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Diffstat (limited to 'pdf')
-rw-r--r--pdf/pdf.go196
1 files changed, 114 insertions, 82 deletions
diff --git a/pdf/pdf.go b/pdf/pdf.go
index 1cd2c2c..bbcafe0 100644
--- a/pdf/pdf.go
+++ b/pdf/pdf.go
@@ -65,8 +65,6 @@ const (
// Object is a PDF token/object thingy. Objects may be composed either from
// one or a sequence of tokens. The PDF Reference doesn't actually speak
// of tokens.
-//
-// TODO(p): We probably want constructors like NewString, NewBool, NewArray, ...
type Object struct {
Kind ObjectKind
@@ -93,6 +91,48 @@ func (o *Object) IsUint() bool {
return o.IsInteger() && o.Number >= 0 && o.Number <= float64(^uint(0))
}
+// 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} }
+
+func NewBool(b bool) Object {
+ var b64 float64
+ if b {
+ b64 = 1
+ }
+ return Object{Kind: Bool, Number: b64}
+}
+
+func NewNumeric(n float64) Object { return Object{Kind: Numeric, Number: n} }
+func NewName(n string) Object { return Object{Kind: Name, String: n} }
+func NewString(s string) Object { return Object{Kind: String, String: s} }
+
+func NewArray(a []Object) Object {
+ return Object{Kind: Array, Array: a}
+}
+
+func NewDict(d map[string]Object) Object {
+ if d == nil {
+ d = make(map[string]Object)
+ }
+ return Object{Kind: Dict, Dict: d}
+}
+
+func NewIndirect(o Object, n, generation uint) Object {
+ return Object{Kind: Indirect, N: n, Generation: generation,
+ Array: []Object{o}}
+}
+
+func NewReference(n, generation uint) Object {
+ return Object{Kind: Reference, N: n, Generation: generation}
+}
+
// -----------------------------------------------------------------------------
const (
@@ -171,7 +211,7 @@ func (lex *Lexer) string() Object {
for {
ch, ok := lex.read()
if !ok {
- return Object{Kind: End, String: "unexpected end of string"}
+ return NewError("unexpected end of string")
}
if lex.eatNewline(ch) {
ch = '\n'
@@ -183,7 +223,7 @@ func (lex *Lexer) string() Object {
}
} else if ch == '\\' {
if ch, ok = lex.read(); !ok {
- return Object{Kind: End, String: "unexpected end of string"}
+ return NewError("unexpected end of string")
} else if lex.eatNewline(ch) {
continue
} else {
@@ -192,7 +232,7 @@ func (lex *Lexer) string() Object {
}
value = append(value, ch)
}
- return Object{Kind: String, String: string(value)}
+ return NewString(string(value))
}
func (lex *Lexer) stringHex() Object {
@@ -200,11 +240,11 @@ func (lex *Lexer) stringHex() Object {
for {
ch, ok := lex.read()
if !ok {
- return Object{Kind: End, String: "unexpected end of hex string"}
+ return NewError("unexpected end of hex string")
} else if ch == '>' {
break
} else if strings.IndexByte(hexAlphabet, ch) < 0 {
- return Object{Kind: End, String: "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))
@@ -215,7 +255,7 @@ func (lex *Lexer) stringHex() Object {
u, _ := strconv.ParseUint(string(buf)+"0", 16, 8)
value = append(value, byte(u))
}
- return Object{Kind: String, String: string(value)}
+ return NewString(string(value))
}
func (lex *Lexer) name() Object {
@@ -237,7 +277,7 @@ func (lex *Lexer) name() Object {
lex.read()
}
if len(hexa) != 2 {
- return Object{Kind: End, String: "invalid name hexa escape"}
+ return NewError("invalid name hexa escape")
}
u, _ := strconv.ParseUint(string(value), 16, 8)
ch = byte(u)
@@ -245,9 +285,9 @@ func (lex *Lexer) name() Object {
value = append(value, ch)
}
if len(value) == 0 {
- return Object{Kind: End, String: "unexpected end of name"}
+ return NewError("unexpected end of name")
}
- return Object{Kind: Name, String: string(value)}
+ return NewName(string(value))
}
func (lex *Lexer) comment() Object {
@@ -260,7 +300,7 @@ func (lex *Lexer) comment() Object {
value = append(value, ch)
lex.read()
}
- return Object{Kind: Comment, String: string(value)}
+ return NewComment(string(value))
}
// XXX: Maybe invalid numbers should rather be interpreted as keywords.
@@ -287,16 +327,16 @@ func (lex *Lexer) number() Object {
lex.read()
}
if !digits {
- return Object{Kind: End, String: "invalid number"}
+ return NewError("invalid number")
}
f, _ := strconv.ParseFloat(string(value), 64)
- return Object{Kind: Numeric, Number: f}
+ return NewNumeric(f)
}
func (lex *Lexer) Next() Object {
ch, ok := lex.peek()
if !ok {
- return Object{Kind: End}
+ return NewEOF()
}
if strings.IndexByte("-0123456789.", ch) >= 0 {
return lex.number()
@@ -315,13 +355,13 @@ func (lex *Lexer) Next() Object {
switch v := string(value); v {
case "":
case "null":
- return Object{Kind: Nil}
+ return New(Nil)
case "true":
- return Object{Kind: Bool, Number: 1}
+ return NewBool(true)
case "false":
- return Object{Kind: Bool, Number: 0}
+ return NewBool(false)
default:
- return Object{Kind: Keyword, String: v}
+ return NewKeyword(v)
}
switch ch, _ := lex.read(); ch {
@@ -332,29 +372,29 @@ func (lex *Lexer) Next() Object {
case '(':
return lex.string()
case '[':
- return Object{Kind: BArray}
+ return New(BArray)
case ']':
- return Object{Kind: EArray}
+ return New(EArray)
case '<':
if ch, _ := lex.peek(); ch == '<' {
lex.read()
- return Object{Kind: BDict}
+ return New(BDict)
}
return lex.stringHex()
case '>':
if ch, _ := lex.peek(); ch == '>' {
lex.read()
- return Object{Kind: EDict}
+ return New(EDict)
}
- return Object{Kind: End, String: "unexpected '>'"}
+ return NewError("unexpected '>'")
default:
if lex.eatNewline(ch) {
- return Object{Kind: NL}
+ return New(NL)
}
if strings.IndexByte(whitespace, ch) >= 0 {
return lex.Next()
}
- return Object{Kind: End, String: "unexpected input"}
+ return NewError("unexpected input")
}
}
@@ -464,7 +504,7 @@ type Updater struct {
func (u *Updater) parseIndirect(lex *Lexer, stack *[]Object) Object {
lenStack := len(*stack)
if lenStack < 2 {
- return Object{Kind: End, String: "missing object ID pair"}
+ return NewError("missing object ID pair")
}
n := (*stack)[lenStack-2]
@@ -472,28 +512,30 @@ func (u *Updater) parseIndirect(lex *Lexer, stack *[]Object) Object {
*stack = (*stack)[:lenStack-2]
if !g.IsUint() || !n.IsUint() {
- return Object{Kind: End, String: "invalid object ID pair"}
+ return NewError("invalid object ID pair")
}
- obj := Object{
- Kind: Indirect, N: uint(n.Number), Generation: uint(g.Number)}
+ var inner []Object
for {
- object := u.parse(lex, &obj.Array)
+ object := u.parse(lex, &inner)
if object.Kind == End {
- return Object{Kind: End, String: "object doesn't end"}
+ return NewError("object doesn't end")
}
if object.Kind == Keyword && object.String == "endobj" {
break
}
- obj.Array = append(obj.Array, object)
+ inner = append(inner, object)
+ }
+ if len(inner) != 1 {
+ return NewError("indirect objects must contain exactly one object")
}
- return obj
+ return NewIndirect(inner[0], uint(n.Number), uint(g.Number))
}
func (u *Updater) parseR(stack *[]Object) Object {
lenStack := len(*stack)
if lenStack < 2 {
- return Object{Kind: End, String: "missing reference ID pair"}
+ return NewError("missing reference ID pair")
}
n := (*stack)[lenStack-2]
@@ -501,10 +543,9 @@ func (u *Updater) parseR(stack *[]Object) Object {
*stack = (*stack)[:lenStack-2]
if !g.IsUint() || !n.IsUint() {
- return Object{Kind: End, String: "invalid reference ID pair"}
+ return NewError("invalid reference ID pair")
}
- return Object{
- Kind: Reference, N: uint(n.Number), Generation: uint(g.Number)}
+ return NewReference(uint(n.Number), uint(g.Number))
}
/// parse reads an object at the lexer's position. Not a strict parser.
@@ -519,20 +560,20 @@ func (u *Updater) parse(lex *Lexer, stack *[]Object) Object {
for {
object := u.parse(lex, &array)
if object.Kind == End {
- return Object{Kind: End, String: "array doesn't end"}
+ return NewError("array doesn't end")
}
if object.Kind == EArray {
break
}
array = append(array, object)
}
- return Object{Kind: Array, Array: array}
+ return NewArray(array)
case BDict:
var array []Object
for {
object := u.parse(lex, &array)
if object.Kind == End {
- return Object{Kind: End, String: "dictionary doesn't end"}
+ return NewError("dictionary doesn't end")
}
if object.Kind == EDict {
break
@@ -540,17 +581,16 @@ func (u *Updater) parse(lex *Lexer, stack *[]Object) Object {
array = append(array, object)
}
if len(array)%2 != 0 {
- return Object{Kind: End, String: "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 Object{
- Kind: End, String: "invalid dictionary key type"}
+ return NewError("invalid dictionary key type")
}
dict[array[i].String] = array[i+1]
}
- return Object{Kind: Dict, Dict: dict}
+ return NewDict(dict)
case Keyword:
// Appears in the document body, typically needs
// to access the cross-reference table.
@@ -560,7 +600,7 @@ func (u *Updater) parse(lex *Lexer, stack *[]Object) Object {
// streams can use the Object.String member.
switch token.String {
case "stream":
- return Object{Kind: End, String: "streams are not supported yet"}
+ return NewError("streams are not supported yet")
case "obj":
return u.parseIndirect(lex, stack)
case "R":
@@ -690,8 +730,7 @@ func (u *Updater) Initialize() error {
xrefOffset = int64(prevOffset.Number)
}
- u.Trailer["Prev"] = Object{
- Kind: Numeric, Number: float64(lastXrefOffset)}
+ u.Trailer["Prev"] = NewNumeric(float64(lastXrefOffset))
lastSize, ok := u.Trailer["Size"]
if !ok || !lastSize.IsInteger() || lastSize.Number <= 0 {
@@ -705,13 +744,13 @@ func (u *Updater) Initialize() error {
// Nil or End with an error.
func (u *Updater) Get(n, generation uint) Object {
if n >= u.xrefSize {
- return Object{Kind: Nil}
+ return New(Nil)
}
ref := u.xref[n]
if !ref.nonfree || ref.generation != generation ||
ref.offset >= int64(len(u.Document)) {
- return Object{Kind: Nil}
+ return New(Nil)
}
lex := Lexer{u.Document[ref.offset:]}
@@ -724,7 +763,7 @@ func (u *Updater) Get(n, generation uint) Object {
if object.Kind != Indirect {
stack = append(stack, object)
} else if object.N != n || object.Generation != generation {
- return Object{Kind: End, String: "object mismatch"}
+ return NewError("object mismatch")
} else {
return object.Array[0]
}
@@ -819,8 +858,8 @@ func (u *Updater) FlushUpdates() {
}
}
- u.Trailer["Size"] = Object{Kind: Numeric, Number: float64(u.xrefSize)}
- trailer := Object{Kind: Dict, Dict: u.Trailer}
+ u.Trailer["Size"] = NewNumeric(float64(u.xrefSize))
+ trailer := NewDict(u.Trailer)
fmt.Fprintf(buf, "trailer\n%s\nstartxref\n%d\n%%%%EOF\n",
trailer.Serialize(), startXref)
@@ -839,14 +878,14 @@ func NewDate(ts time.Time) Object {
} else {
buf = append(buf, 'Z')
}
- return Object{Kind: String, String: string(buf)}
+ return NewString(string(buf))
}
// 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)
if obj.Kind != Dict {
- return Object{Kind: Nil}
+ return New(Nil)
}
// Out of convenience; these aren't filled normally.
@@ -854,11 +893,11 @@ func GetFirstPage(pdf *Updater, nodeN, nodeGeneration uint) Object {
obj.Generation = nodeGeneration
if typ, ok := obj.Dict["Type"]; !ok || typ.Kind != Name {
- return Object{Kind: Nil}
+ return New(Nil)
} else if typ.String == "Page" {
return obj
} else if typ.String != "Pages" {
- return Object{Kind: Nil}
+ return New(Nil)
}
// XXX: Technically speaking, this may be an indirect reference.
@@ -867,7 +906,7 @@ func GetFirstPage(pdf *Updater, nodeN, nodeGeneration uint) Object {
kids, ok := obj.Dict["Kids"]
if !ok || kids.Kind != Array || len(kids.Array) == 0 ||
kids.Array[0].Kind != Reference {
- return Object{Kind: Nil}
+ return New(Nil)
}
// XXX: Nothing prevents us from recursing in an evil circular graph.
@@ -1096,22 +1135,19 @@ func Sign(document []byte, key crypto.PrivateKey, certs []*x509.Certificate) (
signLen += 2
})
- sigfield := Object{Kind: Dict, Dict: map[string]Object{
+ sigfield := NewDict(map[string]Object{
// 8.6.3 Field Types - Signature Fields
- "FT": {Kind: Name, String: "Sig"},
- "V": {Kind: Reference, N: sigdictN, Generation: 0},
+ "FT": NewName("Sig"),
+ "V": NewReference(sigdictN, 0),
// 8.4.5 Annotations Types - Widget Annotations
// We can merge the Signature Annotation and omit Kids here.
- "Subtype": {Kind: Name, String: "Widget"},
- "F": {Kind: Numeric, Number: 2 /* Hidden */},
- "T": {Kind: String, String: "Signature1"},
- "Rect": {Kind: Array, Array: []Object{
- {Kind: Numeric, Number: 0},
- {Kind: Numeric, Number: 0},
- {Kind: Numeric, Number: 0},
- {Kind: Numeric, Number: 0},
- }},
- }}
+ "Subtype": NewName("Widget"),
+ "F": NewNumeric(2 /* Hidden */),
+ "T": NewString("Signature1"),
+ "Rect": NewArray([]Object{
+ NewNumeric(0), NewNumeric(0), NewNumeric(0), NewNumeric(0),
+ }),
+ })
sigfieldN := pdf.Allocate()
pdf.Update(sigfieldN, func(buf BytesWriter) {
@@ -1130,10 +1166,9 @@ func Sign(document []byte, key crypto.PrivateKey, certs []*x509.Certificate) (
// XXX: Assuming this won't be an indirectly referenced array.
annots := page.Dict["Annots"]
if annots.Kind != Array {
- annots = Object{Kind: Array}
+ annots = NewArray(nil)
}
- annots.Array = append(annots.Array, Object{
- Kind: Reference, N: sigfieldN, Generation: 0})
+ annots.Array = append(annots.Array, NewReference(sigfieldN, 0))
page.Dict["Annots"] = annots
pdf.Update(page.N, func(buf BytesWriter) {
@@ -1142,19 +1177,16 @@ func Sign(document []byte, key crypto.PrivateKey, certs []*x509.Certificate) (
// 8.6.1 Interactive Form Dictionary
// XXX: Assuming there are no forms already, overwriting everything.
- root.Dict["AcroForm"] = Object{Kind: Dict, Dict: map[string]Object{
- "Fields": {Kind: Array, Array: []Object{
- {Kind: Reference, N: sigfieldN, Generation: 0},
- }},
- "SigFlags": {Kind: Numeric,
- Number: 3 /* SignaturesExist | AppendOnly */},
- }}
+ root.Dict["AcroForm"] = NewDict(map[string]Object{
+ "Fields": NewArray([]Object{NewReference(sigfieldN, 0)}),
+ "SigFlags": NewNumeric(3 /* SignaturesExist | AppendOnly */),
+ })
// Upgrade the document version for SHA-256 etc.
// XXX: Assuming that it's not newer than 1.6 already--while Cairo can't
// currently use a newer version that 1.5, it's not a bad idea to use
// cairo_pdf_surface_restrict_to_version().
- root.Dict["Version"] = Object{Kind: Name, String: "1.6"}
+ root.Dict["Version"] = NewName("1.6")
pdf.Update(rootRef.N, func(buf BytesWriter) {
buf.WriteString(root.Serialize())
})