[groff] 16/16: [eqn]: Fix Savannah #63299.

[G. Branden Robinson]

gbranden pushed a commit to branch master
in repository groff.

commit dc98a8b09e7f3dcfe968b978eb210f468db78cc9
Author: G. Branden Robinson <g.branden.robinson@gmail.com>
AuthorDate: Mon Oct 31 20:01:34 2022 -0500

    [eqn]: Fix Savannah #63299.
    
    * src/preproc/eqn/main.cpp: Revise input file line number handling.
    
      (read_line): Stop dealing with `current_lineno` here; it's now up to
      its caller (`do_file()`) to manipulate the line number.
    
      (do_file): When reading new file, initialize `current_lineno` to
      1 instead of 0.  Reset it to zero when encountering EOF (so that
        diagnostics will not include a line number at all).  When performing
        nested call to `read_line()` to gather '.EN' from input, increment
        the line number.  Write correct line number in output groff `lf`
        requests; in groff, its first argument assigns the number of the
        _next_ input line.  Increment line number at end of outer
        `read_line()` loop.
    
    Fixes <https://savannah.gnu.org/bugs/index.php?63299>.  Thanks to Alex
    Colomar for the report.
    
    Also wrap long input lines and add explanatory comments.
---
 ChangeLog                | 20 ++++++++++++++++++++
 src/preproc/eqn/main.cpp | 33 ++++++++++++++++++++-------------
 2 files changed, 40 insertions(+), 13 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index c87a94305..9bff3b0d9 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,23 @@
+2022-10-31  G. Branden Robinson <g.branden.robinson@gmail.com>
+
+       [eqn]: Fix Savannah #63299.
+
+       * src/preproc/eqn/main.cpp: Revise input file line number
+       handling.
+       (read_line): Stop dealing with `current_lineno` here; it's now
+       up to its caller (`do_file()`) to manipulate the line number.
+       (do_file): When reading new file, initialize `current_lineno` to
+       1 instead of 0.  Reset it to zero when encountering EOF (so that
+       diagnostics will not include a line number at all).  When
+       performing nested call to `read_line()` to gather '.EN' from
+       input, increment the line number.  Write correct line number in
+       output groff `lf` requests; in groff, its first argument assigns
+       the number of the _next_ input line.  Increment line number at
+       end of outer `read_line()` loop.
+
+       Fixes <https://savannah.gnu.org/bugs/index.php?63299>.  Thanks
+       to Alex Colomar for the report.
+
 2022-10-31  G. Branden Robinson <g.branden.robinson@gmail.com>
 
        [eqn]: Regression-test Savannah #63299.
diff --git a/src/preproc/eqn/main.cpp b/src/preproc/eqn/main.cpp
index 897a291dd..81d518443 100644
--- a/src/preproc/eqn/main.cpp
+++ b/src/preproc/eqn/main.cpp
@@ -88,12 +88,7 @@ static bool read_line(FILE *fp, string *p)
     if (c == '\n')
       break;
   }
-  bool is_end_of_file = (p->length() > 0);
-  if (is_end_of_file)
-    current_lineno = 0;
-  else
-    current_lineno++;
-  return is_end_of_file;
+  return (p->length() > 0);
 }
 
 void do_file(FILE *fp, const char *filename)
@@ -106,13 +101,15 @@ void do_file(FILE *fp, const char *filename)
   current_filename = fn.contents();
   if (output_format == troff)
     printf(".lf 1 %s\n", current_filename);
-  current_lineno = 0;
+  current_lineno = 1;
   while (read_line(fp, &linebuf)) {
     if (linebuf.length() >= 4
        && linebuf[0] == '.' && linebuf[1] == 'l' && linebuf[2] == 'f'
-       && (linebuf[3] == ' ' || linebuf[3] == '\n' || compatible_flag)) {
+       && (linebuf[3] == ' ' || linebuf[3] == '\n' || compatible_flag))
+    {
       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--;
     }
@@ -126,17 +123,23 @@ void do_file(FILE *fp, const char *filename)
       int start_lineno = current_lineno + 1;
       str.clear();
       for (;;) {
-       if (!read_line(fp, &linebuf))
+       if (!read_line(fp, &linebuf)) {
+         current_lineno = 0; // suppress report of line number
          fatal("end of file before .EN");
-       if (linebuf.length() >= 3 && linebuf[0] == '.' && linebuf[1] == 'E') {
+       }
+       if (linebuf.length() >= 3
+           && linebuf[0] == '.'
+           && linebuf[1] == 'E') {
          if (linebuf[2] == 'N'
              && (linebuf.length() == 3 || linebuf[3] == ' '
                  || linebuf[3] == '\n' || compatible_flag))
            break;
          else if (linebuf[2] == 'Q' && linebuf.length() > 3
                   && (linebuf[3] == ' ' || linebuf[3] == '\n'
-                      || compatible_flag))
+                      || compatible_flag)) {
+           current_lineno++; // We just read another line.
            fatal("equations cannot be nested (.EQ within .EQ)");
+         }
        }
        str += linebuf;
       }
@@ -151,12 +154,15 @@ void do_file(FILE *fp, const char *filename)
        if (output_format == mathml)
          putchar('\n');
         else {
-         printf(".lf %d\n", current_lineno - 1);
+         current_lineno++;
+         printf(".lf %d\n", current_lineno);
          output_string();
        }
       }
-      if (output_format == troff)
+      if (output_format == troff) {
+       current_lineno++;
        printf(".lf %d\n", current_lineno);
+      }
       put_string(linebuf, stdout);
     }
     else if (start_delim != '\0' && linebuf.search(start_delim) >= 0
@@ -164,6 +170,7 @@ void do_file(FILE *fp, const char *filename)
       ;
     else
       put_string(linebuf, stdout);
+    current_lineno++;
   }
   current_filename = 0;
   current_lineno = 0;