encoding/json: Include the offset of a SyntaxError
When a SyntaxError occurs, report the current offset within the stream.
The code already accounted for the offset within the current buffer
being scanned. By including how much data was already scanned, the
current offset can be computed.
Fixes #22478
Change-Id: I91ecd4cad0b85a5c1556bc597f3ee914e769af01
Reviewed-on: https://go-review.googlesource.com/74251
Reviewed-by: Joe Tsai <thebrokentoaster@gmail.com>
Run-TryBot: Joe Tsai <thebrokentoaster@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
diff --git a/src/encoding/json/stream.go b/src/encoding/json/stream.go
index f6b62c4..75a4270 100644
--- a/src/encoding/json/stream.go
+++ b/src/encoding/json/stream.go
@@ -12,12 +12,13 @@
// A Decoder reads and decodes JSON values from an input stream.
type Decoder struct {
- r io.Reader
- buf []byte
- d decodeState
- scanp int // start of unread data in buf
- scan scanner
- err error
+ r io.Reader
+ buf []byte
+ d decodeState
+ scanp int // start of unread data in buf
+ scanned int64 // amount of data already scanned
+ scan scanner
+ err error
tokenState int
tokenStack []int
@@ -55,7 +56,7 @@
}
if !dec.tokenValueAllowed() {
- return &SyntaxError{msg: "not at beginning of value"}
+ return &SyntaxError{msg: "not at beginning of value", Offset: dec.offset()}
}
// Read whole value into buffer.
@@ -140,6 +141,7 @@
// Make room to read more into the buffer.
// First slide down data already consumed.
if dec.scanp > 0 {
+ dec.scanned += int64(dec.scanp)
n := copy(dec.buf, dec.buf[dec.scanp:])
dec.buf = dec.buf[:n]
dec.scanp = 0
@@ -306,7 +308,7 @@
return err
}
if c != ',' {
- return &SyntaxError{"expected comma after array element", 0}
+ return &SyntaxError{"expected comma after array element", dec.offset()}
}
dec.scanp++
dec.tokenState = tokenArrayValue
@@ -316,7 +318,7 @@
return err
}
if c != ':' {
- return &SyntaxError{"expected colon after object key", 0}
+ return &SyntaxError{"expected colon after object key", dec.offset()}
}
dec.scanp++
dec.tokenState = tokenObjectValue
@@ -433,7 +435,6 @@
err := dec.Decode(&x)
dec.tokenState = old
if err != nil {
- clearOffset(err)
return nil, err
}
dec.tokenState = tokenObjectColon
@@ -447,7 +448,6 @@
}
var x interface{}
if err := dec.Decode(&x); err != nil {
- clearOffset(err)
return nil, err
}
return x, nil
@@ -455,12 +455,6 @@
}
}
-func clearOffset(err error) {
- if s, ok := err.(*SyntaxError); ok {
- s.Offset = 0
- }
-}
-
func (dec *Decoder) tokenError(c byte) (Token, error) {
var context string
switch dec.tokenState {
@@ -477,7 +471,7 @@
case tokenObjectComma:
context = " after object key:value pair"
}
- return nil, &SyntaxError{"invalid character " + quoteChar(c) + " " + context, 0}
+ return nil, &SyntaxError{"invalid character " + quoteChar(c) + " " + context, dec.offset()}
}
// More reports whether there is another element in the
@@ -505,3 +499,7 @@
err = dec.refill()
}
}
+
+func (dec *Decoder) offset() int64 {
+ return dec.scanned + int64(dec.scanp)
+}
diff --git a/src/encoding/json/stream_test.go b/src/encoding/json/stream_test.go
index d0b3ffb..83c01d1 100644
--- a/src/encoding/json/stream_test.go
+++ b/src/encoding/json/stream_test.go
@@ -342,11 +342,18 @@
{json: ` [{"a": 1} {"a": 2}] `, expTokens: []interface{}{
Delim('['),
decodeThis{map[string]interface{}{"a": float64(1)}},
- decodeThis{&SyntaxError{"expected comma after array element", 0}},
+ decodeThis{&SyntaxError{"expected comma after array element", 11}},
}},
- {json: `{ "a" 1 }`, expTokens: []interface{}{
- Delim('{'), "a",
- decodeThis{&SyntaxError{"expected colon after object key", 0}},
+ {json: `{ "` + strings.Repeat("a", 513) + `" 1 }`, expTokens: []interface{}{
+ Delim('{'), strings.Repeat("a", 513),
+ decodeThis{&SyntaxError{"expected colon after object key", 518}},
+ }},
+ {json: `{ "\a" }`, expTokens: []interface{}{
+ Delim('{'),
+ &SyntaxError{"invalid character 'a' in string escape code", 3},
+ }},
+ {json: ` \a`, expTokens: []interface{}{
+ &SyntaxError{"invalid character '\\\\' looking for beginning of value", 1},
}},
}
@@ -367,15 +374,15 @@
tk, err = dec.Token()
}
if experr, ok := etk.(error); ok {
- if err == nil || err.Error() != experr.Error() {
- t.Errorf("case %v: Expected error %v in %q, but was %v", ci, experr, tcase.json, err)
+ if err == nil || !reflect.DeepEqual(err, experr) {
+ t.Errorf("case %v: Expected error %#v in %q, but was %#v", ci, experr, tcase.json, err)
}
break
} else if err == io.EOF {
t.Errorf("case %v: Unexpected EOF in %q", ci, tcase.json)
break
} else if err != nil {
- t.Errorf("case %v: Unexpected error '%v' in %q", ci, err, tcase.json)
+ t.Errorf("case %v: Unexpected error '%#v' in %q", ci, err, tcase.json)
break
}
if !reflect.DeepEqual(tk, etk) {
