Expose SyntaxError reason with a proper error

diff --git a/bencode/api.go b/bencode/api.go
index 47f246420af8d5f2bfd2dc4babe2c33a2abfdbcc..b4ddcec983dd87a83e38f26bc4c50c552972f40b 100644 (file)
--- a/bencode/api.go
+++ b/bencode/api.go
@@ -1,10 +1,12 @@
 package bencode
 
-import "bytes"
-import "bufio"
-import "reflect"
-import "strconv"
-import "io"
+import (
+       "bufio"
+       "bytes"
+       "fmt"
+       "io"
+       "reflect"
+)
 
 //----------------------------------------------------------------------------
 // Errors
@@ -61,14 +63,12 @@ func (e *UnmarshalFieldError) Error() string {
 
 // Malformed bencode input, unmarshaler failed to parse it.
 type SyntaxError struct {
-       Offset int64  // location of the error
-       what   string // error description
+       Offset int64 // location of the error
+       What   error // error description
 }
 
 func (e *SyntaxError) Error() string {
-       return "bencode: syntax error (offset: " +
-               strconv.FormatInt(e.Offset, 10) +
-               "): " + e.what
+       return fmt.Sprintf("bencode: syntax error (offset: %d): %s", e.Offset, e.What)
 }
 
 // A non-nil error was returned after calling MarshalBencode on a type which
@@ -86,7 +86,7 @@ func (e *MarshalerError) Error() string {
 // implements the Unmarshaler interface.
 type UnmarshalerError struct {
        Type reflect.Type
-       Err error
+       Err  error
 }
 
 func (e *UnmarshalerError) Error() string {

diff --git a/bencode/decode.go b/bencode/decode.go
index 82cad32bbe4b44f27b6f8978ff70aa30123abd5b..7db899aefa7be5a9c11cf76ce12ce8cc0ed19abd 100644 (file)
--- a/bencode/decode.go
+++ b/bencode/decode.go
@@ -1,12 +1,15 @@
 package bencode
 
-import "reflect"
-import "runtime"
-import "bufio"
-import "bytes"
-import "strconv"
-import "strings"
-import "io"
+import (
+       "bufio"
+       "bytes"
+       "errors"
+       "io"
+       "reflect"
+       "runtime"
+       "strconv"
+       "strings"
+)
 
 type decoder struct {
        *bufio.Reader
@@ -38,7 +41,7 @@ func check_for_unexpected_eof(err error, offset int64) {
        if err == io.EOF {
                panic(&SyntaxError{
                        Offset: offset,
-                       what:   "unexpected EOF",
+                       What:   io.ErrUnexpectedEOF,
                })
        }
 }
@@ -70,7 +73,7 @@ func check_for_int_parse_error(err error, offset int64) {
        if err != nil {
                panic(&SyntaxError{
                        Offset: offset,
-                       what:   err.Error(),
+                       What:   err,
                })
        }
 }
@@ -82,7 +85,7 @@ func (d *decoder) parse_int(v reflect.Value) {
        if d.buf.Len() == 0 {
                panic(&SyntaxError{
                        Offset: start,
-                       what:   "empty integer value",
+                       What:   errors.New("empty integer value"),
                })
        }
 
@@ -138,7 +141,7 @@ func (d *decoder) parse_string(v reflect.Value) {
                check_for_unexpected_eof(err, d.offset)
                panic(&SyntaxError{
                        Offset: d.offset,
-                       what:   "unexpected I/O error: " + err.Error(),
+                       What:   errors.New("unexpected I/O error: " + err.Error()),
                })
        }
 
@@ -254,7 +257,7 @@ func (d *decoder) parse_dict(v reflect.Value) {
                                if !ok {
                                        panic(&SyntaxError{
                                                Offset: d.offset,
-                                               what:   "unexpected end of dict, no matching value for a given key",
+                                               What:   errors.New("unexpected end of dict, no matching value for a given key"),
                                        })
                                }
                                continue
@@ -265,7 +268,7 @@ func (d *decoder) parse_dict(v reflect.Value) {
                if !d.parse_value(valuev) {
                        panic(&SyntaxError{
                                Offset: d.offset,
-                               what:   "unexpected end of dict, no matching value for a given key",
+                               What:   errors.New("unexpected end of dict, no matching value for a given key"),
                        })
                }
 
@@ -359,7 +362,7 @@ func (d *decoder) read_one_value() bool {
                                check_for_unexpected_eof(err, d.offset)
                                panic(&SyntaxError{
                                        Offset: d.offset,
-                                       what:   "unexpected I/O error: " + err.Error(),
+                                       What:   errors.New("unexpected I/O error: " + err.Error()),
                                })
                        }
                        break
@@ -368,7 +371,7 @@ func (d *decoder) read_one_value() bool {
                // unknown value
                panic(&SyntaxError{
                        Offset: d.offset - 1,
-                       what:   "unknown value type (invalid bencode?)",
+                       What:   errors.New("unknown value type (invalid bencode?)"),
                })
        }
 
@@ -453,7 +456,7 @@ func (d *decoder) parse_value(v reflect.Value) bool {
                // unknown value
                panic(&SyntaxError{
                        Offset: d.offset - 1,
-                       what:   "unknown value type (invalid bencode?)",
+                       What:   errors.New("unknown value type (invalid bencode?)"),
                })
        }
 
@@ -487,7 +490,7 @@ func (d *decoder) parse_value_interface() (interface{}, bool) {
                // unknown value
                panic(&SyntaxError{
                        Offset: d.offset - 1,
-                       what:   "unknown value type (invalid bencode?)",
+                       What:   errors.New("unknown value type (invalid bencode?)"),
                })
        }
        panic("unreachable")
@@ -499,7 +502,7 @@ func (d *decoder) parse_int_interface() interface{} {
        if d.buf.Len() == 0 {
                panic(&SyntaxError{
                        Offset: start,
-                       what:   "empty integer value",
+                       What:   errors.New("empty integer value"),
                })
        }
 
@@ -524,7 +527,7 @@ func (d *decoder) parse_string_interface() interface{} {
                check_for_unexpected_eof(err, d.offset)
                panic(&SyntaxError{
                        Offset: d.offset,
-                       what:   "unexpected I/O error: " + err.Error(),
+                       What:   errors.New("unexpected I/O error: " + err.Error()),
                })
        }
 
@@ -545,7 +548,7 @@ func (d *decoder) parse_dict_interface() interface{} {
                if !ok {
                        panic(&SyntaxError{
                                Offset: d.offset,
-                               what:   "non-string key in a dict",
+                               What:   errors.New("non-string key in a dict"),
                        })
                }
 
@@ -553,7 +556,7 @@ func (d *decoder) parse_dict_interface() interface{} {
                if !ok {
                        panic(&SyntaxError{
                                Offset: d.offset,
-                               what:   "unexpected end of dict, no matching value for a given key",
+                               What:   errors.New("unexpected end of dict, no matching value for a given key"),
                        })
                }