GNU bug report logs - #19508
[PATCH] diff: compare major, minor numbers of block/character special files

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Message #5 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Ondřej Svoboda <ondrej <at> svobodasoft.cz>
To: bug-diffutils <at> gnu.org
Subject: [PATCH] diff: compare major, minor numbers of block/character special
 files
Date: Sun, 04 Jan 2015 21:51:50 +0100

This deals with situation such as

  File dev1/block1 is a block special file while file dev2/block1 is
  a block special file

in case the major and minor numbers are identical.
If stat.st_rdev does not match, a message is given:

  Block special files dev1/block1 and dev2/block1 differ: 1,2 (3,2)
---
 src/diff.c | 23 +++++++++++++++++++++++
 src/diff.h |  1 +
 src/util.c |  9 +++++++++
 3 files changed, 33 insertions(+)

diff --git a/src/diff.c b/src/diff.c
index ff28377..a3e1b6f 100644
--- a/src/diff.c
+++ b/src/diff.c
@@ -1276,6 +1276,29 @@ compare_files (struct comparison const *parent,
 	      status = EXIT_FAILURE;
 	    }
 	}
+      else if ((S_ISBLK (cmp.file[0].stat.st_mode)
+	        && S_ISBLK (cmp.file[1].stat.st_mode))
+	       || (S_ISCHR (cmp.file[0].stat.st_mode)
+	           && S_ISCHR (cmp.file[1].stat.st_mode)))
+	{
+	  if (cmp.file[0].stat.st_rdev != cmp.file[1].stat.st_rdev)
+	    {
+	      char major_minor0[20], major_minor1[20];
+	      format_major_minor (major_minor0, cmp.file[0].stat.st_rdev);
+	      format_major_minor (major_minor1, cmp.file[1].stat.st_rdev);
+
+	      const char *message = S_ISBLK (cmp.file[0].stat.st_mode) ?
+			"Block special files %s and %s differ: %s (%s)\n" :
+			"Character special files %s and %s differ: %s (%s)\n";
+	      message5 (message,
+			file_label[0] ? file_label[0] : cmp.file[0].name,
+			file_label[1] ? file_label[1] : cmp.file[1].name,
+			major_minor0, major_minor1);
+
+	      /* This is a difference.  */
+	      status = EXIT_FAILURE;
+	    }
+	}
       else
 	{
 	  /* We have two files that are not to be compared.  */
diff --git a/src/diff.h b/src/diff.h
index 465e4bc..098e75f 100644
--- a/src/diff.h
+++ b/src/diff.h
@@ -390,3 +390,4 @@ extern void print_script (struct change *, struct 
change * (*) (struct change *)
 extern void setup_output (char const *, char const *, bool);
 extern void translate_range (struct file_data const *, lin, lin,
                              long int *, long int *);
+extern void format_major_minor (char *buffer, const dev_t st_rdev);
diff --git a/src/util.c b/src/util.c
index 2d6d3fc..4773003 100644
--- a/src/util.c
+++ b/src/util.c
@@ -24,6 +24,7 @@
 #include <system-quote.h>
 #include <xalloc.h>
 #include "xvasprintf.h"
+#include <sys/types.h>
  char const pr_program[] = PR_PROGRAM;
 @@ -907,3 +908,11 @@ debug_script (struct change *sp)
    fflush (stderr);
 }
+
+/* Format a device number as major,minor. */
+
+void
+format_major_minor (char *buffer, const dev_t st_rdev)
+{
+  sprintf (buffer, "%u,%u", (major (st_rdev)), (minor (st_rdev)));
+}
-- 
2.2.1

Message #8 received at 19508 <at> debbugs.gnu.org (full text, mbox):

From: Ondřej Svoboda <ondrej <at> svobodasoft.cz>
To: 19508 <at> debbugs.gnu.org, Paul Eggert <eggert <at> cs.ucla.edu>
Subject: Re: [bug-diffutils] bug#19508: [PATCH] diff: compare major, minor
 numbers of block/character special files
Date: Thu, 12 Feb 2015 00:40:15 +0100

Paul, this is the first patch in the series (and is succeeded by the 
fifo one), I am sorry for the confusion.

Could you please give it a look?

Thanks :-)
Ondra Svoboda

On 4.1.2015 21:51, Ondřej Svoboda wrote:
> This deals with situation such as
>
>   File dev1/block1 is a block special file while file dev2/block1 is
>   a block special file
>
> in case the major and minor numbers are identical.
> If stat.st_rdev does not match, a message is given:
>
>   Block special files dev1/block1 and dev2/block1 differ: 1,2 (3,2)
> ---
>  src/diff.c | 23 +++++++++++++++++++++++
>  src/diff.h |  1 +
>  src/util.c |  9 +++++++++
>  3 files changed, 33 insertions(+)
>
> diff --git a/src/diff.c b/src/diff.c
> index ff28377..a3e1b6f 100644
> --- a/src/diff.c
> +++ b/src/diff.c
> @@ -1276,6 +1276,29 @@ compare_files (struct comparison const *parent,
>            status = EXIT_FAILURE;
>          }
>      }
> +      else if ((S_ISBLK (cmp.file[0].stat.st_mode)
> +            && S_ISBLK (cmp.file[1].stat.st_mode))
> +           || (S_ISCHR (cmp.file[0].stat.st_mode)
> +               && S_ISCHR (cmp.file[1].stat.st_mode)))
> +    {
> +      if (cmp.file[0].stat.st_rdev != cmp.file[1].stat.st_rdev)
> +        {
> +          char major_minor0[20], major_minor1[20];
> +          format_major_minor (major_minor0, cmp.file[0].stat.st_rdev);
> +          format_major_minor (major_minor1, cmp.file[1].stat.st_rdev);
> +
> +          const char *message = S_ISBLK (cmp.file[0].stat.st_mode) ?
> +            "Block special files %s and %s differ: %s (%s)\n" :
> +            "Character special files %s and %s differ: %s (%s)\n";
> +          message5 (message,
> +            file_label[0] ? file_label[0] : cmp.file[0].name,
> +            file_label[1] ? file_label[1] : cmp.file[1].name,
> +            major_minor0, major_minor1);
> +
> +          /* This is a difference.  */
> +          status = EXIT_FAILURE;
> +        }
> +    }
>        else
>      {
>        /* We have two files that are not to be compared.  */
> diff --git a/src/diff.h b/src/diff.h
> index 465e4bc..098e75f 100644
> --- a/src/diff.h
> +++ b/src/diff.h
> @@ -390,3 +390,4 @@ extern void print_script (struct change *, struct 
> change * (*) (struct change *)
>  extern void setup_output (char const *, char const *, bool);
>  extern void translate_range (struct file_data const *, lin, lin,
>                               long int *, long int *);
> +extern void format_major_minor (char *buffer, const dev_t st_rdev);
> diff --git a/src/util.c b/src/util.c
> index 2d6d3fc..4773003 100644
> --- a/src/util.c
> +++ b/src/util.c
> @@ -24,6 +24,7 @@
>  #include <system-quote.h>
>  #include <xalloc.h>
>  #include "xvasprintf.h"
> +#include <sys/types.h>
>   char const pr_program[] = PR_PROGRAM;
>  @@ -907,3 +908,11 @@ debug_script (struct change *sp)
>     fflush (stderr);
>  }
> +
> +/* Format a device number as major,minor. */
> +
> +void
> +format_major_minor (char *buffer, const dev_t st_rdev)
> +{
> +  sprintf (buffer, "%u,%u", (major (st_rdev)), (minor (st_rdev)));
> +}

Message #11 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Ondřej Svoboda <ondrej <at> svobodasoft.cz>
To: bug-diffutils <at> gnu.org
Subject: [bug-diffutils] bug#19508: [PATCH] diff: compare major, minor numbers
 of block/character special files
Date: Sat, 12 Mar 2016 14:55:56 +0100

[Message part 1 (text/plain, inline)]

Hi everybody,

I rebased the patch on current master and tested it (as root) like this:

# mkdir /tmp/a /tmp/b
# mknod /tmp/a/block1 b 1 2; mknod /tmp/b/block1 b 1 2
# mknod /tmp/a/block2 b 2 3; mknod /tmp/b/block2 b 2 4
# mknod /tmp/a/block3 b 3 4; mknod /tmp/b/block3 b 5 4
# mknod /tmp/a/char1 c 1 2; mknod /tmp/b/char1 c 1 2
# mknod /tmp/a/char2 c 2 3; mknod /tmp/b/char2 c 2 4
# mknod /tmp/a/char3 c 3 4; mknod /tmp/b/char3 c 5 4

# LC_ALL=C ls -l /tmp/a
total 0
brw-r--r-- 1 root root 1, 2 Mar 12 14:51 block1
brw-r--r-- 1 root root 2, 3 Mar 12 14:51 block2
brw-r--r-- 1 root root 3, 4 Mar 12 14:51 block3
crw-r--r-- 1 root root 1, 2 Mar 12 14:51 char1
crw-r--r-- 1 root root 2, 3 Mar 12 14:51 char2
crw-r--r-- 1 root root 3, 4 Mar 12 14:51 char3

# LC_ALL=C ls -l /tmp/b
total 0
brw-r--r-- 1 root root 1, 2 Mar 12 14:51 block1
brw-r--r-- 1 root root 2, 4 Mar 12 14:51 block2
brw-r--r-- 1 root root 5, 4 Mar 12 14:51 block3
crw-r--r-- 1 root root 1, 2 Mar 12 14:51 char1
crw-r--r-- 1 root root 2, 4 Mar 12 14:51 char2
crw-r--r-- 1 root root 5, 4 Mar 12 14:51 char3

# LC_ALL=C diff -s -r /tmp/a /tmp/b
Files /tmp/a/block1 and /tmp/b/block1 are identical
File /tmp/a/block2 is a block special file while file /tmp/b/block2 is a 
block special file
File /tmp/a/block3 is a block special file while file /tmp/b/block3 is a 
block special file
Files /tmp/a/char1 and /tmp/b/char1 are identical
File /tmp/a/char2 is a character special file while file /tmp/b/char2 is 
a character special file
File /tmp/a/char3 is a character special file while file /tmp/b/char3 is 
a character special file

# LC_ALL=C /usr/local/bin/diff -s -r /tmp/a /tmp/b
Files /tmp/a/block1 and /tmp/b/block1 are identical
Block special files /tmp/a/block2 and /tmp/b/block2 differ: 2,3 (2,4)
Block special files /tmp/a/block3 and /tmp/b/block3 differ: 3,4 (5,4)
Files /tmp/a/char1 and /tmp/b/char1 are identical
Character special files /tmp/a/char2 and /tmp/b/char2 differ: 2,3 (2,4)
Character special files /tmp/a/char3 and /tmp/b/char3 differ: 3,4 (5,4)

The reason why diff compared block1 as identical perhaps because it 
descended to diff_2_files, I would know if I stepped through the code 
which I currently don't have much time to do.

Please share your comments!

Cheers,
Ondra

[0001-diff-compare-major-minor-numbers-of-block-character-.patch (text/x-patch, attachment)]

Message #14 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Ondřej Svoboda <ondrej <at> svobodasoft.cz>
To: bug-diffutils <at> gnu.org
Subject: Re: [bug-diffutils] bug#19508: bug#19508: [PATCH] diff: compare
 major, minor numbers of block/character special files
Date: Sat, 12 Mar 2016 15:16:49 +0100

Please see the follow-up on testing below.

On 12.3.2016 14:55, Ondřej Svoboda wrote:
> Hi everybody,
>
> I rebased the patch on current master and tested it (as root) like this:
>
> # mkdir /tmp/a /tmp/b
> # mknod /tmp/a/block1 b 1 2; mknod /tmp/b/block1 b 1 2
> # mknod /tmp/a/block2 b 2 3; mknod /tmp/b/block2 b 2 4
> # mknod /tmp/a/block3 b 3 4; mknod /tmp/b/block3 b 5 4
> # mknod /tmp/a/char1 c 1 2; mknod /tmp/b/char1 c 1 2
> # mknod /tmp/a/char2 c 2 3; mknod /tmp/b/char2 c 2 4
> # mknod /tmp/a/char3 c 3 4; mknod /tmp/b/char3 c 5 4
>
> # LC_ALL=C ls -l /tmp/a
> total 0
> brw-r--r-- 1 root root 1, 2 Mar 12 14:51 block1
> brw-r--r-- 1 root root 2, 3 Mar 12 14:51 block2
> brw-r--r-- 1 root root 3, 4 Mar 12 14:51 block3
> crw-r--r-- 1 root root 1, 2 Mar 12 14:51 char1
> crw-r--r-- 1 root root 2, 3 Mar 12 14:51 char2
> crw-r--r-- 1 root root 3, 4 Mar 12 14:51 char3
>
> # LC_ALL=C ls -l /tmp/b
> total 0
> brw-r--r-- 1 root root 1, 2 Mar 12 14:51 block1
> brw-r--r-- 1 root root 2, 4 Mar 12 14:51 block2
> brw-r--r-- 1 root root 5, 4 Mar 12 14:51 block3
> crw-r--r-- 1 root root 1, 2 Mar 12 14:51 char1
> crw-r--r-- 1 root root 2, 4 Mar 12 14:51 char2
> crw-r--r-- 1 root root 5, 4 Mar 12 14:51 char3
>
> # LC_ALL=C diff -s -r /tmp/a /tmp/b
> Files /tmp/a/block1 and /tmp/b/block1 are identical
> File /tmp/a/block2 is a block special file while file /tmp/b/block2 is 
> a block special file
> File /tmp/a/block3 is a block special file while file /tmp/b/block3 is 
> a block special file
> Files /tmp/a/char1 and /tmp/b/char1 are identical
> File /tmp/a/char2 is a character special file while file /tmp/b/char2 
> is a character special file
> File /tmp/a/char3 is a character special file while file /tmp/b/char3 
> is a character special file
>
> # LC_ALL=C /usr/local/bin/diff -s -r /tmp/a /tmp/b
> Files /tmp/a/block1 and /tmp/b/block1 are identical
> Block special files /tmp/a/block2 and /tmp/b/block2 differ: 2,3 (2,4)
> Block special files /tmp/a/block3 and /tmp/b/block3 differ: 3,4 (5,4)
> Files /tmp/a/char1 and /tmp/b/char1 are identical
> Character special files /tmp/a/char2 and /tmp/b/char2 differ: 2,3 (2,4)
> Character special files /tmp/a/char3 and /tmp/b/char3 differ: 3,4 (5,4)
>
> The reason why diff compared block1 as identical perhaps because it 
> descended to diff_2_files, I would know if I stepped through the code 
> which I currently don't have much time to do.

# touch /tmp/b/*

# LC_ALL=C ls -l /tmp/b
total 0
brw-r--r-- 1 root root 1, 2 Mar 12 15:09 block1
brw-r--r-- 1 root root 2, 4 Mar 12 15:09 block2
brw-r--r-- 1 root root 5, 4 Mar 12 15:09 block3
crw-r--r-- 1 root root 1, 2 Mar 12 15:09 char1
crw-r--r-- 1 root root 2, 4 Mar 12 15:09 char2
crw-r--r-- 1 root root 5, 4 Mar 12 15:09 char3

# LC_ALL=C diff -s -r /tmp/a /tmp/b
File /tmp/a/block1 is a block special file while file /tmp/b/block1 is a 
block special file
File /tmp/a/block2 is a block special file while file /tmp/b/block2 is a 
block special file
File /tmp/a/block3 is a block special file while file /tmp/b/block3 is a 
block special file
File /tmp/a/char1 is a character special file while file /tmp/b/char1 is 
a character special file
File /tmp/a/char2 is a character special file while file /tmp/b/char2 is 
a character special file
File /tmp/a/char3 is a character special file while file /tmp/b/char3 is 
a character special file

# LC_ALL=C /usr/local/bin/diff -s -r /tmp/a /tmp/b :(
Files /tmp/a/block1 and /tmp/b/block1 are identical
Block special files /tmp/a/block2 and /tmp/b/block2 differ: 2,3 (2,4)
Block special files /tmp/a/block3 and /tmp/b/block3 differ: 3,4 (5,4)
Files /tmp/a/char1 and /tmp/b/char1 are identical
Character special files /tmp/a/char2 and /tmp/b/char2 differ: 2,3 (2,4)
Character special files /tmp/a/char3 and /tmp/b/char3 differ: 3,4 (5,4)

After changing the modification datetime, both block1 and char1 compared 
differently with diffutils 3.3-2 (on Arch Linux) while they were found 
to be the same with the patched diff from master.

> Please share your comments!
>
> Cheers,
> Ondra

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