Allow @ to be used for -protoset

cmd/grpcurl/grpcurl.go

@@ -72,7 +72,8 @@ var (
 		requests. It defaults to the given address.`))
 	data = flags.String("d", "", prettify(`
 		Data for request contents. If the value is '@' then the request contents
-		are read from stdin. For calls that accept a stream of requests, the
+		are read from stdin. Note that '@' cannot be used for both -data and -protoset
+		in the same invocation. For calls that accept a stream of requests, the
 		contents should include all such request messages concatenated together
 		(possibly delimited; see -format).`))
 	format = flags.String("format", "json", prettify(`
@@ -139,7 +140,9 @@ func init() {
 		those exposed by the remote server), and the 'describe' action describes
 		symbols found in the given descriptors. May specify more than one via
 		multiple -protoset flags. It is an error to use both -protoset and
-		-proto flags.`))
+		-proto flags. If the value is '@' then the protoset is read from stdin.
+		Note that '@' cannot be used for both -data and -protoset in the same
+		invocation.`))
 	flags.Var(&protoFiles, "proto", prettify(`
 		The name of a proto source file. Source files given will be used to
 		determine the RPC schema instead of querying for it from the remote
@@ -278,6 +281,14 @@ func main() {
 		warn("The -import-path argument is not used unless -proto files are used.")
 	}
 
+	if *data == "@" && len(protoset) > 0 {
+		for _, fileName := range protoset {
+			if fileName == "@" {
+				fail(nil, "Cannot use '@' for both -data and -protoset.")
+			}
+		}
+	}
+
 	ctx := context.Background()
 	if *maxTime > 0 {
 		timeout := time.Duration(*maxTime * float64(time.Second))

desc_source.go

@@ -5,6 +5,7 @@ import (
 	"fmt"
 	"io"
 	"io/ioutil"
+	"os"
 	"sync"
 
 	"github.com/golang/protobuf/proto"
@@ -38,10 +39,23 @@ type DescriptorSource interface {
 
 // DescriptorSourceFromProtoSets creates a DescriptorSource that is backed by the named files, whose contents
 // are encoded FileDescriptorSet protos.
+//
+// The special fileName "@" denotes to read from os.Stdin. Multiple "@" values will result
+// in only one read from stdin.
 func DescriptorSourceFromProtoSets(fileNames ...string) (DescriptorSource, error) {
+	stdinProcessed := false
 	files := &descpb.FileDescriptorSet{}
 	for _, fileName := range fileNames {
-		b, err := ioutil.ReadFile(fileName)
+		var b []byte
+		var err error
+		if fileName == "@" {
+			if !stdinProcessed {
+				stdinProcessed = true
+				b, err = ioutil.ReadAll(os.Stdin)
+			}
+		} else {
+			b, err = ioutil.ReadFile(fileName)
+		}
 		if err != nil {
 			return nil, fmt.Errorf("could not load protoset file %q: %v", fileName, err)
 		}