Expand \n(.$ (the number of macro arguments) right in roff_userdef(),

before even reparsing the expanded macro.
That is the least dirty way to fix the bug that \(.$ remained set
after execution of the user-defined macro ended.  Any other way
to fix it would probably require changes to read.c, which really
shouldn't be bothered with such roff(7) internals.

diff --git a/usr.bin/mandoc/roff.c b/usr.bin/mandoc/roff.c
index c085475..ee9d45c 100644 (file)
--- a/usr.bin/mandoc/roff.c
+++ b/usr.bin/mandoc/roff.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: roff.c,v 1.208 2018/08/19 17:43:39 schwarze Exp $ */
+/*     $OpenBSD: roff.c,v 1.209 2018/08/20 17:31:44 schwarze Exp $ */
 /*
  * Copyright (c) 2008-2012, 2014 Kristaps Dzonsons <kristaps@bsd.lv>
  * Copyright (c) 2010-2015, 2017, 2018 Ingo Schwarze <schwarze@openbsd.org>
@@ -105,7 +105,6 @@ struct      roff {
        int              rstacksz; /* current size limit of rstack */
        int              rstackpos; /* position in rstack */
        int              format; /* current file in mdoc or man format */
-       int              argc; /* number of args of the last macro */
        char             control; /* control character */
        char             escape; /* escape character */
 };
@@ -2661,7 +2660,7 @@ roff_getregro(const struct roff *r, const char *name)
 
        switch (*name) {
        case '$':  /* Number of arguments of the last macro evaluated. */
-               return r->argc;
+               return 0;
        case 'A':  /* ASCII approximation mode is always off. */
                return 0;
        case 'g':  /* Groff compatibility mode is always on. */
@@ -3379,22 +3378,22 @@ roff_userdef(ROFF_ARGS)
 {
        const char       *arg[16], *ap;
        char             *cp, *n1, *n2;
-       int               expand_count, i, ib, ie;
-       size_t            asz, rsz;
+       int               argc, expand_count, i, ib, ie;
+       size_t            asz, esz, rsz;
 
        /*
         * Collect pointers to macro argument strings
         * and NUL-terminate them.
         */
 
-       r->argc = 0;
+       argc = 0;
        cp = buf->buf + pos;
        for (i = 0; i < 16; i++) {
                if (*cp == '\0')
                        arg[i] = "";
                else {
                        arg[i] = mandoc_getarg(r->parse, &cp, ln, &pos);
-                       r->argc = i + 1;
+                       argc = i + 1;
                }
        }
 
@@ -3416,7 +3415,7 @@ roff_userdef(ROFF_ARGS)
                        continue;
                if (*cp == '*') {  /* \\$* inserts all arguments */
                        ib = 0;
-                       ie = r->argc - 1;
+                       ie = argc - 1;
                } else {  /* \\$1 .. \\$9 insert one argument */
                        ib = ie = *cp - '1';
                        if (ib < 0 || ib > 8)
@@ -3504,6 +3503,34 @@ roff_userdef(ROFF_ARGS)
                }
        }
 
+       /*
+        * Expand the number of arguments, if it is used.
+        * This never makes the expanded macro longer.
+        */
+
+       for (cp = n1; *cp != '\0'; cp++) {
+               if (cp[0] != '\\')
+                       continue;
+               if (cp[1] == '\\') {
+                       cp++;
+                       continue;
+               }
+               if (strncmp(cp + 1, "n(.$", 4) == 0)
+                       esz = 5;
+               else if (strncmp(cp + 1, "n[.$]", 5) == 0)
+                       esz = 6;
+               else
+                       continue;
+               asz = snprintf(cp, esz, "%d", argc);
+               assert(asz < esz);
+               rsz = buf->sz - (cp - n1) - esz;
+               memmove(cp + asz, cp + esz, rsz);
+               buf->sz -= esz - asz;
+               n2 = mandoc_realloc(n1, buf->sz);
+               cp = n2 + (cp - n1) + asz;
+               n1 = n2;
+       }
+
        /*
         * Replace the macro invocation
         * by the expanded macro.