From 1021729727ac2c61740781a335bb7a2977208264 Mon Sep 17 00:00:00 2001
From: EliotJones <elioty@hotmail.co.uk>
Date: Tue, 15 Jul 2025 20:49:43 -0500
Subject: [PATCH] fall back to times-roman as standard 14 font when lenient

if parsing in lenient mode and encountering a malformed base name
(in this case 'helveticai') we fallback to times-roman as the adobe font
metrics file for a standard 14 font. this aligns with the behavior of pdfbox.
we also log a more informative error in non-lenient modes

this fixes document 0000086.pdf from the corpus
---
 .../Parser/PdfDocumentFactory.cs              |  6 +++-
 .../Parser/Handlers/Type1FontHandler.cs       | 31 +++++++++++++++----
 2 files changed, 30 insertions(+), 7 deletions(-)

diff --git a/src/UglyToad.PdfPig/Parser/PdfDocumentFactory.cs b/src/UglyToad.PdfPig/Parser/PdfDocumentFactory.cs
index 1ce4a84d..8a09f81a 100644
--- a/src/UglyToad.PdfPig/Parser/PdfDocumentFactory.cs
+++ b/src/UglyToad.PdfPig/Parser/PdfDocumentFactory.cs
@@ -168,7 +168,11 @@
                 pdfScanner,
                 parsingOptions);
 
-            var type1Handler = new Type1FontHandler(pdfScanner, filterProvider, encodingReader);
+            var type1Handler = new Type1FontHandler(
+                pdfScanner,
+                filterProvider,
+                encodingReader,
+                parsingOptions.UseLenientParsing);
 
             var trueTypeHandler = new TrueTypeFontHandler(parsingOptions.Logger,
                 pdfScanner,
diff --git a/src/UglyToad.PdfPig/PdfFonts/Parser/Handlers/Type1FontHandler.cs b/src/UglyToad.PdfPig/PdfFonts/Parser/Handlers/Type1FontHandler.cs
index 7bac246b..5cf1b7aa 100644
--- a/src/UglyToad.PdfPig/PdfFonts/Parser/Handlers/Type1FontHandler.cs
+++ b/src/UglyToad.PdfPig/PdfFonts/Parser/Handlers/Type1FontHandler.cs
@@ -20,13 +20,18 @@
         private readonly IPdfTokenScanner pdfScanner;
         private readonly ILookupFilterProvider filterProvider;
         private readonly IEncodingReader encodingReader;
+        private readonly bool isLenientParsing;
 
-        public Type1FontHandler(IPdfTokenScanner pdfScanner, ILookupFilterProvider filterProvider,
-            IEncodingReader encodingReader)
+        public Type1FontHandler(
+            IPdfTokenScanner pdfScanner,
+            ILookupFilterProvider filterProvider,
+            IEncodingReader encodingReader,
+            bool isLenientParsing)
         {
             this.pdfScanner = pdfScanner;
             this.filterProvider = filterProvider;
             this.encodingReader = encodingReader;
+            this.isLenientParsing = isLenientParsing;
         }
 
         public IFont Generate(DictionaryToken dictionary)
@@ -69,12 +74,26 @@
                 widths = [];
             }
 
-            if (!dictionary.TryGet(NameToken.FontDescriptor, out var _))
+            if (!dictionary.TryGet(NameToken.FontDescriptor, out _))
             {
-                if (dictionary.TryGet(NameToken.BaseFont, out var baseFontToken) &&
-                    DirectObjectFinder.TryGet(baseFontToken, pdfScanner, out NameToken? baseFontName))
+                if (dictionary.TryGet(NameToken.BaseFont, pdfScanner, out NameToken? baseFontToken))
                 {
-                    var metrics = Standard14.GetAdobeFontMetrics(baseFontName.Data);
+                    var metrics = Standard14.GetAdobeFontMetrics(baseFontToken.Data);
+
+                    if (metrics == null)
+                    {
+                        if (isLenientParsing)
+                        {
+                            // We can support a fallback here to return content.
+                            // https://github.com/apache/pdfbox/blob/f81c7c5a06126db68aa985a0e755cdbffed7d270/pdfbox/src/main/java/org/apache/pdfbox/pdmodel/font/FontMapperImpl.java#L304
+                            metrics = Standard14.GetAdobeFontMetrics(Standard14Font.TimesRoman);
+                        }
+                        else
+                        {
+                            throw new PdfDocumentFormatException(
+                                $"Type 1 Standard 14 font with name {baseFontToken} requested, this is an invalid name.");
+                        }
+                    }
 
                     var overrideEncoding = encodingReader.Read(dictionary);