[bug #66586] [troff] be even more pernickety about input

[G. Branden Robinson]

URL:
  <https://savannah.gnu.org/bugs/?66586>

                 Summary: [troff] be even more pernickety about input
                   Group: GNU roff
               Submitter: gbranden
               Submitted: Thu 19 Dec 2024 06:08:05 PM UTC
                Category: Core
                Severity: 1 - Wish
              Item Group: Warning/Suspicious behaviour
                  Status: Postponed
                 Privacy: Public
             Assigned to: None
             Open/Closed: Open
         Discussion Lock: Any
         Planned Release: None


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Follow-up Comments:


-------------------------------------------------------
Date: Thu 19 Dec 2024 06:08:05 PM UTC By: G. Branden Robinson <gbranden>
We warn about trailing garbage in `nr` requests but not in other contexts.

This is because request handlers tend to hurl themselves bodily into
`skip_line()` immediately upon reaching the end of any argument that satisfies
them.

Here's a patch that makes `skip_line()` gripe if it encounters anything but
syntactical nullities.

It causes warnings all over the place, because a lot of requests don't advance
the input token pointer off the last (valid) character they read before
calling `skip_line()`.  So this patch also illustrates a remedy in the case of
the `af` request handler.

A similar change would have to be made lots of other places.

That sounds like a _groff_ 1.25 project.


diff --git a/src/roff/troff/input.cpp b/src/roff/troff/input.cpp
index da9361d4d..b613fd238 100644
--- a/src/roff/troff/input.cpp
+++ b/src/roff/troff/input.cpp
@@ -2737,11 +2737,19 @@ const char *token::description()
 
 void skip_line()
 {
+  bool was_warned = false;
   while (!tok.is_newline())
     if (tok.is_eof())
       return;
-    else
+    else {
+      if (!tok.is_space() && !tok.is_tab() && !was_warned) {
+       warning(WARN_SYNTAX,
+               "unexpected %1 in request;"
+               " ignoring rest of line", tok.description());
+       was_warned = true;
+      }
       tok.next();
+    }
   tok.next();
 }
 
diff --git a/src/roff/troff/reg.cpp b/src/roff/troff/reg.cpp
index c22b088c2..b8c1ac9ae 100644
--- a/src/roff/troff/reg.cpp
+++ b/src/roff/troff/reg.cpp
@@ -438,8 +438,10 @@ void assign_register_format_request()
     } while (csdigit(tok.ch()));
     r->alter_format('1', n);
   }
-  else if (c == 'i' || c == 'I' || c == 'a' || c == 'A')
+  else if (c == 'i' || c == 'I' || c == 'a' || c == 'A') {
     r->alter_format(c);
+    tok.next();
+  }
   else if (!has_arg())
     warning(WARN_MISSING, "register interpolation format assignment"
            " request register format as second argument");









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