diff options
| -rw-r--r-- | pdf/pdf.go | 66 |
1 files changed, 58 insertions, 8 deletions
@@ -59,6 +59,7 @@ const ( // higher-level objects Array Dict + Stream Indirect Reference ) @@ -72,7 +73,8 @@ type Object struct { String string // Comment/Keyword/Name/String Number float64 // Bool, Numeric Array []Object // Array, Indirect - Dict map[string]Object // Dict, in the future also Stream + Dict map[string]Object // Dict, Stream + Stream []byte // Stream N, Generation uint // Indirect, Reference } @@ -458,6 +460,10 @@ func (o *Object) Serialize() string { fmt.Fprint(b, " /", k, " ", v.Serialize()) } return "<<" + b.String() + " >>" + case Stream: + d := NewDict(o.Dict) + d.Dict["Length"] = NewNumeric(float64(len(o.Stream))) + return d.Serialize() + "\nstream\n" + string(o.Stream) + "\nendstream" case Indirect: return fmt.Sprintf("%d %d obj\n%s\nendobj", o.N, o.Generation, o.Array[0].Serialize()) @@ -497,6 +503,54 @@ type Updater struct { Trailer map[string]Object } +func (u *Updater) parseStream(lex *Lexer, stack *[]Object) (Object, error) { + lenStack := len(*stack) + if lenStack < 1 { + return newError("missing stream dictionary") + } + dict := (*stack)[lenStack-1] + if dict.Kind != Dict { + return newError("stream not preceded by a dictionary") + } + + *stack = (*stack)[:lenStack-1] + length, ok := dict.Dict["Length"] + if !ok { + return newError("missing stream Length") + } + length, err := u.Dereference(length) + if err != nil { + return length, err + } + if !length.IsUint() || length.Number > math.MaxInt { + return newError("stream Length not an unsigned integer") + } + + // Expect exactly one newline. + if nl, err := lex.Next(); err != nil { + return nl, err + } else if nl.Kind != NL { + return newError("stream does not start with a newline") + } + + size := int(length.Number) + if len(lex.P) < size { + return newError("stream is longer than the document") + } + + dict.Kind = Stream + dict.Stream = lex.P[:size] + lex.P = lex.P[size:] + + // Skip any number of trailing newlines or comments. + if end, err := u.parse(lex, stack); err != nil { + return end, err + } else if end.Kind != Keyword || end.String != "endstream" { + return newError("improperly terminated stream") + } + return dict, nil +} + func (u *Updater) parseIndirect(lex *Lexer, stack *[]Object) (Object, error) { lenStack := len(*stack) if lenStack < 2 { @@ -590,15 +644,11 @@ func (u *Updater) parse(lex *Lexer, stack *[]Object) (Object, error) { } return NewDict(dict), nil case Keyword: - // Appears in the document body, typically needs - // to access the cross-reference table. - // - // TODO(p): Use the xref to read /Length etc. once we - // actually need to read such objects; presumably - // streams can use the Object.String member. switch token.String { case "stream": - return newError("streams are not supported yet") + // Appears in the document body, + // typically needs to access the cross-reference table. + return u.parseStream(lex, stack) case "obj": return u.parseIndirect(lex, stack) case "R": |