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List:       busybox
Subject:    Re: passwd - no stty echo after Ctrl-C
From:       Denys Vlasenko <vda.linux () googlemail ! com>
Date:       2007-10-20 19:02:22
Message-ID: 200710202002.22576.vda.linux () googlemail ! com
[Download RAW message or body]

On Thursday 18 October 2007 04:56, Alexander Kriegisch wrote:
> Platform: mipsel
> BB version: 1.7.2 or i386
> 
> When issuing Ctrl-C during password entry, I still have invisible
> characters at the ash prompt. The output is okay, though. As soon as I
> call "stty echo" manually, the shell prompt is okay again.
> 
> Reproduce like this on i386:
> bash $ ./busybox ash
> ash $ ./busybox passwd
> Changing password for root
> New password: [Ctrl-C]
> ash $ <now type something>
> ash $ stty echo  # repair
> 
> Can this be fixed?

Try attached patches.
--
vda

["8.patch" (text/x-diff)]

diff -d -urpN busybox.7/libbb/bb_askpass.c busybox.8/libbb/bb_askpass.c
--- busybox.7/libbb/bb_askpass.c	2007-10-20 02:55:58.000000000 +0100
+++ busybox.8/libbb/bb_askpass.c	2007-10-20 19:59:35.000000000 +0100
@@ -17,7 +17,7 @@ static void askpass_timeout(int ATTRIBUT
 {
 }
 
-char *bb_askpass(int timeout, const char * prompt)
+char *bb_askpass(int timeout, const char *prompt)
 {
 	/* Was static char[BIGNUM] */
 	enum { sizeof_passwd = 128 };
@@ -25,35 +25,36 @@ char *bb_askpass(int timeout, const char
 
 	char *ret;
 	int i;
-	struct sigaction sa;
-	struct termios old, new;
+	struct sigaction sa, oldsa;
+	struct termios tio, oldtio;
 
 	if (!passwd)
 		passwd = xmalloc(sizeof_passwd);
 	memset(passwd, 0, sizeof_passwd);
 
-	tcgetattr(STDIN_FILENO, &old);
+	tcgetattr(STDIN_FILENO, &oldtio);
 	tcflush(STDIN_FILENO, TCIFLUSH);
+	tio = oldtio;
+	tio.c_iflag &= ~(IUCLC|IXON|IXOFF|IXANY);
+	tio.c_lflag &= ~(ECHO|ECHOE|ECHOK|ECHONL|TOSTOP);
+	tcsetattr(STDIN_FILENO, TCSANOW, &tio);
 
-	fputs(prompt, stdout);
-	fflush(stdout);
-
-	tcgetattr(STDIN_FILENO, &new);
-	new.c_iflag &= ~(IUCLC|IXON|IXOFF|IXANY);
-	new.c_lflag &= ~(ECHO|ECHOE|ECHOK|ECHONL|TOSTOP);
-	tcsetattr(STDIN_FILENO, TCSANOW, &new);
-
+	memset(&sa, 0, sizeof(sa));
+	/* sa.sa_flags = 0; - no SA_RESTART! */
+	/* SIGINT and SIGALRM will interrupt read below */
+	sa.sa_handler = askpass_timeout;
+	sigaction(SIGINT, &sa, &oldsa);
 	if (timeout) {
-		sa.sa_flags = 0;
-		sa.sa_handler = askpass_timeout;
 		sigaction(SIGALRM, &sa, NULL);
 		alarm(timeout);
 	}
 
+	fputs(prompt, stdout);
+	fflush(stdout);
 	ret = NULL;
-	/* On timeout, read will hopefully be interrupted by SIGALRM,
+	/* On timeout or Ctrl-C, read will hopefully be interrupted,
 	 * and we return NULL */
-	if (read(STDIN_FILENO, passwd, sizeof_passwd-1) > 0) {
+	if (read(STDIN_FILENO, passwd, sizeof_passwd - 1) > 0) {
 		ret = passwd;
 		i = 0;
 		/* Last byte is guaranteed to be 0
@@ -67,8 +68,9 @@ char *bb_askpass(int timeout, const char
 	if (timeout) {
 		alarm(0);
 	}
+	sigaction(SIGINT, &oldsa, NULL);
 
-	tcsetattr(STDIN_FILENO, TCSANOW, &old);
+	tcsetattr(STDIN_FILENO, TCSANOW, &oldtio);
 	bb_putchar('\n');
 	fflush(stdout);
 	return ret;

["7.patch" (text/x-diff)]

diff -d -urpN busybox.6/libbb/lineedit.c busybox.7/libbb/lineedit.c
--- busybox.6/libbb/lineedit.c	2007-10-20 02:55:58.000000000 +0100
+++ busybox.7/libbb/lineedit.c	2007-10-20 19:19:41.000000000 +0100
@@ -1270,6 +1270,15 @@ int read_line_input(const char* prompt, 
 	smalluint prevc;
 #endif
 
+	getTermSettings(0, (void *) &initial_settings);
+	/* Happens when e.g. stty -echo was run before */
+	if (!(initial_settings.c_lflag & ECHO)) {
+		parse_prompt(prompt);
+		fflush(stdout);
+		fgets(command, maxsize, stdin);
+		return strlen(command);
+	}
+
 // FIXME: audit & improve this
 	if (maxsize > MAX_LINELEN)
 		maxsize = MAX_LINELEN;
@@ -1287,7 +1296,6 @@ int read_line_input(const char* prompt, 
 	command_ps = command;
 	command[0] = '\0';
 
-	getTermSettings(0, (void *) &initial_settings);
 	memcpy(&new_settings, &initial_settings, sizeof(new_settings));
 	new_settings.c_lflag &= ~ICANON;        /* unbuffered input */
 	/* Turn off echoing and CTRL-C, so we can trap it */


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