From: Denys Vlasenko Date: Sun, 27 Nov 2016 21:25:07 +0000 (+0100) Subject: lineedit: fix two bugs in SIGWINCH signal handling X-Git-Tag: 1_26_0~24 X-Git-Url: https://git.librecmc.org/?a=commitdiff_plain;h=bff71d3b9d4244abc5182c38d0a98f4913188391;p=oweals%2Fbusybox.git lineedit: fix two bugs in SIGWINCH signal handling (1) restore entire sigaction, not only signal handler function (2) do not use stdio when not sure WINCH did not interrupt a printf() or such. function old new delta cmdedit_setwidth - 81 +81 read_line_input 3682 3722 +40 lineedit_read_key 138 155 +17 put_prompt 55 51 -4 win_changed 93 47 -46 ------------------------------------------------------------------------------ (add/remove: 1/0 grow/shrink: 2/2 up/down: 138/-50) Total: 88 bytes Signed-off-by: Denys Vlasenko --- diff --git a/libbb/lineedit.c b/libbb/lineedit.c index 4d7828cfa..7a1b5433d 100644 --- a/libbb/lineedit.c +++ b/libbb/lineedit.c @@ -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;