Fix setcchar invocation

It could be made more complicated but I guess it's fine for now.

We've learnt to run pagers.

sdn.cpp

@@ -41,6 +41,8 @@
 
 #include <sys/inotify.h>
 #include <sys/xattr.h>
+#include <sys/types.h>
+#include <sys/wait.h>
 #include <acl/libacl.h>
 #include <ncurses.h>
 
@@ -106,7 +108,19 @@ fun split (const string &s, const string &sep) -> vector<string> {
 	vector<string> result; split (s, sep, result); return result;
 }
 
+fun needs_shell_quoting (const string &v) -> bool {
+	// IEEE Std 1003.1 sh + the exclamation mark because of csh/bash
+	// history expansion, implicitly also the NUL character
+	for (auto c : v)
+		if (strchr ("|&;<>()$`\\\"' \t\n" "*?[#˜=%" "!", c))
+			return true;
+	return false;
+}
+
 fun shell_escape (const string &v) -> string {
+	if (!needs_shell_quoting (v))
+		return v;
+
 	string result;
 	for (auto c : v)
 		if (c == '\'')
@@ -143,6 +157,21 @@ template<class T> fun shift (vector<T> &v) -> T {
 	auto front = v.front (); v.erase (begin (v)); return front;
 }
 
+fun capitalize (const string &s) -> string {
+	string result;
+	for (auto c : s)
+		result += result.empty () ? toupper (c) : tolower (c);
+	return result;
+}
+
+/// Underlining for teletypes, also imitated in more(1) and less(1)
+fun underline (const string& s) -> string {
+	string result;
+	for (auto c : s)
+		result.append ({c, 8, '_'});
+	return result;
+}
+
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 
 fun xdg_config_home () -> string {
@@ -173,8 +202,8 @@ fun xdg_config_find (const string &suffix) -> unique_ptr<ifstream> {
 using ncstring = basic_string<cchar_t>;
 
 fun cchar (chtype attrs, wchar_t c) -> cchar_t {
-	cchar_t ch {};
+	cchar_t ch {}; wchar_t ws[] = {c, 0};
-	setcchar (&ch, &c, attrs, PAIR_NUMBER (attrs), nullptr);
+	setcchar (&ch, ws, attrs, PAIR_NUMBER (attrs), nullptr);
 	return ch;
 }
 
@@ -221,6 +250,13 @@ fun print (const ncstring &nc, int limit) -> int {
 	return total_width;
 }
 
+fun compute_width (const wstring &w) -> int {
+	int total = 0;
+	for (const auto &c : w)
+		total += wcwidth (c);
+	return total;
+}
+
 fun compute_width (const ncstring &nc) -> int {
 	int total = 0;
 	for (const auto &c : nc)
@@ -269,21 +305,7 @@ enum { ALT = 1 << 24, SYM = 1 << 25 };  // Outside the range of Unicode
 #define KEY(name) (SYM | KEY_ ## name)
 #define CTRL 31 &
 
-struct entry {
+#define ACTIONS(XX) XX(NONE) XX(CHOOSE) XX(CHOOSE_FULL) XX(HELP) XX(QUIT) \
-	string filename, target_path;
-	struct stat info = {}, target_info = {};
-
-	enum { MODES, USER, GROUP, SIZE, MTIME, FILENAME, COLUMNS };
-	ncstring cols[COLUMNS];
-
-	auto operator< (const entry &other) -> bool {
-		auto a = S_ISDIR (info.st_mode);
-		auto b = S_ISDIR (other.info.st_mode);
-		return (a && !b) || (a == b && filename < other.filename);
-	}
-};
-
-#define ACTIONS(XX) XX(NONE) XX(CHOOSE) XX(CHOOSE_FULL) XX(QUIT) \
 	XX(UP) XX(DOWN) XX(TOP) XX(BOTTOM) XX(PAGE_PREVIOUS) XX(PAGE_NEXT) \
 	XX(SCROLL_UP) XX(SCROLL_DOWN) XX(GO_START) XX(GO_HOME) \
 	XX(SEARCH) XX(RENAME) XX(RENAME_PREFILL) \
@@ -300,7 +322,7 @@ static const char *g_action_names[] = {ACTIONS(XX)};
 
 static map<wint_t, action> g_normal_actions = {
 	{ALT | '\r', ACTION_CHOOSE_FULL}, {ALT | KEY (ENTER), ACTION_CHOOSE_FULL},
-	{'\r', ACTION_CHOOSE}, {KEY (ENTER), ACTION_CHOOSE},
+	{'\r', ACTION_CHOOSE}, {KEY (ENTER), ACTION_CHOOSE}, {'h', ACTION_HELP},
 	// M-o ought to be the same shortcut the navigator is launched with
 	{ALT | 'o', ACTION_QUIT}, {'q', ACTION_QUIT},
 	{'k', ACTION_UP}, {CTRL 'p', ACTION_UP}, {KEY (UP), ACTION_UP},
@@ -347,10 +369,30 @@ struct stringcaseless {
 	}
 };
 
+struct entry {
+	string filename, target_path;
+	struct stat info = {}, target_info = {};
+
+	enum { MODES, USER, GROUP, SIZE, MTIME, FILENAME, COLUMNS };
+	ncstring cols[COLUMNS];
+
+	auto operator< (const entry &other) -> bool {
+		auto a = S_ISDIR (info.st_mode);
+		auto b = S_ISDIR (other.info.st_mode);
+		return (a && !b) || (a == b && filename < other.filename);
+	}
+};
+
+struct level {
+	int offset, cursor;                 ///< Scroll offset and cursor position
+	string path, filename;              ///< Level path and filename at cursor
+};
+
 static struct {
 	string cwd;                         ///< Current working directory
 	string start_dir;                   ///< Starting directory
 	vector<entry> entries;              ///< Current directory entries
+	vector<level> levels;               ///< Upper directory levels
 	int offset, cursor;                 ///< Scroll offset and cursor position
 	bool full_view;                     ///< Show extended information
 	int max_widths[entry::COLUMNS];     ///< Column widths
@@ -361,8 +403,10 @@ static struct {
 	int inotify_fd, inotify_wd = -1;    ///< File watch
 	bool out_of_date;                   ///< Entries may be out of date
 
-	wchar_t editor;                     ///< Prompt character for editing
+	const wchar_t *editor;              ///< Prompt string for editing
 	wstring editor_line;                ///< Current user input
+	void (*editor_on_change) ();        ///< Callback on editor change
+	void (*editor_on_confirm) ();       ///< Callback on editor confirmation
 
 	enum { AT_CURSOR, AT_BAR, AT_CWD, AT_INPUT, AT_COUNT };
 	chtype attrs[AT_COUNT] = {A_REVERSE, 0, A_BOLD, 0};
@@ -372,7 +416,9 @@ static struct {
 	map<string, chtype> ls_exts;        ///< LS_COLORS file extensions
 	bool ls_symlink_as_target;          ///< ln=target in dircolors
 
-	map<string, wint_t, stringcaseless> key_names;
+	map<string, wint_t, stringcaseless> name_to_key;
+	map<wint_t, string> key_to_name;
+	string action_names[ACTION_COUNT];  ///< Stylized action names
 
 	// Refreshed by reload():
 
@@ -455,7 +501,7 @@ fun make_entry (const struct dirent *f) -> entry {
 	entry e;
 	e.filename = f->d_name;
 	e.info.st_mode = DTTOIF (f->d_type);
-	auto& info = e.info;
+	auto &info = e.info;
 
 	// TODO: benchmark just readdir() vs. lstat(), also on dead mounts;
 	//   it might make sense to stat asynchronously in threads
@@ -559,7 +605,7 @@ fun update () {
 	attrset (g.attrs[g.AT_INPUT]);
 	if (g.editor) {
 		move (LINES - 1, 0);
-		auto p = apply_attrs ({g.editor, L' ', L'\0'}, 0);
+		auto p = apply_attrs (wstring (g.editor) + L": ", 0);
 		move (LINES - 1, print (p + apply_attrs (g.editor_line, 0), COLS - 1));
 		curs_set (1);
 	} else
@@ -608,6 +654,71 @@ fun reload () {
 		(IN_ALL_EVENTS | IN_ONLYDIR | IN_EXCL_UNLINK) & ~(IN_ACCESS | IN_OPEN));
 }
 
+// TODO: we should be able to signal failures to the user
+fun run_pager (FILE *contents) {
+	// We don't really need to set O_CLOEXEC, so we're not going to
+	rewind (contents);
+	endwin ();
+
+	switch (pid_t child = fork ()) {
+		int status;
+	case -1:
+		break;
+	case 0:
+		// Put the child in a new foreground process group...
+		setpgid (0, 0);
+		tcsetpgrp (STDOUT_FILENO, getpgid (0));
+		dup2 (fileno (contents), STDIN_FILENO);
+
+		// Behaviour copies man-db's man(1), similar to POSIX man(1)
+		for (auto pager : {(const char *) getenv ("PAGER"), "pager", "cat"})
+			if (pager) execl ("/bin/sh", "/bin/sh", "-c", pager, NULL);
+		_exit (EXIT_FAILURE);
+	default:
+		// ...and make sure of it in the parent as well
+		(void) setpgid (child, child);
+		waitpid (child, &status, 0);
+		tcsetpgrp (STDOUT_FILENO, getpgid (0));
+	}
+
+	refresh ();
+	update ();
+}
+
+fun encode_key (wint_t key) -> string {
+	string encoded;
+	if (key & ALT)
+		encoded.append ("M-");
+	wchar_t bare = key & ~ALT;
+	if (g.key_to_name.count (bare))
+		encoded.append (capitalize (g.key_to_name.at (bare)));
+	else if (bare < 32)
+		encoded.append ("C-").append ({char (tolower (bare + 64))});
+	else
+		encoded.append (to_mb ({bare}));
+	return encoded;
+}
+
+fun show_help () {
+	FILE *contents = tmpfile ();
+	if (!contents)
+		return;
+
+	for (const auto &kv : g_binding_contexts) {
+		fprintf (contents, "%s\n",
+			underline (capitalize (kv.first + " key bindings")).c_str ());
+		for (const auto &kv : *kv.second) {
+			auto key = encode_key (kv.first);
+			key.append (max (0, 10 - compute_width (to_wide (key))), ' ');
+			fprintf (contents, "%s %s\n",
+				key.c_str (), g.action_names[kv.second].c_str ());
+		}
+		fprintf (contents, "\n");
+	}
+	run_pager (contents);
+	fclose (contents);
+}
+
 fun search (const wstring &needle) {
 	int best = g.cursor, best_n = 0;
 	for (int i = 0; i < int (g.entries.size ()); i++) {
@@ -621,13 +732,40 @@ fun search (const wstring &needle) {
 	g.cursor = best;
 }
 
-fun change_dir (const string& path) {
+fun is_ancestor_dir (const string &ancestor, const string &of) -> bool {
+	if (strncmp (ancestor.c_str (), of.c_str (), ancestor.length ()))
+		return false;
+	return of.c_str ()[ancestor.length ()] == '/'
+		|| (ancestor == "/" && ancestor != of);
+}
+
+fun change_dir (const string &path) {
 	if (chdir (path.c_str ())) {
 		beep ();
-	} else {
+		return;
-		// TODO: remember cursor going down, then restore going up
+	}
-		g.cursor = 0;
+
+	level last {g.offset, g.cursor, g.cwd, g.entries[g.cursor].filename};
 	reload ();
+
+	if (is_ancestor_dir (last.path, g.cwd)) {
+		g.levels.push_back (last);
+		g.offset = g.cursor = 0;
+	} else {
+		string anchor;
+		auto i = g.levels.rbegin ();
+		while (i != g.levels.rend () && !is_ancestor_dir (i->path, g.cwd)) {
+			if (i->path == g.cwd) {
+				g.offset = i->offset;
+				g.cursor = i->cursor;
+				anchor = i->filename;
+			}
+			i++;
+			g.levels.pop_back ();
+		}
+		if (!anchor.empty () && (g.cursor >= g.entries.size ()
+			|| g.entries[g.cursor].filename != anchor))
+			search (to_wide (anchor));
 	}
 }
 
@@ -643,21 +781,17 @@ fun choose (const entry &entry) -> bool {
 }
 
 fun handle_editor (wint_t c) {
-	// FIXME: do not check editor actions by the prompt letter
 	auto i = g_input_actions.find (c);
 	switch (i == g_input_actions.end () ? ACTION_NONE : i->second) {
+	case ACTION_INPUT_CONFIRM:
+		if (g.editor_on_confirm)
+			g.editor_on_confirm ();
+		// Fall-through
 	case ACTION_INPUT_ABORT:
 		g.editor_line.clear ();
 		g.editor = 0;
-		break;
+		g.editor_on_change = nullptr;
-	case ACTION_INPUT_CONFIRM:
+		g.editor_on_confirm = nullptr;
-		if (g.editor == L'e') {
-			auto mb = to_mb (g.editor_line);
-			rename (g.entries[g.cursor].filename.c_str (), mb.c_str ());
-			reload ();
-		}
-		g.editor_line.clear ();
-		g.editor = 0;
 		break;
 	case ACTION_INPUT_B_DELETE:
 		if (!g.editor_line.empty ())
@@ -668,9 +802,8 @@ fun handle_editor (wint_t c) {
 			beep ();
 		} else {
 			g.editor_line += c;
-			if (g.editor == L'/'
+			if (g.editor_on_change)
-			 || g.editor == L's')
+				g.editor_on_change ();
-				search (g.editor_line);
 		}
 	}
 }
@@ -693,6 +826,9 @@ fun handle (wint_t c) -> bool {
 		if (choose (current))
 			break;
 		return false;
+	case ACTION_HELP:
+		show_help ();
+		return true;
 	case ACTION_QUIT:
 		return false;
 
@@ -733,13 +869,21 @@ fun handle (wint_t c) -> bool {
 		break;
 
 	case ACTION_SEARCH:
-		g.editor = c;
+		g.editor = L"search";
+		g.editor_on_change = [] {
+			search (g.editor_line);
+		};
 		break;
 	case ACTION_RENAME_PREFILL:
 		g.editor_line = to_wide (current.filename);
 		// Fall-through
 	case ACTION_RENAME:
-		g.editor = c & ~ALT;
+		g.editor = L"rename";
+		g.editor_on_confirm = [] {
+			auto mb = to_mb (g.editor_line);
+			rename (g.entries[g.cursor].filename.c_str (), mb.c_str ());
+			reload ();
+		};
 		break;
 
 	case ACTION_TOGGLE_FULL:
@@ -895,7 +1039,6 @@ fun parse_key (const string &key_name) -> wint_t {
 		c |= ALT;
 		p += 2;
 	}
-
 	if (!strncmp (p, "C-", 2)) {
 		p += 2;
 		if (*p < 32) {
@@ -904,9 +1047,8 @@ fun parse_key (const string &key_name) -> wint_t {
 		}
 		c |= CTRL *p;
 		p += 1;
-	} else if (g.key_names.count (p)) {
+	} else if (g.name_to_key.count (p)) {
-		c |= g.key_names.at (p);
+		return c | g.name_to_key.at (p);
-		p += strlen (p);
 	} else {
 		wchar_t w; mbstate_t mb {};
 		auto len = strlen (p) + 1, res = mbrtowc (&w, p, len, &mb);
@@ -928,8 +1070,13 @@ fun parse_key (const string &key_name) -> wint_t {
 	return c;
 }
 
+fun learn_named_key (const string &name, wint_t key) {
+	g.name_to_key[g.key_to_name[key] = name] = key;
+}
+
 fun load_bindings () {
-	g.key_names["space"] = ' ';
+	learn_named_key ("space", ' ');
+	learn_named_key ("escape", 0x1b);
 	for (int kc = KEY_MIN; kc < KEY_MAX; kc++) {
 		const char *name = keyname (kc);
 		if (!name)
@@ -941,7 +1088,7 @@ fun load_bindings () {
 			if (*name != '(' && *name != ')')
 				filtered += *name;
 		}
-		g.key_names[filtered] = kc;
+		learn_named_key (filtered, SYM | kc);
 	}
 
 	auto config = xdg_config_find ("/" PROJECT_NAME "/bindings");
@@ -950,11 +1097,12 @@ fun load_bindings () {
 
 	// Stringization in the preprocessor is a bit limited, we want lisp-case
 	map<string, action> actions;
-	int a;
+	int a = 0;
 	for (auto p : g_action_names) {
 		string name;
 		for (; *p; p++)
 			name += *p == '_' ? '-' : *p + 'a' - 'A';
+		g.action_names[a] = name;
 		actions[name] = action (a++);
 	}
 
@@ -1001,6 +1149,9 @@ int main (int argc, char *argv[]) {
 	auto output_fd = dup (STDOUT_FILENO);
 	dup2 (STDIN_FILENO, STDOUT_FILENO);
 
+	// So that the neither us nor our children stop on tcsetpgrp()
+	signal (SIGTTOU, SIG_IGN);
+
 	if ((g.inotify_fd = inotify_init1 (IN_NONBLOCK)) < 0) {
 		cerr << "cannot initialize inotify" << endl;
 		return 1;