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Diffstat (limited to 'pdf')
-rw-r--r--pdf/pdf.go152
1 files changed, 77 insertions, 75 deletions
diff --git a/pdf/pdf.go b/pdf/pdf.go
index bbcafe0..3292149 100644
--- a/pdf/pdf.go
+++ b/pdf/pdf.go
@@ -68,7 +68,7 @@ const (
type Object struct {
Kind ObjectKind
- // End (error message), Comment/Keyword/Name/String
+ // Comment/Keyword/Name/String
String string
// Bool, Numeric
Number float64
@@ -92,11 +92,7 @@ func (o *Object) IsUint() bool {
}
// A slew of constructors that will hopefully get all inlined.
-// TODO(p): We should probably ditch NewError for multiple return values.
-// It could be a private function that returns New(End) and error.
-func NewEOF() Object { return Object{Kind: End} }
-func NewError(e string) Object { return Object{Kind: End, String: e} }
func NewComment(c string) Object { return Object{Kind: Comment, String: c} }
func NewKeyword(k string) Object { return Object{Kind: Keyword, String: k} }
func New(kind ObjectKind) Object { return Object{Kind: kind} }
@@ -133,6 +129,8 @@ func NewReference(n, generation uint) Object {
return Object{Kind: Reference, N: n, Generation: generation}
}
+func newError(msg string) (Object, error) { return New(End), errors.New(msg) }
+
// -----------------------------------------------------------------------------
const (
@@ -205,13 +203,13 @@ func (lex *Lexer) unescape(ch byte) byte {
return ch
}
-func (lex *Lexer) string() Object {
+func (lex *Lexer) string() (Object, error) {
var value []byte
parens := 1
for {
ch, ok := lex.read()
if !ok {
- return NewError("unexpected end of string")
+ return newError("unexpected end of string")
}
if lex.eatNewline(ch) {
ch = '\n'
@@ -223,7 +221,7 @@ func (lex *Lexer) string() Object {
}
} else if ch == '\\' {
if ch, ok = lex.read(); !ok {
- return NewError("unexpected end of string")
+ return newError("unexpected end of string")
} else if lex.eatNewline(ch) {
continue
} else {
@@ -232,19 +230,19 @@ func (lex *Lexer) string() Object {
}
value = append(value, ch)
}
- return NewString(string(value))
+ return NewString(string(value)), nil
}
-func (lex *Lexer) stringHex() Object {
+func (lex *Lexer) stringHex() (Object, error) {
var value, buf []byte
for {
ch, ok := lex.read()
if !ok {
- return NewError("unexpected end of hex string")
+ return newError("unexpected end of hex string")
} else if ch == '>' {
break
} else if strings.IndexByte(hexAlphabet, ch) < 0 {
- return NewError("invalid hex string")
+ return newError("invalid hex string")
} else if buf = append(buf, ch); len(buf) == 2 {
u, _ := strconv.ParseUint(string(buf), 16, 8)
value = append(value, byte(u))
@@ -255,10 +253,10 @@ func (lex *Lexer) stringHex() Object {
u, _ := strconv.ParseUint(string(buf)+"0", 16, 8)
value = append(value, byte(u))
}
- return NewString(string(value))
+ return NewString(string(value)), nil
}
-func (lex *Lexer) name() Object {
+func (lex *Lexer) name() (Object, error) {
var value []byte
for {
ch, ok := lex.peek()
@@ -277,7 +275,7 @@ func (lex *Lexer) name() Object {
lex.read()
}
if len(hexa) != 2 {
- return NewError("invalid name hexa escape")
+ return newError("invalid name hexa escape")
}
u, _ := strconv.ParseUint(string(value), 16, 8)
ch = byte(u)
@@ -285,12 +283,12 @@ func (lex *Lexer) name() Object {
value = append(value, ch)
}
if len(value) == 0 {
- return NewError("unexpected end of name")
+ return newError("unexpected end of name")
}
- return NewName(string(value))
+ return NewName(string(value)), nil
}
-func (lex *Lexer) comment() Object {
+func (lex *Lexer) comment() (Object, error) {
var value []byte
for {
ch, ok := lex.peek()
@@ -300,11 +298,11 @@ func (lex *Lexer) comment() Object {
value = append(value, ch)
lex.read()
}
- return NewComment(string(value))
+ return NewComment(string(value)), nil
}
// XXX: Maybe invalid numbers should rather be interpreted as keywords.
-func (lex *Lexer) number() Object {
+func (lex *Lexer) number() (Object, error) {
var value []byte
ch, ok := lex.peek()
if ch == '-' {
@@ -327,16 +325,16 @@ func (lex *Lexer) number() Object {
lex.read()
}
if !digits {
- return NewError("invalid number")
+ return newError("invalid number")
}
f, _ := strconv.ParseFloat(string(value), 64)
- return NewNumeric(f)
+ return NewNumeric(f), nil
}
-func (lex *Lexer) Next() Object {
+func (lex *Lexer) Next() (Object, error) {
ch, ok := lex.peek()
if !ok {
- return NewEOF()
+ return New(End), nil
}
if strings.IndexByte("-0123456789.", ch) >= 0 {
return lex.number()
@@ -355,13 +353,13 @@ func (lex *Lexer) Next() Object {
switch v := string(value); v {
case "":
case "null":
- return New(Nil)
+ return New(Nil), nil
case "true":
- return NewBool(true)
+ return NewBool(true), nil
case "false":
- return NewBool(false)
+ return NewBool(false), nil
default:
- return NewKeyword(v)
+ return NewKeyword(v), nil
}
switch ch, _ := lex.read(); ch {
@@ -372,29 +370,29 @@ func (lex *Lexer) Next() Object {
case '(':
return lex.string()
case '[':
- return New(BArray)
+ return New(BArray), nil
case ']':
- return New(EArray)
+ return New(EArray), nil
case '<':
if ch, _ := lex.peek(); ch == '<' {
lex.read()
- return New(BDict)
+ return New(BDict), nil
}
return lex.stringHex()
case '>':
if ch, _ := lex.peek(); ch == '>' {
lex.read()
- return New(EDict)
+ return New(EDict), nil
}
- return NewError("unexpected '>'")
+ return newError("unexpected '>'")
default:
if lex.eatNewline(ch) {
- return New(NL)
+ return New(NL), nil
}
if strings.IndexByte(whitespace, ch) >= 0 {
return lex.Next()
}
- return NewError("unexpected input")
+ return newError("unexpected input")
}
}
@@ -501,10 +499,10 @@ type Updater struct {
Trailer map[string]Object
}
-func (u *Updater) parseIndirect(lex *Lexer, stack *[]Object) Object {
+func (u *Updater) parseIndirect(lex *Lexer, stack *[]Object) (Object, error) {
lenStack := len(*stack)
if lenStack < 2 {
- return NewError("missing object ID pair")
+ return newError("missing object ID pair")
}
n := (*stack)[lenStack-2]
@@ -512,14 +510,14 @@ func (u *Updater) parseIndirect(lex *Lexer, stack *[]Object) Object {
*stack = (*stack)[:lenStack-2]
if !g.IsUint() || !n.IsUint() {
- return NewError("invalid object ID pair")
+ return newError("invalid object ID pair")
}
var inner []Object
for {
- object := u.parse(lex, &inner)
+ object, _ := u.parse(lex, &inner)
if object.Kind == End {
- return NewError("object doesn't end")
+ return newError("object doesn't end")
}
if object.Kind == Keyword && object.String == "endobj" {
break
@@ -527,15 +525,15 @@ func (u *Updater) parseIndirect(lex *Lexer, stack *[]Object) Object {
inner = append(inner, object)
}
if len(inner) != 1 {
- return NewError("indirect objects must contain exactly one object")
+ return newError("indirect objects must contain exactly one object")
}
- return NewIndirect(inner[0], uint(n.Number), uint(g.Number))
+ return NewIndirect(inner[0], uint(n.Number), uint(g.Number)), nil
}
-func (u *Updater) parseR(stack *[]Object) Object {
+func (u *Updater) parseR(stack *[]Object) (Object, error) {
lenStack := len(*stack)
if lenStack < 2 {
- return NewError("missing reference ID pair")
+ return newError("missing reference ID pair")
}
n := (*stack)[lenStack-2]
@@ -543,14 +541,16 @@ func (u *Updater) parseR(stack *[]Object) Object {
*stack = (*stack)[:lenStack-2]
if !g.IsUint() || !n.IsUint() {
- return NewError("invalid reference ID pair")
+ return newError("invalid reference ID pair")
}
- return NewReference(uint(n.Number), uint(g.Number))
+ return NewReference(uint(n.Number), uint(g.Number)), nil
}
-/// parse reads an object at the lexer's position. Not a strict parser.
-func (u *Updater) parse(lex *Lexer, stack *[]Object) Object {
- switch token := lex.Next(); token.Kind {
+// parse reads an object at the lexer's position. Not a strict parser.
+//
+// TODO(p): We should fix all uses of this not to eat the error.
+func (u *Updater) parse(lex *Lexer, stack *[]Object) (Object, error) {
+ switch token, err := lex.Next(); token.Kind {
case NL, Comment:
// These are not important to parsing,
// not even for this procedure's needs.
@@ -558,22 +558,22 @@ func (u *Updater) parse(lex *Lexer, stack *[]Object) Object {
case BArray:
var array []Object
for {
- object := u.parse(lex, &array)
+ object, _ := u.parse(lex, &array)
if object.Kind == End {
- return NewError("array doesn't end")
+ return newError("array doesn't end")
}
if object.Kind == EArray {
break
}
array = append(array, object)
}
- return NewArray(array)
+ return NewArray(array), nil
case BDict:
var array []Object
for {
- object := u.parse(lex, &array)
+ object, _ := u.parse(lex, &array)
if object.Kind == End {
- return NewError("dictionary doesn't end")
+ return newError("dictionary doesn't end")
}
if object.Kind == EDict {
break
@@ -581,16 +581,16 @@ func (u *Updater) parse(lex *Lexer, stack *[]Object) Object {
array = append(array, object)
}
if len(array)%2 != 0 {
- return NewError("unbalanced dictionary")
+ return newError("unbalanced dictionary")
}
dict := make(map[string]Object)
for i := 0; i < len(array); i += 2 {
if array[i].Kind != Name {
- return NewError("invalid dictionary key type")
+ return newError("invalid dictionary key type")
}
dict[array[i].String] = array[i+1]
}
- return NewDict(dict)
+ return NewDict(dict), nil
case Keyword:
// Appears in the document body, typically needs
// to access the cross-reference table.
@@ -600,7 +600,7 @@ func (u *Updater) parse(lex *Lexer, stack *[]Object) Object {
// streams can use the Object.String member.
switch token.String {
case "stream":
- return NewError("streams are not supported yet")
+ return newError("streams are not supported yet")
case "obj":
return u.parseIndirect(lex, stack)
case "R":
@@ -608,18 +608,18 @@ func (u *Updater) parse(lex *Lexer, stack *[]Object) Object {
}
fallthrough
default:
- return token
+ return token, err
}
}
func (u *Updater) loadXref(lex *Lexer, loadedEntries map[uint]struct{}) error {
var throwawayStack []Object
- if keyword := u.parse(lex,
+ if keyword, _ := u.parse(lex,
&throwawayStack); keyword.Kind != Keyword || keyword.String != "xref" {
return errors.New("invalid xref table")
}
for {
- object := u.parse(lex, &throwawayStack)
+ object, _ := u.parse(lex, &throwawayStack)
if object.Kind == End {
return errors.New("unexpected EOF while looking for the trailer")
}
@@ -627,16 +627,16 @@ func (u *Updater) loadXref(lex *Lexer, loadedEntries map[uint]struct{}) error {
break
}
- second := u.parse(lex, &throwawayStack)
+ second, _ := u.parse(lex, &throwawayStack)
if !object.IsUint() || !second.IsUint() {
return errors.New("invalid xref section header")
}
start, count := uint(object.Number), uint(second.Number)
for i := uint(0); i < count; i++ {
- off := u.parse(lex, &throwawayStack)
- gen := u.parse(lex, &throwawayStack)
- key := u.parse(lex, &throwawayStack)
+ off, _ := u.parse(lex, &throwawayStack)
+ gen, _ := u.parse(lex, &throwawayStack)
+ key, _ := u.parse(lex, &throwawayStack)
if !off.IsInteger() || off.Number < 0 ||
off.Number > float64(len(u.Document)) ||
!gen.IsInteger() || gen.Number < 0 || gen.Number > 65535 ||
@@ -710,7 +710,7 @@ func (u *Updater) Initialize() error {
return err
}
- trailer := u.parse(&lex, &throwawayStack)
+ trailer, _ := u.parse(&lex, &throwawayStack)
if trailer.Kind != Dict {
return errors.New("invalid trailer dictionary")
}
@@ -742,30 +742,32 @@ func (u *Updater) Initialize() error {
// Get retrieves an object by its number and generation--may return
// Nil or End with an error.
-func (u *Updater) Get(n, generation uint) Object {
+//
+// TODO(p): We should fix all uses of this not to eat the error.
+func (u *Updater) Get(n, generation uint) (Object, error) {
if n >= u.xrefSize {
- return New(Nil)
+ return New(Nil), nil
}
ref := u.xref[n]
if !ref.nonfree || ref.generation != generation ||
ref.offset >= int64(len(u.Document)) {
- return New(Nil)
+ return New(Nil), nil
}
lex := Lexer{u.Document[ref.offset:]}
var stack []Object
for {
- object := u.parse(&lex, &stack)
+ object, err := u.parse(&lex, &stack)
if object.Kind == End {
- return object
+ return object, err
}
if object.Kind != Indirect {
stack = append(stack, object)
} else if object.N != n || object.Generation != generation {
- return NewError("object mismatch")
+ return newError("object mismatch")
} else {
- return object.Array[0]
+ return object.Array[0], nil
}
}
}
@@ -883,7 +885,7 @@ func NewDate(ts time.Time) Object {
// GetFirstPage retrieves the first page of the document or a Nil object.
func GetFirstPage(pdf *Updater, nodeN, nodeGeneration uint) Object {
- obj := pdf.Get(nodeN, nodeGeneration)
+ obj, _ := pdf.Get(nodeN, nodeGeneration)
if obj.Kind != Dict {
return New(Nil)
}
@@ -1104,7 +1106,7 @@ func Sign(document []byte, key crypto.PrivateKey, certs []*x509.Certificate) (
if !ok || rootRef.Kind != Reference {
return nil, errors.New("trailer does not contain a reference to Root")
}
- root := pdf.Get(rootRef.N, rootRef.Generation)
+ root, _ := pdf.Get(rootRef.N, rootRef.Generation)
if root.Kind != Dict {
return nil, errors.New("invalid Root dictionary reference")
}
generated by cgit v1.2.3-70-g09d2 (git 2.47.0) at 2024-11-23 02:29:41 +0000