Add lots more stub versions of standard code modules.

These are all going to be used by a test program I have in the works,
which will need to link against a lot more of the code base than any
so far. So we need a pile of new stubs.

The trickiest of these was stubs/no-network.c, which had to
conditionally define a couple of extra network functions, because
there are Windows-specific plug_closing_system_error and
plug_closing_winsock_error functions.

stubs/no-agent.c

@@ -0,0 +1,11 @@
+#include "putty.h"
+
+bool agent_exists(void) { return false; }
+Socket *agent_connect(Plug *plug) {
+    return new_error_socket_fmt(
+        plug, "no actual networking in this application");
+}
+void agent_cancel_query(agent_pending_query *pq) {}
+agent_pending_query *agent_query(
+    strbuf *query, void **out, int *outlen,
+    void (*callback)(void *, void *, int), void *callback_ctx) {return NULL;}

stubs/no-callback.c

@@ -0,0 +1,33 @@
+/*
+ * Stub version of the callback.c functions. Doesn't let anyone
+ * _schedule_ a callback (because that would lead them into the false
+ * assumption that it would actually happen later on), but permits the
+ * other functions without error, on the grounds that it's well
+ * defined what they would do if nobody had scheduled any callbacks.
+ */
+
+#include "putty.h"
+
+void queue_idempotent_callback(struct IdempotentCallback *ic)
+{
+    unreachable("callbacks are not supported in this application");
+}
+
+void delete_callbacks_for_context(void *ctx)
+{
+}
+
+void queue_toplevel_callback(toplevel_callback_fn_t fn, void *ctx)
+{
+    unreachable("callbacks are not supported in this application");
+}
+
+bool run_toplevel_callbacks(void)
+{
+    return false;
+}
+
+bool toplevel_callback_pending(void)
+{
+    return false;
+}

stubs/no-gss.c

@@ -6,6 +6,25 @@
 
 #include "putty.h"
 
+#include "ssh/pgssapi.h"
+#include "ssh/gss.h"
+#include "ssh/gssc.h"
+
 const int ngsslibs = 0;
 const char *const gsslibnames[1] = { "dummy" };
 const struct keyvalwhere gsslibkeywords[1] = { { "dummy", 0, -1, -1 } };
+
+struct ssh_gss_liblist *ssh_gss_setup(Conf *conf)
+{
+    struct ssh_gss_liblist *list = snew(struct ssh_gss_liblist);
+
+    list->libraries = NULL;
+    list->nlibraries = 0;
+    return list;
+}
+
+void ssh_gss_cleanup(struct ssh_gss_liblist *list)
+{
+    sfree(list->libraries); /* I know it's always NULL, but stay consistent */
+    sfree(list);
+}

stubs/no-ldisc.c

@@ -0,0 +1,37 @@
+#include "putty.h"
+
+struct Ldisc_tag {
+    int dummy;
+};
+
+Ldisc *ldisc_create(Conf *conf, Terminal *term, Backend *backend, Seat *seat)
+{
+    Ldisc *ldisc = snew(Ldisc);
+    memset(ldisc, 0, sizeof(Ldisc));
+    return ldisc;
+}
+
+void ldisc_configure(Ldisc *ldisc, Conf *conf)
+{
+}
+
+void ldisc_free(Ldisc *ldisc)
+{
+    sfree(ldisc);
+}
+
+void ldisc_echoedit_update(Ldisc *ldisc)
+{
+}
+
+void ldisc_provide_userpass_le(Ldisc *ldisc, TermLineEditor *le)
+{
+}
+
+void ldisc_check_sendok(Ldisc *ldisc)
+{
+}
+
+void ldisc_send(Ldisc *ldisc, const void *vbuf, int len, bool interactive)
+{
+}

stubs/no-network.c

@@ -0,0 +1,144 @@
+/*
+ * Stub version of the whole networking abstraction.
+ */
+
+#include "putty.h"
+#include "network.h"
+
+struct SockAddr {
+    int dummy;
+};
+
+void sk_init(void)
+{
+}
+
+void sk_cleanup(void)
+{
+}
+
+SockAddr *sk_namelookup(const char *host, char **canonicalname,
+                        int address_family)
+{
+    return snew(SockAddr);
+}
+SockAddr *sk_nonamelookup(const char *host)
+{
+    return snew(SockAddr);
+}
+
+void sk_getaddr(SockAddr *addr, char *buf, int buflen)
+{
+    strncpy(buf, "nonsense", buflen);
+}
+
+bool sk_addr_needs_port(SockAddr *addr)
+{
+    return true;
+}
+
+bool sk_hostname_is_local(const char *name)
+{
+    return false;
+}
+
+bool sk_address_is_local(SockAddr *addr)
+{
+    return false;
+}
+
+bool sk_address_is_special_local(SockAddr *addr)
+{
+    return false;
+}
+
+int sk_addrtype(SockAddr *addr)
+{
+    return ADDRTYPE_UNSPEC;
+}
+
+void sk_addrcopy(SockAddr *addr, char *buf)
+{
+}
+
+void sk_addr_free(SockAddr *addr)
+{
+    sfree(addr);
+}
+
+SockAddr *sk_addr_dup(SockAddr *addr)
+{
+    return snew(SockAddr);
+}
+
+Socket *sk_new(SockAddr *addr, int port, bool privport, bool oobinline,
+               bool nodelay, bool keepalive, Plug *plug)
+{
+    return new_error_socket_fmt(
+        plug, "no actual networking in this application");
+}
+
+Socket *sk_newlistener(const char *srcaddr, int port, Plug *plug,
+                       bool local_host_only, int orig_address_family)
+{
+    return new_error_socket_fmt(
+        plug, "no actual networking in this application");
+}
+
+void *(sk_getxdmdata)(Socket *sock, int *lenp)
+{
+    return NULL;
+}
+
+void plug_closing_errno(Plug *plug, int error)
+{
+    plug_closing(plug, PLUGCLOSE_ERROR, "dummy");
+}
+
+const char *sk_addr_error(SockAddr *addr)
+{
+    return "no actual network addresses in this application";
+}
+
+int net_service_lookup(const char *service)
+{
+    return 0;
+}
+
+char *get_hostname(void)
+{
+    return dupstr("dummy-hostname");
+}
+
+SockAddr *platform_get_x11_unix_address(const char *sockpath, int displaynum)
+{
+    return snew(SockAddr);
+}
+
+SockAddr *unix_sock_addr(const char *path)
+{
+    return snew(SockAddr);
+}
+
+SockAddr *sk_namedpipe_addr(const char *pipename)
+{
+    return snew(SockAddr);
+}
+
+Socket *new_unix_listener(SockAddr *listenaddr, Plug *plug)
+{
+    return new_error_socket_fmt(
+        plug, "no actual networking in this application");
+}
+
+Socket *platform_start_subprocess(const char *cmd, Plug *plug,
+                                  const char *prefix)
+{
+    return new_error_socket_fmt(
+        plug, "no actual networking in this application");
+}
+
+#ifdef PUTTY_WINDOWS_PLATFORM_H
+void plug_closing_system_error(Plug *plug, DWORD error) {}
+void plug_closing_winsock_error(Plug *plug, DWORD error) {}
+#endif

stubs/no-timing.c

@@ -19,3 +19,8 @@ unsigned long schedule_timer(int ticks, timer_fn_t fn, void *ctx)
 void expire_timer_context(void *ctx)
 {
 }
+
+unsigned long timing_last_clock(void)
+{
+    return 0;
+}

unix/stubs/no-uxsel.c

@@ -0,0 +1,31 @@
+/*
+ * Stub version of uxsel.c, for test programs.
+ */
+
+#include "putty.h"
+
+void uxsel_init(void)
+{
+}
+
+void uxsel_set(int fd, int rwx, uxsel_callback_fn callback)
+{
+}
+
+void uxsel_del(int fd)
+{
+}
+
+int next_fd(int *state, int *rwx)
+{
+    return -1;
+}
+
+int first_fd(int *state, int *rwx)
+{
+    return -1;
+}
+
+void select_result(int fd, int event)
+{
+}