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Go: less API stupidity coming from the C++ heritage

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This commit is contained in:
Přemysl Eric Janouch
2018-10-04 14:46:12 +02:00
parent 9d2412398a
commit 0ea296de67
1 changed files with 20 additions and 19 deletions
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39
pdf/pdf.go
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@@ -141,21 +141,21 @@ const (
// Lexer is a basic lexical analyser for the Portable Document Format,
// giving limited error information.
type Lexer struct {
p []byte // input buffer
P []byte // input buffer
}
func (lex *Lexer) read() (byte, bool) {
if len(lex.p) > 0 {
ch := lex.p[0]
lex.p = lex.p[1:]
if len(lex.P) > 0 {
ch := lex.P[0]
lex.P = lex.P[1:]
return ch, true
}
return 0, false
}
func (lex *Lexer) peek() (byte, bool) {
if len(lex.p) > 0 {
return lex.p[0], true
if len(lex.P) > 0 {
return lex.P[0], true
}
return 0, false
}
@@ -671,9 +671,10 @@ func (u *Updater) loadXref(lex *Lexer, loadedEntries map[uint]struct{}) error {
var haystackRE = regexp.MustCompile(`(?s:.*)\sstartxref\s+(\d+)\s+%%EOF`)
// Initialize builds the cross-reference table and prepares
// a new trailer dictionary.
func (u *Updater) Initialize() error {
// NewUpdater initializes an Updater, building the cross-reference table and
// preparing a new trailer dictionary.
func NewUpdater(document []byte) (*Updater, error) {
u := &Updater{Document: document}
u.updated = make(map[uint]struct{})
// We only need to look for startxref roughly within
@@ -685,7 +686,7 @@ func (u *Updater) Initialize() error {
m := haystackRE.FindSubmatch(haystack)
if m == nil {
return errors.New("cannot find startxref")
return nil, errors.New("cannot find startxref")
}
xrefOffset, _ := strconv.ParseInt(string(m[1]), 10, 64)
@@ -696,20 +697,20 @@ func (u *Updater) Initialize() error {
var throwawayStack []Object
for {
if _, ok := loadedXrefs[xrefOffset]; ok {
return errors.New("circular xref offsets")
return nil, errors.New("circular xref offsets")
}
if xrefOffset >= int64(len(u.Document)) {
return errors.New("invalid xref offset")
return nil, errors.New("invalid xref offset")
}
lex := Lexer{u.Document[xrefOffset:]}
if err := u.loadXref(&lex, loadedEntries); err != nil {
return err
return nil, err
}
trailer, _ := u.parse(&lex, &throwawayStack)
if trailer.Kind != Dict {
return errors.New("invalid trailer dictionary")
return nil, errors.New("invalid trailer dictionary")
}
if len(loadedXrefs) == 0 {
u.Trailer = trailer.Dict
@@ -722,7 +723,7 @@ func (u *Updater) Initialize() error {
}
// FIXME: We don't check for size_t over or underflow.
if !prevOffset.IsInteger() {
return errors.New("invalid Prev offset")
return nil, errors.New("invalid Prev offset")
}
xrefOffset = int64(prevOffset.Number)
}
@@ -731,10 +732,10 @@ func (u *Updater) Initialize() error {
lastSize, ok := u.Trailer["Size"]
if !ok || !lastSize.IsInteger() || lastSize.Number <= 0 {
return errors.New("invalid or missing cross-reference table Size")
return nil, errors.New("invalid or missing cross-reference table Size")
}
u.xrefSize = uint(lastSize.Number)
return nil
return u, nil
}
// Get retrieves an object by its number and generation--may return
@@ -1097,8 +1098,8 @@ func FillInSignature(document []byte, signOff, signLen int,
// PDF 1.6.
func Sign(document []byte,
key crypto.PrivateKey, certs []*x509.Certificate) ([]byte, error) {
pdf := &Updater{Document: document}
if err := pdf.Initialize(); err != nil {
pdf, err := NewUpdater(document)
if err != nil {
return nil, err
}