gotracer

A calltree for Go projects.
Does not support calls to third party libraries.

This project was built using std only and can only be
used on std only Go projects.

Installation

Download the latest release

wget https://github.com/bfoersterling/gotracer/releases/latest/download/gotracer_linux_amd64 -O /tmp/gotracer
sudo install -v -m 755 /tmp/gotracer /usr/local/bin/.

Or build it:

make
sudo make install

Usage

Show tree of Go function calls in the current dir:

$ ./gotracer
main
|--parse_dir_afps
|  `--get_gofiles
`--verbose_calltree
   |--new_func_center
   |  |--get_fds_from_afps
   |  `--get_func_uses
   |     `--get_type_info
   |--(func_center).get_fcalls
   |  |--get_tree_string
   |  `--is_method
   `--calltree
      |--get_fcall_from_slice
      |--(fcall).get_children
      |  `--get_builtin_funcs
      |--calltree->calltree (recursive)
      `--calltree->calltree (recursive)

The default entry point is the main function.

To specify another entry point.
Which is the first call that is found when traversing function calls:

$ gotracer -d . -e calltree
calltree
|--get_fcall_from_slice
|--(fcall).get_children
|  `--get_builtin_funcs
|--calltree->calltree (recursive)
`--calltree->calltree (recursive)

For methods make sure to quote the name of the function call:

gotracer -e '(cli_args).evaluate' -d test_files/makefile_parser/

To list all possible entryponts:

gotracer -l

To list uncalled functions:

gotracer -u

Implementation

This program exclusively uses Go's standard library.
There are no external dependencies.

Performance

gotracer uses the type checker that is part of the Go standard library in go/types.

The Check method from the go/types package initially runs for all Go files.
That is the performance bottleneck.

Writing a custom type checker for is currently not an option.

Another option would be to use pointer analysis. But there is no stable implementation of this.
The google x project is deprecated.

Why Are Third Party Imports Not Supported?

Go's type checker from std is not up to date with the go tool
due to backwards compatibility.
Temporarily setting GOMODCACHE to GOROOT/src might be an option.
Or creating a hidden subdir in the directory where gotracer parses files.
But this implementation does not provide a clean way to do it.

TODO

• option to list unreachable functions (needs correct entrypoint and will not work with external libs)
• maybe include external calls