Add "n:/pdf-name" to qpdf JSON for binary names (fixes #1072)

ChangeLog

@@ -1,5 +1,12 @@
 2023-12-21  Jay Berkenbilt  <ejb@ql.org>
 
+	* Fix to QPDF JSON: the syntax "n:/pdf-syntax" is now accepted as
+	an alternative way to represent names. This can be used for any
+	name (e.g. "n:/text#2fplain"), but it is necessary when the name
+	contains binary characters. For example, /one#a0two must be
+	represented as "n:/one#a0two" since the single byte a0 is not
+	valid in JSON. Fixes #1072.
+
 	* From M. Holger: Refactor QPDFParser for performance. See #1059
 	for a discussion.
 

libqpdf/QPDF_Name.cc

@@ -57,6 +57,14 @@ QPDF_Name::getJSON(int json_version)
     if (json_version == 1) {
         return JSON::makeString(normalizeName(this->name));
     } else {
-        return JSON::makeString(this->name);
+        bool has_8bit_chars;
+        bool is_valid_utf8;
+        bool is_utf16;
+        QUtil::analyze_encoding(this->name, has_8bit_chars, is_valid_utf8, is_utf16);
+        if (!has_8bit_chars || is_valid_utf8) {
+            return JSON::makeString(this->name);
+        } else {
+            return JSON::makeString("n:" + normalizeName(this->name));
+        }
     }
 }

libqpdf/QPDF_json.cc

@@ -144,6 +144,12 @@ is_name(std::string const& v)
     return ((v.length() > 1) && (v.at(0) == '/'));
 }
 
+static bool
+is_pdf_name(std::string const& v)
+{
+    return ((v.length() > 3) && (v.substr(0, 3) == "n:/"));
+}
+
 bool
 QPDF::test_json_validators()
 {
@@ -740,6 +746,8 @@ QPDF::JSONReactor::makeObject(JSON const& value)
             result = QPDFObjectHandle::newString(QUtil::hex_decode(str));
         } else if (is_name(str_v)) {
             result = QPDFObjectHandle::newName(str_v);
+        } else if (is_pdf_name(str_v)) {
+            result = QPDFObjectHandle::parse(str_v.substr(2));
         } else {
             QTC::TC("qpdf", "QPDF_json unrecognized string value");
             error(value.getStart(), "unrecognized string value");

manual/json.rst

@@ -258,6 +258,12 @@ Object Values
     syntax resolved. For example, the name whose canonical form (per
     the PDF specification) is ``text/plain`` would be represented in
     JSON as ``"/text/plain"`` and in PDF as ``"/text#2fplain"``.
+    Starting with qpdf 11.7.0, the syntax ``"n:/pdf-syntax"`` is
+    accepted as an alternative. This can be used for any name (e.g.
+    ``"n:/text#2fplain"``), but it is necessary when the name contains
+    binary characters. For example, ``/one#a0two`` must be represented
+    as ``"n:/one#a0two"`` since the single byte ``a0`` is not valid in
+    JSON.
 
   - Indirect object references are represented as JSON strings that
     look like a PDF indirect object reference and have the form
@@ -824,7 +830,8 @@ version 2.
   - Names are shown in qpdf's canonical form rather than in PDF
     syntax. (Example: the PDF-syntax name ``/text#2fplain`` appeared
     as ``"/text#2fplain"`` in v1 but appears as ``"/text/plain"`` in
-    v2.
+    v2. In qpdf 11.7.0, a fix was made to accept ``"n:/pdf-syntax"``
+    for names containing binary characters.
 
   - The top-level representation of an object in ``"objects"`` is a
     dictionary containing either a ``"value"`` key or a ``"stream"``

manual/release-notes.rst

@@ -45,6 +45,13 @@ Planned changes for future 12.x (subject to change):
       reference streams, linearization hint streams, and object
       streams. This has been fixed.
 
+    - Fix to QPDF JSON: the syntax ``"n:/pdf-syntax"`` is now accepted
+      as an alternative way to represent names. This can be used for
+      any name (e.g. ``"n:/text#2fplain"``), but it is necessary when
+      the name contains binary characters. For example, ``/one#a0two``
+      must be represented as ``"n:/one#a0two"`` since the single byte
+      ``a0`` is not valid in JSON.
+
   - Build Enhancements:
 
     - The qpdf test suite now passes when qpdf is linked with an

qpdf/qtest/qpdf-json.test

@@ -61,6 +61,7 @@ my @goodfiles = (
     'form-fields-and-annotations.pdf',
     'need-appearances.pdf',
     'fxo-blue.pdf',
+    'weird-tokens.pdf',
     );
 $n_tests += 6 * scalar(@goodfiles);
 
@@ -341,5 +342,21 @@ $td->runtest("check C API write to JSON stream",
              {$td->FILE => "auto-4"},
              {$td->FILE => "qpdf-ctest-47-4"});
 
+# Bugs #1072 and #1079 illustrate cases that qpdf-json got wrong. In
+# #1072, it was noticed that name tokens containing binary characters
+# (using #xx) would generate invalid JSON, even though qpdf's own JSON
+# parser would accept it. Also, the JSON spec allows real numbers in
+# scientific notation, but the PDF spec does not.
+$n_tests += 2;
+$td->runtest("handle binary names",
+             {$td->COMMAND =>
+                  "qpdf --json-output weird-tokens.pdf a.json"},
+             {$td->STRING => "", $td->EXIT_STATUS => 0});
+# Round-trip is tested above.
+$td->runtest("check json",
+             {$td->FILE => "a.json"},
+             {$td->FILE => "weird-tokens.json"},
+             $td->NORMALIZE_NEWLINES);
+
 cleanup();
 $td->report($n_tests);

qpdf/qtest/qpdf/weird-tokens.json

@@ -0,0 +1,83 @@
+{
+  "qpdf": [
+    {
+      "jsonversion": 2,
+      "pdfversion": "2.0",
+      "pushedinheritedpageresources": false,
+      "calledgetallpages": false,
+      "maxobjectid": 6
+    },
+    {
+      "obj:1 0 R": {
+        "value": {
+          "/Extra": [
+            "u:Names with binary data",
+            "n:/ABCDEF+#ba#da#cc#e5",
+            "/ABCEDEF+π",
+            "n:/one+#a0two",
+            "/text/plain",
+            "u:Very small/large reals",
+            0.00001,
+            1000000000000
+          ],
+          "/Pages": "2 0 R",
+          "/Type": "/Catalog"
+        }
+      },
+      "obj:2 0 R": {
+        "value": {
+          "/Count": 1,
+          "/Kids": [
+            "3 0 R"
+          ],
+          "/Type": "/Pages"
+        }
+      },
+      "obj:3 0 R": {
+        "value": {
+          "/Contents": "4 0 R",
+          "/MediaBox": [
+            0,
+            0,
+            612,
+            792
+          ],
+          "/Parent": "2 0 R",
+          "/Resources": {
+            "/Font": {
+              "/F1": "6 0 R"
+            }
+          },
+          "/Type": "/Page"
+        }
+      },
+      "obj:4 0 R": {
+        "stream": {
+          "data": "QlQKICAvRjEgMjQgVGYKICA3MiA3MjAgVGQKICAoUG90YXRvKSBUagpFVAo=",
+          "dict": {}
+        }
+      },
+      "obj:5 0 R": {
+        "value": 44
+      },
+      "obj:6 0 R": {
+        "value": {
+          "/BaseFont": "/Helvetica",
+          "/Encoding": "/WinAnsiEncoding",
+          "/Subtype": "/Type1",
+          "/Type": "/Font"
+        }
+      },
+      "trailer": {
+        "value": {
+          "/ID": [
+            "b:42841c13bbf709d79a200fa1691836f8",
+            "b:728c020f464c3cf7e02c12605fa7d88b"
+          ],
+          "/Root": "1 0 R",
+          "/Size": 7
+        }
+      }
+    }
+  ]
+}

qpdf/qtest/qpdf/weird-tokens.pdf

@@ -0,0 +1,95 @@
+%PDF-2.0
+%¿÷¢þ
+%QDF-1.0
+
+1 0 obj
+<<
+  /Extra [
+    (Names with binary data)
+    /ABCDEF+#ba#da#cc#e5
+    /ABCEDEF+#cf#80
+    /one+#a0two
+    /text#2fplain
+    (Very small/large reals)
+    0.00001
+    1000000000000
+  ]
+  /Pages 2 0 R
+  /Type /Catalog
+>>
+endobj
+
+2 0 obj
+<<
+  /Count 1
+  /Kids [
+    3 0 R
+  ]
+  /Type /Pages
+>>
+endobj
+
+%% Page 1
+3 0 obj
+<<
+  /Contents 4 0 R
+  /MediaBox [
+    0
+    0
+    612
+    792
+  ]
+  /Parent 2 0 R
+  /Resources <<
+    /Font <<
+      /F1 6 0 R
+    >>
+  >>
+  /Type /Page
+>>
+endobj
+
+%% Contents for page 1
+4 0 obj
+<<
+  /Length 5 0 R
+>>
+stream
+BT
+  /F1 24 Tf
+  72 720 Td
+  (Potato) Tj
+ET
+endstream
+endobj
+
+5 0 obj
+44
+endobj
+
+6 0 obj
+<<
+  /BaseFont /Helvetica
+  /Encoding /WinAnsiEncoding
+  /Subtype /Type1
+  /Type /Font
+>>
+endobj
+
+xref
+0 7
+0000000000 65535 f 
+0000000025 00000 n 
+0000000261 00000 n 
+0000000343 00000 n 
+0000000539 00000 n 
+0000000638 00000 n 
+0000000657 00000 n 
+trailer <<
+  /Root 1 0 R
+  /Size 7
+  /ID [<42841c13bbf709d79a200fa1691836f8><728c020f464c3cf7e02c12605fa7d88b>]
+>>
+startxref
+763
+%%EOF