hush: Make exit a shell builtin

'exit' used to do its job by returning value < 0. This is a sign
for hush that 'exit' is executed. This has problems:

- Often commands accidently return a negative value. This causes
  the shell to exit.
- execute_binfmt returns a negative value when it does not find
  a binary to execute. This again causes the shell to exit.
  Returning a negative error value seems to be the right thing
  to do, but catching this in the shell would mean that the exit
  command does not work anymore.
- if called without arguments exit is supposed to return the code
  of the last command. As a command exit has no access to this code.

This patch changes exit to be a builtin and also fixes the last return
code problem. While at it, update the help text.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

2 files changed, 31 insertions, 25 deletions

diff --git a/common/command.c b/common/command.c
index c18998c129..2bfc5117e8 100644
--- a/common/command.c
+++ b/common/command.c
@@ -38,26 +38,6 @@
 LIST_HEAD(command_list);
 EXPORT_SYMBOL(command_list);
 
-#ifdef CONFIG_SHELL_HUSH
-
-static int do_exit(int argc, char *argv[])
-{
-	int r;
-
-	r = 0;
-	if (argc > 1)
-		r = simple_strtoul(argv[1], NULL, 0);
-
-	return -r - 2;
-}
-
-BAREBOX_CMD_START(exit)
-	.cmd		= do_exit,
-	.usage		= "exit script",
-BAREBOX_CMD_END
-
-#endif
-
 void barebox_cmd_usage(struct command *cmdtp)
 {
 #ifdef	CONFIG_LONGHELP
diff --git a/common/hush.c b/common/hush.c
index 8200931387..288114c6cf 100644
--- a/common/hush.c
+++ b/common/hush.c
@@ -557,6 +557,18 @@ static int builtin_getopt(struct p_context *ctx, struct child_prog *child,
 }
 #endif
 
+static int builtin_exit(struct p_context *ctx, struct child_prog *child,
+		int argc, char *argv[])
+{
+	int r;
+
+	r = last_return_code;
+	if (argc > 1)
+		r = simple_strtoul(argv[1], NULL, 0);
+
+	return -r - 2;
+}
+
 static void remove_quotes_in_str(char *src)
 {
 	char *trg = src;
@@ -775,6 +787,8 @@ static int run_pipe_real(struct p_context *ctx, struct pipe *pi)
 
 	if (!strcmp(globbuf.gl_pathv[0], "getopt"))
 		ret = builtin_getopt(ctx, child, globbuf.gl_pathc, globbuf.gl_pathv);
+	else if (!strcmp(globbuf.gl_pathv[0], "exit"))
+		ret = builtin_exit(ctx, child, globbuf.gl_pathc, globbuf.gl_pathv);
 	else
 		ret = execute_binfmt(globbuf.gl_pathc, globbuf.gl_pathv);
 
@@ -1885,16 +1899,28 @@ BAREBOX_CMD_START(source)
 	BAREBOX_CMD_HELP(cmd_source_help)
 BAREBOX_CMD_END
 
-#ifdef CONFIG_HUSH_GETOPT
-static int do_getopt(int argc, char *argv[])
+static int do_dummy_command(int argc, char *argv[])
 {
 	/*
-	 * This function is never reached. The 'getopt' command is
-	 * only here to provide a help text for the getopt builtin.
+	 * This function is never reached. These commands are only here to
+	 * provide help texts for the builtins.
 	 */
 	return 0;
 }
 
+static const __maybe_unused char cmd_exit_help[] =
+"Usage: exit [n]\n"
+"\n"
+"exit script with a status of n. If n is omitted, the exit status is that\n"
+"of the last command executed\n";
+
+BAREBOX_CMD_START(exit)
+	.cmd		= do_dummy_command,
+	.usage		= "exit script",
+	BAREBOX_CMD_HELP(cmd_exit_help)
+BAREBOX_CMD_END
+
+#ifdef CONFIG_HUSH_GETOPT
 static const __maybe_unused char cmd_getopt_help[] =
 "Usage: getopt <optstring> <var>\n"
 "\n"
@@ -1905,7 +1931,7 @@ static const __maybe_unused char cmd_getopt_help[] =
 "can be accessed starting from $1\n";
 
 BAREBOX_CMD_START(getopt)
-	.cmd		= do_getopt,
+	.cmd		= do_dummy_command,
 	.usage		= "getopt <optstring> <var>",
 	BAREBOX_CMD_HELP(cmd_getopt_help)
 BAREBOX_CMD_END