Common Queries

The following examples were written for the source code of the VLC Media Player v3.0.8. You can download the source code here.

Basic Analysis

Methods

• List all methods that match .*parse.* to the shell

ocular> cpg.method.name(".*parse.*").name.l

• Dump all methods that match .*parse.* to the shell (syntax-highlighted)

ocular> cpg.method.name(".*parse.*").dump

• Create K-V pair of all methods that match .*parse.* and their code

ocular> cpg.method.name(".*parse.*").map( m=> (m.name, m.start.dump)).l

• Dump all methods that match .*parse.* to file (no highlighting)

ocular> cpg.method.name(".*parse.*").dumpRaw |> "/tmp/foo.c"

• View all methods that match .*parse.* in a pager (e.g., less)

ocular> browse(cpg.method.name(".*parse.*").dump)

• Dump dot representations of ASTs for all methods that match parse into file

ocular> cpg.method.name("parse_public_key_packet").dot |> "/tmp/foo.dot"

• Find all local variables defined in a method

ocular> cpg.method.name("parse_public_key_packet").local.name.l

• Find which file and line number they are in

ocular> cpg.method.name("parse_public_key_packet").location.map( x=> (x.lineNumber.get, x.filename)).l

• Find the type of the first local variable defined in a method

ocular> cpg.method.name("parse_public_key_packet").local.typ.name.l.head

• Find all outgoing calls (call-sites) in a method

ocular> cpg.method.name("parse_public_key_packet").callOut.name.l

• Find which method calls a method

ocular> cpg.method.name("parse_public_key_packet").caller.name.l

Types and Filters

• List all local variables of type vlc_.*

ocular> cpg.types.name("vlc_.*").localsOfType.name.l

• Find member variables of a struct

ocular> cpg.types.name("vlc_log_t").map( x=> (x.name, x.start.member.name.l)).l

• Find local variables and filter them by their type

ocular> cpg.local.where(_.typ.name("vlc_log_t")).name.l

• Which method are they used in?

ocular> cpg.local.where(_.typ.name("vlc_log_t")).method.dump

• Get the filenames where these methods are

ocular> cpg.local.where(_.typ.name("vlc_log_t")).method.file.name.l

Insights

Overview

• Identify functions with more than 4 parameters

ocular> cpg.method.filter(_.parameter.size > 4).name.l

• Identify functions with > 4 control structures (cyclomatic complexity)

ocular> cpg.method.filter(_.controlStructure.size > 4).name.l

• Identify functions with more than 500 lines of code

ocular> cpg.method.filter(_.numberOfLines >= 500).name.l

• Identify functions with multiple return statements

ocular> cpg.method.filter(_.ast.isReturn.l.size > 1).name.l

• Identify functions with more than 4 loop statements (including loops nested inside other loops)

ocular> cpg.method.filter(_.ast.isControlStructure.parserTypeName("(For|Do|While).*").size > 4).name.l

• Identify functions with nesting depth larger than 3

ocular> cpg.method.filter(_.depth(_.isControlStructure) > 3).name.l

Calls into libraries

• All names of external methods used by the program

ocular> cpg.method.external.name.l.distinct.sorted

• All calls to strcpy

ocular> cpg.call("str.*").code.l

• All methods that call strcpy

ocular> cpg.call("str.*").method.name.l

• Looking into parameters: second argument to sprintf is NOT a literal

ocular> cpg.call("sprintf").argument(2).whereNot(_.isLiteral).code.l

• Quickly see this method above

ocular> cpg.call("sprintf").argument(2).whereNot(_.isLiteral).dump