Convert a lot of 'int' variables to 'bool'.

My normal habit these days, in new code, is to treat int and bool as
_almost_ completely separate types. I'm still willing to use C's
implicit test for zero on an integer (e.g. 'if (!blob.len)' is fine,
no need to spell it out as blob.len != 0), but generally, if a
variable is going to be conceptually a boolean, I like to declare it
bool and assign to it using 'true' or 'false' rather than 0 or 1.

PuTTY is an exception, because it predates the C99 bool, and I've
stuck to its existing coding style even when adding new code to it.
But it's been annoying me more and more, so now that I've decided C99
bool is an acceptable thing to require from our toolchain in the first
place, here's a quite thorough trawl through the source doing
'boolification'. Many variables and function parameters are now typed
as bool rather than int; many assignments of 0 or 1 to those variables
are now spelled 'true' or 'false'.

I managed this thorough conversion with the help of a custom clang
plugin that I wrote to trawl the AST and apply heuristics to point out
where things might want changing. So I've even managed to do a decent
job on parts of the code I haven't looked at in years!

To make the plugin's work easier, I pushed platform front ends
generally in the direction of using standard 'bool' in preference to
platform-specific boolean types like Windows BOOL or GTK's gboolean;
I've left the platform booleans in places they _have_ to be for the
platform APIs to work right, but variables only used by my own code
have been converted wherever I found them.

In a few places there are int values that look very like booleans in
_most_ of the places they're used, but have a rarely-used third value,
or a distinction between different nonzero values that most users
don't care about. In these cases, I've _removed_ uses of 'true' and
'false' for the return values, to emphasise that there's something
more subtle going on than a simple boolean answer:
 - the 'multisel' field in dialog.h's list box structure, for which
   the GTK front end in particular recognises a difference between 1
   and 2 but nearly everything else treats as boolean
 - the 'urgent' parameter to plug_receive, where 1 vs 2 tells you
   something about the specific location of the urgent pointer, but
   most clients only care about 0 vs 'something nonzero'
 - the return value of wc_match, where -1 indicates a syntax error in
   the wildcard.
 - the return values from SSH-1 RSA-key loading functions, which use
   -1 for 'wrong passphrase' and 0 for all other failures (so any
   caller which already knows it's not loading an _encrypted private_
   key can treat them as boolean)
 - term->esc_query, and the 'query' parameter in toggle_mode in
   terminal.c, which _usually_ hold 0 for ESC[123h or 1 for ESC[?123h,
   but can also hold -1 for some other intervening character that we
   don't support.

In a few places there's an integer that I haven't turned into a bool
even though it really _can_ only take values 0 or 1 (and, as above,
tried to make the call sites consistent in not calling those values
true and false), on the grounds that I thought it would make it more
confusing to imply that the 0 value was in some sense 'negative' or
bad and the 1 positive or good:
 - the return value of plug_accepting uses the POSIXish convention of
   0=success and nonzero=error; I think if I made it bool then I'd
   also want to reverse its sense, and that's a job for a separate
   piece of work.
 - the 'screen' parameter to lineptr() in terminal.c, where 0 and 1
   represent the default and alternate screens. There's no obvious
   reason why one of those should be considered 'true' or 'positive'
   or 'success' - they're just indices - so I've left it as int.

ssh_scp_recv had particularly confusing semantics for its previous int
return value: its call sites used '<= 0' to check for error, but it
never actually returned a negative number, just 0 or 1. Now the
function and its call sites agree that it's a bool.

In a couple of places I've renamed variables called 'ret', because I
don't like that name any more - it's unclear whether it means the
return value (in preparation) for the _containing_ function or the
return value received from a subroutine call, and occasionally I've
accidentally used the same variable for both and introduced a bug. So
where one of those got in my way, I've renamed it to 'toret' or 'retd'
(the latter short for 'returned') in line with my usual modern
practice, but I haven't done a thorough job of finding all of them.

Finally, one amusing side effect of doing this is that I've had to
separate quite a few chained assignments. It used to be perfectly fine
to write 'a = b = c = TRUE' when a,b,c were int and TRUE was just a
the 'true' defined by stdbool.h, that idiom provokes a warning from
gcc: 'suggest parentheses around assignment used as truth value'!

unix/uxpgnt.c

@@ -114,7 +114,7 @@ void keylist_update(void)
 
 const char *const appname = "Pageant";
 
-static int time_to_die = false;
+static bool time_to_die = false;
 
 /* Stub functions to permit linking against x11fwd.c. These never get
  * used, because in LIFE_X11 mode we connect to the X server using a
@@ -122,30 +122,30 @@ static int time_to_die = false;
  * forwarding too. */
 void chan_remotely_opened_confirmation(Channel *chan) { }
 void chan_remotely_opened_failure(Channel *chan, const char *err) { }
-int chan_default_want_close(Channel *chan, int s, int r) { return false; }
-int chan_no_exit_status(Channel *ch, int s) { return false; }
-int chan_no_exit_signal(Channel *ch, ptrlen s, int c, ptrlen m)
+bool chan_default_want_close(Channel *chan, bool s, bool r) { return false; }
+bool chan_no_exit_status(Channel *ch, int s) { return false; }
+bool chan_no_exit_signal(Channel *ch, ptrlen s, bool c, ptrlen m)
 { return false; }
-int chan_no_exit_signal_numeric(Channel *ch, int s, int c, ptrlen m)
+bool chan_no_exit_signal_numeric(Channel *ch, int s, bool c, ptrlen m)
 { return false; }
-int chan_no_run_shell(Channel *chan) { return false; }
-int chan_no_run_command(Channel *chan, ptrlen command) { return false; }
-int chan_no_run_subsystem(Channel *chan, ptrlen subsys) { return false; }
-int chan_no_enable_x11_forwarding(
-    Channel *chan, int oneshot, ptrlen authproto, ptrlen authdata,
+bool chan_no_run_shell(Channel *chan) { return false; }
+bool chan_no_run_command(Channel *chan, ptrlen command) { return false; }
+bool chan_no_run_subsystem(Channel *chan, ptrlen subsys) { return false; }
+bool chan_no_enable_x11_forwarding(
+    Channel *chan, bool oneshot, ptrlen authproto, ptrlen authdata,
     unsigned screen_number) { return false; }
-int chan_no_enable_agent_forwarding(Channel *chan) { return false; }
-int chan_no_allocate_pty(
+bool chan_no_enable_agent_forwarding(Channel *chan) { return false; }
+bool chan_no_allocate_pty(
     Channel *chan, ptrlen termtype, unsigned width, unsigned height,
     unsigned pixwidth, unsigned pixheight, struct ssh_ttymodes modes)
 { return false; }
-int chan_no_set_env(Channel *chan, ptrlen var, ptrlen value) { return false; }
-int chan_no_send_break(Channel *chan, unsigned length) { return false; }
-int chan_no_send_signal(Channel *chan, ptrlen signame) { return false; }
-int chan_no_change_window_size(
+bool chan_no_set_env(Channel *chan, ptrlen var, ptrlen value) { return false; }
+bool chan_no_send_break(Channel *chan, unsigned length) { return false; }
+bool chan_no_send_signal(Channel *chan, ptrlen signame) { return false; }
+bool chan_no_change_window_size(
     Channel *chan, unsigned width, unsigned height,
     unsigned pixwidth, unsigned pixheight) { return false; }
-void chan_no_request_response(Channel *chan, int success) {}
+void chan_no_request_response(Channel *chan, bool success) {}
 
 /*
  * These functions are part of the plug for our connection to the X
@@ -158,7 +158,7 @@ static void x11_log(Plug *p, int type, SockAddr *addr, int port,
 static void x11_receive(Plug *plug, int urgent, char *data, int len) {}
 static void x11_sent(Plug *plug, int bufsize) {}
 static void x11_closing(Plug *plug, const char *error_msg, int error_code,
-			int calling_back)
+			bool calling_back)
 {
     time_to_die = true;
 }
@@ -206,7 +206,7 @@ void pageant_print_env(int pid)
     }
 }
 
-void pageant_fork_and_print_env(int retain_tty)
+void pageant_fork_and_print_env(bool retain_tty)
 {
     pid_t pid = fork();
     if (pid == -1) {
@@ -279,7 +279,7 @@ struct cmdline_key_action {
     const char *filename;
 };
 
-int is_agent_action(keyact action)
+bool is_agent_action(keyact action)
 {
     return action == KEYACT_AGENT_LOAD;
 }
@@ -299,7 +299,7 @@ void add_keyact(keyact action, const char *filename)
     keyact_tail = a;
 }
 
-int have_controlling_tty(void)
+bool have_controlling_tty(void)
 {
     int fd = open("/dev/tty", O_RDONLY);
     if (fd < 0) {
@@ -347,11 +347,11 @@ static char *askpass_tty(const char *prompt)
 static char *askpass_gui(const char *prompt)
 {
     char *passphrase;
-    int success;
+    bool success;
 
     /* in gtkask.c */
     char *gtk_askpass_main(const char *display, const char *wintitle,
-                           const char *prompt, int *success);
+                           const char *prompt, bool *success);
 
     passphrase = gtk_askpass_main(
         display, "Pageant passphrase prompt", prompt, &success);
@@ -395,10 +395,11 @@ static char *askpass(const char *prompt)
     }
 }
 
-static int unix_add_keyfile(const char *filename_str)
+static bool unix_add_keyfile(const char *filename_str)
 {
     Filename *filename = filename_from_str(filename_str);
-    int status, ret;
+    int status;
+    bool ret;
     char *err;
 
     ret = true;
@@ -457,12 +458,12 @@ void key_list_callback(void *ctx, const char *fingerprint,
 
 struct key_find_ctx {
     const char *string;
-    int match_fp, match_comment;
+    bool match_fp, match_comment;
     struct pageant_pubkey *found;
     int nfound;
 };
 
-int match_fingerprint_string(const char *string, const char *fingerprint)
+bool match_fingerprint_string(const char *string, const char *fingerprint)
 {
     const char *hash;
 
@@ -503,8 +504,8 @@ struct pageant_pubkey *find_key(const char *string, char **retstr)
 {
     struct key_find_ctx actx, *ctx = &actx;
     struct pageant_pubkey key_in, *key_ret;
-    int try_file = true, try_fp = true, try_comment = true;
-    int file_errors = false;
+    bool try_file = true, try_fp = true, try_comment = true;
+    bool file_errors = false;
 
     /*
      * Trim off disambiguating prefixes telling us how to interpret
@@ -512,17 +513,21 @@ struct pageant_pubkey *find_key(const char *string, char **retstr)
      */
     if (!strncmp(string, "file:", 5)) {
         string += 5;
-        try_fp = try_comment = false;
+        try_fp = false;
+        try_comment = false;
         file_errors = true; /* also report failure to load the file */
     } else if (!strncmp(string, "comment:", 8)) {
         string += 8;
-        try_file = try_fp = false;
+        try_file = false;
+        try_fp = false;
     } else if (!strncmp(string, "fp:", 3)) {
         string += 3;
-        try_file = try_comment = false;
+        try_file = false;
+        try_comment = false;
     } else if (!strncmp(string, "fingerprint:", 12)) {
         string += 12;
-        try_file = try_comment = false;
+        try_file = false;
+        try_comment = false;
     }
 
     /*
@@ -633,7 +638,7 @@ void run_client(void)
 {
     const struct cmdline_key_action *act;
     struct pageant_pubkey *key;
-    int errors = false;
+    bool errors = false;
     char *retstr;
 
     if (!agent_exists()) {
@@ -735,7 +740,7 @@ void run_agent(void)
     int fd;
     int i, fdcount, fdsize, fdstate;
     int termination_pid = -1;
-    int errors = false;
+    bool errors = false;
     Conf *conf;
     const struct cmdline_key_action *act;
 
@@ -799,7 +804,7 @@ void run_agent(void)
         conn->plug.vt = &X11Connection_plugvt;
         s = new_connection(sk_addr_dup(disp->addr),
                            disp->realhost, disp->port,
-                           0, 1, 0, 0, &conn->plug, conf);
+                           false, true, false, false, &conn->plug, conf);
         if ((err = sk_socket_error(s)) != NULL) {
             fprintf(stderr, "pageant: unable to connect to X server: %s", err);
             exit(1);
@@ -999,7 +1004,7 @@ void run_agent(void)
 
 int main(int argc, char **argv)
 {
-    int doing_opts = true;
+    bool doing_opts = true;
     keyact curr_keyact = KEYACT_AGENT_LOAD;
     const char *standalone_askpass_prompt = NULL;
 
@@ -1121,9 +1126,9 @@ int main(int argc, char **argv)
      * actions of KEYACT_AGENT_* type.
      */
     {
-        int has_agent_actions = false;
-        int has_client_actions = false;
-        int has_lifetime = false;
+        bool has_agent_actions = false;
+        bool has_client_actions = false;
+        bool has_lifetime = false;
         const struct cmdline_key_action *act;
 
         for (act = keyact_head; act; act = act->next) {