[groff] 05/10: [troff]: Fix Savannah #64469 (`-o` out of bounds).

[G. Branden Robinson]

gbranden pushed a commit to branch master
in repository groff.

commit 40644c648efc313eb818b89725787fe2a10ba773
Author: G. Branden Robinson <g.branden.robinson@gmail.com>
AuthorDate: Thu Oct 17 11:11:45 2024 -0500

    [troff]: Fix Savannah #64469 (`-o` out of bounds).
    
    [troff]: Better handle inapplicable or out-of-bounds (but still
    numerically valid) output page selection list (`-o` argument).
    
    * src/roff/troff/node.cpp: New global Boolean
      `was_any_page_in_output_list` tracks this datum; defaults false.
    
      (troff_output_file::trailer): When finishing up, don't write a
      "trailer" grout command (and vertical motion) if no page ever began.
      Insted, throw a warning in category `range`.
    
      (real_output_file::begin_page): Make `was_any_page_in_output_list`
      true if any page is written.
    
    Fixes <https://savannah.gnu.org/bugs/?64469>.  Thanks to Dave Kemper for
    the report.
    
    Exhibit:
    
    $ echo hello | ~/groff-stable/bin/groff -o 2
    grops:<standard input>:5: fatal error: 'V' command invalid before first 'p' 
command
    $ echo hello | ./build/test-groff -o 2 > /dev/null
    $ echo hello | ./build/test-groff -o 2 -wrange > /dev/null
    troff: warning: no pages in output page selection list
---
 ChangeLog               | 16 ++++++++++++++++
 src/roff/troff/node.cpp | 19 +++++++++++++------
 2 files changed, 29 insertions(+), 6 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index a80ec8925..f2aa87cda 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,19 @@
+2024-10-17  G. Branden Robinson <g.branden.robinson@gmail.com>
+
+       [troff]: Better handle inapplicable or out-of-bounds (but still
+       numerically valid) output page selection list (`-o` argument).
+
+       * src/roff/troff/node.cpp: New global Boolean
+       `was_any_page_in_output_list` tracks this datum; defaults false.
+       (troff_output_file::trailer): When finishing up, don't write a
+       "trailer" grout command (and vertical motion) if no page ever
+       began.  Insted, throw a warning in category `range`.
+       (real_output_file::begin_page): Make
+       `was_any_page_in_output_list` true if any page is written.
+
+       Fixes <https://savannah.gnu.org/bugs/?64469>.  Thanks to Dave
+       Kemper for the report.
+
 2024-10-17  G. Branden Robinson <g.branden.robinson@gmail.com>
 
        * src/roff/troff/input.cpp (parse_output_page_list): Enhance
diff --git a/src/roff/troff/node.cpp b/src/roff/troff/node.cpp
index 74b66672a..d18d4eebe 100644
--- a/src/roff/troff/node.cpp
+++ b/src/roff/troff/node.cpp
@@ -73,6 +73,7 @@ tfont *make_tfont(tfont_spec &);
 
 int image_no = 0;
 static int suppression_starting_page_number = 0;
+static bool was_any_page_in_output_list = false;
 
 #define STORE_WIDTH 1
 
@@ -1603,12 +1604,16 @@ troff_output_file::~troff_output_file()
 void troff_output_file::trailer(vunits page_length)
 {
   flush_tbuf();
-  if (page_length > V0) {
-    put("x trailer\n");
-    put('V');
-    put(page_length.to_units());
-    put('\n');
+  if (was_any_page_in_output_list) {
+    if (page_length > V0) {
+      put("x trailer\n");
+      put('V');
+      put(page_length.to_units());
+      put('\n');
+    }
   }
+  else
+    warning(WARN_RANGE, "no pages in output page selection list");
   put("x stop\n");
 }
 
@@ -1735,8 +1740,10 @@ int real_output_file::is_printing()
 void real_output_file::begin_page(int pageno, vunits page_length)
 {
   printing = in_output_page_list(pageno);
-  if (printing)
+  if (printing) {
+    was_any_page_in_output_list = true;
     really_begin_page(pageno, page_length);
+  }
 }
 
 void real_output_file::copy_file(hunits x, vunits y,