halcmd: warn about an arrow written against a name

docs/src/man/man1/halcmd.1.adoc

@@ -144,7 +144,10 @@ requested component with a call to *dlopen(3)*.
   _arrow_ can be "`=>`", "`<=`", "`<=>`", or omitted. *halcmd* ignores
   arrows, but they can be useful in command files to document the
   direction of data flow. Arrows should not be used on the command line
-  since the shell might try to interpret them. Fails if either _pinname_
+  since the shell might try to interpret them. An arrow is only an arrow
+  when spaces separate it from the names: "`lube-pump=>`" is a signal
+  name, and *halcmd* warns about a name that starts or ends with an
+  arrow. Fails if either _pinname_
   or _signame_ does not exist, or if they are not the same type type.
 *linksp* _signame_ [_arrow_] _pinname_::
   (OBSOLETE - use *net* instead) (_link_ __s__ignal to __p__in) Works

src/hal/utils/halcmd.c

@@ -303,6 +303,14 @@ static int count_args(const char **argv) {
     return i;
 }
 
+/* "lube-pump=>" or "=>io.relay": an arrow written without a space */
+static int has_attached_arrow(const char *arg) {
+    size_t len = strlen(arg);
+    if(len < 3) return 0;
+    return !strncmp(arg, "<=", 2) || !strncmp(arg, "=>", 2) ||
+	   !strcmp(arg + len - 2, "<=") || !strcmp(arg + len - 2, "=>");
+}
+
 #define ARG(i) (argc > i ? argv[i] : NULL)
 #define REST(i) (argc > i ? argv + i : argv + argc)
 
@@ -338,6 +346,10 @@ static int parse_cmd1(const char **argv) {
 		   !strcmp(argv[s], "<=>")) {
 		    continue;
 		} else {
+		    if(has_attached_arrow(argv[s]))
+			halcmd_warning("'%s' has an arrow attached, it is taken"
+			    " as part of the name; put a space between the name"
+			    " and the arrow\n", argv[s]);
 		    argv[d++] = argv[s];
 		}
 	    }

src/hal/utils/halcmd_commands.cc

@@ -2517,7 +2517,7 @@ int do_help_cmd(const char *command)
 	printf("linksp signame [arrow] pinname\n");
 	printf("  Links pin 'pinname' to signal 'signame'.  Both forms do\n");
 	printf("  the same thing.  Use whichever makes sense.  The optional\n");
-	printf("  'arrow' can be '==>', '<==', or '<=>' and is ignored.  It\n");
+	printf("  'arrow' can be '=>', '<=', or '<=>' and is ignored.  It\n");
 	printf("  can be used in files to show the direction of data flow,\n");
 	printf("  but don't use arrows on the command line.\n");
     } else if(strcmp(command, "net") == 0) {