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// Copyright 2018 The gVisor Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package main
import (
"bytes"
"flag"
"fmt"
"go/ast"
"go/format"
"go/parser"
"go/token"
"os"
"path/filepath"
"strconv"
"gvisor.dev/gvisor/tools/constraintutil"
)
var (
output = flag.String("o", "", "output `file`")
)
func fatalf(s string, args ...interface{}) {
fmt.Fprintf(os.Stderr, s, args...)
os.Exit(1)
}
func main() {
flag.Usage = func() {
fmt.Fprintf(os.Stderr, "Usage: %s [options] <input1> [<input2> ...]\n", os.Args[0])
flag.PrintDefaults()
}
flag.Parse()
if *output == "" || len(flag.Args()) == 0 {
flag.Usage()
os.Exit(1)
}
// Load all files.
files := make(map[string]*ast.File)
fset := token.NewFileSet()
var name string
for _, fname := range flag.Args() {
f, err := parser.ParseFile(fset, fname, nil, parser.ParseComments|parser.DeclarationErrors|parser.SpuriousErrors)
if err != nil {
fatalf("%v\n", err)
}
files[fname] = f
if name == "" {
name = f.Name.Name
} else if name != f.Name.Name {
fatalf("Expected '%s' for package name instead of '%s'.\n", name, f.Name.Name)
}
}
// Merge all files into one.
pkg := &ast.Package{
Name: name,
Files: files,
}
f := ast.MergePackageFiles(pkg, ast.FilterUnassociatedComments|ast.FilterFuncDuplicates|ast.FilterImportDuplicates)
// Create a new declaration slice with all imports at the top, merging any
// redundant imports.
imports := make(map[string]*ast.ImportSpec)
var importNames []string // Keep imports in the original order to get deterministic output.
var anonImports []*ast.ImportSpec
for _, d := range f.Decls {
if g, ok := d.(*ast.GenDecl); ok && g.Tok == token.IMPORT {
for _, s := range g.Specs {
i := s.(*ast.ImportSpec)
p, _ := strconv.Unquote(i.Path.Value)
var n string
if i.Name == nil {
n = filepath.Base(p)
} else {
n = i.Name.Name
}
if n == "_" {
anonImports = append(anonImports, i)
} else {
if i2, ok := imports[n]; ok {
if first, second := i.Path.Value, i2.Path.Value; first != second {
fatalf("Conflicting paths for import name '%s': '%s' vs. '%s'\n", n, first, second)
}
} else {
imports[n] = i
importNames = append(importNames, n)
}
}
}
}
}
newDecls := make([]ast.Decl, 0, len(f.Decls))
if l := len(imports) + len(anonImports); l > 0 {
// Non-NoPos Lparen is needed for Go to recognize more than one spec in
// ast.GenDecl.Specs.
d := &ast.GenDecl{
Tok: token.IMPORT,
Lparen: token.NoPos + 1,
Specs: make([]ast.Spec, 0, l),
}
for _, i := range importNames {
d.Specs = append(d.Specs, imports[i])
}
for _, i := range anonImports {
d.Specs = append(d.Specs, i)
}
newDecls = append(newDecls, d)
}
for _, d := range f.Decls {
if g, ok := d.(*ast.GenDecl); !ok || g.Tok != token.IMPORT {
newDecls = append(newDecls, d)
}
}
f.Decls = newDecls
// Infer build constraints for the output file.
bcexpr, err := constraintutil.CombineFromFiles(flag.Args())
if err != nil {
fatalf("Failed to read build constraints: %v\n", err)
}
// Write the output file.
var buf bytes.Buffer
if err := format.Node(&buf, fset, f); err != nil {
fatalf("fomatting: %v\n", err)
}
outf, err := os.OpenFile(*output, os.O_CREATE|os.O_WRONLY|os.O_TRUNC, 0644)
if err != nil {
fatalf("opening output: %v\n", err)
}
defer outf.Close()
outf.WriteString(constraintutil.Lines(bcexpr))
if _, err := outf.Write(buf.Bytes()); err != nil {
fatalf("write: %v\n", err)
}
}
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