cmd: exit: Fix return value propagation out of environment scripts

Make sure the 'exit' command as well as 'exit $val' command exits
from environment scripts immediately and propagates return value
out of those scripts fully. That means the following behavior is
expected:

"
=> setenv foo 'echo bar ; exit 1' ; run foo ; echo $?
bar
1
=> setenv foo 'echo bar ; exit 0' ; run foo ; echo $?
bar
0
=> setenv foo 'echo bar ; exit -2' ; run foo ; echo $?
bar
0
"

As well as the followin behavior:

"
=> setenv foo 'echo bar ; exit 3 ; echo fail'; run foo; echo $?
bar
3
=> setenv foo 'echo bar ; exit 1 ; echo fail'; run foo; echo $?
bar
1
=> setenv foo 'echo bar ; exit 0 ; echo fail'; run foo; echo $?
bar
0
=> setenv foo 'echo bar ; exit -1 ; echo fail'; run foo; echo $?
bar
0
=> setenv foo 'echo bar ; exit -2 ; echo fail'; run foo; echo $?
bar
0
=> setenv foo 'echo bar ; exit ; echo fail'; run foo; echo $?
bar
0
"

Fixes: 8c4e3b79bd ("cmd: exit: Fix return value")
Reviewed-by: Hector Palacios <hector.palacios@digi.com>
Signed-off-by: Marek Vasut <marex@denx.de>

cmd/exit.c

@@ -10,10 +10,13 @@
 static int do_exit(struct cmd_tbl *cmdtp, int flag, int argc,
 		   char *const argv[])
 {
-	if (argc > 1)
-		return dectoul(argv[1], NULL);
+	int r;
 
-	return 0;
+	r = 0;
+	if (argc > 1)
+		r = simple_strtoul(argv[1], NULL, 10);
+
+	return -r - 2;
 }
 
 U_BOOT_CMD(

common/cli.c

@@ -146,7 +146,7 @@ int run_commandf(const char *fmt, ...)
 #if defined(CONFIG_CMD_RUN)
 int do_run(struct cmd_tbl *cmdtp, int flag, int argc, char *const argv[])
 {
-	int i;
+	int i, ret;
 
 	if (argc < 2)
 		return CMD_RET_USAGE;
@@ -160,8 +160,9 @@ int do_run(struct cmd_tbl *cmdtp, int flag, int argc, char *const argv[])
 			return 1;
 		}
 
-		if (run_command(arg, flag | CMD_FLAG_ENV) != 0)
-			return 1;
+		ret = run_command(arg, flag | CMD_FLAG_ENV);
+		if (ret)
+			return ret;
 	}
 	return 0;
 }

common/cli_hush.c

@@ -1901,7 +1901,7 @@ static int run_list_real(struct pipe *pi)
 			last_return_code = -rcode - 2;
 			return -2;	/* exit */
 		}
-		last_return_code=(rcode == 0) ? 0 : 1;
+		last_return_code = rcode;
 #endif
 #ifndef __U_BOOT__
 		pi->num_progs = save_num_progs; /* restore number of programs */
@@ -3211,7 +3211,15 @@ static int parse_stream_outer(struct in_str *inp, int flag)
 					printf("exit not allowed from main input shell.\n");
 					continue;
 				}
-				break;
+				/*
+				 * DANGER
+				 * Return code -2 is special in this context,
+				 * it indicates exit from inner pipe instead
+				 * of return code itself, the return code is
+				 * stored in 'last_return_code' variable!
+				 * DANGER
+				 */
+				return -2;
 			}
 			if (code == -1)
 			    flag_repeat = 0;
@@ -3248,9 +3256,9 @@ int parse_string_outer(const char *s, int flag)
 #endif	/* __U_BOOT__ */
 {
 	struct in_str input;
+	int rcode;
 #ifdef __U_BOOT__
 	char *p = NULL;
-	int rcode;
 	if (!s)
 		return 1;
 	if (!*s)
@@ -3262,11 +3270,12 @@ int parse_string_outer(const char *s, int flag)
 		setup_string_in_str(&input, p);
 		rcode = parse_stream_outer(&input, flag);
 		free(p);
-		return rcode;
+		return rcode == -2 ? last_return_code : rcode;
 	} else {
 #endif
 	setup_string_in_str(&input, s);
-	return parse_stream_outer(&input, flag);
+	rcode = parse_stream_outer(&input, flag);
+	return rcode == -2 ? last_return_code : rcode;
 #ifdef __U_BOOT__
 	}
 #endif
@@ -3286,7 +3295,7 @@ int parse_file_outer(void)
 	setup_file_in_str(&input);
 #endif
 	rcode = parse_stream_outer(&input, FLAG_PARSE_SEMICOLON);
-	return rcode;
+	return rcode == -2 ? last_return_code : rcode;
 }
 
 #ifdef __U_BOOT__

doc/usage/cmd/exit.rst

@@ -37,4 +37,6 @@ executed.
 Return value
 ------------
 
-$? is always set to 0 (true).
+$? is default set to 0 (true). In case zero or positive integer parameter
+is passed to the command, the return value is the parameter value. In case
+negative integer parameter is passed to the command, the return value is 0.