Patch Name: PHCO_27021

Patch Description: s700_800 10.20 diff(1) patch

Creation Date: 02/06/13

Post Date:  02/06/24

Hardware Platforms - OS Releases:
	s700: 10.20
	s800: 10.20

Products: N/A

Filesets:
	OS-Core.CMDS-AUX

Automatic Reboot?: No

Status: General Release

Critical: No

Path Name: /hp-ux_patches/s700_800/10.X/PHCO_27021

Symptoms:
	PHCO_27021:
	1. diff(1) command in few cases does not return the
	   proper exit value when comparing sub-directories.

	2. diff(1) command in few cases does not report minimal
	   results.

Defect Description:
	PHCO_27021:
	1. diff(1) command returns wrong exit value in some
	   cases when comparing the directories i.e. if the
	   sub-directories of the two input directories
	   differ, diff(1)  command  reports  the  correct
	   differences, but it returns with an exit value "0".
	   The expected (documented) behaviour is to return
	   with an exit value "1" for any differences ( files,
	   directories or sub directories).
	   The problem can be reproduced as follows:

	   $mkdir -p dir1/subdir1 dir2/subdir1
	   $touch dir1/subdir1/file1
	   $diff -r dir1 dir2
	   Common subdirectories: dir1/subdir1 and dir2/subdir1
	   Only in dir1/subdir1: file1
	   $echo $?
	   0          <--- This is wrong. Expected exit value is 1.
	   $

	Resolution :
	   Initially the status of child process was not properly
	   trapped in the parent process. Now the code is modified
	   to capture the exit status of the child process. So if
	   the subdirectories differ, then diff(1) will return with
	   an exit value "1".

	2. diff(1) command for some files does not report minimal
	   differences.
	   The problem can be reproduced as follows:

	   $cat file1
	   12345678
	   01081679
	   $cat file2
	   01081679
	   $diff file1 file2
	   1,2c1
	   < 12345678
	   < 01081679
	   ---
	   > 01081679
	   $

	   The expected output is

	   $diff file1 file2
	   1d0
	   < 12345678
	   $

	   diff(1) command uses the hashing algorithm to compare
	   the files. A hash value is generated for each line in
	   the two files specified. diff(1) used to generate 16
	   bit hashing values. Because of this, the possibilities
	   of having hash collisions(having the same hash values
	   for two different lines) were high. If mth line of file1
	   and nth line of file2 computes to same hash value, then
	   diff(1) assumes the two lines could be identical and
	   hence applies the character-wise comparison on these
	   two lines only. On finding them different,it just outputs
	   them as the difference, without considering the situation
	   that there could be an another line in file2 which is
	   identical to mth line of file1. Hence diff(1) is not
	   able to report minimal difference. The output differs
	   depending on the ordering of lines in the input files.

	Resolution :
	   The problem is addressed by modifying diff(1) command
	   to generate 32bit hash values instead of 16bit values.
	   This fix only minimizes the hash collisions. Even
	   after this fix, there could be rare possibilities of
	   getting hash value collisions in which case one could
	   again see the command not generating minimal output.

SR:
	8606192634 8606251084

Patch Files:
	/usr/bin/diff

what(1) Output:
	/usr/bin/diff:
		$Revision: 78.2.1.10 $
		PATCH_10_20: diff.o diffdir.o diffreg.o hpux_rel.o 0
			2/06/13
		PATCH-PHCO_20441 for 10.20; for 10.30, 11.x compatib
			ility libc.a_ID@@/main/r10dav/libc_dav/libc_
			dav_cpe/9
		/ux/core/libs/libc/archive_pa1/libc.a_ID
		Nov 10 1999 10:43:44

cksum(1) Output:
	722829 270336 /usr/bin/diff

Patch Conflicts: None

Patch Dependencies: None

Hardware Dependencies: None

Other Dependencies: None

Supersedes: None

Equivalent Patches: None

Patch Package Size: 320 KBytes

Installation Instructions:
	Please review all instructions and the Hewlett-Packard
	SupportLine User Guide or your Hewlett-Packard support terms
	and conditions for precautions, scope of license,
	restrictions, and, limitation of liability and warranties,
	before installing this patch.
	------------------------------------------------------------
	1. Back up your system before installing a patch.

	2. Login as root.

	3. Copy the patch to the /tmp directory.

	4. Move to the /tmp directory and unshar the patch:

		cd /tmp
		sh PHCO_27021

	5a. For a standalone system, run swinstall to install the
	    patch:

		swinstall -x autoreboot=true -x match_target=true \
			-s /tmp/PHCO_27021.depot

	By default swinstall will archive the original software in
	/var/adm/sw/patch/PHCO_27021.  If you do not wish to retain a
	copy of the original software, you can create an empty file
	named /var/adm/sw/patch/PATCH_NOSAVE.

	WARNING: If this file exists when a patch is installed, the
	         patch cannot be deinstalled.  Please be careful
		 when using this feature.

	It is recommended that you move the PHCO_27021.text file to
	/var/adm/sw/patch for future reference.

	To put this patch on a magnetic tape and install from the
	tape drive, use the command:

		dd if=/tmp/PHCO_27021.depot of=/dev/rmt/0m bs=2k

Special Installation Instructions: None