mandoc: Dummy implementation of the roff(7) \V (interpolate environment

mandoc: Dummy implementation of the roff(7) \V (interpolate environment

[schwarze]

Log Message:
-----------
Dummy implementation of the roff(7) \V (interpolate environment variable)
escape sequence.  This is needed to get \V into the correct parsing
class, ESCAPE_EXPAND.

It is intentional that mandoc(1) output is *not* influenced by environment
variables, so interpolate the name of the variable with some decorating
punctuation rather than interpolating its value.

Modified Files:
--------------
    mandoc:
        roff.c
        roff_escape.c
        roff.7
    mandoc/regress/roff/esc:
        Makefile

Added Files:
-----------
    mandoc/regress/roff/esc:
        V1.in
        V1.out_ascii
        V1.out_lint

Revision Data
-------------
Index: roff.7
===================================================================
RCS file: /home/cvs/mandoc/mandoc/roff.7,v
retrieving revision 1.117
retrieving revision 1.118
diff -Lroff.7 -Lroff.7 -u -p -r1.117 -r1.118
--- roff.7
+++ roff.7
@@ -2188,12 +2188,16 @@ Horizontal tab; ignored by
 Move up by half a line; ignored by
 .Xr mandoc 1 .
 .It Ic \eV[ Ns Ar name Ns Ic \&]
-Interpolate an environment variable; ignored by
-.Xr mandoc 1 .
+Interpolate an environment variable.
 For short names, there are variants
 .Ic \eV Ns Ar c
 and
 .Ic \eV( Ns Ar cc .
+This escape sequence is intentionally unsupported;
+.Xr mandoc 1
+prints the string
+.Dq Pf $ Brq Ar name
+instead of inspecting the environment.
 .It Ic \ev\(aq Ns Ar number Ns Ic \(aq
 Vertical motion; ignored by
 .Xr mandoc 1 .
Index: roff_escape.c
===================================================================
RCS file: /home/cvs/mandoc/mandoc/roff_escape.c,v
retrieving revision 1.2
retrieving revision 1.3
diff -Lroff_escape.c -Lroff_escape.c -u -p -r1.2 -r1.3
--- roff_escape.c
+++ roff_escape.c
@@ -157,13 +157,13 @@ roff_escape(const char *buf, const int l
 
 	case '$':
 	case '*':
+	case 'V':
 	case 'n':
 		rval = ESCAPE_EXPAND;
 		break;
 	case 'F':
 	case 'M':
 	case 'O':
-	case 'V':
 	case 'Y':
 	case 'g':
 	case 'k':
Index: roff.c
===================================================================
RCS file: /home/cvs/mandoc/mandoc/roff.c,v
retrieving revision 1.388
retrieving revision 1.389
diff -Lroff.c -Lroff.c -u -p -r1.388 -r1.389
--- roff.c
+++ roff.c
@@ -1529,6 +1529,12 @@ roff_expand(struct roff *r, struct buf *
 			ubuf[1] = '\0';
 			res = ubuf;
 			break;
+		case 'V':
+			mandoc_msg(MANDOCERR_UNSUPP, ln, iesc,
+			    "%.*s", iend - iesc, buf->buf + iesc);
+			roff_expand_patch(buf, iendarg, "}", iend);
+			roff_expand_patch(buf, iesc, "${", iarg);
+			continue;
 		case 'n':
 			if (iendarg > iarg)
 				(void)snprintf(ubuf, sizeof(ubuf), "%d",
@@ -1567,9 +1573,8 @@ roff_expand_patch(struct buf *buf, int s
 {
 	char	*nbuf;
 
-	buf->buf[start] = '\0';
-	buf->sz = mandoc_asprintf(&nbuf, "%s%s%s", buf->buf, repl,
-	    buf->buf + end) + 1;
+	buf->sz = mandoc_asprintf(&nbuf, "%.*s%s%s", start, buf->buf,
+	    repl, buf->buf + end) + 1;
 	free(buf->buf);
 	buf->buf = nbuf;
 }
--- /dev/null
+++ regress/roff/esc/V1.out_ascii
@@ -0,0 +1,11 @@
+ESC-V1(1)                   General Commands Manual                  ESC-V1(1)
+
+N\bNA\bAM\bME\bE
+       esc-V1 - interpolate environment variables
+
+D\bDE\bES\bSC\bCR\bRI\bIP\bPT\bTI\bIO\bON\bN
+       single-character name: "${N}"
+       double-character name: "${VN}"
+       multi-character name: "${VARNAME}"
+
+OpenBSD                          May 31, 2022                        ESC-V1(1)
--- /dev/null
+++ regress/roff/esc/V1.out_lint
@@ -0,0 +1,3 @@
+mandoc: V1.in:6:25: UNSUPP: unsupported feature: \VN
+mandoc: V1.in:8:25: UNSUPP: unsupported feature: \V(VN
+mandoc: V1.in:10:24: UNSUPP: unsupported feature: \V[VARNAME]
Index: Makefile
===================================================================
RCS file: /home/cvs/mandoc/mandoc/regress/roff/esc/Makefile,v
retrieving revision 1.11
retrieving revision 1.12
diff -Lregress/roff/esc/Makefile -Lregress/roff/esc/Makefile -u -p -r1.11 -r1.12
--- regress/roff/esc/Makefile
+++ regress/roff/esc/Makefile
@@ -1,10 +1,10 @@
-# $OpenBSD: Makefile,v 1.21 2022/05/20 13:06:27 schwarze Exp $
+# $OpenBSD: Makefile,v 1.22 2022/05/30 22:50:40 schwarze Exp $
 
 REGRESS_TARGETS	 = one two multi comment
-REGRESS_TARGETS	+= B bs_man bs_mdoc c c_man E1 e f h hneg l O1 o p r w z
+REGRESS_TARGETS	+= B bs_man bs_mdoc c c_man E1 e f h hneg l O1 o p r V1 w z
 REGRESS_TARGETS	+= ignore invalid unsupp
 HTML_TARGETS	 = f
-LINT_TARGETS	 = comment B h l O1 r w ignore invalid unsupp
+LINT_TARGETS	 = comment B h l O1 r V1 w ignore invalid unsupp
 
 # mandoc defects:
 # - \h with a negative argument replaces output characters
@@ -12,5 +12,10 @@ LINT_TARGETS	 = comment B h l O1 r w ign
 # - \r does not return to the previous output line
 
 SKIP_GROFF	 = hneg r
+
+# intentional difference:
+# - mandoc does not inspect the environment
+
+SKIP_GROFF	+= V1
 
 .include <bsd.regress.mk>
--- /dev/null
+++ regress/roff/esc/V1.in
@@ -0,0 +1,10 @@
+.\" $OpenBSD: V1.in,v 1.1 2022/05/30 22:50:40 schwarze Exp $
+.TH ESC-V1 1 "May 31, 2022"
+.SH NAME
+esc-V1 \- interpolate environment variables
+.SH DESCRIPTION
+single-character name: "\VN"
+.br
+double-character name: "\V(VN"
+.br
+multi-character name: "\V[VARNAME]"
--
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