From 10761f623b1944bd299e8c9435f1cddb7b4e4fef Mon Sep 17 00:00:00 2001
From: Hraban Luyat <hraban@0brg.net>
Date: Mon, 10 Oct 2016 14:18:10 +0100
Subject: [PATCH] Make opus errors wrapped ints, expose names

Allows comparing error values by value instead of just by human readable
string.
---
 decoder.go   |  6 +++---
 encoder.go   |  6 +++---
 errors.go    | 45 ++++++++++++++++++++++++++++++++++++++-------
 opus_test.go |  8 ++++----
 4 files changed, 48 insertions(+), 17 deletions(-)

diff --git a/decoder.go b/decoder.go
index c77a5ba..3674894 100644
--- a/decoder.go
+++ b/decoder.go
@@ -51,7 +51,7 @@ func (dec *Decoder) Init(sample_rate int, channels int) error {
 		C.opus_int32(sample_rate),
 		C.int(channels))
 	if errno != 0 {
-		return opuserr(int(errno))
+		return opusError(errno)
 	}
 	return nil
 }
@@ -76,7 +76,7 @@ func (dec *Decoder) Decode(data []byte, pcm []int16) (int, error) {
 		C.int(cap(pcm)),
 		0))
 	if n < 0 {
-		return 0, opuserr(n)
+		return 0, opusError(n)
 	}
 	return n, nil
 }
@@ -101,7 +101,7 @@ func (dec *Decoder) DecodeFloat32(data []byte, pcm []float32) (int, error) {
 		C.int(cap(pcm)),
 		0))
 	if n < 0 {
-		return 0, opuserr(n)
+		return 0, opusError(n)
 	}
 	return n, nil
 }
diff --git a/encoder.go b/encoder.go
index 976091b..bd50405 100644
--- a/encoder.go
+++ b/encoder.go
@@ -77,7 +77,7 @@ func (enc *Encoder) Init(sample_rate int, channels int, application Application)
 		C.int(channels),
 		C.int(application)))
 	if errno != 0 {
-		return opuserr(int(errno))
+		return opusError(int(errno))
 	}
 	return nil
 }
@@ -101,7 +101,7 @@ func (enc *Encoder) Encode(pcm []int16, data []byte) (int, error) {
 		(*C.uchar)(&data[0]),
 		C.opus_int32(cap(data))))
 	if n < 0 {
-		return 0, opuserr(n)
+		return 0, opusError(n)
 	}
 	return n, nil
 }
@@ -125,7 +125,7 @@ func (enc *Encoder) EncodeFloat32(pcm []float32, data []byte) (int, error) {
 		(*C.uchar)(&data[0]),
 		C.opus_int32(cap(data))))
 	if n < 0 {
-		return 0, opuserr(n)
+		return 0, opusError(n)
 	}
 	return n, nil
 }
diff --git a/errors.go b/errors.go
index 928bec6..3c47287 100644
--- a/errors.go
+++ b/errors.go
@@ -14,6 +14,18 @@ import (
 #include <opusfile.h>
 
 // Access the preprocessor from CGO
+
+// Errors for libopus
+const int CONST_OPUS_OK = OPUS_OK;
+const int CONST_OPUS_BAD_ARG = OPUS_BAD_ARG;
+const int CONST_OPUS_BUFFER_TOO_SMALL = OPUS_BUFFER_TOO_SMALL;
+const int CONST_OPUS_INTERNAL_ERROR = OPUS_INTERNAL_ERROR;
+const int CONST_OPUS_INVALID_PACKET = OPUS_INVALID_PACKET;
+const int CONST_OPUS_UNIMPLEMENTED = OPUS_UNIMPLEMENTED;
+const int CONST_OPUS_INVALID_STATE = OPUS_INVALID_STATE;
+const int CONST_OPUS_ALLOC_FAIL = OPUS_ALLOC_FAIL;
+
+// Errors for libopusfile
 const int CONST_OP_FALSE = OP_FALSE;
 const int CONST_OP_EOF = OP_EOF;
 const int CONST_OP_HOLE = OP_HOLE;
@@ -32,8 +44,33 @@ const int CONST_OP_EBADTIMESTAMP = OP_EBADTIMESTAMP;
 */
 import "C"
 
+type opusError int
+
+var _ error = opusError(0)
+
+// Libopus errors
+var (
+	ERR_OPUS_OK               = opusError(C.CONST_OPUS_OK)
+	ERR_OPUS_BAD_ARG          = opusError(C.CONST_OPUS_BAD_ARG)
+	ERR_OPUS_BUFFER_TOO_SMALL = opusError(C.CONST_OPUS_BUFFER_TOO_SMALL)
+	ERR_OPUS_INTERNAL_ERROR   = opusError(C.CONST_OPUS_INTERNAL_ERROR)
+	ERR_OPUS_INVALID_PACKET   = opusError(C.CONST_OPUS_INVALID_PACKET)
+	ERR_OPUS_UNIMPLEMENTED    = opusError(C.CONST_OPUS_UNIMPLEMENTED)
+	ERR_OPUS_INVALID_STATE    = opusError(C.CONST_OPUS_INVALID_STATE)
+	ERR_OPUS_ALLOC_FAIL       = opusError(C.CONST_OPUS_ALLOC_FAIL)
+)
+
+// Error string (in human readable format) for libopus errors.
+func (e opusError) Error() string {
+	return fmt.Sprintf("opus: %s", C.GoString(C.opus_strerror(C.int(e))))
+}
+
 type opusFileError int
 
+var _ error = opusFileError(0)
+
+// Libopusfile errors. The names are copied verbatim from the libopusfile
+// library.
 var (
 	ERR_OP_FALSE         = opusFileError(C.CONST_OP_FALSE)
 	ERR_OP_EOF           = opusFileError(C.CONST_OP_EOF)
@@ -85,12 +122,6 @@ func (i opusFileError) Error() string {
 	case ERR_OP_EBADTIMESTAMP:
 		return "OP_EBADTIMESTAMP"
 	default:
-		return "libopus error: %d (unknown code)"
+		return "libopusfile error: %d (unknown code)"
 	}
 }
-
-// opuserr translates libopus (not libopusfile) error codes to human readable
-// strings
-func opuserr(code int) error {
-	return fmt.Errorf("opus: %s", C.GoString(C.opus_strerror(C.int(code))))
-}
diff --git a/opus_test.go b/opus_test.go
index b600abe..230f426 100644
--- a/opus_test.go
+++ b/opus_test.go
@@ -62,13 +62,13 @@ func TestDecoderUnitialized(t *testing.T) {
 	}
 }
 
-func TestOpuserr(t *testing.T) {
+func TestOpusErrstr(t *testing.T) {
 	// I scooped this -1 up from opus_defines.h, it's OPUS_BAD_ARG. Not pretty,
 	// but it's better than not testing at all. Again, accessing #defines from
 	// CGO is not possible.
-	err := opuserr(-1)
-	if err.Error() != "opus: invalid argument" {
-		t.Errorf("Expected \"invalid argument\" error message for error code -1: %v")
+	if ERR_OPUS_BAD_ARG.Error() != "opus: invalid argument" {
+		t.Errorf("Expected \"invalid argument\" error message for error code %d: %v",
+			ERR_OPUS_BAD_ARG, ERR_OPUS_BAD_ARG)
 	}
 }
 
-- 
2.48.1