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cdbb6957f

Denys Vlasenko

2025-08-03

SUCCESS Duration: 152s

Subject

hush: don't save history in subshells; on NOMMU, don't be interactive on reexec

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Architecture & Compiler Flags

Architecture: x86_64-linux-gnu Compiler: gcc (Ubuntu 11.4.0-1ubuntu1~22.04.3) 11.4.0

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Commit Diff GitHub →

shell/hush.c +72 -54

shell/hush.c+72 -54

@@ -930,6 +930,12 @@ struct globals {
	# define G_flag_return_in_progress 0
	#endif
	smallint exiting; /* used to prevent EXIT trap recursion */
+	#if !BB_MMU
+	smallint reexeced_on_NOMMU;
+	# define G_reexeced_on_NOMMU (G.reexeced_on_NOMMU)
+	#else
+	# define G_reexeced_on_NOMMU 0
+	#endif
	/* These support $? */
	smalluint last_exitcode;
	smalluint expand_exitcode;
@@ -2105,7 +2111,9 @@ static const char* FAST_FUNC get_local_var_value(const char *name);
	static void save_history_run_exit_trap_and_exit(int exitcode)
	{
	#if ENABLE_FEATURE_EDITING_SAVE_ON_EXIT
-	if (G.line_input_state) {
+	if (G.line_input_state
+	&& getpid() == G.root_pid /* exits in subshells do not save history */
+	) {
	const char *hp;
	# if ENABLE_FEATURE_SH_HISTFILESIZE
	// in bash:
@@ -10218,6 +10226,53 @@ static int run_and_free_list(struct pipe *pi)
	/*
	* Initialization and main
	*/
+	#if ENABLE_FEATURE_EDITING
+	static void init_line_editing(void)
+	{
+	G.line_input_state = new_line_input_t(FOR_SHELL);
+	# if ENABLE_FEATURE_TAB_COMPLETION
+	G.line_input_state->get_exe_name = hush_command_name;
+	# endif
+	# if EDITING_HAS_sh_get_var
+	G.line_input_state->sh_get_var = get_local_var_value;
+	# endif
+	# if ENABLE_HUSH_SAVEHISTORY && MAX_HISTORY > 0
+	{
+	const char *hp = get_local_var_value("HISTFILE");
+	if (!hp) {
+	hp = get_local_var_value("HOME");
+	if (hp) {
+	hp = concat_path_file(hp, ".hush_history");
+	/* Make HISTFILE set on exit (else history won't be saved) */
+	set_local_var_from_halves("HISTFILE", hp);
+	}
+	} else {
+	hp = xstrdup(hp);
+	}
+	if (hp) {
+	G.line_input_state->hist_file = hp;
+	}
+	# if ENABLE_FEATURE_SH_HISTFILESIZE
+	hp = get_local_var_value("HISTSIZE");
+	/* Using HISTFILESIZE above to limit max_history would be WRONG:
+	* users may set HISTFILESIZE=0 in their profile scripts
+	* to prevent _saving_ of history files, but still want to have
+	* non-zero history limit for in-memory list.
+	*/
+	// in bash, runtime history size is controlled by HISTSIZE (0=no history),
+	// HISTFILESIZE controls on-disk history file size (in lines, 0=no history):
+	G.line_input_state->max_history = size_from_HISTFILESIZE(hp);
+	// HISTFILESIZE: "The shell sets the default value to the value of HISTSIZE after reading any startup files."
+	// HISTSIZE: "The shell sets the default value to 500 after reading any startup files."
+	// (meaning: if the value wasn't set after startup files, the default value is set as described above)
+	# endif
+	}
+	# endif
+	}
+	#else
+	# define init_line_editing() ((void)0)
+	#endif
+
	static void install_sighandlers(unsigned mask)
	{
	sighandler_t old_handler;
@@ -10356,7 +10411,6 @@ static int set_mode(int state, char mode, const char *o_opt)
	int hush_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
	int hush_main(int argc, char **argv)
	{
-	pid_t cached_getpid;
	enum {
	OPT_login = (1 << 0),
	};
@@ -10384,9 +10438,6 @@ int hush_main(int argc, char **argv)
	_exit(0);
	}
	G.argv0_for_re_execing = argv[0];
-	if (G.argv0_for_re_execing[0] == '-')
-	/* reexeced hush should never be a login shell */
-	G.argv0_for_re_execing++;
	#endif
	#if ENABLE_HUSH_TRAP
	# if ENABLE_HUSH_FUNCTIONS
@@ -10399,9 +10450,8 @@ int hush_main(int argc, char **argv)
	G.count_SIGCHLD++; /* ensure it is != G.handled_SIGCHLD */
	#endif

-	cached_getpid = getpid(); /* for tcsetpgrp() during init */
-	G.root_pid = cached_getpid; /* for $PID (NOMMU can override via -$HEXPID:HEXPPID:...) */
-	G.root_ppid = getppid(); /* for $PPID (NOMMU can override) */
+	G.root_pid = getpid(); /* for $PID (NOMMU can override via -$HEXPID:HEXPPID:...) */
+	G.root_ppid = getppid(); /* for $PPID (NOMMU can override) */

	/* Deal with HUSH_VERSION */
	debug_printf_env("unsetenv '%s'\n", "HUSH_VERSION");
@@ -10568,6 +10618,7 @@ int hush_main(int argc, char **argv)
	case '$': {
	unsigned long long empty_trap_mask;

+	G.reexeced_on_NOMMU = 1;
	G.root_pid = bb_strtou(optarg, &optarg, 16);
	optarg++;
	G.root_ppid = bb_strtou(optarg, &optarg, 16);
@@ -10647,7 +10698,9 @@ int hush_main(int argc, char **argv)
	G.global_argv[0] = argv[0];

	/* If we are login shell... */
-	if (flags & OPT_login) {
+	if (!G_reexeced_on_NOMMU /* reexeced hush should never be a login shell */
+	&& (flags & OPT_login)
+	) {
	const char *hp = NULL;
	HFILE *input;

@@ -10767,7 +10820,9 @@ int hush_main(int argc, char **argv)
	* Refer to Posix.2, the description of the 'sh' utility.
	*/
	#if ENABLE_HUSH_JOB
-	if (isatty(STDIN_FILENO) && isatty(STDOUT_FILENO)) {
+	if (!G_reexeced_on_NOMMU
+	&& isatty(STDIN_FILENO) && isatty(STDOUT_FILENO)
+	) {
	G_saved_tty_pgrp = tcgetpgrp(STDIN_FILENO);
	debug_printf("saved_tty_pgrp:%d\n", G_saved_tty_pgrp);
	if (G_saved_tty_pgrp < 0)
@@ -10813,57 +10868,18 @@ int hush_main(int argc, char **argv)
	* (bash, too, does this only if ctty is available) */
	bb_setpgrp(); /* is the same as setpgid(our_pid, our_pid); */
	/* Grab control of the terminal */
-	tcsetpgrp(G_interactive_fd, cached_getpid);
+	tcsetpgrp(G_interactive_fd, G.root_pid);
	}
	enable_restore_tty_pgrp_on_exit();
-
-	# if ENABLE_FEATURE_EDITING
-	G.line_input_state = new_line_input_t(FOR_SHELL);
-	# if ENABLE_FEATURE_TAB_COMPLETION
-	G.line_input_state->get_exe_name = hush_command_name;
-	# endif
-	# if EDITING_HAS_sh_get_var
-	G.line_input_state->sh_get_var = get_local_var_value;
-	# endif
-	# endif
-	# if ENABLE_HUSH_SAVEHISTORY && MAX_HISTORY > 0
-	{
-	const char *hp = get_local_var_value("HISTFILE");
-	if (!hp) {
-	hp = get_local_var_value("HOME");
-	if (hp) {
-	hp = concat_path_file(hp, ".hush_history");
-	/* Make HISTFILE set on exit (else history won't be saved) */
-	set_local_var_from_halves("HISTFILE", hp);
-	}
-	} else {
-	hp = xstrdup(hp);
-	}
-	if (hp) {
-	G.line_input_state->hist_file = hp;
-	}
-	# if ENABLE_FEATURE_SH_HISTFILESIZE
-	hp = get_local_var_value("HISTSIZE");
-	/* Using HISTFILESIZE above to limit max_history would be WRONG:
-	* users may set HISTFILESIZE=0 in their profile scripts
-	* to prevent _saving_ of history files, but still want to have
-	* non-zero history limit for in-memory list.
-	*/
-	// in bash, runtime history size is controlled by HISTSIZE (0=no history),
-	// HISTFILESIZE controls on-disk history file size (in lines, 0=no history):
-	G.line_input_state->max_history = size_from_HISTFILESIZE(hp);
-	// HISTFILESIZE: "The shell sets the default value to the value of HISTSIZE after reading any startup files."
-	// HISTSIZE: "The shell sets the default value to 500 after reading any startup files."
-	// (meaning: if the value wasn't set after startup files, the default value is set as described above)
-	# endif
-	}
-	# endif
+	init_line_editing();
	} else {
	install_special_sighandlers();
	}
	#elif ENABLE_HUSH_INTERACTIVE
	/* No job control compiled in, only prompt/line editing */
-	if (isatty(STDIN_FILENO) && isatty(STDOUT_FILENO)) {
+	if (!G_reexeced_on_NOMMU
+	&& isatty(STDIN_FILENO) && isatty(STDOUT_FILENO)
+	) {
	G_interactive_fd = dup_CLOEXEC(STDIN_FILENO, 254);
	if (G_interactive_fd < 0) {
	/* try to dup to any fd */
@@ -10872,6 +10888,8 @@ int hush_main(int argc, char **argv)
	/* give up */
	G_interactive_fd = 0;
	}
+	if (G_interactive_fd)
+	init_line_editing();
	}
	install_special_sighandlers();
	#else