1 files changed, 163 insertions, 0 deletions
diff --git a/go/tools/builders/link.go b/go/tools/builders/link.go
new file mode 100644
index 00000000..723bb193
--- /dev/null
+++ b/go/tools/builders/link.go
@@ -0,0 +1,163 @@
+// Copyright 2017 The Bazel Authors. All rights reserved.
+//
+// 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.
+
+// link combines the results of a compile step using "go tool link". It is invoked by the
+// Go rules as an action.
+package main
+
+import (
+	"bufio"
+	"bytes"
+	"errors"
+	"flag"
+	"fmt"
+	"io/ioutil"
+	"os"
+	"path/filepath"
+	"regexp"
+	"runtime"
+	"strings"
+)
+
+func link(args []string) error {
+	// Parse arguments.
+	args, _, err := expandParamsFiles(args)
+	if err != nil {
+		return err
+	}
+	builderArgs, toolArgs := splitArgs(args)
+	stamps := multiFlag{}
+	xdefs := multiFlag{}
+	archives := archiveMultiFlag{}
+	flags := flag.NewFlagSet("link", flag.ExitOnError)
+	goenv := envFlags(flags)
+	main := flags.String("main", "", "Path to the main archive.")
+	packagePath := flags.String("p", "", "Package path of the main archive.")
+	outFile := flags.String("o", "", "Path to output file.")
+	flags.Var(&archives, "arc", "Label, package path, and file name of a dependency, separated by '='")
+	packageList := flags.String("package_list", "", "The file containing the list of standard library packages")
+	buildmode := flags.String("buildmode", "", "Build mode used.")
+	flags.Var(&xdefs, "X", "A string variable to replace in the linked binary (repeated).")
+	flags.Var(&stamps, "stamp", "The name of a file with stamping values.")
+	conflictErrMsg := flags.String("conflict_err", "", "Error message about conflicts to report if there's a link error.")
+	if err := flags.Parse(builderArgs); err != nil {
+		return err
+	}
+	if err := goenv.checkFlags(); err != nil {
+		return err
+	}
+
+	if *conflictErrMsg != "" {
+		return errors.New(*conflictErrMsg)
+	}
+
+	// On Windows, take the absolute path of the output file and main file.
+	// This is needed on Windows because the relative path is frequently too long.
+	// os.Open on Windows converts absolute paths to some other path format with
+	// longer length limits. Absolute paths do not work on macOS for .dylib
+	// outputs because they get baked in as the "install path".
+	if runtime.GOOS != "darwin" && runtime.GOOS != "ios" {
+		*outFile = abs(*outFile)
+	}
+	*main = abs(*main)
+
+	// If we were given any stamp value files, read and parse them
+	stampMap := map[string]string{}
+	for _, stampfile := range stamps {
+		stampbuf, err := ioutil.ReadFile(stampfile)
+		if err != nil {
+			return fmt.Errorf("Failed reading stamp file %s: %v", stampfile, err)
+		}
+		scanner := bufio.NewScanner(bytes.NewReader(stampbuf))
+		for scanner.Scan() {
+			line := strings.SplitN(scanner.Text(), " ", 2)
+			switch len(line) {
+			case 0:
+				// Nothing to do here
+			case 1:
+				// Map to the empty string
+				stampMap[line[0]] = ""
+			case 2:
+				// Key and value
+				stampMap[line[0]] = line[1]
+			}
+		}
+	}
+
+	// Build an importcfg file.
+	importcfgName, err := buildImportcfgFileForLink(archives, *packageList, goenv.installSuffix, filepath.Dir(*outFile))
+	if err != nil {
+		return err
+	}
+	if !goenv.shouldPreserveWorkDir {
+		defer os.Remove(importcfgName)
+	}
+
+	// generate any additional link options we need
+	goargs := goenv.goTool("link")
+	goargs = append(goargs, "-importcfg", importcfgName)
+
+	parseXdef := func(xdef string) (pkg, name, value string, err error) {
+		eq := strings.IndexByte(xdef, '=')
+		if eq < 0 {
+			return "", "", "", fmt.Errorf("-X flag does not contain '=': %s", xdef)
+		}
+		dot := strings.LastIndexByte(xdef[:eq], '.')
+		if dot < 0 {
+			return "", "", "", fmt.Errorf("-X flag does not contain '.': %s", xdef)
+		}
+		pkg, name, value = xdef[:dot], xdef[dot+1:eq], xdef[eq+1:]
+		if pkg == *packagePath {
+			pkg = "main"
+		}
+		return pkg, name, value, nil
+	}
+	for _, xdef := range xdefs {
+		pkg, name, value, err := parseXdef(xdef)
+		if err != nil {
+			return err
+		}
+		var missingKey bool
+		value = regexp.MustCompile(`\{.+?\}`).ReplaceAllStringFunc(value, func(key string) string {
+			if value, ok := stampMap[key[1:len(key)-1]]; ok {
+				return value
+			}
+			missingKey = true
+			return key
+		})
+		if !missingKey {
+			goargs = append(goargs, "-X", fmt.Sprintf("%s.%s=%s", pkg, name, value))
+		}
+	}
+
+	if *buildmode != "" {
+		goargs = append(goargs, "-buildmode", *buildmode)
+	}
+	goargs = append(goargs, "-o", *outFile)
+
+	// add in the unprocess pass through options
+	goargs = append(goargs, toolArgs...)
+	goargs = append(goargs, *main)
+	if err := goenv.runCommand(goargs); err != nil {
+		return err
+	}
+
+	if *buildmode == "c-archive" {
+		if err := stripArMetadata(*outFile); err != nil {
+			return fmt.Errorf("error stripping archive metadata: %v", err)
+		}
+	}
+
+	return nil
+}