Optimise reading of only Build metainformation

[goredo.git] / dep.go

diff --git a/dep.go b/dep.go
index 18f5db6bcfb5c47ddb68977b98878477ba5f633f..40245196c4b7a7a649eeabdbbac6c2ac9fe2cbaf 100644 (file)
--- a/dep.go
+++ b/dep.go
@@ -155,6 +155,8 @@ type DepInfo struct {
        ifchanges []map[string]string
 }
 
+var missingBuild = errors.New(".rec missing Build:")
+
 func depRead(fdDep io.Reader) (*DepInfo, error) {
        r := recfile.NewReader(fdDep)
        m, err := r.NextMap()
@@ -164,7 +166,7 @@ func depRead(fdDep io.Reader) (*DepInfo, error) {
        depInfo := DepInfo{}
        b := m["Build"]
        if b == "" {
-               return nil, errors.New(".rec missing Build:")
+               return nil, missingBuild
        }
        depInfo.build = b
        for {
@@ -199,3 +201,21 @@ func depRead(fdDep io.Reader) (*DepInfo, error) {
        }
        return &depInfo, nil
 }
+
+func depReadBuild(pth string) (string, error) {
+       fd, err := os.Open(pth)
+       if err != nil {
+               return "", err
+       }
+       r := recfile.NewReader(fd)
+       m, err := r.NextMap()
+       fd.Close()
+       if err != nil {
+               return "", err
+       }
+       build := m["Build"]
+       if build == "" {
+               err = missingBuild
+       }
+       return build, err
+}