cmd/go: consistent output for -json failures

When the -json flag is passed to go mod download,
the sumdb error is embedded in the json Error field.
Other errors for the same command behave this way as
well such as module not found. The fix is done by changing
base.Fatalf into proper error returns.

Fixes #34485

Change-Id: I2727a5c70c7ab03988cad8661894d0f8ec71a768
Reviewed-on: https://go-review.googlesource.com/c/go/+/197062
Run-TryBot: Jay Conrod <jayconrod@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Jay Conrod <jayconrod@google.com>

src/cmd/go/internal/modfetch/cache.go

@@ -230,7 +230,9 @@ func (r *cachingRepo) GoMod(version string) ([]byte, error) {
 
 		text, err = r.r.GoMod(version)
 		if err == nil {
-			checkGoMod(r.path, version, text)
+			if err := checkGoMod(r.path, version, text); err != nil {
+				return cached{text, err}
+			}
 			if err := writeDiskGoMod(file, text); err != nil {
 				fmt.Fprintf(os.Stderr, "go: writing go.mod cache: %v\n", err)
 			}
@@ -490,7 +492,9 @@ func readDiskGoMod(path, rev string) (file string, data []byte, err error) {
 	}
 
 	if err == nil {
-		checkGoMod(path, rev, data)
+		if err := checkGoMod(path, rev, data); err != nil {
+			return "", nil, err
+		}
 	}
 
 	return file, data, err

src/cmd/go/internal/modfetch/fetch.go

@@ -250,7 +250,9 @@ func downloadZip(mod module.Version, zipfile string) (err error) {
 	if err != nil {
 		return err
 	}
-	checkModSum(mod, hash)
+	if err := checkModSum(mod, hash); err != nil {
+		return err
+	}
 
 	if err := renameio.WriteFile(zipfile+"hash", []byte(hash), 0666); err != nil {
 		return err
@@ -282,21 +284,22 @@ var goSum struct {
 }
 
 // initGoSum initializes the go.sum data.
-// It reports whether use of go.sum is now enabled.
+// The boolean it returns reports whether the
+// use of go.sum is now enabled.
 // The goSum lock must be held.
-func initGoSum() bool {
+func initGoSum() (bool, error) {
 	if GoSumFile == "" {
-		return false
+		return false, nil
 	}
 	if goSum.m != nil {
-		return true
+		return true, nil
 	}
 
 	goSum.m = make(map[module.Version][]string)
 	goSum.checked = make(map[modSum]bool)
 	data, err := renameio.ReadFile(GoSumFile)
 	if err != nil && !os.IsNotExist(err) {
-		base.Fatalf("go: %v", err)
+		return false, err
 	}
 	goSum.enabled = true
 	readGoSum(goSum.m, GoSumFile, data)
@@ -314,7 +317,7 @@ func initGoSum() bool {
 		}
 		goSum.modverify = alt
 	}
-	return true
+	return true, nil
 }
 
 // emptyGoModHash is the hash of a 1-file tree containing a 0-length go.mod.
@@ -324,7 +327,7 @@ const emptyGoModHash = "h1:G7mAYYxgmS0lVkHyy2hEOLQCFB0DlQFTMLWggykrydY="
 
 // readGoSum parses data, which is the content of file,
 // and adds it to goSum.m. The goSum lock must be held.
-func readGoSum(dst map[module.Version][]string, file string, data []byte) {
+func readGoSum(dst map[module.Version][]string, file string, data []byte) error {
 	lineno := 0
 	for len(data) > 0 {
 		var line []byte
@@ -341,7 +344,7 @@ func readGoSum(dst map[module.Version][]string, file string, data []byte) {
 			continue
 		}
 		if len(f) != 3 {
-			base.Fatalf("go: malformed go.sum:\n%s:%d: wrong number of fields %v", file, lineno, len(f))
+			return fmt.Errorf("malformed go.sum:\n%s:%d: wrong number of fields %v", file, lineno, len(f))
 		}
 		if f[2] == emptyGoModHash {
 			// Old bug; drop it.
@@ -350,6 +353,7 @@ func readGoSum(dst map[module.Version][]string, file string, data []byte) {
 		mod := module.Version{Path: f[0], Version: f[1]}
 		dst[mod] = append(dst[mod], f[2])
 	}
+	return nil
 }
 
 // checkMod checks the given module's checksum.
@@ -377,7 +381,9 @@ func checkMod(mod module.Version) {
 		base.Fatalf("verifying %v", module.VersionError(mod, fmt.Errorf("unexpected ziphash: %q", h)))
 	}
 
-	checkModSum(mod, h)
+	if err := checkModSum(mod, h); err != nil {
+		base.Fatalf("%s", err)
+	}
 }
 
 // goModSum returns the checksum for the go.mod contents.
@@ -389,17 +395,17 @@ func goModSum(data []byte) (string, error) {
 
 // checkGoMod checks the given module's go.mod checksum;
 // data is the go.mod content.
-func checkGoMod(path, version string, data []byte) {
+func checkGoMod(path, version string, data []byte) error {
 	h, err := goModSum(data)
 	if err != nil {
-		base.Fatalf("verifying %s %s go.mod: %v", path, version, err)
+		return &module.ModuleError{Path: path, Version: version, Err: fmt.Errorf("verifying go.mod: %v", err)}
 	}
 
-	checkModSum(module.Version{Path: path, Version: version + "/go.mod"}, h)
+	return checkModSum(module.Version{Path: path, Version: version + "/go.mod"}, h)
 }
 
 // checkModSum checks that the recorded checksum for mod is h.
-func checkModSum(mod module.Version, h string) {
+func checkModSum(mod module.Version, h string) error {
 	// We lock goSum when manipulating it,
 	// but we arrange to release the lock when calling checkSumDB,
 	// so that parallel calls to checkModHash can execute parallel calls
@@ -407,19 +413,24 @@ func checkModSum(mod module.Version, h string) {
 
 	// Check whether mod+h is listed in go.sum already. If so, we're done.
 	goSum.mu.Lock()
-	inited := initGoSum()
+	inited, err := initGoSum()
+	if err != nil {
+		return err
+	}
 	done := inited && haveModSumLocked(mod, h)
 	goSum.mu.Unlock()
 
 	if done {
-		return
+		return nil
 	}
 
 	// Not listed, so we want to add them.
 	// Consult checksum database if appropriate.
 	if useSumDB(mod) {
 		// Calls base.Fatalf if mismatch detected.
-		checkSumDB(mod, h)
+		if err := checkSumDB(mod, h); err != nil {
+			return err
+		}
 	}
 
 	// Add mod+h to go.sum, if it hasn't appeared already.
@@ -428,6 +439,7 @@ func checkModSum(mod module.Version, h string) {
 		addModSumLocked(mod, h)
 		goSum.mu.Unlock()
 	}
+	return nil
 }
 
 // haveModSumLocked reports whether the pair mod,h is already listed in go.sum.
@@ -461,22 +473,23 @@ func addModSumLocked(mod module.Version, h string) {
 
 // checkSumDB checks the mod, h pair against the Go checksum database.
 // It calls base.Fatalf if the hash is to be rejected.
-func checkSumDB(mod module.Version, h string) {
+func checkSumDB(mod module.Version, h string) error {
 	db, lines, err := lookupSumDB(mod)
 	if err != nil {
-		base.Fatalf("verifying %s@%s: %v", mod.Path, mod.Version, err)
+		return module.VersionError(mod, fmt.Errorf("verifying module: %v", err))
 	}
 
 	have := mod.Path + " " + mod.Version + " " + h
 	prefix := mod.Path + " " + mod.Version + " h1:"
 	for _, line := range lines {
 		if line == have {
-			return
+			return nil
 		}
 		if strings.HasPrefix(line, prefix) {
-			base.Fatalf("verifying %s@%s: checksum mismatch\n\tdownloaded: %v\n\t%s: %v"+sumdbMismatch, mod.Path, mod.Version, h, db, line[len(prefix)-len("h1:"):])
+			return module.VersionError(mod, fmt.Errorf("verifying module: checksum mismatch\n\tdownloaded: %v\n\t%s: %v"+sumdbMismatch, h, db, line[len(prefix)-len("h1:"):]))
 		}
 	}
+	return nil
 }
 
 // Sum returns the checksum for the downloaded copy of the given module,
@@ -586,7 +599,11 @@ func WriteGoSum() {
 func TrimGoSum(keep map[module.Version]bool) {
 	goSum.mu.Lock()
 	defer goSum.mu.Unlock()
-	if !initGoSum() {
+	inited, err := initGoSum()
+	if err != nil {
+		base.Fatalf("%s", err)
+	}
+	if !inited {
 		return
 	}
 

src/cmd/go/testdata/script/mod_download_json.txt

@@ -0,0 +1,10 @@
+env GO111MODULE=on
+env GOPROXY=$GOPROXY/quiet
+env GOSUMDB=$sumdb' '$proxy/sumdb-wrong
+
+# download -json with version should print JSON on sumdb failure
+! go mod download -json 'rsc.io/quote@<=v1.5.0'
+stdout '"Error": ".*verifying module'
+
+-- go.mod --
+module m

src/cmd/go/testdata/script/mod_sumdb.txt

@@ -9,7 +9,7 @@ env dbname=localhost.localdev/sumdb
 cp go.mod.orig go.mod
 env GOSUMDB=$sumdb' '$proxy/sumdb-wrong
 ! go get -d rsc.io/quote
-stderr 'verifying rsc.io/quote@v1.5.2: checksum mismatch'
+stderr 'go get rsc.io/quote: rsc.io/quote@v1.5.2: verifying module: checksum mismatch'
 stderr 'downloaded: h1:3fEy'
 stderr 'localhost.localdev/sumdb: h1:wrong'
 stderr 'SECURITY ERROR\nThis download does NOT match the one reported by the checksum server.'

src/cmd/go/testdata/script/mod_sumdb_file_path.txt

@@ -13,7 +13,7 @@ env GOPATH=$WORK/gopath1
 [windows] env GOPROXY=file:///$WORK/sumproxy,https://proxy.golang.org
 [!windows] env GOPROXY=file://$WORK/sumproxy,https://proxy.golang.org
 ! go get -d golang.org/x/text@v0.3.2
-stderr '^verifying golang.org/x/text@v0.3.2: golang.org/x/text@v0.3.2: reading file://.*/sumdb/sum.golang.org/lookup/golang.org/x/text@v0.3.2: (no such file or directory|.*cannot find the file specified.*)'
+stderr '^go get golang.org/x/text@v0.3.2: golang.org/x/text@v0.3.2: verifying module: golang.org/x/text@v0.3.2: reading file://.*/sumdb/sum.golang.org/lookup/golang.org/x/text@v0.3.2: (no such file or directory|.*cannot find the file specified.*)'
 
 # If the proxy does not claim to support the database,
 # checksum verification should fall through to the next proxy,