[groff] 79/83: [eqn]: Fix Savannah #64105.

[G. Branden Robinson]

gbranden pushed a commit to branch branden-2023-05-06
in repository groff.

commit 6de5791ea8dc6213e28d99fc8074abe30777854b
Author: G. Branden Robinson <g.branden.robinson@gmail.com>
AuthorDate: Sun Apr 30 06:06:51 2023 -0500

    [eqn]: Fix Savannah #64105.
    
    * src/preproc/eqn/main.cpp (do_file): Increment the line number if a
      malformed `lf` request was encountered, instead of decrementing it if
      a valid one was.  Increment it when processing an end eqn macro call
      (".EN"), not just a start one.  Drop an incrementation of the line
      number that applied too generally.
    
    This ensures we don't throw the line numbers off in normal input
    processing.  Fixes a problem introduced by me in commit dc98a8b09e, 31
    October.
    
    Fixes <https://savannah.gnu.org/bugs/?64105>.
---
 ChangeLog                | 17 +++++++++++++++++
 src/preproc/eqn/main.cpp | 14 ++++++++------
 2 files changed, 25 insertions(+), 6 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index fa1081442..e7c1ac245 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,20 @@
+2023-04-30  G. Branden Robinson <g.branden.robinson@gmail.com>
+
+       [eqn]: Fix Savannah #64105.
+
+       * src/preproc/eqn/main.cpp (do_file): Increment the line number
+       if a malformed `lf` request was encountered, instead of
+       decrementing it if a valid one was.  Increment it when
+       processing an end eqn macro call (".EN"), not just a start one.
+       Drop an incrementation of the line number that applied too
+       generally.
+
+       This ensures we don't throw the line numbers off in normal input
+       processing.  Fixes a problem introduced by me in commit
+       dc98a8b09e, 31 October.
+
+       Fixes <https://savannah.gnu.org/bugs/?64105>.
+
 2023-04-30  G. Branden Robinson <g.branden.robinson@gmail.com>
 
        [eqn]: Improve tests of line number accuracy.
diff --git a/src/preproc/eqn/main.cpp b/src/preproc/eqn/main.cpp
index 324e2b4fb..f2678c2fa 100644
--- a/src/preproc/eqn/main.cpp
+++ b/src/preproc/eqn/main.cpp
@@ -109,9 +109,10 @@ void do_file(FILE *fp, const char *filename)
     {
       put_string(linebuf, stdout);
       linebuf += '\0';
-      // In GNU roff, `lf` assigns the number of the _next_ line.
-      if (interpret_lf_args(linebuf.contents() + 3))
-       current_lineno--;
+      // In GNU roff, `lf` assigns the number of the _next_ line.  If it
+      // is malformed, it is nevertheless an input line.
+      if (!(interpret_lf_args(linebuf.contents() + 3)))
+       current_lineno++;
     }
     else if (linebuf.length() >= 4
             && linebuf[0] == '.'
@@ -132,12 +133,14 @@ void do_file(FILE *fp, const char *filename)
            && linebuf[1] == 'E') {
          if (linebuf[2] == 'N'
              && (linebuf.length() == 3 || linebuf[3] == ' '
-                 || linebuf[3] == '\n' || compatible_flag))
+                 || linebuf[3] == '\n' || compatible_flag)) {
+           current_lineno++;
            break;
+         }
          else if (linebuf[2] == 'Q' && linebuf.length() > 3
                   && (linebuf[3] == ' ' || linebuf[3] == '\n'
                       || compatible_flag)) {
-           current_lineno++; // We just read another line.
+           current_lineno++;
            fatal("equations cannot be nested (.EQ within .EQ)");
          }
        }
@@ -170,7 +173,6 @@ void do_file(FILE *fp, const char *filename)
       ;
     else
       put_string(linebuf, stdout);
-    current_lineno++;
   }
   current_filename = 0;
   current_lineno = 0;