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lineedit: fix two bugs in SIGWINCH signal handling

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(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 <vda.linux@googlemail.com>
This commit is contained in:
Denys Vlasenko 2016-11-27 22:25:07 +01:00
parent 710b6ce9b0
commit bff71d3b9d
1 changed files with 41 additions and 29 deletions
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66
libbb/lineedit.c
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@ -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)
{
if (S.ok_to_redraw) {
/* We are in read_key(), safe to redraw immediately */
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);
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;