Tweak utf8 checks

libqpdf/QUtil.cc

@@ -1825,16 +1825,12 @@ QUtil::analyze_encoding(
     bool any_errors = false;
     while (pos < len) {
         bool error = false;
-        auto old_pos = pos;
+        auto o_pos = pos;
-        unsigned long codepoint = get_next_utf8_codepoint(val, pos, error);
+        get_next_utf8_codepoint(val, pos, error);
         if (error) {
             any_errors = true;
-            for (auto p = old_pos; p < pos; p++) {
-                if (static_cast<unsigned char>(val.at(p)) >= 128) {
-                    has_8bit_chars = true;
         }
-            }
+        if (pos - o_pos > 1 || val[o_pos] & 0x80) {
-        } else if (codepoint >= 128) {
             has_8bit_chars = true;
         }
     }

libtests/qutil.cc

@@ -269,20 +269,21 @@ to_utf8_test()
 
     // Overlong characters: characters represented by more bytes than necessary.
     size_t pos = 0;
-    std::string utf8 = "\xC0\x80"                  // 1 << 7
+    std::string utf8 = "\xC0\x81"                  // 1 << 7
-                       "\xE0\x80\x80"              // 1 << 11
+                       "\xE0\x80\x82"              // 1 << 11
-                       "\xF0\x80\x80\x80"          // 1 << 16
+                       "\xF0\x80\x80\x83"          // 1 << 16
-                       "\xF8\x80\x80\x80\x80"      // 1 << 21
+                       "\xF8\x80\x80\x80\x84"      // 1 << 21
-                       "\xFC\x80\x80\x80\x80\x80"; // 1 << 26
+                       "\xFC\x80\x80\x80\x80\x85"; // 1 << 26
-    auto check = [&pos, &utf8](unsigned long wanted_pos) {
+    auto check = [&pos, &utf8](unsigned long val, unsigned long wanted_pos) {
         bool error = false;
-        assert(QUtil::get_next_utf8_codepoint(utf8, pos, error) == 0 && error && pos == wanted_pos);
+        assert(
+            QUtil::get_next_utf8_codepoint(utf8, pos, error) == val && error && pos == wanted_pos);
     };
-    check(2);
+    check(1, 2);
-    check(5);
+    check(2, 5);
-    check(9);
+    check(3, 9);
-    check(14);
+    check(4, 14);
-    check(20);
+    check(5, 20);
 }
 
 static void
@@ -361,7 +362,8 @@ check_analyze(std::string const& str, bool has8bit, bool utf8, bool utf16)
     bool is_utf16 = false;
     QUtil::analyze_encoding(str, has_8bit_chars, is_valid_utf8, is_utf16);
     if (!((has_8bit_chars == has8bit) && (is_valid_utf8 == utf8) && (is_utf16 == utf16))) {
-        std::cout << "analysis failed: " << str << std::endl;
+        std::cout << "analysis failed: " << str << ": 8bit: " << has_8bit_chars
+                  << ", utf8: " << is_valid_utf8 << ", utf16: " << is_utf16 << std::endl;
     }
 }
 
@@ -389,6 +391,7 @@ transcoding_test()
     check_analyze("pi = \317\200", true, true, false);
     check_analyze("pi != \317", true, false, false);
     check_analyze("pi != 22/7", false, false, false);
+    check_analyze("\xE0\x80\x82", true, false, false);
     check_analyze(std::string("\xfe\xff\x00\x51", 4), true, false, true);
     check_analyze(std::string("\xff\xfe\x51\x00", 4), true, false, true);
     std::cout << "analysis done" << std::endl;

qpdf/qtest/qpdf/weird-tokens-alt.json

@@ -16,6 +16,8 @@
             "n:/OVERLONG+#c0#81",
             "n:/OVERLONG+#e0#81#82",
             "n:/OVERLONG+#f0#81#82#83",
+            "n:/range+#01",
+            "n:/low+#18",
             "/ABCEDEF+π",
             "n:/one+#a0two",
             "n:/text#2fplain",

qpdf/qtest/qpdf/weird-tokens.json

@@ -16,6 +16,8 @@
             "n:/OVERLONG+#c0#81",
             "n:/OVERLONG+#e0#81#82",
             "n:/OVERLONG+#f0#81#82#83",
+            "/range+\u0001",
+            "/low+\u0018",
             "/ABCEDEF+π",
             "n:/one+#a0two",
             "/text/plain",

qpdf/qtest/qpdf/weird-tokens.pdf

@@ -10,6 +10,8 @@
     /OVERLONG+#c0#81
     /OVERLONG+#e0#81#82
     /OVERLONG+#f0#81#82#83
+    /range+#01
+    /low+#18
     /ABCEDEF+#cf#80
     /one+#a0two
     /text#2fplain
@@ -83,16 +85,16 @@ xref
 0 7
 0000000000 65535 f 
 0000000025 00000 n 
-0000000333 00000 n 
+0000000361 00000 n 
-0000000415 00000 n 
+0000000443 00000 n 
-0000000611 00000 n 
+0000000639 00000 n 
-0000000710 00000 n 
+0000000738 00000 n 
-0000000729 00000 n 
+0000000757 00000 n 
 trailer <<
   /Root 1 0 R
   /Size 7
   /ID [<42841c13bbf709d79a200fa1691836f8><728c020f464c3cf7e02c12605fa7d88b>]
 >>
 startxref
-835
+863
 %%EOF