--- /dev/null
+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package cgo
+
+import (
+ "errors"
+ "fmt"
+ "go/build"
+ "os/exec"
+ "strings"
+)
+
+// pkgConfig runs pkg-config with the specified arguments and returns the flags it prints.
+func pkgConfig(mode string, pkgs []string) (flags []string, err error) {
+ cmd := exec.Command("pkg-config", append([]string{mode}, pkgs...)...)
+ out, err := cmd.CombinedOutput()
+ if err != nil {
+ s := fmt.Sprintf("%s failed: %v", strings.Join(cmd.Args, " "), err)
+ if len(out) > 0 {
+ s = fmt.Sprintf("%s: %s", s, out)
+ }
+ return nil, errors.New(s)
+ }
+ if len(out) > 0 {
+ flags = strings.Fields(string(out))
+ }
+ return
+}
+
+// pkgConfigFlags calls pkg-config if needed and returns the cflags
+// needed to build the package.
+func pkgConfigFlags(p *build.Package) (cflags []string, err error) {
+ if len(p.CgoPkgConfig) == 0 {
+ return nil, nil
+ }
+ return pkgConfig("--cflags", p.CgoPkgConfig)
+}