Add `limit_errors` tracking to global options

Enhance the `global` namespace by introducing `limit_errors` for tracking the number of exceeded limits. Update related tests and documentation to ensure functionality and clarity.

Add `limit_errors` tracking to global options
Enhance the `global` namespace by introducing `limit_errors` for tracking the number of exceeded limits. Update related tests and documentation to ensure functionality and clarity.
m-holger
1 parent 34db6e30
Showing 8 changed files with 61 additions and 7 deletions
include/qpdf/Constants.h
include/qpdf/global.hh
libqpdf/QPDFParser.cc
libqpdf/global.cc
libqpdf/qpdf/global_private.hh
libtests/objects.cc
qpdf/qtest/qpdf/issue-146.out
qpdf/qtest/qpdf/issue-202.out
@@ -273,12 +273,15 @@ enum qpdf_result_e {
  *          options or global limits.For the meaning of individual parameters see `qpdf/global.cc`
  */
 enum qpdf_param_e {
+    /* global state */
+    qpdf_p_limit_errors = 0x10020,
+
     /* global options */
-    qpdf_p_default_limits = 0x10100,
+    qpdf_p_default_limits = 0x11100,
     /* global limits */
  
     /* object - parser limits */
-    qpdf_p_objects_max_nesting = 0x11000,
+    qpdf_p_objects_max_nesting = 0x12000,
     qpdf_p_objects_max_errors,
     qpdf_p_objects_max_container_size,
     qpdf_p_objects_max_container_size_damaged,
@@ -54,6 +54,18 @@ namespace qpdf::global
         handle_result(qpdf_global_set_uint32(param, value));
     }
  
+    /// @brief Retrieves the number of limit errors.
+    ///
+    /// Returns the number a global limit was exceeded. This item is reaf only.
+    ///
+    /// @return The number of limit errors.
+    ///
+    /// @since 12.3
+    uint32_t inline limit_errors()
+    {
+        return get_uint32(qpdf_p_limit_errors);
+    }
+
     namespace options
     {
         /// @brief  Retrieves whether default limits are enabled.
@@ -437,7 +437,8 @@ QPDFParser::parseRemainder(bool content_stream)
         case QPDFTokenizer::tt_array_open:
         case QPDFTokenizer::tt_dict_open:
             if (stack.size() > max_nesting) {
-                warn("ignoring excessively deeply nested data structure");
+                global::Limits::error();
+                warn("limits error: ignoring excessively deeply nested data structure");
                 return {};
             } else {
                 b_contents = false;
@@ -647,8 +648,10 @@ QPDFParser::check_too_many_bad_tokens()
     auto limit = Limits::objects_max_container_size(bad_count || sanity_checks);
     if (frame->olist.size() > limit || frame->dict.size() > limit) {
         if (bad_count) {
+            Limits::error();
             warn(
-                "encountered errors while parsing an array or dictionary with more than " +
+                "limits error: encountered errors while parsing an array or dictionary with more "
+                "than " +
                 std::to_string(limit) + " elements; giving up on reading object");
             throw Error();
         }
@@ -38,6 +38,9 @@ qpdf_global_get_uint32(qpdf_param_e param, uint32_t* value)
     case qpdf_p_default_limits:
         *value = Options::default_limits();
         return qpdf_r_ok;
+    case qpdf_p_limit_errors:
+        *value = Limits::errors();
+        return qpdf_r_ok;
     case qpdf_p_objects_max_nesting:
         *value = Limits::objects_max_nesting();
         return qpdf_r_ok;
@@ -48,6 +48,21 @@ namespace qpdf::global
  
         static void objects_max_container_size(bool damaged, uint32_t value);
  
+        /// Record a limit error.
+        static void
+        error()
+        {
+            if (l.errors_ < std::numeric_limits<uint32_t>::max()) {
+                ++l.errors_;
+            }
+        }
+
+        static uint32_t const&
+        errors()
+        {
+            return l.errors_;
+        }
+
         static void disable_defaults();
  
       private:
@@ -56,6 +71,8 @@ namespace qpdf::global
  
         static Limits l;
  
+        uint32_t errors_{0};
+
         uint32_t objects_max_nesting_{499};
         uint32_t objects_max_errors_{15};
         bool objects_max_errors_set_{false};
@@ -221,6 +221,22 @@ test_2(QPDF&amp; pdf, char const* arg2)
         thrown = true;
     }
     assert(thrown);
+
+    /* Test limit errors */
+    assert(qpdf::global::limit_errors() == 0);
+    QPDFObjectHandle::parse("[[[[]]]]");
+    assert(qpdf::global::limit_errors() == 0);
+    objects_max_nesting(3);
+    try {
+        QPDFObjectHandle::parse("[[[[[]]]]]");
+    } catch (std::exception&) {
+    }
+    assert(qpdf::global::limit_errors() == 1);
+    try {
+        QPDFObjectHandle::parse("[[[[[]]]]]");
+    } catch (std::exception&) {
+    }
+    assert(qpdf::global::limit_errors() == 2);
 }
  
 void
 WARNING: issue-146.pdf: file is damaged
 WARNING: issue-146.pdf: can't find startxref
 WARNING: issue-146.pdf: Attempting to reconstruct cross-reference table
-WARNING: issue-146.pdf (trailer, offset 695): ignoring excessively deeply nested data structure
+WARNING: issue-146.pdf (trailer, offset 695): limits error: ignoring excessively deeply nested data structure
 WARNING: issue-146.pdf (object 1 0, offset 92): expected endobj
 WARNING: issue-146.pdf (object 7 0, offset 146): unknown token while reading object; treating as null
 WARNING: issue-146.pdf (object 7 0, offset 168): expected endobj
-WARNING: issue-202.pdf (trailer, offset 55770): ignoring excessively deeply nested data structure
+WARNING: issue-202.pdf (trailer, offset 55770): limits error: ignoring excessively deeply nested data structure
 WARNING: issue-202.pdf: file is damaged
 WARNING: issue-202.pdf (offset 54769): expected trailer dictionary
 WARNING: issue-202.pdf: Attempting to reconstruct cross-reference table
-WARNING: issue-202.pdf (trailer, offset 55770): ignoring excessively deeply nested data structure
+WARNING: issue-202.pdf (trailer, offset 55770): limits error: ignoring excessively deeply nested data structure
 WARNING: issue-202.pdf (object 222 0, offset 50101): dictionary has duplicated key /Creator; last occurrence overrides earlier ones
 WARNING: issue-202.pdf (object 222 0, offset 50101): dictionary has duplicated key /Producer; last occurrence overrides earlier ones
 WARNING: issue-202.pdf: unable to find trailer dictionary while recovering damaged file