Ensure that strings copied by strncpy() are NUL-terminated

strncpy() does not guarantee that the destination buffer will be
NUL-terminated, so this change ensures that by explicitly setting the
last element to NUL.

POSIX.1-2024 defines the function strlcpy() for that purpose, but
given the standard's freshness and the limited number of occurrences
in ROBODoc's source code, it was easier just to amend the few uses.

Author: scfc

Source/robohdrs.c

@@ -301,11 +301,13 @@ cmdLine( int argc, char **argv )
         case 't':
             /* specify version control tag */
             strncpy( vcTag, optarg, MAXNAME );
+            vcTag[sizeof(vcTag) - 1] = '\0';
             break;
 
         case 'p':
             /* specify project name */
             strncpy( projName, optarg, MAXNAME );
+            projName[sizeof(projName) - 1] = '\0';
             break;
 
         case 'i':
@@ -329,6 +331,7 @@ cmdLine( int argc, char **argv )
                 c = c->next = nc;
             }
             strncpy( c->name, optarg, MAXNAME );
+            c->name[sizeof(c->name) - 1] = '\0';
             break;
 
         case 'l':
@@ -370,6 +373,7 @@ cmdLine( int argc, char **argv )
 
         case 'x':
             strncpy( ctagsBin, optarg, MAXNAME );
+            ctagsBin[sizeof(ctagsBin) - 1] = '\0';
             break;
 
         case '?':
@@ -559,9 +563,13 @@ addList( ctags_t * e, char *fname, char *name, char *decl, char *type,
     e->cnt++;
 
     strncpy( ctag->fname, fname, MAXNAME );
+    ctag->fname[sizeof(ctag->fname) - 1] = '\0';
     strncpy( ctag->name, name, MAXNAME );
+    ctag->name[sizeof(ctag->name) - 1] = '\0';
     strncpy( ctag->decl, decl, MAXLINE );
+    ctag->decl[sizeof(ctag->decl) - 1] = '\0';
     strncpy( ctag->type, type, MAXNAME );
+    ctag->type[sizeof(ctag->type) - 1] = '\0';
     ctag->linenum = linenum;
 }