[CWEB] Discard rest of overfull input lines.

In the context of the recent bug fix, I noticed that CWEAVE produced
significantly different output than WEAVE from my test case for overfull
lines, which -- in part -- had to be broken.

Although I am aware that Silvio Levy changed CWEAVE's behaviour already
in CWEB 0.5 (1987), I apply this new change in order to revert to DEK's
idea in WEAVE. Now the resulting TeX output has correctly placed comment
markers at the beginning of the broken lines. (To date, CWEAVE issued
material beyond 'buf_size' in overfull lines without such '%' markers.)

Of course, the resulting TeX output might not be processed as expected
because of the discarded material beyond 'buf_size', but the user has
been warned accordingly. :o).

git-svn-id: svn://tug.org/texlive/trunk/Build/source@67662 c570f23f-e606-0410-a88d-b1316a301751

texk/web2c/ChangeLog

@@ -1,3 +1,7 @@
+2023-07-18  Andreas Scherer  <https://ascherer.github.io>
+
+	* cwebboot.cin: Discard rest of overfull input line.
+
 2023-07-17  Andreas Scherer  <https://ascherer.github.io>
 
 	* weave.ch: Deal with malign user input.

texk/web2c/cwebboot.cin

@@ -630,10 +630,10 @@ while(k<=buffer_end&&(c= getc(fp))!=EOF&&c!='\n')
 #line 92 "cwebdir/comm-w2c.ch"
 if((*(k++)= c)!=' '&&c!='\r')limit= k;
 #line 166 "cwebdir/common.w"
-if(k> buffer_end)
-if((c= getc(fp))!=EOF&&c!='\n'){
+if(k> buffer_end){
+while((c= getc(fp))!=EOF&&c!='\n');
 #line 98 "cwebdir/comm-w2c.ch"
-ungetc(c,fp);loc= buffer;err_print(_("! Input line too long"));
+loc= buffer;err_print(_("! Input line too long"));
 #line 169 "cwebdir/common.w"
 
 }

texk/web2c/cwebdir/ChangeLog

@@ -1,3 +1,10 @@
+2023-07-18  Andreas Scherer  <https://ascherer.github.io>
+
+	* cwebdir/comm-mac.ch,
+	* cwebdir/comm-w2c.ch,
+	* cwebdir/common.c,
+	* cwebdir/common.w: Discard rest of overfull input line.
+
 2023-07-17  Andreas Scherer  <https://ascherer.github.io>
 
 	* cweave.w: Deal with malign user input.

texk/web2c/cwebdir/comm-mac.ch

@@ -24,9 +24,9 @@ FILE *fp) /* what file to read from */
   limit = k = buffer; /* beginning of buffer */
   while (k<=buffer_end && (c=getc(fp)) != EOF && c!='\n')
     if ((*(k++) = c) != ' ') limit = k;
-  if (k>buffer_end)
-    if ((c=getc(fp))!=EOF && c!='\n') {
-      ungetc(c,fp); loc=buffer; err_print("! Input line too long");
+  if (k>buffer_end) {
+    while ((c=getc(fp))!=EOF && c!='\n'); /* discard rest of line */
+    loc=buffer; err_print("! Input line too long");
 @.Input line too long@>
     }
   if (c==EOF && limit==buffer) return false; /* there was nothing after
@@ -61,7 +61,7 @@ FILE *fp) /* what file to read from */
       return true;
     }
     else if (k>buffer_end) {
-      ungetc(c,fp); loc=buffer; err_print("! Input line too long");
+      while ((c=getc(fp))!=EOF && c!='\n' && c!='\r'); /* discard rest of line */
       return true;
 @.Input line too long@>
     }

texk/web2c/cwebdir/comm-w2c.ch

@@ -93,9 +93,9 @@ cweb program; /* \.{CTANGLE} or \.{CWEAVE} or \.{CTWILL}? */
 @z
 
 @x
-      ungetc(c,fp); loc=buffer; err_print("! Input line too long");
+    loc=buffer; err_print("! Input line too long");
 @y
-      ungetc(c,fp); loc=buffer; err_print(_("! Input line too long"));
+    loc=buffer; err_print(_("! Input line too long"));
 @z
 
 @x

texk/web2c/cwebdir/common.c

@@ -459,9 +459,9 @@ if(feof(fp))return false;
 limit= k= buffer;
 while(k<=buffer_end&&(c= getc(fp))!=EOF&&c!='\n')
 if((*(k++)= c)!=' ')limit= k;
-if(k> buffer_end)
-if((c= getc(fp))!=EOF&&c!='\n'){
-ungetc(c,fp);loc= buffer;err_print("! Input line too long");
+if(k> buffer_end){
+while((c= getc(fp))!=EOF&&c!='\n');
+loc= buffer;err_print("! Input line too long");
 
 }
 if(c==EOF&&limit==buffer)return false;

texk/web2c/cwebdir/common.w

@@ -163,9 +163,9 @@ FILE *fp) /* what file to read from */
   limit = k = buffer; /* beginning of buffer */
   while (k<=buffer_end && (c=getc(fp)) != EOF && c!='\n')
     if ((*(k++) = c) != ' ') limit = k;
-  if (k>buffer_end)
-    if ((c=getc(fp))!=EOF && c!='\n') {
-      ungetc(c,fp); loc=buffer; err_print("! Input line too long");
+  if (k>buffer_end) {
+    while ((c=getc(fp))!=EOF && c!='\n'); /* discard rest of line */
+    loc=buffer; err_print("! Input line too long");
 @.Input line too long@>
     }
   if (c==EOF && limit==buffer) return false; /* there was nothing after