Improve messages related to the roff(7) .so request.

In all these messages, show the filename argument that was passed
to the .so request.

In case of failure, show an additional message reporting the file
and the line number where the failing request was found.
The existing message reporting the reason for the failure -
for example, "Permission denied" - is left in place, unchanged.

Inspired by a question asked by Nick@ after he saw the
confusing old messages that used to be emitted in this area.

3 files changed, 12 insertions, 5 deletions

diff --git a/mandoc.h b/mandoc.h
index 5627d4d8..5189e234 100644
--- a/mandoc.h
+++ b/mandoc.h
@@ -162,7 +162,8 @@ enum	mandocerr {
 	MANDOCERR_SYNTARGVCOUNT, /* argument count wrong, violates syntax */
 	MANDOCERR_SYNTCHILD, /* child violates parent syntax */
 	MANDOCERR_SYNTARGCOUNT, /* argument count wrong, violates syntax */
-	MANDOCERR_SOPATH, /* NOT IMPLEMENTED: .so with absolute path or ".." */
+	MANDOCERR_SO_PATH, /* NOT IMPLEMENTED: .so with absolute path or ".." */
+	MANDOCERR_SO_FAIL, /* .so request failed */
 	MANDOCERR_NODOCPROLOG, /* no document prologue */
 	MANDOCERR_MEM, /* static buffer exhausted */
 
diff --git a/read.c b/read.c
index 3b6242cf..e5c75a7c 100644
--- a/read.c
+++ b/read.c
@@ -206,6 +206,7 @@ static	const char * const	mandocerrs[MANDOCERR_MAX] = {
 	"child violates parent syntax",
 	"argument count wrong, violates syntax",
 	"NOT IMPLEMENTED: .so with absolute path or \"..\"",
+	".so request failed",
 	"no document prologue",
 	"static buffer exhausted",
 
@@ -506,8 +507,12 @@ rerun:
 			if (curp->secondary)
 				curp->secondary->sz -= pos + 1;
 			mparse_readfd(curp, -1, ln.buf + of);
-			if (MANDOCLEVEL_FATAL <= curp->file_status)
+			if (MANDOCLEVEL_FATAL <= curp->file_status) {
+				mandoc_vmsg(MANDOCERR_SO_FAIL,
+				    curp, curp->line, pos,
+				    ".so %s", ln.buf + of);
 				break;
+			}
 			pos = 0;
 			continue;
 		default:
diff --git a/roff.c b/roff.c
index eed432e4..e29df8fd 100644
--- a/roff.c
+++ b/roff.c
@@ -1938,7 +1938,8 @@ roff_so(ROFF_ARGS)
 {
 	char *name;
 
-	mandoc_msg(MANDOCERR_SO, r->parse, ln, ppos, NULL);
+	name = *bufp + pos;
+	mandoc_vmsg(MANDOCERR_SO, r->parse, ln, ppos, ".so %s", name);
 
 	/*
 	 * Handle `so'.  Be EXTREMELY careful, as we shouldn't be
@@ -1947,9 +1948,9 @@ roff_so(ROFF_ARGS)
 	 * or using absolute paths.
 	 */
 
-	name = *bufp + pos;
 	if ('/' == *name || strstr(name, "../") || strstr(name, "/..")) {
-		mandoc_msg(MANDOCERR_SOPATH, r->parse, ln, pos, NULL);
+		mandoc_vmsg(MANDOCERR_SO_PATH, r->parse, ln, ppos,
+		    ".so %s", name);
 		return(ROFF_ERR);
 	}