From dd64f1797ee2cefa59cb2c8e093fb0a02f9b3cae Mon Sep 17 00:00:00 2001
From: Charan Rathore <180254320+charan-rathore@users.noreply.github.com>
Date: Sun, 18 Oct 2026 16:43:48 +0530
Subject: [PATCH] hayro-cmap patch: an unresolved usecmap with no mappings
 reports failure

---
 vendor/hayro-cmap/src/parse.rs | 31 ++++++++++++++++++++++++-------
 1 file changed, 24 insertions(+), 7 deletions(-)

diff --git a/vendor/hayro-cmap/src/parse.rs b/vendor/hayro-cmap/src/parse.rs
index 2a89fdbac..1137ab078 100644
--- a/vendor/hayro-cmap/src/parse.rs
+++ b/vendor/hayro-cmap/src/parse.rs
@@ -53,6 +53,12 @@ pub(crate) fn parse_inner<'a>(
     // unparseable tail keeps the entries read so far instead of being
     // discarded wholesale; one that yielded nothing still reports failure.
     let mut truncated = false;
+
+    // PdfCraft patch: track a `usecmap` reference that could not be resolved
+    // or parsed. When the stream yields no mappings of its own, the caller
+    // must see failure rather than an empty map, so its encoding fallback
+    // paths run exactly as they did before the tolerant-usecmap change.
+    let mut usecmap_failed = false;
     while !scanner.at_end() {
         let Ok(obj) = scanner.parse_object() else {
             truncated = true;
@@ -110,11 +116,20 @@ pub(crate) fn parse_inner<'a>(
                 }
                 Some("usecmap") => {
                     // PdfCraft patch: an unresolvable or unparseable `usecmap`
-                    // reference drops only the base, not the whole CMap.
-                    if let Some(name) = last_name.as_deref() {
-                        if let Some(nested_data) = (ctx.get_cmap)(CMapName::from_bytes(name)) {
-                            base = parse_inner(nested_data, ctx.get_cmap.clone(), depth + 1).map(Box::new);
+                    // reference drops only the base, not the whole CMap, but
+                    // is remembered so a stream that then yields no mappings
+                    // at all still reports failure.
+                    let resolved = last_name.as_deref().and_then(|name| {
+                        (ctx.get_cmap)(CMapName::from_bytes(name))
+                    });
+                    match resolved {
+                        Some(nested_data) => {
+                            match parse_inner(nested_data, ctx.get_cmap.clone(), depth + 1) {
+                                Some(nested) => base = Some(Box::new(nested)),
+                                None => usecmap_failed = true,
+                            }
                         }
+                        None => usecmap_failed = true,
                     }
                 }
                 _ => {}
@@ -147,9 +162,11 @@ pub(crate) fn parse_inner<'a>(
         writing_mode,
     };
 
-    // PdfCraft patch: a truncated CMap that yielded nothing still reports failure,
-    // so callers fall back to the font's own encoding exactly as before.
-    if truncated
+    // PdfCraft patch: a CMap that was cut short or whose `usecmap` base could
+    // not be resolved, and that yielded no mappings of its own, still reports
+    // failure, so callers fall back to the font's own encoding exactly as
+    // before.
+    if (truncated || usecmap_failed)
         && ranges.is_empty()
         && notdef_ranges.is_empty()
         && bf_entries.is_empty()