Re: [PATCH 5/7] mke2fs: proceed if the user doesn't type anything after 5 seconds

[Eric Sandeen <sandeen@redhat.com>]

On 4/26/14, 7:00 PM, Theodore Ts'o wrote:
> If mke2fs needs to ask the user for permission, and the user doesn't
> type anything for five seconds, proceed as if the user had said yes.
> 
> This will allow us to add more stringent checks without breaking
> existing scripts (much).

Hm, this sounds a little dangerous - "-F" overrides a lot.

What motivates this?

Would it be worth treating this differently depending on whether or
not we're on a tty?

While we're at it, I see that you've added another tunable to a conf file.
Where are these documented?

Thanks,

-Eric

> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
> ---
>  misc/mke2fs.c  | 12 ++++++++----
>  misc/tune2fs.c |  2 +-
>  misc/util.c    | 29 ++++++++++++++++++++++++++---
>  misc/util.h    |  2 +-
>  4 files changed, 36 insertions(+), 9 deletions(-)
> 
> diff --git a/misc/mke2fs.c b/misc/mke2fs.c
> index a2b1f65..799132a 100644
> --- a/misc/mke2fs.c
> +++ b/misc/mke2fs.c
> @@ -102,6 +102,7 @@ static __u32	fs_stride;
>  static int	quotatype = -1;  /* Initialize both user and group quotas by default */
>  static __u64	offset;
>  static blk64_t journal_location = ~0LL;
> +static int	proceed_delay = -1;
>  
>  static struct ext2_super_block fs_param;
>  static char *fs_uuid = NULL;
> @@ -1749,9 +1750,12 @@ profile_error:
>  	if (optind < argc)
>  		usage();
>  
> +	profile_get_integer(profile, "options", "proceed_delay", 0, 5,
> +			    &proceed_delay);
> +
>  	if (!check_plausibility(device_name, CREATE_FILE,
>  				&is_device) && !force)
> -		proceed_question();
> +		proceed_question(proceed_delay);
>  
>  	check_mount(device_name, force, _("filesystem"));
>  
> @@ -1797,7 +1801,7 @@ profile_error:
>  	} else if (!force && is_device && (fs_blocks_count > dev_size)) {
>  		com_err(program_name, 0, "%s",
>  			_("Filesystem larger than apparent device size."));
> -		proceed_question();
> +		proceed_question(proceed_delay);
>  	}
>  
>  	if (!fs_type)
> @@ -2071,7 +2075,7 @@ profile_error:
>  			com_err(program_name, 0,
>  				_("%d-byte blocks too big for system (max %d)"),
>  				blocksize, sys_page_size);
> -			proceed_question();
> +			proceed_question(proceed_delay);
>  		}
>  		fprintf(stderr, _("Warning: %d-byte blocks too big for system "
>  				  "(max %d), forced to continue\n"),
> @@ -2785,7 +2789,7 @@ int main (int argc, char *argv[])
>  
>  		if (!check_plausibility(journal_device, CHECK_BLOCK_DEV,
>  					NULL) && !force)
> -			proceed_question();
> +			proceed_question(proceed_delay);
>  		check_mount(journal_device, force, _("journal"));
>  
>  		retval = ext2fs_open(journal_device, EXT2_FLAG_RW|
> diff --git a/misc/tune2fs.c b/misc/tune2fs.c
> index fbf5f52..7b3723b 100644
> --- a/misc/tune2fs.c
> +++ b/misc/tune2fs.c
> @@ -675,7 +675,7 @@ static int add_journal(ext2_filsys fs)
>  	if (journal_device) {
>  		if (!check_plausibility(journal_device, CHECK_BLOCK_DEV,
>  					NULL))
> -			proceed_question();
> +			proceed_question(-1);
>  		check_mount(journal_device, 0, _("journal"));
>  #ifdef CONFIG_TESTIO_DEBUG
>  		if (getenv("TEST_IO_FLAGS") || getenv("TEST_IO_BLOCK")) {
> diff --git a/misc/util.c b/misc/util.c
> index f85942e..afb0058 100644
> --- a/misc/util.c
> +++ b/misc/util.c
> @@ -14,6 +14,8 @@
>  
>  #include "config.h"
>  #include <fcntl.h>
> +#include <setjmp.h>
> +#include <signal.h>
>  #include <stdio.h>
>  #include <string.h>
>  #ifdef HAVE_ERRNO_H
> @@ -68,18 +70,39 @@ char *get_progname(char *argv_zero)
>  		return cp+1;
>  }
>  
> -void proceed_question(void)
> +static jmp_buf alarm_env;
> +
> +static void alarm_signal(int signal)
> +{
> +	longjmp(alarm_env, 1);
> +}
> +
> +void proceed_question(int delay)
>  {
>  	char buf[256];
>  	const char *short_yes = _("yY");
>  
>  	fflush(stdout);
>  	fflush(stderr);
> -	fputs(_("Proceed anyway? (y,n) "), stdout);
> +	if (delay > 0) {
> +		if (setjmp(alarm_env)) {
> +			signal(SIGALRM, SIG_IGN);
> +			printf(_("<proceeding>\n"));
> +			return;
> +		}
> +		signal(SIGALRM, alarm_signal);
> +		printf(_("Proceed anyway (or wait %d seconds) ? (y,n) "),
> +		       delay);
> +		alarm(delay);
> +	} else
> +		fputs(_("Proceed anyway? (y,n) "), stdout);
>  	buf[0] = 0;
>  	if (!fgets(buf, sizeof(buf), stdin) ||
> -	    strchr(short_yes, buf[0]) == 0)
> +	    strchr(short_yes, buf[0]) == 0) {
> +		putc('\n', stdout);
>  		exit(1);
> +	}
> +	signal(SIGALRM, SIG_IGN);
>  }
>  
>  /*
> diff --git a/misc/util.h b/misc/util.h
> index b80d489..9de3fbf 100644
> --- a/misc/util.h
> +++ b/misc/util.h
> @@ -25,7 +25,7 @@ extern char	*journal_location_string;
>  extern int strcasecmp (char *s1, char *s2);
>  #endif
>  extern char *get_progname(char *argv_zero);
> -extern void proceed_question(void);
> +extern void proceed_question(int delay);
>  extern int check_plausibility(const char *device, int flags,
>  			      int *ret_is_dev);
>  extern void parse_journal_opts(const char *opts);
>