ash,hush: allow builtins to be tab-completed, closes 7532

function                                             old     new   delta
complete_cmd_dir_file                                678     830    +152
get_builtin_name                                       -      35     +35
optschanged                                          125     132      +7
hush_main                                           1069    1076      +7
save_command_ps_at_cur_history                        76      78      +2
------------------------------------------------------------------------------
(add/remove: 1/0 grow/shrink: 4/0 up/down: 203/0)             Total: 203 bytes

Signed-off-by: Ron Yorston <rmy@pobox.com>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

include/libbb.h

@@ -1818,10 +1818,19 @@ unsigned size_from_HISTFILESIZE(const char *hp) FAST_FUNC;
 # else
 #  define MAX_HISTORY 0
 # endif
+typedef const char *get_exe_name_t(int i) FAST_FUNC;
 typedef struct line_input_t {
 	int flags;
 	int timeout;
 	const char *path_lookup;
+# if ENABLE_FEATURE_TAB_COMPLETION \
+&& (ENABLE_ASH  || ENABLE_SH_IS_ASH  || ENABLE_BASH_IS_ASH \
+||  ENABLE_HUSH || ENABLE_SH_IS_HUSH || ENABLE_BASH_IS_HUSH \
+)
+	/* function to fetch additional application-specific names to match */
+	get_exe_name_t *get_exe_name;
+#  define EDITING_HAS_get_exe_name 1
+# endif
 # if MAX_HISTORY
 	int cnt_history;
 	int cur_history;
@@ -1868,6 +1877,10 @@ int read_line_input(const char* prompt, char* command, int maxsize) FAST_FUNC;
 	read_line_input(prompt, command, maxsize)
 #endif
 
+#ifndef EDITING_HAS_get_exe_name
+# define EDITING_HAS_get_exe_name 0
+#endif
+
 
 #ifndef COMM_LEN
 # ifdef TASK_COMM_LEN

libbb/lineedit.c

@@ -813,18 +813,29 @@ static NOINLINE unsigned complete_cmd_dir_file(const char *command, int type)
 	}
 	pf_len = strlen(pfind);
 
-# if ENABLE_FEATURE_SH_STANDALONE && NUM_APPLETS != 1
 	if (type == FIND_EXE_ONLY && !dirbuf) {
+# if ENABLE_FEATURE_SH_STANDALONE && NUM_APPLETS != 1
 		const char *p = applet_names;
-
 		while (*p) {
 			if (strncmp(pfind, p, pf_len) == 0)
 				add_match(xstrdup(p));
 			while (*p++ != '\0')
 				continue;
 		}
-	}
 # endif
+# if EDITING_HAS_get_exe_name
+		if (state->get_exe_name) {
+			i = 0;
+			for (;;) {
+				const char *b = state->get_exe_name(i++);
+				if (!b)
+					break;
+				if (strncmp(pfind, b, pf_len) == 0)
+					add_match(xstrdup(b));
+			}
+		}
+# endif
+	}
 
 	for (i = 0; i < npaths; i++) {
 		DIR *dir;

shell/ash.c

@@ -9523,6 +9523,11 @@ evalpipe(union node *n, int flags)
 	return status;
 }
 
+/* setinteractive needs this forward reference */
+#if EDITING_HAS_get_exe_name
+static const char *get_builtin_name(int i) FAST_FUNC;
+#endif
+
 /*
  * Controls whether the shell is interactive or not.
  */
@@ -9554,8 +9559,12 @@ setinteractive(int on)
 		}
 #endif
 #if ENABLE_FEATURE_EDITING
-		if (!line_input_state)
+		if (!line_input_state) {
 			line_input_state = new_line_input_t(FOR_SHELL | WITH_PATH_LOOKUP);
+# if EDITING_HAS_get_exe_name
+			line_input_state->get_exe_name = get_builtin_name;
+# endif
+		}
 #endif
 	}
 }
@@ -10023,6 +10032,14 @@ find_builtin(const char *name)
 	return bp;
 }
 
+#if EDITING_HAS_get_exe_name
+static const char * FAST_FUNC
+get_builtin_name(int i)
+{
+	return /*i >= 0 &&*/ i < ARRAY_SIZE(builtintab) ? builtintab[i].name + 1 : NULL;
+}
+#endif
+
 /*
  * Execute a simple command.
  */

shell/hush.c

@@ -7889,6 +7889,20 @@ static const struct built_in_command *find_builtin(const char *name)
 	return find_builtin_helper(name, bltins2, &bltins2[ARRAY_SIZE(bltins2)]);
 }
 
+#if EDITING_HAS_get_exe_name
+static const char * FAST_FUNC get_builtin_name(int i)
+{
+	if (/*i >= 0 && */ i < ARRAY_SIZE(bltins1)) {
+		return bltins1[i].b_cmd;
+	}
+	i -= ARRAY_SIZE(bltins1);
+	if (i < ARRAY_SIZE(bltins2)) {
+		return bltins2[i].b_cmd;
+	}
+	return NULL;
+}
+#endif
+
 static void remove_nested_vars(void)
 {
 	struct variable *cur;
@@ -10268,6 +10282,9 @@ int hush_main(int argc, char **argv)
 
 # if ENABLE_FEATURE_EDITING
 		G.line_input_state = new_line_input_t(FOR_SHELL);
+#  if EDITING_HAS_get_exe_name
+		G.line_input_state->get_exe_name = get_builtin_name;
+#  endif
 # endif
 # if ENABLE_HUSH_SAVEHISTORY && MAX_HISTORY > 0
 		{