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bff71d3b9

Denys Vlasenko

2016-11-27

SUCCESS Duration: 240s

Subject

lineedit: fix two bugs in SIGWINCH signal handling

Binary

No binary (build failed)

Architecture & Compiler Flags

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

—

Build Log

(log yok)

Commit Diff GitHub →

libbb/lineedit.c +41 -29

libbb/lineedit.c+41 -29

@@ -129,8 +129,7 @@ static const char null_str[] ALIGN1 = "";
	struct lineedit_statics {
	line_input_t *state;

-	volatile unsigned cmdedit_termw; /* = 80; / / actual terminal width */
-	sighandler_t previous_SIGWINCH_handler;
+	unsigned cmdedit_termw; /* = 80; / / actual terminal width */

	unsigned cmdedit_x; /* real x (col) terminal position */
	unsigned cmdedit_y; /* pseudoreal y (row) terminal position */
@@ -155,15 +154,22 @@ struct lineedit_statics {
	unsigned num_matches;
	#endif

+	unsigned SIGWINCH_saved;
+	volatile unsigned SIGWINCH_count;
+	volatile smallint ok_to_redraw;
+
	#if ENABLE_FEATURE_EDITING_VI
	# define DELBUFSIZ 128
-	CHAR_T *delptr;
	smallint newdelflag; /* whether delbuf should be reused yet */
+	CHAR_T *delptr;
	CHAR_T delbuf[DELBUFSIZ]; /* a place to store deleted characters */
	#endif
	#if ENABLE_FEATURE_EDITING_ASK_TERMINAL
	smallint sent_ESC_br6n;
	#endif
+
+	/* Largish struct, keeping it last results in smaller code */
+	struct sigaction SIGWINCH_handler;
	};

	/* See lineedit_ptr_hack.c */
@@ -172,7 +178,6 @@ extern struct lineedit_statics *const lineedit_ptr_to_statics;
	#define S (*lineedit_ptr_to_statics)
	#define state (S.state )
	#define cmdedit_termw (S.cmdedit_termw )
-	#define previous_SIGWINCH_handler (S.previous_SIGWINCH_handler)
	#define cmdedit_x (S.cmdedit_x )
	#define cmdedit_y (S.cmdedit_y )
	#define cmdedit_prmt_len (S.cmdedit_prmt_len)
@@ -434,14 +439,11 @@ static void beep(void)

	static void put_prompt(void)
	{
-	unsigned w;
-
	fputs(cmdedit_prompt, stdout);
	fflush_all();
	cursor = 0;
-	w = cmdedit_termw; /* read volatile var once */
-	cmdedit_y = cmdedit_prmt_len / w; /* new quasireal y */
-	cmdedit_x = cmdedit_prmt_len % w;
+	cmdedit_y = cmdedit_prmt_len / cmdedit_termw; /* new quasireal y */
+	cmdedit_x = cmdedit_prmt_len % cmdedit_termw;
	}

	/* Move back one character */
@@ -513,13 +515,11 @@ static void input_backward(unsigned num)
	put_cur_glyph_and_inc_cursor();
	} else {
	int lines_up;
-	unsigned width;
	/* num = chars to go back from the beginning of current line: */
	num -= cmdedit_x;
-	width = cmdedit_termw; /* read volatile var once */
	/* num=1...w: one line up, w+1...2w: two, etc: */
-	lines_up = 1 + (num - 1) / width;
-	cmdedit_x = (width * cmdedit_y - num) % width;
+	lines_up = 1 + (num - 1) / cmdedit_termw;
+	cmdedit_x = (cmdedit_termw * cmdedit_y - num) % cmdedit_termw;
	cmdedit_y -= lines_up;
	/* go to 1st column; go up */
	printf("\r" ESC"[%uA", lines_up);
@@ -1978,28 +1978,29 @@ static void parse_and_put_prompt(const char *prmt_ptr)
	}
	#endif

-	static void cmdedit_setwidth(unsigned w, int redraw_flg)
+	static void cmdedit_setwidth(int redraw_flg)
	{
-	cmdedit_termw = w;
+	get_terminal_width_height(STDIN_FILENO, &cmdedit_termw, NULL);
	if (redraw_flg) {
	/* new y for current cursor */
-	int new_y = (cursor + cmdedit_prmt_len) / w;
+	int new_y = (cursor + cmdedit_prmt_len) / cmdedit_termw;
	/* redraw */
	redraw((new_y >= cmdedit_y ? new_y : cmdedit_y), command_len - cursor);
	fflush_all();
	}
	}

-	static void win_changed(int nsig)
+	static void win_changed(int nsig UNUSED_PARAM)
	{
-	int sv_errno = errno;
-	unsigned width;
-
-	get_terminal_width_height(0, &width, NULL);
-	//FIXME: cmdedit_setwidth() -> redraw() -> printf() -> KABOOM! (we are in signal handler!)
-	cmdedit_setwidth(width, /redraw_flg:/ nsig);
-
-	errno = sv_errno;
+	if (S.ok_to_redraw) {
+	/* We are in read_key(), safe to redraw immediately */
+	int sv_errno = errno;
+	cmdedit_setwidth(/redraw_flg:/ 1);
+	errno = sv_errno;
+	} else {
+	/* Signal main loop that redraw is necessary */
+	S.SIGWINCH_count++;
+	}
	}

	static int lineedit_read_key(char *read_key_buffer, int timeout)
@@ -2018,7 +2019,9 @@ static int lineedit_read_key(char *read_key_buffer, int timeout)
	*
	* Note: read_key sets errno to 0 on success.
	*/
+	S.ok_to_redraw = 1;
	ic = read_key(STDIN_FILENO, read_key_buffer, timeout);
+	S.ok_to_redraw = 0;
	if (errno) {
	#if ENABLE_UNICODE_SUPPORT
	if (errno == EAGAIN && unicode_idx != 0)
@@ -2355,9 +2358,11 @@ int FAST_FUNC read_line_input(line_input_t st, const char prompt, char *comman
	ask_terminal();

	/* Install window resize handler (NB: after all init is complete) */
-	//FIXME: save entire sigaction!
-	previous_SIGWINCH_handler = signal(SIGWINCH, win_changed);
-	win_changed(0); /* get initial window size */
+	S.SIGWINCH_handler.sa_handler = win_changed;
+	S.SIGWINCH_handler.sa_flags = SA_RESTART;
+	sigaction(SIGWINCH, &S.SIGWINCH_handler, &S.SIGWINCH_handler);
+
+	cmdedit_setwidth(/redraw_flg:/ 0); /* get initial window size */

	read_key_buffer[0] = 0;
	while (1) {
@@ -2370,6 +2375,13 @@ int FAST_FUNC read_line_input(line_input_t st, const char prompt, char *comman
	* in one place.
	*/
	int32_t ic, ic_raw;
+	unsigned count;
+
+	count = S.SIGWINCH_count;
+	if (S.SIGWINCH_saved != count) {
+	S.SIGWINCH_saved = count;
+	cmdedit_setwidth(/redraw_flg:/ 1);
+	}

	fflush_all();
	ic = ic_raw = lineedit_read_key(read_key_buffer, timeout);
@@ -2808,7 +2820,7 @@ int FAST_FUNC read_line_input(line_input_t st, const char prompt, char *comman
	/* restore initial_settings */
	tcsetattr_stdin_TCSANOW(&initial_settings);
	/* restore SIGWINCH handler */
-	signal(SIGWINCH, previous_SIGWINCH_handler);
+	sigaction_set(SIGWINCH, &S.SIGWINCH_handler);
	fflush_all();

	len = command_len;