func checkCallsExpectation(prog *ssa.Program, e *expectation, callgraph call.Graph) bool {
found := make(map[string]int)
err := call.GraphVisitEdges(callgraph, func(edge call.Edge) error {
// Name-based matching is inefficient but it allows us to
// match functions whose names that would not appear in an
// index ("<root>") or which are not unique ("[email protected]").
if edge.Caller.Func().String() == e.args[0] {
calleeStr := edge.Callee.Func().String()
if calleeStr == e.args[1] {
return errOK // expectation satisified; stop the search
}
found[calleeStr]++
}
return nil
})
if err == errOK {
return true
}
if len(found) == 0 {
e.errorf("didn't find any calls from %s", e.args[0])
}
e.errorf("found no call from %s to %s, but only to %s",
e.args[0], e.args[1], join(found))
return false
}
// Callers reports the possible callers of the function
// immediately enclosing the specified source location.
//
// TODO(adonovan): if a caller is a wrapper, show the caller's caller.
//
func callers(o *Oracle, qpos *QueryPos) (queryResult, error) {
pkg := o.prog.Package(qpos.info.Pkg)
if pkg == nil {
return nil, fmt.Errorf("no SSA package")
}
if !ssa.HasEnclosingFunction(pkg, qpos.path) {
return nil, fmt.Errorf("this position is not inside a function")
}
buildSSA(o)
target := ssa.EnclosingFunction(pkg, qpos.path)
if target == nil {
return nil, fmt.Errorf("no SSA function built for this location (dead code?)")
}
// Run the pointer analysis, recording each
// call found to originate from target.
o.config.BuildCallGraph = true
callgraph := ptrAnalysis(o).CallGraph
var edges []call.Edge
call.GraphVisitEdges(callgraph, func(edge call.Edge) error {
if edge.Callee.Func() == target {
edges = append(edges, edge)
}
return nil
})
// TODO(adonovan): sort + dedup calls to ensure test determinism.
return &callersResult{
target: target,
callgraph: callgraph,
edges: edges,
}, nil
}
// This program demonstrates how to use the pointer analysis to
// obtain a conservative call-graph of a Go program.
//
func Example() {
const myprog = `
package main
import "fmt"
type I interface {
f()
}
type C struct{}
func (C) f() {
fmt.Println("C.f()")
}
func main() {
var i I = C{}
i.f() // dynamic method call
}
`
// Construct an importer.
// Imports will be loaded as if by 'go build'.
imp := importer.New(&importer.Config{Build: &build.Default})
// Parse the input file.
file, err := parser.ParseFile(imp.Fset, "myprog.go", myprog, parser.DeclarationErrors)
if err != nil {
fmt.Print(err) // parse error
return
}
// Create a "main" package containing one file.
mainInfo := imp.LoadMainPackage(file)
// Create SSA-form program representation.
var mode ssa.BuilderMode
prog := ssa.NewProgram(imp.Fset, mode)
if err := prog.CreatePackages(imp); err != nil {
fmt.Print(err) // type error in some package
return
}
mainPkg := prog.Package(mainInfo.Pkg)
// Build SSA code for bodies of all functions in the whole program.
prog.BuildAll()
// Run the pointer analysis and build the complete callgraph.
config := &pointer.Config{
Mains: []*ssa.Package{mainPkg},
BuildCallGraph: true,
}
result := pointer.Analyze(config)
// Find edges originating from the main package.
// By converting to strings, we de-duplicate nodes
// representing the same function due to context sensitivity.
var edges []string
call.GraphVisitEdges(result.CallGraph, func(edge call.Edge) error {
caller := edge.Caller.Func()
if caller.Pkg == mainPkg {
edges = append(edges, fmt.Sprint(caller, " --> ", edge.Callee.Func()))
}
return nil
})
// Print the edges in sorted order.
sort.Strings(edges)
for _, edge := range edges {
fmt.Println(edge)
}
// Output:
// (main.C).f --> fmt.Println
// main.init --> fmt.init
// main.main --> (main.C).f
}
