autobuilder: extract out attempted build commands

Author: Sauyon Lee

extractor/autobuilder/autobuilder.go

@@ -0,0 +1,81 @@
+// Package autobuilder implements a simple system that attempts to run build commands for common
+// build frameworks, if the relevant files exist.
+package autobuilder
+
+import (
+	"log"
+	"os"
+	"os/exec"
+
+	"github.com/github/codeql-go/extractor/util"
+)
+
+// CheckExtracted sets whether the autobuilder should check whether source files have been extracted
+// to the CodeQL source directory as well as whether the build command executed successfully.
+var CheckExtracted = false
+
+// checkEmpty checks whether a directory either doesn't exist or is empty.
+func checkEmpty(dir string) (bool, error) {
+	if !util.DirExists(dir) {
+		return true, nil
+	}
+
+	d, err := os.Open(dir)
+	if err != nil {
+		return false, err
+	}
+	defer d.Close()
+
+	names, err := d.Readdirnames(-1)
+	if err != nil {
+		return false, err
+	}
+	return len(names) == 0, nil
+}
+
+// checkExtractorRun checks whether the CodeQL Go extractor has run, by checking if the source
+// archive directory is empty or not.
+func checkExtractorRun() bool {
+	srcDir := os.Getenv("CODEQL_EXTRACTOR_GO_SOURCE_ARCHIVE_DIR")
+	if srcDir != "" {
+		empty, err := checkEmpty(srcDir)
+		if err != nil {
+			log.Fatalf("Unable to read source archive directory %s.", srcDir)
+		}
+		if empty {
+			log.Printf("No Go code seen; continuing to try other builds.")
+			return false
+		}
+		return true
+	} else {
+		log.Fatalf("No source directory set.")
+		return false
+	}
+}
+
+// tryBuildIfExists tries to run the command `cmd args...` if the file `buildFile` exists and is not
+// a directory. Returns true if the command was successful and false if not.
+func tryBuildIfExists(buildFile, cmd string, args ...string) bool {
+	if util.FileExists(buildFile) {
+		log.Printf("%s found.\n", buildFile)
+		return tryBuild(cmd, args...)
+	}
+	return false
+}
+
+// tryBuild tries to run `cmd args...`, returning true if successful and false if not.
+func tryBuild(cmd string, args ...string) bool {
+	log.Printf("Trying build command %s %v", cmd, args)
+	res := util.RunCmd(exec.Command(cmd, args...))
+	return res && (!CheckExtracted || checkExtractorRun())
+}
+
+// Autobuild attempts to detect build system and run the corresponding command.
+func Autobuild() bool {
+	return tryBuildIfExists("Makefile", "make") ||
+		tryBuildIfExists("makefile", "make") ||
+		tryBuildIfExists("GNUmakefile", "make") ||
+		tryBuildIfExists("build.ninja", "ninja") ||
+		tryBuildIfExists("build", "./build") ||
+		tryBuildIfExists("build.sh", "./build.sh")
+}

extractor/cli/go-autobuilder/go-autobuilder.go

@@ -13,6 +13,7 @@ import (
 	"runtime"
 	"strings"
 
+	"github.com/github/codeql-go/extractor/autobuilder"
 	"github.com/github/codeql-go/extractor/util"
 )
 
@@ -403,13 +404,8 @@ func main() {
 	inst := util.Getenv("CODEQL_EXTRACTOR_GO_BUILD_COMMAND", "LGTM_INDEX_BUILD_COMMAND")
 	shouldInstallDependencies := false
 	if inst == "" {
-		// if there is a build file, run the corresponding build tool
-		buildSucceeded := tryBuild("Makefile", "make") ||
-			tryBuild("makefile", "make") ||
-			tryBuild("GNUmakefile", "make") ||
-			tryBuild("build.ninja", "ninja") ||
-			tryBuild("build", "./build") ||
-			tryBuild("build.sh", "./build.sh")
+		// try to build the project
+		buildSucceeded := autobuilder.Autobuild()
 
 		if !buildSucceeded {
 			// Build failed; we'll try to install dependencies ourselves