Give BackendVtable separate id and displayname fields.

The previous 'name' field was awkwardly serving both purposes: it was
a machine-readable identifier for the backend used in the saved
session format, and it was also used in error messages when Plink
wanted to complain that it didn't support a particular backend. Now
there are two separate name fields for those purposes.

putty.h

@@ -512,7 +512,11 @@ struct BackendVtable {
      * connection-sharing upstream exists for a given configuration. */
     bool (*test_for_upstream)(const char *host, int port, Conf *conf);
 
-    const char *name;
+    /* 'id' is a machine-readable name for the backend, used in
+     * saved-session storage. 'displayname' is a human-readable name
+     * for error messages. */
+    const char *id, *displayname;
+
     int protocol;
     int default_port;
 };

raw.c

@@ -324,7 +324,7 @@ const struct BackendVtable raw_backend = {
     raw_unthrottle,
     raw_cfg_info,
     NULL /* test_for_upstream */,
-    "raw",
+    "raw", "Raw",
     PROT_RAW,
     0
 };

rlogin.c

@@ -422,7 +422,7 @@ const struct BackendVtable rlogin_backend = {
     rlogin_unthrottle,
     rlogin_cfg_info,
     NULL /* test_for_upstream */,
-    "rlogin",
+    "rlogin", "Rlogin",
     PROT_RLOGIN,
     513
 };

settings.c

@@ -82,7 +82,7 @@ const struct BackendVtable *backend_vt_from_name(const char *name)
 {
     const struct BackendVtable *const *p;
     for (p = backends; *p != NULL; p++)
-        if (!strcmp((*p)->name, name))
+        if (!strcmp((*p)->id, name))
             return *p;
     return NULL;
 }
@@ -556,7 +556,7 @@ void save_open_settings(settings_w *sesskey, Conf *conf)
         const struct BackendVtable *vt =
             backend_vt_from_proto(conf_get_int(conf, CONF_protocol));
         if (vt)
-            p = vt->name;
+            p = vt->id;
     }
     write_setting_s(sesskey, "Protocol", p);
     write_setting_i(sesskey, "PortNumber", conf_get_int(conf, CONF_port));

ssh.c

@@ -1190,7 +1190,7 @@ const struct BackendVtable ssh_backend = {
     ssh_unthrottle,
     ssh_cfg_info,
     ssh_test_for_upstream,
-    "ssh",
+    "ssh", "SSH",
     PROT_SSH,
     22
 };

telnet.c

@@ -1064,7 +1064,7 @@ const struct BackendVtable telnet_backend = {
     telnet_unthrottle,
     telnet_cfg_info,
     NULL /* test_for_upstream */,
-    "telnet",
+    "telnet", "Telnet",
     PROT_TELNET,
     23
 };

testback.c

@@ -57,14 +57,14 @@ const struct BackendVtable null_backend = {
     null_init, null_free, null_reconfig, null_send, null_sendbuffer, null_size,
     null_special, null_get_specials, null_connected, null_exitcode, null_sendok,
     null_ldisc, null_provide_ldisc, null_unthrottle,
-    null_cfg_info, NULL /* test_for_upstream */, "null", -1, 0
+    null_cfg_info, NULL /* test_for_upstream */, "null", "null", -1, 0
 };
 
 const struct BackendVtable loop_backend = {
     loop_init, loop_free, null_reconfig, loop_send, null_sendbuffer, null_size,
     null_special, null_get_specials, null_connected, null_exitcode, null_sendok,
     null_ldisc, null_provide_ldisc, null_unthrottle,
-    null_cfg_info, NULL /* test_for_upstream */, "loop", -1, 0
+    null_cfg_info, NULL /* test_for_upstream */, "loop", "loop", -1, 0
 };
 
 struct loop_state {

unix/uxplink.c

@@ -891,8 +891,8 @@ int main(int argc, char **argv)
 
     if (just_test_share_exists) {
         if (!backvt->test_for_upstream) {
-            fprintf(stderr, "Connection sharing not supported for connection "
+            fprintf(stderr, "Connection sharing not supported for this "
-                    "type '%s'\n", backvt->name);
+                    "connection type (%s)'\n", backvt->displayname);
             return 1;
         }
         if (backvt->test_for_upstream(conf_get_str(conf, CONF_host),

unix/uxpty.c

@@ -1601,7 +1601,7 @@ const struct BackendVtable pty_backend = {
     pty_unthrottle,
     pty_cfg_info,
     NULL /* test_for_upstream */,
-    "pty",
+    "pty", "pty",
     -1,
     0
 };

unix/uxser.c

@@ -576,7 +576,7 @@ const struct BackendVtable serial_backend = {
     serial_unthrottle,
     serial_cfg_info,
     NULL /* test_for_upstream */,
-    "serial",
+    "serial", "Serial",
     PROT_SERIAL,
     0
 };

windows/winplink.c

@@ -413,8 +413,8 @@ int main(int argc, char **argv)
 
     if (just_test_share_exists) {
         if (!vt->test_for_upstream) {
-            fprintf(stderr, "Connection sharing not supported for connection "
+            fprintf(stderr, "Connection sharing not supported for this "
-                    "type '%s'\n", vt->name);
+                    "connection type (%s)'\n", vt->displayname);
             return 1;
         }
         if (vt->test_for_upstream(conf_get_str(conf, CONF_host),

windows/winser.c

@@ -444,7 +444,7 @@ const struct BackendVtable serial_backend = {
     serial_unthrottle,
     serial_cfg_info,
     NULL /* test_for_upstream */,
-    "serial",
+    "serial", "Serial",
     PROT_SERIAL,
     0
 };