[PATCH 1/4] fdisk: remove stack jumping

[PATCH 1/4] fdisk: remove stack jumping

[Davidlohr Bueso]

From: Davidlohr Bueso <dave@gnu.org>

This patch eliminates the long/setjmp code. The current logic does not do anything with stack jumps as it only exits from
print_partition_table_from_option() when a fatal error occurs.

Signed-off-by: Davidlohr Bueso <dave@gnu.org>
---
 fdisk/fdisk.c |   17 ++---------------
 1 files changed, 2 insertions(+), 15 deletions(-)

diff --git a/fdisk/fdisk.c b/fdisk/fdisk.c
index 4054b4d..886f011 100644
--- a/fdisk/fdisk.c
+++ b/fdisk/fdisk.c
@@ -14,7 +14,6 @@
 #include <string.h>
 #include <fcntl.h>
 #include <ctype.h>
-#include <setjmp.h>
 #include <errno.h>
 #include <getopt.h>
 #include <sys/stat.h>
@@ -245,8 +244,6 @@ int has_topology;
 
 enum labeltype disklabel;	/* Current disklabel */
 
-jmp_buf listingbuf;
-
 static void __attribute__ ((__noreturn__)) usage(FILE *out)
 {
 	fprintf(out, _("Usage:\n"
@@ -266,13 +263,8 @@ static void __attribute__ ((__noreturn__)) usage(FILE *out)
 	exit(out == stderr ? EXIT_FAILURE : EXIT_SUCCESS);
 }
 
-void fatal(enum failure why) {
-
-	if (listing) {
-		close(fd);
-		longjmp(listingbuf, 1);
-	}
-
+void fatal(enum failure why)
+{
 	switch (why) {
 		case unable_to_open:
 			err(EXIT_FAILURE, _("unable to open %s"), disk_device);
@@ -2708,8 +2700,6 @@ print_partition_table_from_option(char *device)
 	int gb;
 
 	disk_device = device;
-	if (setjmp(listingbuf))
-		return;
 	gpt_warning(device);
 	gb = get_boot(1);
 	if (gb < 0) { /* no DOS signature */
@@ -2950,9 +2940,6 @@ main(int argc, char **argv) {
 		nowarn = 1;
 		if (argc > optind) {
 			int k;
-			/* avoid gcc warning:
-			   variable `k' might be clobbered by `longjmp' */
-			dummy(&k);
 			listing = 1;
 			for (k = optind; k < argc; k++)
 				print_partition_table_from_option(argv[k]);
-- 
1.7.4.1

Re: [PATCH 1/4] fdisk: remove stack jumping

[Petr Uzel]

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On Fri, Apr 27, 2012 at 01:23:42PM +0200, Davidlohr Bueso wrote:
> From: Davidlohr Bueso <dave@gnu.org>
> 
> This patch eliminates the long/setjmp code. The current logic
> does not do anything with stack jumps as it only exits from
> print_partition_table_from_option() when a fatal error occurs.

The stack jumping makes fdisk remain silent and return success (!)
if the listing fails on any of the devices. Not that I think this
is useful behavior, but IMHO this change in behavior is worth
mentioning in the release notes.

Reviewed-by: Petr Uzel <petr.uzel@suse.cz>

> Signed-off-by: Davidlohr Bueso <dave@gnu.org>
> ---
>  fdisk/fdisk.c |   17 ++---------------
>  1 files changed, 2 insertions(+), 15 deletions(-)
> 
> diff --git a/fdisk/fdisk.c b/fdisk/fdisk.c
> index 4054b4d..886f011 100644
> --- a/fdisk/fdisk.c
> +++ b/fdisk/fdisk.c
> @@ -14,7 +14,6 @@
>  #include <string.h>
>  #include <fcntl.h>
>  #include <ctype.h>
> -#include <setjmp.h>
>  #include <errno.h>
>  #include <getopt.h>
>  #include <sys/stat.h>
> @@ -245,8 +244,6 @@ int has_topology;
>  
>  enum labeltype disklabel;	/* Current disklabel */
>  
> -jmp_buf listingbuf;
> -
>  static void __attribute__ ((__noreturn__)) usage(FILE *out)
>  {
>  	fprintf(out, _("Usage:\n"
> @@ -266,13 +263,8 @@ static void __attribute__ ((__noreturn__)) usage(FILE *out)
>  	exit(out == stderr ? EXIT_FAILURE : EXIT_SUCCESS);
>  }
>  
> -void fatal(enum failure why) {
> -
> -	if (listing) {
> -		close(fd);
> -		longjmp(listingbuf, 1);
> -	}
> -
> +void fatal(enum failure why)
> +{
>  	switch (why) {
>  		case unable_to_open:
>  			err(EXIT_FAILURE, _("unable to open %s"), disk_device);
> @@ -2708,8 +2700,6 @@ print_partition_table_from_option(char *device)
>  	int gb;
>  
>  	disk_device = device;
> -	if (setjmp(listingbuf))
> -		return;
>  	gpt_warning(device);
>  	gb = get_boot(1);
>  	if (gb < 0) { /* no DOS signature */
> @@ -2950,9 +2940,6 @@ main(int argc, char **argv) {
>  		nowarn = 1;
>  		if (argc > optind) {
>  			int k;
> -			/* avoid gcc warning:
> -			   variable `k' might be clobbered by `longjmp' */
> -			dummy(&k);
>  			listing = 1;
>  			for (k = optind; k < argc; k++)
>  				print_partition_table_from_option(argv[k]);
> -- 
> 1.7.4.1
> 
> 
> 
> 
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Petr

-- 
Petr Uzel
IRC: ptr_uzl @ freenode

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Re: [PATCH 1/4] fdisk: remove stack jumping

[Karel Zak]

On Fri, Apr 27, 2012 at 01:23:42PM +0200, Davidlohr Bueso wrote:
>  fdisk/fdisk.c |   17 ++---------------
>  1 files changed, 2 insertions(+), 15 deletions(-)

 Applied, thanks.

-- 
 Karel Zak  <kzak@redhat.com>
 http://karelzak.blogspot.com