Add QPDF::Xref_table methods type, offset, stream_number and stream_index

m-holger
1 parent d64b1491
Showing 3 changed files with 74 additions and 54 deletions
libqpdf/QPDF.cc
libqpdf/QPDF_linearization.cc
libqpdf/qpdf/QPDF_private.hh
@@ -1769,20 +1769,17 @@ QPDF::readObjectAtOffset(
         if (try_recovery) {
             // Try again after reconstructing xref table
             m->xref_table.reconstruct(e);
-            if (m->xref_table.count(exp_og) && (m->xref_table[exp_og].getType() == 1)) {
-                qpdf_offset_t new_offset = m->xref_table[exp_og].getOffset();
-                QPDFObjectHandle result =
-                    readObjectAtOffset(false, new_offset, description, exp_og, og, false);
+            if (m->xref_table.type(exp_og) == 1) {
                 QTC::TC("qpdf", "QPDF recovered in readObjectAtOffset");
-                return result;
+                return readObjectAtOffset(
+                    false, m->xref_table.offset(exp_og), description, exp_og, og, false);
             } else {
                 QTC::TC("qpdf", "QPDF object gone after xref reconstruction");
                 warn(damagedPDF(
                     "",
                     0,
                     ("object " + exp_og.unparse(' ') +
-                     " not found in file after regenerating cross reference "
-                     "table")));
+                     " not found in file after regenerating cross reference table")));
                 return QPDFObjectHandle::newNull();
             }
         } else {
@@ -1815,7 +1812,7 @@ QPDF::readObjectAtOffset(
             }
         }
         qpdf_offset_t end_after_space = m->file->tell();
-        if (skip_cache_if_in_xref && m->xref_table.count(og)) {
+        if (skip_cache_if_in_xref && m->xref_table.type(og)) {
             // Ordinarily, an object gets read here when resolved through xref table or stream. In
             // the special case of the xref stream and linearization hint tables, the offset comes
             // from another source. For the specific case of xref streams, the xref stream is read
@@ -1867,33 +1864,32 @@ QPDF::resolve(QPDFObjGen og)
     }
     ResolveRecorder rr(this, og);
-    if (m->xref_table.count(og) != 0) {
-        QPDFXRefEntry const& entry = m->xref_table[og];
-        try {
-            switch (entry.getType()) {
-            case 1:
-                {
-                    qpdf_offset_t offset = entry.getOffset();
-                    // Object stored in cache by readObjectAtOffset
-                    QPDFObjGen a_og;
-                    QPDFObjectHandle oh = readObjectAtOffset(true, offset, "", og, a_og, false);
-                }
-                break;
+    try {
+        switch (m->xref_table.type(og)) {
+        case 0:
+            break;
+        case 1:
+            {
+                // Object stored in cache by readObjectAtOffset
+                QPDFObjGen a_og;
+                QPDFObjectHandle oh =
+                    readObjectAtOffset(true, m->xref_table.offset(og), "", og, a_og, false);
+            }
+            break;
-            case 2:
-                resolveObjectsInStream(entry.getObjStreamNumber());
-                break;
+        case 2:
+            resolveObjectsInStream(m->xref_table.stream_number(og.getObj()));
+            break;
-            default:
-                throw damagedPDF(
-                    "", 0, ("object " + og.unparse('/') + " has unexpected xref entry type"));
-            }
-        } catch (QPDFExc& e) {
-            warn(e);
-        } catch (std::exception& e) {
-            warn(damagedPDF(
-                "", 0, ("object " + og.unparse('/') + ": error reading object: " + e.what())));
+        default:
+            throw damagedPDF(
+                "", 0, ("object " + og.unparse('/') + " has unexpected xref entry type"));
         }
+    } catch (QPDFExc& e) {
+        warn(e);
+    } catch (std::exception& e) {
+        warn(damagedPDF(
+            "", 0, ("object " + og.unparse('/') + ": error reading object: " + e.what())));
     }
     if (isUnresolved(og)) {
@@ -2107,7 +2103,7 @@ QPDF::getObjectForParser(int id, int gen, bool parse_pdf)
     if (auto iter = m->obj_cache.find(og); iter != m->obj_cache.end()) {
         return iter->second.object;
     }
-    if (m->xref_table.count(og) || !m->xref_table.parsed) {
+    if (m->xref_table.type(og) || !m->xref_table.parsed) {
         return m->obj_cache.insert({og, QPDF_Unresolved::create(this, og)}).first->second.object;
     }
     if (parse_pdf) {
@@ -2123,9 +2119,8 @@ QPDF::getObjectForJSON(int id, int gen)
     auto [it, inserted] = m->obj_cache.try_emplace(og);
     auto& obj = it->second.object;
     if (inserted) {
-        obj = (m->xref_table.parsed && !m->xref_table.count(og))
-            ? QPDF_Null::create(this, og)
-            : QPDF_Unresolved::create(this, og);
+        obj = (m->xref_table.parsed && !m->xref_table.type(og)) ? QPDF_Null::create(this, og)
+                                                                : QPDF_Unresolved::create(this, og);
     }
     return obj;
 }
@@ -2135,7 +2130,7 @@ QPDF::getObject(QPDFObjGen const&amp; og)
 {
     if (auto it = m->obj_cache.find(og); it != m->obj_cache.end()) {
         return {it->second.object};
-    } else if (m->xref_table.parsed && !m->xref_table.count(og)) {
+    } else if (m->xref_table.parsed && !m->xref_table.type(og)) {
         return QPDF_Null::create();
     } else {
         auto result = m->obj_cache.try_emplace(og, QPDF_Unresolved::create(this, og), -1, -1);
@@ -445,7 +445,7 @@ QPDF::checkLinearizationInternal()
     for (size_t i = 0; i < toS(npages); ++i) {
         QPDFObjectHandle const& page = pages.at(i);
         QPDFObjGen og(page.getObjGen());
-        if (m->xref_table[og].getType() == 2) {
+        if (m->xref_table.type(og) == 2) {
             linearizationWarning(
                 "page dictionary for page " + std::to_string(i) + " is compressed");
         }
@@ -556,23 +556,18 @@ QPDF::maxEnd(ObjUser const&amp; ou)
 qpdf_offset_t
 QPDF::getLinearizationOffset(QPDFObjGen const& og)
 {
-    QPDFXRefEntry entry = m->xref_table[og];
-    qpdf_offset_t result = 0;
-    switch (entry.getType()) {
+    switch (m->xref_table.type(og)) {
     case 1:
-        result = entry.getOffset();
-        break;
+        return m->xref_table.offset(og);
     case 2:
         // For compressed objects, return the offset of the object stream that contains them.
-        result = getLinearizationOffset(QPDFObjGen(entry.getObjStreamNumber(), 0));
-        break;
+        return getLinearizationOffset(QPDFObjGen(m->xref_table.stream_number(og.getObj()), 0));
     default:
         stopOnError("getLinearizationOffset called for xref entry not of type 1 or 2");
-        break;
+        return 0; // unreachable
     }
-    return result;
 }
 QPDFObjectHandle
@@ -603,7 +598,7 @@ QPDF::lengthNextN(int first_object, int n)
     int length = 0;
     for (int i = 0; i < n; ++i) {
         QPDFObjGen og(first_object + i, 0);
-        if (m->xref_table.count(og) == 0) {
+        if (m->xref_table.type(og) == 0) {
             linearizationWarning(
                 "no xref table entry for " + std::to_string(first_object + i) + " 0");
         } else {
@@ -635,7 +630,7 @@ QPDF::checkHPageOffset(
     int npages = toI(pages.size());
     qpdf_offset_t table_offset = adjusted_offset(m->page_offset_hints.first_page_offset);
     QPDFObjGen first_page_og(pages.at(0).getObjGen());
-    if (m->xref_table.count(first_page_og) == 0) {
+    if (m->xref_table.type(first_page_og) == 0) {
         stopOnError("supposed first page object is not known");
     }
     qpdf_offset_t offset = getLinearizationOffset(first_page_og);
@@ -646,7 +641,7 @@ QPDF::checkHPageOffset(
     for (int pageno = 0; pageno < npages; ++pageno) {
         QPDFObjGen page_og(pages.at(toS(pageno)).getObjGen());
         int first_object = page_og.getObj();
-        if (m->xref_table.count(page_og) == 0) {
+        if (m->xref_table.type(page_og) == 0) {
             stopOnError("unknown object in page offset hint table");
         }
         offset = getLinearizationOffset(page_og);
@@ -768,7 +763,7 @@ QPDF::checkHSharedObject(std::vector&lt;QPDFObjectHandle&gt; const&amp; pages, std::map&lt;in
                 cur_object = so.first_shared_obj;
                 QPDFObjGen og(cur_object, 0);
-                if (m->xref_table.count(og) == 0) {
+                if (m->xref_table.type(og) == 0) {
                     stopOnError("unknown object in shared object hint table");
                 }
                 qpdf_offset_t offset = getLinearizationOffset(og);
@@ -819,7 +814,7 @@ QPDF::checkHOutlines()
                 return;
             }
             QPDFObjGen og(outlines.getObjGen());
-            if (m->xref_table.count(og) == 0) {
+            if (m->xref_table.type(og) == 0) {
                 stopOnError("unknown object in outlines hint table");
             }
             qpdf_offset_t offset = getLinearizationOffset(og);
@@ -838,8 +833,7 @@ QPDF::checkHOutlines()
                     std::to_string(table_length) + "; computed = " + std::to_string(length));
             }
         } else {
-            linearizationWarning("incorrect first object number in outline "
-                                 "hints table.");
+            linearizationWarning("incorrect first object number in outline hints table.");
         }
     } else {
         linearizationWarning("incorrect object count in outline hint table");
@@ -19,6 +19,37 @@ class QPDF::Xref_table: public std::map&lt;QPDFObjGen, QPDFXRefEntry&gt;
     void show();
     bool resolve();
+    // Returns 0 if og is not in table.
+    int
+    type(QPDFObjGen og) const
+    {
+        auto it = find(og);
+        return it == end() ? 0 : it->second.getType();
+    }
+
+    // Returns 0 if og is not in table.
+    qpdf_offset_t
+    offset(QPDFObjGen og) const
+    {
+        auto it = find(og);
+        return it == end() ? 0 : it->second.getOffset();
+    }
+
+    // Returns 0 if og is not in table.
+    int
+    stream_number(int id) const
+    {
+        auto it = find(QPDFObjGen(id, 0));
+        return it == end() ? 0 : it->second.getObjStreamNumber();
+    }
+
+    int
+    stream_index(int id) const
+    {
+        auto it = find(QPDFObjGen(id, 0));
+        return it == end() ? 0 : it->second.getObjStreamIndex();
+    }
+
     QPDFObjectHandle trailer;
     bool reconstructed{false};
     // Various tables are indexed by object id, with potential size id + 1