infer_clone/website/docs/01-advanced-features.md

id	title
advanced-features	Advanced usage

In this section we discuss how to use Infer if you wish to make contributions to it or just look under the hood to learn more about how it is working. There are, for instance, debug options and ways to obtain the specs from the methods.

Structure of the results folder

After a successful Infer run, a directory is created to store the results of the analysis. By default this directory is called infer-out.

infer-out
├── captured/
├── log/
├── specs/
├── bugs.txt
├── report.json
├── toplevel.log
└── ...

• captured/ contains information for each file analyzed by Infer. See below for more information.
• specs/ contains the specs of each function that was analyzed, as inferred by Infer.
• log/ and toplevel.log contains logs
• bugs.txt and report.json contain the Infer reports in text and JSON formats
• there are other folders reserved for Infer's internal workings

Captured folder

Inside the folder infer-out/captured there is a folder for each captured file. Assume we captured a file called example.c. Then, Infer creates the following files inside the folder infer-out/captured/example.c/:

• example.c.cfg
• example.c.cg
• example.c.tenv

The files .cfg, .cg and .tenv contain the intermediate representation of that file. This data is passed to the backend of Infer, which then performs the analysis. The files contain serialized OCaml data structures. The .cfg file contains a control flow graph for each function or method implemented in the file. The file .cg contains the call graph of the functions defined or called from that file. Finally, the file .tenv contains all the types that are defined or used in the file.

Debug mode

With the debug option enabled infer run --debug -- <build command>, Infer outputs debug information in infer-out/log/. The option --stats provides only light debug information, and --print-logs outputs every message on the console as well as in the log files.

In each captured folder, we obtain the file icfg.dot, which is the graphical representation of the file .cfg and the file call_graph.dot, that is the graphical representation of the call graph.

Moreover, we obtain an HTML page for each captured file inside infer-out/captured. This HTML file contains the source file. In each line of the file there are links to the nodes of the control flow graph that correspond to that line of code. So one can see what the translation looks like. Moreover, when you click on those links you can see details of the symbolic execution of that particular node. If the option --no_test is also passed to infer, then the page pointed to from the nodes contains the printout of the whole symbolic execution.

Print the specs

It is also possible to print the specs created by Infer using the subcommand infer report. You can print one particular spec that corresponds to one method, or you can print all the specs in the results directory. Let us look at an example:

class Hello {
    int x;
    void setX(int newX) {
	    this.x = newX;
    }
}

We run Infer on this example with:

infer run -- javac Hello.java

Infer saves the spec for the method setX in infer-out/specs and we can print it with the command:

infer report infer-out/specs/Hello.setX{98B5}:void.specs

The convention for method names in Java is <class name>.<method name>. This outputs the following:

Procedure: void Hello.setX(int)
void void Hello.setX(int)(class Hello *this, int newX)
Timestamp: 1
Status: INACTIVE
Phase: RE_EXECUTION
Dependency_map:
TIME:0.006893 s TIMEOUT:N SYMOPS:34 CALLS:0,0
ERRORS:
--------------------------- 1 of 1 [nvisited: 4 5 6] ---------------------------
PRE:
this = val$1: ;
newX = val$3: ;
this|->{Hello.x:val$2}:
POST 1 of 1:
this = val$1: ;
return = val$4: ;
newX = val$3: ;
this|->{Hello.x:newX}:
----------------------------------------------------------------

which expresses the fact that this needs to be allocated at the beginning of the method, and that at the end of the method the field x is equal to newX.

Moreover, you can print all the specs in the results directory with the command:

infer report

Run internal tests

There are many tests in the Infer code base that check that Infer behaves correctly on small program examples. This is how you'd typically run the tests; you can adapt the figure 8 depending on the number of cores available on your machine:

make -j8 test