semgrep v0.0.1

sgrep

sgrep is a tool for easily detecting and preventing bugs and anti-patterns in your codebase. It combines the convenience of grep with the correctness of syntactical and semantic search. Quickly write rules so you can code with confidence.

Try it now: https://sgrep.live

Overview

Language support:

Example patterns:

Installation

Install sgrep with Docker:

$ docker pull returntocorp/sgrep

And double check that it was installed correctly:

$ docker run --rm returntocorp/sgrep --help

Installation with Brew (Experimental)

brew tap returntocorp/sgrep https://github.com/returntocorp/sgrep.git
brew install semgrep

Usage

Start with a simple example:

$ cat << EOF > test.py
a = 1
b = 2
if a == a:  # oops, supposed to be a == b
    print('sgrep test')
EOF

$ docker run --rm -v "${PWD}:/home/repo" returntocorp/sgrep --lang python --pattern '$X == $X' test.py
test.py
3:if a == a:  # oops, supposed to be a == b

From here you can use our rules to search for issues in your codebase:

$ cd /path/to/code
$ docker run --rm -v "${PWD}:/home/repo" returntocorp/sgrep --config r2c

You can also create your own rules:

$ cd /path/to/code
$ docker run --rm -v "${PWD}:/home/repo" returntocorp/sgrep --generate-config
$ docker run --rm -v "${PWD}:/home/repo" returntocorp/sgrep

Configuration

For simple patterns use the --lang and --pattern flags. This mode of operation is useful for quickly iterating on a pattern on a single file or folder:

$ docker run --rm -v "${PWD}:/home/repo" returntocorp/sgrep --lang javascript --pattern 'eval(...)' path/to/file.js

To fine-tune your searching, specify the --help flag:

$ docker run --rm returntocorp/sgrep --help

Configuration Files

For advanced configuration use the --config flag. This flag automagically handles a multitude of input types:

• --config <file|folder|yaml_url|tarball_url|registy_name>

In the absense of this flag, a default configuration is loaded from .sgrep.yml or multiple files matching .sgrep/**/*.yml.

Operators

Configuration files make use of two primary operators:

• Metavariables like $X, $WIDGET, or $USERS. Metavariable names can only contain uppercase characters - names like $x or $SOME_VALUE are invalid. Metavariables are used to track a variable across a specific code scope.
• The ... (ellipsis) operator. The ellipsis operator abstracts away sequences so you don't have to sweat the details of a particular code pattern.

Let's consider an example:

rules:
  - id: open-never-closed
    patterns:
      - pattern: $FILE = open(...)
      - pattern-not-inside: |
          $FILE = open(...)
          ...
          $FILE.close()
    message: "file object opened without corresponding close"
    languages: [python]
    severity: ERROR

This rule looks for files that are opened but never closed. It accomplishes this by looking for the open(...) pattern and not a following close() pattern. The $FILE metavariable ensures that the same variable name is used in the open and close calls. The ellipsis operator allows for any arguments to be passed to open and any sequence of code statements in-between the open and close calls. We don't care how open is called or what happens up to a close call, we just need to make sure close is called.

For a more complete introduction to the configuration format please see the advanced configuration documentation.

Equivalences

Equivalences are another key concept in sgrep. sgrep automatically searches for code that is semantically equivalent. For example, the following patterns are semantically equivalent

subprocess.Popen(...)

from subprocess import Popen as sub_popen
result = sub_popen("ls")

For a full list of sgrep feature support by language see the language matrix.

Registry

As mentioned above, you may also specify a registry name as configuration. r2c provides a registry of configuration files. These rules have been tuned on thousands of repositories using our analysis platform.

$ docker run --rm -v "${PWD}:/home/repo" returntocorp/sgrep --config r2c

Resources

• r2c sgrep meetup slides
• Simple configuration documentation
• Advanced configuration documentation
• Integrations
• Development
• Bug reports

Contribution

sgrep is LGPL-licensed, feel free to help out: CONTRIBUTING.