . ./virt/bin/activate
 159     rehash # if using zsh
 160     ./setup.py install
 161     (cd tests && ./test.bash)
 162
 163 You can specify [Bats](https://github.com/sstephenson/bats) options to
 164 `./test.bash`, like `--tap` to get a [TAP](https://testanything.org/)
 165 output.
 166
 167 You can exit the virtual environment by running `deactivate`.