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bpf2go: enable ebpf code reuse across go packages
New -import command line option specifies golang packages to pull headers from. Scan packages for header files, and expose headers to clang. C code consumes headers by providing a go package path in include directive, e.g. frob.c: #include "example.org/foo/foo.h" It is handy for sharing code between multiple ebpf blobs within a project. Even better, it enables sharing ebpf code between multiple projects using go modules as delivery vehicle. "Build" dependencies are recorded in generated files so that "go mod tidy" can see them. Further, we don't check if -import refers to internal packages, but "go build" will. Signed-off-by: Nick Zavaritsky <[email protected]>
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
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@@ -32,24 +32,12 @@ func TestRun(t *testing.T) { | |
| } | ||
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| modDir := t.TempDir() | ||
| execInModule := func(name string, args ...string) { | ||
| t.Helper() | ||
|
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| cmd := exec.Command(name, args...) | ||
| cmd.Dir = modDir | ||
| if out, err := cmd.CombinedOutput(); err != nil { | ||
| if out := string(out); out != "" { | ||
| t.Log(out) | ||
| } | ||
| t.Fatalf("Can't execute %s: %v", name, args) | ||
| } | ||
| } | ||
|
|
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| module := internal.CurrentModule | ||
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| execInModule("go", "mod", "init", "bpf2go-test") | ||
| execInDir(t, modDir, "go", "mod", "init", "bpf2go-test") | ||
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| execInModule("go", "mod", "edit", | ||
| execInDir(t, modDir, "go", "mod", "edit", | ||
| // Require the module. The version doesn't matter due to the replace | ||
| // below. | ||
| fmt.Sprintf("-require=%[email protected]", module), | ||
|
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@@ -106,6 +94,66 @@ func main() { | |
| } | ||
| } | ||
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| func execInDir(t *testing.T, dir, name string, args ...string) { | ||
| t.Helper() | ||
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| cmd := exec.Command(name, args...) | ||
| cmd.Dir = dir | ||
| if out, err := cmd.CombinedOutput(); err != nil { | ||
| if out := string(out); out != "" { | ||
| t.Log(out) | ||
| } | ||
| t.Fatalf("Can't execute %s: %v", name, args) | ||
| } | ||
| } | ||
|
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||
| func TestImports(t *testing.T) { | ||
| dir := t.TempDir() | ||
| mustWriteFile(t, dir, "foo/foo.go", "package foo") | ||
| mustWriteFile(t, dir, "foo/foo.h", "#define EXAMPLE_ORG__FOO__FOO_H 1") | ||
| mustWriteFile(t, dir, "bar/nested/nested.go", "package nested") | ||
| mustWriteFile(t, dir, "bar/nested/nested.h", "#define EXAMPLE_ORG__BAR__NESTED__NESTED_H 1") | ||
| mustWriteFile(t, dir, "bar/bar.c", ` | ||
| //go:build ignore | ||
| // include from current module, package listed in -import | ||
| #include "example.org/bar/nested/nested.h" | ||
| #ifndef EXAMPLE_ORG__BAR__NESTED__NESTED_H | ||
| #error "example.org/bar/nested/nested.h: unexpected file contents" | ||
| #endif | ||
| // include from external module, package listed in -import | ||
| #include "example.org/foo/foo.h" | ||
| #ifndef EXAMPLE_ORG__FOO__FOO_H | ||
| #error "example.org/foo/foo.h: unexpected file contents" | ||
| #endif`) | ||
|
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| fooModDir := filepath.Join(dir, "foo") | ||
| execInDir(t, fooModDir, "go", "mod", "init", "example.org/foo") | ||
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| barModDir := filepath.Join(dir, "bar") | ||
| execInDir(t, barModDir, "go", "mod", "init", "example.org/bar") | ||
| execInDir(t, barModDir, "go", "mod", "edit", "-require=example.org/[email protected]") | ||
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| execInDir(t, dir, "go", "work", "init") | ||
| execInDir(t, dir, "go", "work", "use", fooModDir) | ||
| execInDir(t, dir, "go", "work", "use", barModDir) | ||
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||
| err := run(io.Discard, []string{ | ||
| "-go-package", "bar", | ||
| "-output-dir", barModDir, | ||
| "-cc", testutils.ClangBin(t), | ||
| "-import", "example.org/bar/nested", | ||
| "-import", "example.org/foo", | ||
| "bar", | ||
| filepath.Join(barModDir, "bar.c"), | ||
| }) | ||
|
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| if err != nil { | ||
| t.Fatal("Can't run:", err) | ||
| } | ||
| } | ||
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| func TestHelp(t *testing.T) { | ||
| var stdout bytes.Buffer | ||
| err := run(&stdout, []string{"-help"}) | ||
|
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@@ -383,6 +431,9 @@ func TestParseArgs(t *testing.T) { | |
| func mustWriteFile(tb testing.TB, dir, name, contents string) { | ||
| tb.Helper() | ||
| tmpFile := filepath.Join(dir, name) | ||
| if err := os.MkdirAll(filepath.Dir(tmpFile), 0770); err != nil { | ||
| tb.Fatal(err) | ||
| } | ||
| if err := os.WriteFile(tmpFile, []byte(contents), 0660); err != nil { | ||
| tb.Fatal(err) | ||
| } | ||
|
|
||
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,107 @@ | ||
| package main | ||
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| import ( | ||
| "encoding/json" | ||
| "fmt" | ||
| "go/build" | ||
| "os" | ||
| "path/filepath" | ||
| "slices" | ||
| "strings" | ||
| ) | ||
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| // vfs is LLVM virtual file system parsed from a file | ||
| // | ||
| // In a nutshell, it is a tree of "directory" nodes with leafs being | ||
| // either "file" (a reference to file) or "directory-remap" (a reference | ||
| // to directory). | ||
| // | ||
| // https://github.com/llvm/llvm-project/blob/llvmorg-18.1.0/llvm/include/llvm/Support/VirtualFileSystem.h#L637 | ||
| type vfs struct { | ||
| Version int `json:"version"` | ||
| CaseSensitive bool `json:"case-sensitive"` | ||
| Roots []vfsItem `json:"roots"` | ||
| } | ||
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| type vfsItem struct { | ||
| Name string `json:"name"` | ||
| Type vfsItemType `json:"type"` | ||
| Contents []vfsItem `json:"contents,omitempty"` | ||
| ExternalContents string `json:"external-contents,omitempty"` | ||
| } | ||
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| type vfsItemType string | ||
|
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| const ( | ||
| vfsFile vfsItemType = "file" | ||
| vfsDirectory vfsItemType = "directory" | ||
| ) | ||
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| func (vi *vfsItem) addDir(path string) (*vfsItem, error) { | ||
| for _, name := range strings.Split(path, "/") { | ||
| idx := vi.index(name) | ||
| if idx == -1 { | ||
| idx = len(vi.Contents) | ||
| vi.Contents = append(vi.Contents, vfsItem{Name: name, Type: vfsDirectory}) | ||
| } | ||
| vi = &vi.Contents[idx] | ||
| if vi.Type != vfsDirectory { | ||
| return nil, fmt.Errorf("adding %q: non-directory object already exists", path) | ||
| } | ||
| } | ||
| return vi, nil | ||
| } | ||
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| func (vi *vfsItem) index(name string) int { | ||
| return slices.IndexFunc(vi.Contents, func(item vfsItem) bool { | ||
| return item.Name == name | ||
| }) | ||
| } | ||
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| func persistVfs(vfs *vfs) (_ string, retErr error) { | ||
| temp, err := os.CreateTemp("", "") | ||
| if err != nil { | ||
| return "", err | ||
| } | ||
| defer func() { | ||
| temp.Close() | ||
| if retErr != nil { | ||
| os.Remove(temp.Name()) | ||
| } | ||
| }() | ||
|
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| if err = json.NewEncoder(temp).Encode(vfs); err != nil { | ||
| return "", err | ||
| } | ||
|
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| return temp.Name(), nil | ||
| } | ||
|
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| // vfsRootDir is the (virtual) directory where we mount go module sources | ||
| // for the C includes to pick them, e.g. "<vfsRootDir>/github.com/cilium/ebpf". | ||
| const vfsRootDir = "/.vfsoverlay.d" | ||
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| // createVfs produces a vfs from a list of packages. It creates a | ||
| // (virtual) directory tree reflecting package import paths and adds | ||
| // links to header files. E.g. for github.com/foo/bar containing awesome.h: | ||
| // | ||
| // github.com/ | ||
| // foo/ | ||
| // bar/ | ||
| // awesome.h -> $HOME/go/pkg/mod/github.com/foo/bar@version/awesome.h | ||
| func createVfs(pkgs []*build.Package) (*vfs, error) { | ||
| roots := [1]vfsItem{{Name: vfsRootDir, Type: vfsDirectory}} | ||
| for _, pkg := range pkgs { | ||
| var headers []vfsItem | ||
| for _, h := range hfiles(pkg) { | ||
| headers = append(headers, vfsItem{Name: h, Type: vfsFile, | ||
| ExternalContents: filepath.Join(pkg.Dir, h)}) | ||
| } | ||
| dir, err := roots[0].addDir(pkg.ImportPath) | ||
| if err != nil { | ||
| return nil, err | ||
| } | ||
| dir.Contents = headers // NB don't append inplace, same package could be imported twice | ||
| } | ||
| return &vfs{CaseSensitive: true, Roots: roots[:]}, nil | ||
| } |