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9c46a0688

Denys Vlasenko

2025-07-03

SUCCESS Duration: 156s

Subject

shell: update HISTFILESIZE code to be actually useful

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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 →

include/libbb.h +1 -1 libbb/Config.src +2 -2 libbb/lineedit.c +54 -44 shell/Config.src +4 -3 shell/ash.c +24 -2 shell/hush.c +35 -6

include/libbb.h+1 -1

@@ -1989,7 +1989,7 @@ typedef struct line_input_t {
	# if MAX_HISTORY
	int cnt_history;
	int cur_history;
-	int max_history; /* must never be <= 0 */
+	int max_history; /* must never be < 0 */
	# if ENABLE_FEATURE_EDITING_SAVEHISTORY
	/* meaning of this field depends on FEATURE_EDITING_SAVE_ON_EXIT:
	* if !FEATURE_EDITING_SAVE_ON_EXIT: "how many lines are

libbb/Config.src+2 -2

@@ -182,8 +182,8 @@ config FEATURE_EDITING_VI
	config FEATURE_EDITING_HISTORY
	int "History size"
	# Don't allow way too big values here, code uses fixed "char *history[N]" struct member
-	range 0 9999
-	default 255
+	range 0 2000
+	default 200
	depends on FEATURE_EDITING
	help
	Specify command history size (0 - disable).

libbb/lineedit.c+54 -44

@@ -1406,8 +1406,8 @@ unsigned FAST_FUNC size_from_HISTFILESIZE(const char *hp)
	int size = MAX_HISTORY;
	if (hp) {
	size = atoi(hp);
-	if (size <= 0)
-	return 1;
+	if (size < 0)
+	return 0;
	if (size > MAX_HISTORY)
	return MAX_HISTORY;
	}
@@ -1501,18 +1501,21 @@ static void load_history(line_input_t *st_parm)
	/* NB: do not trash old history if file can't be opened */

	fp = fopen_for_read(st_parm->hist_file);
-	if (fp) {
-	/* clean up old history */
-	for (idx = st_parm->cnt_history; idx > 0;) {
-	idx--;
-	free(st_parm->history[idx]);
-	st_parm->history[idx] = NULL;
-	}
+	if (!fp)
+	return;

-	/* fill temp_h[], retaining only last MAX_HISTORY lines */
-	memset(temp_h, 0, sizeof(temp_h));
-	idx = 0;
-	st_parm->cnt_history_in_file = 0;
+	/* clean up old history */
+	for (idx = st_parm->cnt_history; idx > 0;) {
+	idx--;
+	free(st_parm->history[idx]);
+	st_parm->history[idx] = NULL;
+	}
+
+	/* fill temp_h[], retaining only last max_history lines */
+	memset(temp_h, 0, sizeof(temp_h));
+	idx = 0;
+	st_parm->cnt_history_in_file = 0;
+	if (st_parm->max_history != 0) {
	while ((line = xmalloc_fgetline(fp)) != NULL) {
	if (line[0] == '\0') {
	free(line);
@@ -1525,34 +1528,34 @@ static void load_history(line_input_t *st_parm)
	if (idx == st_parm->max_history)
	idx = 0;
	}
-	fclose(fp);
-
-	/* find first non-NULL temp_h[], if any */
-	if (st_parm->cnt_history_in_file) {
-	while (temp_h[idx] == NULL) {
-	idx++;
-	if (idx == st_parm->max_history)
-	idx = 0;
-	}
-	}
+	}
+	fclose(fp);

-	/* copy temp_h[] to st_parm->history[] */
-	for (i = 0; i < st_parm->max_history;) {
-	line = temp_h[idx];
-	if (!line)
-	break;
+	/* find first non-NULL temp_h[], if any */
+	if (st_parm->cnt_history_in_file != 0) {
+	while (temp_h[idx] == NULL) {
	idx++;
	if (idx == st_parm->max_history)
	idx = 0;
-	line_len = strlen(line);
-	if (line_len >= MAX_LINELEN)
-	line[MAX_LINELEN-1] = '\0';
-	st_parm->history[i++] = line;
	}
-	st_parm->cnt_history = i;
-	if (ENABLE_FEATURE_EDITING_SAVE_ON_EXIT)
-	st_parm->cnt_history_in_file = i;
	}
+
+	/* copy temp_h[] to st_parm->history[] */
+	for (i = 0; i < st_parm->max_history;) {
+	line = temp_h[idx];
+	if (!line)
+	break;
+	idx++;
+	if (idx == st_parm->max_history)
+	idx = 0;
+	line_len = strlen(line);
+	if (line_len >= MAX_LINELEN)
+	line[MAX_LINELEN-1] = '\0';
+	st_parm->history[i++] = line;
+	}
+	st_parm->cnt_history = i;
+	if (ENABLE_FEATURE_EDITING_SAVE_ON_EXIT)
+	st_parm->cnt_history_in_file = i;
	}

	# if ENABLE_FEATURE_EDITING_SAVE_ON_EXIT
@@ -1563,14 +1566,23 @@ void FAST_FUNC save_history(line_input_t *st)
	if (!st \|\| !st->hist_file)
	return;
	if (st->cnt_history <= st->cnt_history_in_file)
-	return;
+	return; /* no new entries were added */
+	/* note: if st->max_history is 0, we do not abort: we truncate the history to 0 lines */

-	fp = fopen(st->hist_file, "a");
+	fp = fopen(st->hist_file, (st->max_history == 0 ? "w" : "a"));
	if (fp) {
	int i, fd;
	char *new_name;
	line_input_t *st_temp;

+	/* max_history==0 needs special-casing in general code,
+	* just handle it in a simpler way: */
+	if (st->max_history == 0) {
+	/* fopen("w") already truncated it */
+	fclose(fp);
+	return;
+	}
+
	for (i = st->cnt_history_in_file; i < st->cnt_history; i++)
	fprintf(fp, "%s\n", st->history[i]);
	fclose(fp);
@@ -1580,6 +1592,8 @@ void FAST_FUNC save_history(line_input_t *st)
	st_temp = new_line_input_t(st->flags);
	st_temp->hist_file = st->hist_file;
	st_temp->max_history = st->max_history;
+	/* load no more than max_history last lines */
+	/* (in unlikely case that file disappeared, st_temp gets empty history) */
	load_history(st_temp);

	/* write out temp file and replace hist_file atomically */
@@ -1609,7 +1623,6 @@ static void save_history(char *str)
	fd = open(state->hist_file, O_WRONLY \| O_CREAT \| O_APPEND, 0600);
	if (fd < 0)
	return;
-	xlseek(fd, 0, SEEK_END); /* paranoia */
	len = strlen(str);
	str[len] = '\n'; /* we (try to) do atomic write */
	len2 = full_write(fd, str, len + 1);
@@ -1664,13 +1677,10 @@ static void remember_in_history(char *str)
	if (str[0] == '\0')
	return;
	i = state->cnt_history;
-	/* Don't save dupes */
-	if (i && strcmp(state->history[i-1], str) == 0)
+	/* Don't save dups */
+	if (i != 0 && strcmp(state->history[i-1], str) == 0)
	return;

-	free(state->history[state->max_history]); /* redundant, paranoia */
-	state->history[state->max_history] = NULL; /* redundant, paranoia */
-
	/* If history[] is full, remove the oldest command */
	/* we need to keep history[state->max_history] empty, hence >=, not > */
	if (i >= state->max_history) {
@@ -1683,7 +1693,7 @@ static void remember_in_history(char *str)
	state->cnt_history_in_file--;
	# endif
	}
-	/* i <= state->max_history-1 */
+	/* i < state->max_history */
	state->history[i++] = xstrdup(str);
	/* i <= state->max_history */
	state->cur_history = i;

shell/Config.src+4 -3

@@ -166,9 +166,10 @@ config FEATURE_SH_HISTFILESIZE
	default y
	depends on SHELL_ASH \|\| SHELL_HUSH
	help
-	This option makes busybox shells to use $HISTFILESIZE variable
-	to set shell history size. Note that its max value is capped
-	by "History size" setting in library tuning section.
+	This option makes busybox shells to use $HISTSIZE and
+	$HISTFILESIZE variables to set shell history size.
+	Note that its max value is capped by "History size" setting
+	in library tuning section.

	config FEATURE_SH_EMBEDDED_SCRIPTS
	bool "Embed scripts in the binary"

shell/ash.c+24 -2

@@ -14525,8 +14525,25 @@ exitshell(void)
	char *p;

	#if ENABLE_FEATURE_EDITING_SAVE_ON_EXIT
-	save_history(line_input_state); /* may be NULL */
+	if (line_input_state) {
+	const char *hp;
+	# if ENABLE_FEATURE_SH_HISTFILESIZE
+	// in bash:
+	// HISTFILESIZE controls the on-disk history file size (in lines, 0=no history):
+	// "When this variable is assigned a value, the history file is truncated, if necessary"
+	// but we do it only at exit, not on assignment:
+	/* Use HISTFILESIZE to limit file size */
+	hp = lookupvar("HISTFILESIZE");
+	if (hp)
+	line_input_state->max_history = size_from_HISTFILESIZE(hp);
+	# endif
+	/* HISTFILE: "If unset, the command history is not saved when a shell exits." */
+	hp = lookupvar("HISTFILE");
+	line_input_state->hist_file = hp;
+	save_history(line_input_state); /* no-op if hist_file is NULL */
+	}
	#endif
+
	savestatus = exitstatus;
	TRACE(("pid %d, exitshell(%d)\n", getpid(), savestatus));
	if (setjmp(loc.loc))
@@ -14867,7 +14884,12 @@ int ash_main(int argc UNUSED_PARAM, char **argv)
	if (hp)
	line_input_state->hist_file = xstrdup(hp);
	# if ENABLE_FEATURE_SH_HISTFILESIZE
-	hp = lookupvar("HISTFILESIZE");
+	hp = lookupvar("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.
+	*/
	line_input_state->max_history = size_from_HISTFILESIZE(hp);
	# endif
	}

shell/hush.c+35 -6

@@ -2099,11 +2099,29 @@ static sighandler_t pick_sighandler(unsigned sig)
	return handler;
	}

+	static const char* FAST_FUNC get_local_var_value(const char *name);
+
	/* Restores tty foreground process group, and exits. */
	static void hush_exit(int exitcode)
	{
	#if ENABLE_FEATURE_EDITING_SAVE_ON_EXIT
-	save_history(G.line_input_state); /* may be NULL */
+	if (G.line_input_state) {
+	const char *hp;
+	# if ENABLE_FEATURE_SH_HISTFILESIZE
+	// in bash:
+	// HISTFILESIZE controls the on-disk history file size (in lines, 0=no history):
+	// "When this variable is assigned a value, the history file is truncated, if necessary"
+	// but we do it only at exit, not on every assignment:
+	/* Use HISTFILESIZE to limit file size */
+	hp = get_local_var_value("HISTFILESIZE");
+	if (hp)
+	G.line_input_state->max_history = size_from_HISTFILESIZE(hp);
+	# endif
+	/* HISTFILE: "If unset, the command history is not saved when a shell exits." */
+	hp = get_local_var_value("HISTFILE");
+	G.line_input_state->hist_file = hp;
+	save_history(G.line_input_state); /* no-op if hist_file is NULL */
+	}
	#endif

	fflush_all();
@@ -10427,7 +10445,7 @@ int hush_main(int argc, char **argv)
	if (!get_local_var_value("PATH"))
	set_local_var_from_halves("PATH", bb_default_root_path);

-	/* PS1/PS2 are set later, if we determine that we are interactive */
+	/* PS1/PS2/HISTFILE are set later, if we determine that we are interactive */

	/* bash also exports SHLVL and _,
	* and sets (but doesn't export) the following variables:
@@ -10449,7 +10467,6 @@ int hush_main(int argc, char **argv)
	* BASH_SOURCE=()
	* DIRSTACK=()
	* PIPESTATUS=([0]="0")
-	* HISTFILE=/<xxx>/.bash_history
	* HISTFILESIZE=500
	* HISTSIZE=500
	* MAILCHECK=60
@@ -10809,18 +10826,30 @@ int hush_main(int argc, char **argv)
	const char *hp = get_local_var_value("HISTFILE");
	if (!hp) {
	hp = get_local_var_value("HOME");
-	if (hp)
+	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;
-	//set_local_var(xasprintf("HISTFILE=%s", ...));
	}
	# if ENABLE_FEATURE_SH_HISTFILESIZE
-	hp = get_local_var_value("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