diff options
Diffstat (limited to 'libbb/lineedit.c')
| -rw-r--r-- | libbb/lineedit.c | 38 |
1 files changed, 33 insertions, 5 deletions
diff --git a/libbb/lineedit.c b/libbb/lineedit.c index bfd0e3346..2e1bc5d2e 100644 --- a/libbb/lineedit.c +++ b/libbb/lineedit.c @@ -370,6 +370,7 @@ static void input_backward(unsigned num) static void put_prompt(void) { out1str(cmdedit_prompt); + fflush(NULL); if (ENABLE_FEATURE_EDITING_ASK_TERMINAL) { /* Ask terminal where is the cursor now. * lineedit_read_key handles response and corrects @@ -380,7 +381,33 @@ static void put_prompt(void) * Note: we print it _after_ prompt, because * prompt may contain CR. Example: PS1='\[\r\n\]\w ' */ - out1str("\033" "[6n"); + /* Problem: if there is buffered input on stdin, + * the response will be delivered later, + * possibly to an unsuspecting application. + * Testcase: "sleep 1; busybox ash" + press and hold [Enter]. + * Result: + * ~/srcdevel/bbox/fix/busybox.t4 # + * ~/srcdevel/bbox/fix/busybox.t4 # + * ^[[59;34~/srcdevel/bbox/fix/busybox.t4 # <-- garbage + * ~/srcdevel/bbox/fix/busybox.t4 # + * + * Checking for input with poll only makes the race narrower, + * I still can trigger it. Strace: + * + * write(1, "~/srcdevel/bbox/fix/busybox.t4 # ", 33) = 33 + * poll([{fd=0, events=POLLIN}], 1, 0) = 0 (Timeout) <-- no input exists + * write(1, "\33[6n", 4) = 4 <-- send the ESC sequence, quick! + * poll([{fd=0, events=POLLIN}], 1, 4294967295) = 1 ([{fd=0, revents=POLLIN}]) + * read(0, "\n", 1) = 1 <-- oh crap, user's input got in first + */ + struct pollfd pfd; + + pfd.fd = STDIN_FILENO; + pfd.events = POLLIN; + if (safe_poll(&pfd, 1, 0) == 0) { + out1str("\033" "[6n"); + fflush(NULL); /* make terminal see it ASAP! */ + } } cursor = 0; { @@ -1603,7 +1630,7 @@ static void cmdedit_setwidth(unsigned w, int redraw_flg) int new_y = (cursor + cmdedit_prmt_len) / w; /* redraw */ redraw((new_y >= cmdedit_y ? new_y : cmdedit_y), command_len - cursor); - fflush(stdout); + fflush(NULL); } } @@ -1640,6 +1667,7 @@ static int lineedit_read_key(char *read_key_buffer) ic = read_key(STDIN_FILENO, read_key_buffer); if (ENABLE_FEATURE_EDITING_ASK_TERMINAL + && cursor == 0 /* otherwise it may be bogus */ && (int32_t)ic == KEYCODE_CURSOR_POS ) { int col = ((ic >> 32) & 0x7fff) - 1; @@ -1708,7 +1736,7 @@ int FAST_FUNC read_line_input(const char *prompt, char *command, int maxsize, li ) { /* Happens when e.g. stty -echo was run before */ parse_and_put_prompt(prompt); - fflush(stdout); + /* fflush(stdout); - done by parse_and_put_prompt */ if (fgets(command, maxsize, stdin) == NULL) len = -1; /* EOF or error */ else @@ -2190,7 +2218,7 @@ int FAST_FUNC read_line_input(const char *prompt, char *command, int maxsize, li tcsetattr_stdin_TCSANOW(&initial_settings); /* restore SIGWINCH handler */ signal(SIGWINCH, previous_SIGWINCH_handler); - fflush(stdout); + fflush(NULL); len = command_len; DEINIT_S(); @@ -2204,7 +2232,7 @@ int FAST_FUNC read_line_input(const char *prompt, char *command, int maxsize, li int FAST_FUNC read_line_input(const char* prompt, char* command, int maxsize) { fputs(prompt, stdout); - fflush(stdout); + fflush(NULL); fgets(command, maxsize, stdin); return strlen(command); } |