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Date: Sat,  3 May 2014 13:38:42 +0200 (CEST)
From: Thomas Quinot <thomas@cuivre.fr.eu.org>
Reply-To: Thomas Quinot <thomas@cuivre.fr.eu.org>
To: FreeBSD-gnats-submit@freebsd.org
Cc:
Subject: dd(1): may write junk if conv=sparse with obs < ibs
X-Send-Pr-Version: 3.114
X-GNATS-Notify:

>Number:         189284
>Category:       bin
>Synopsis:       dd(1): may write junk if conv=sparse with obs < ibs
>Confidential:   no
>Severity:       serious
>Priority:       high
>Responsible:    freebsd-bugs
>State:          closed
>Quarter:        
>Keywords:       
>Date-Required:  
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Sat May 03 11:40:00 UTC 2014
>Closed-Date:    Wed May 07 19:55:44 UTC 2014
>Last-Modified:  Wed May 21 07:50:01 UTC 2014
>Originator:     Thomas Quinot
>Release:        FreeBSD 9.2-STABLE amd64
>Organization:
>Environment:
System: FreeBSD melamine.cuivre.fr.eu.org 9.2-STABLE FreeBSD 9.2-STABLE #0 r256080: Sun Oct 6 15:33:30 CEST 2013 thomas@melamine.cuivre.fr.eu.org:/usr/obj/users/thomas/projects/FreeBSD/base/stable/9/sys/GENERIC amd64


	
>Description:
	When ibs is an integral multiple of ibs, and there is a sequence
	of obs consecutive zeroes at the end of the last input block,
	the last character written by dd may be some different (non-zero)
	byte from the input stream.
>How-To-Repeat:

$ perl -e 'print "ABCDEFGH\0\0\0\0\0\0\0\0"'|dd ibs=16 obs=8 conv=sparse of=toto 
1+0 records in
2+0 records out
16 bytes transferred in 0.001373 secs (11653 bytes/sec)
$ od -a toto
0000000    A   B   C   D   E   F   G   H nul nul nul nul nul nul nul   A
0000020

>Fix:

	


>Release-Note:
>Audit-Trail:

From: dfilter@FreeBSD.ORG (dfilter service)
To: bug-followup@FreeBSD.org
Cc:  
Subject: Re: bin/189284: commit references a PR
Date: Wed,  7 May 2014 19:33:34 +0000 (UTC)

 Author: thomas
 Date: Wed May  7 19:33:29 2014
 New Revision: 265593
 URL: http://svnweb.freebsd.org/changeset/base/265593
 
 Log:
   (dd_out): Fix handling of all-zeroes block at end of input with
   conv=sparse.
   
   This change fixes two separate issues observed when the last output
   block is all zeroes, and conv=sparse is in use. In this case, care
   must be taken to roll back the last seek and write the entire last zero
   block at the original offset where it should have occurred: when the
   destination file is a block device, it is not possible to roll back
   by just one character as the write would then not be properly aligned.
   
   Furthermore, the buffer used to write this last all-zeroes block
   needs to be properly zeroed-out. This was not the case previously,
   resulting in a junk data byte appearing instead of a zero in the
   output stream.
   
   PR:		bin/189174
   PR:		bin/189284
   Reviewed by:	kib
   MFC after:	2 weeks
 
 Modified:
   head/bin/dd/dd.c
 
 Modified: head/bin/dd/dd.c
 ==============================================================================
 --- head/bin/dd/dd.c	Wed May  7 19:30:28 2014	(r265592)
 +++ head/bin/dd/dd.c	Wed May  7 19:33:29 2014	(r265593)
 @@ -51,6 +51,7 @@ __FBSDID("$FreeBSD$");
  #include <sys/disklabel.h>
  #include <sys/filio.h>
  
 +#include <assert.h>
  #include <ctype.h>
  #include <err.h>
  #include <errno.h>
 @@ -77,6 +78,7 @@ STAT	st;			/* statistics */
  void	(*cfunc)(void);		/* conversion function */
  uintmax_t cpy_cnt;		/* # of blocks to copy */
  static off_t	pending = 0;	/* pending seek if sparse */
 +static off_t	last_sp = 0;	/* size of last added sparse block */
  u_int	ddflags = 0;		/* conversion options */
  size_t	cbsz;			/* conversion block size */
  uintmax_t files_cnt = 1;	/* # of files to copy */
 @@ -174,6 +176,8 @@ setup(void)
  	} else if ((in.db = malloc(MAX(in.dbsz, cbsz) + cbsz)) == NULL ||
  	    (out.db = malloc(out.dbsz + cbsz)) == NULL)
  		err(1, "output buffer");
 +
 +	/* dbp is the first free position in each buffer. */
  	in.dbp = in.db;
  	out.dbp = out.db;
  
 @@ -436,8 +440,15 @@ dd_out(int force)
  	 * we play games with the buffer size, and it's usually a partial write.
  	 */
  	outp = out.db;
 +
 +	/*
 +	 * If force, first try to write all pending data, else try to write
 +	 * just one block. Subsequently always write data one full block at
 +	 * a time at most.
 +	 */
  	for (n = force ? out.dbcnt : out.dbsz;; n = out.dbsz) {
 -		for (cnt = n;; cnt -= nw) {
 +		cnt = n;
 +		do {
  			sparse = 0;
  			if (ddflags & C_SPARSE) {
  				sparse = 1;	/* Is buffer sparse? */
 @@ -449,18 +460,24 @@ dd_out(int force)
  			}
  			if (sparse && !force) {
  				pending += cnt;
 +				last_sp = cnt;
  				nw = cnt;
  			} else {
  				if (pending != 0) {
 -					if (force)
 -						pending--;
 +					/* If forced to write, and we have no
 +					 * data left, we need to write the last
 +					 * sparse block explicitly.
 +					 */
 +					if (force && cnt == 0) {
 +						pending -= last_sp;
 +						assert(outp == out.db);
 +						memset(outp, 0, cnt);
 +					}
  					if (lseek(out.fd, pending, SEEK_CUR) ==
  					    -1)
  						err(2, "%s: seek error creating sparse file",
  						    out.name);
 -					if (force)
 -						write(out.fd, outp, 1);
 -					pending = 0;
 +					pending = last_sp = 0;
  				}
  				if (cnt)
  					nw = write(out.fd, outp, cnt);
 @@ -475,27 +492,29 @@ dd_out(int force)
  					err(1, "%s", out.name);
  				nw = 0;
  			}
 +
  			outp += nw;
  			st.bytes += nw;
 -			if ((size_t)nw == n) {
 -				if (n != out.dbsz)
 -					++st.out_part;
 -				else
 -					++st.out_full;
 -				break;
 -			}
 -			++st.out_part;
 -			if ((size_t)nw == cnt)
 -				break;
 -			if (out.flags & ISTAPE)
 -				errx(1, "%s: short write on tape device",
 -				    out.name);
 -			if (out.flags & ISCHR && !warned) {
 -				warned = 1;
 -				warnx("%s: short write on character device",
 -				    out.name);
 +
 +			if ((size_t)nw == n && n == out.dbsz)
 +				++st.out_full;
 +			else
 +				++st.out_part;
 +
 +			if ((size_t) nw != cnt) {
 +				if (out.flags & ISTAPE)
 +					errx(1, "%s: short write on tape device",
 +				    	out.name);
 +				if (out.flags & ISCHR && !warned) {
 +					warned = 1;
 +					warnx("%s: short write on character device",
 +				    	out.name);
 +				}
  			}
 -		}
 +
 +			cnt -= nw;
 +		} while (cnt != 0);
 +
  		if ((out.dbcnt -= n) < out.dbsz)
  			break;
  	}
 _______________________________________________
 svn-src-all@freebsd.org mailing list
 http://lists.freebsd.org/mailman/listinfo/svn-src-all
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State-Changed-From-To: open->closed 
State-Changed-By: thomas 
State-Changed-When: Wed May 7 19:55:36 UTC 2014 
State-Changed-Why:  
Fixed in head. 

http://www.freebsd.org/cgi/query-pr.cgi?pr=189284 

From: dfilter@FreeBSD.ORG (dfilter service)
To: bug-followup@FreeBSD.org
Cc:  
Subject: Re: bin/189284: commit references a PR
Date: Wed, 21 May 2014 07:21:41 +0000 (UTC)

 Author: thomas
 Date: Wed May 21 07:21:36 2014
 New Revision: 266488
 URL: http://svnweb.freebsd.org/changeset/base/266488
 
 Log:
   MFC rev. 265593:
   (dd_out): Fix handling of all-zeroes block at end of input with
   conv=sparse.
   
   PR:		bin/189174
   PR:		bin/189284
   Reviewed by:	kib
 
 Modified:
   stable/10/bin/dd/dd.c
 Directory Properties:
   stable/10/   (props changed)
 
 Modified: stable/10/bin/dd/dd.c
 ==============================================================================
 --- stable/10/bin/dd/dd.c	Wed May 21 06:33:21 2014	(r266487)
 +++ stable/10/bin/dd/dd.c	Wed May 21 07:21:36 2014	(r266488)
 @@ -52,6 +52,7 @@ __FBSDID("$FreeBSD$");
  #include <sys/filio.h>
  #include <sys/time.h>
  
 +#include <assert.h>
  #include <ctype.h>
  #include <err.h>
  #include <errno.h>
 @@ -76,6 +77,7 @@ STAT	st;			/* statistics */
  void	(*cfunc)(void);		/* conversion function */
  uintmax_t cpy_cnt;		/* # of blocks to copy */
  static off_t	pending = 0;	/* pending seek if sparse */
 +static off_t	last_sp = 0;	/* size of last added sparse block */
  u_int	ddflags = 0;		/* conversion options */
  size_t	cbsz;			/* conversion block size */
  uintmax_t files_cnt = 1;	/* # of files to copy */
 @@ -173,6 +175,8 @@ setup(void)
  	} else if ((in.db = malloc(MAX(in.dbsz, cbsz) + cbsz)) == NULL ||
  	    (out.db = malloc(out.dbsz + cbsz)) == NULL)
  		err(1, "output buffer");
 +
 +	/* dbp is the first free position in each buffer. */
  	in.dbp = in.db;
  	out.dbp = out.db;
  
 @@ -434,8 +438,15 @@ dd_out(int force)
  	 * we play games with the buffer size, and it's usually a partial write.
  	 */
  	outp = out.db;
 +
 +	/*
 +	 * If force, first try to write all pending data, else try to write
 +	 * just one block. Subsequently always write data one full block at
 +	 * a time at most.
 +	 */
  	for (n = force ? out.dbcnt : out.dbsz;; n = out.dbsz) {
 -		for (cnt = n;; cnt -= nw) {
 +		cnt = n;
 +		do {
  			sparse = 0;
  			if (ddflags & C_SPARSE) {
  				sparse = 1;	/* Is buffer sparse? */
 @@ -447,18 +458,24 @@ dd_out(int force)
  			}
  			if (sparse && !force) {
  				pending += cnt;
 +				last_sp = cnt;
  				nw = cnt;
  			} else {
  				if (pending != 0) {
 -					if (force)
 -						pending--;
 +					/* If forced to write, and we have no
 +					 * data left, we need to write the last
 +					 * sparse block explicitly.
 +					 */
 +					if (force && cnt == 0) {
 +						pending -= last_sp;
 +						assert(outp == out.db);
 +						memset(outp, 0, cnt);
 +					}
  					if (lseek(out.fd, pending, SEEK_CUR) ==
  					    -1)
  						err(2, "%s: seek error creating sparse file",
  						    out.name);
 -					if (force)
 -						write(out.fd, outp, 1);
 -					pending = 0;
 +					pending = last_sp = 0;
  				}
  				if (cnt)
  					nw = write(out.fd, outp, cnt);
 @@ -473,27 +490,29 @@ dd_out(int force)
  					err(1, "%s", out.name);
  				nw = 0;
  			}
 +
  			outp += nw;
  			st.bytes += nw;
 -			if ((size_t)nw == n) {
 -				if (n != out.dbsz)
 -					++st.out_part;
 -				else
 -					++st.out_full;
 -				break;
 -			}
 -			++st.out_part;
 -			if ((size_t)nw == cnt)
 -				break;
 -			if (out.flags & ISTAPE)
 -				errx(1, "%s: short write on tape device",
 -				    out.name);
 -			if (out.flags & ISCHR && !warned) {
 -				warned = 1;
 -				warnx("%s: short write on character device",
 -				    out.name);
 +
 +			if ((size_t)nw == n && n == out.dbsz)
 +				++st.out_full;
 +			else
 +				++st.out_part;
 +
 +			if ((size_t) nw != cnt) {
 +				if (out.flags & ISTAPE)
 +					errx(1, "%s: short write on tape device",
 +				    	out.name);
 +				if (out.flags & ISCHR && !warned) {
 +					warned = 1;
 +					warnx("%s: short write on character device",
 +				    	out.name);
 +				}
  			}
 -		}
 +
 +			cnt -= nw;
 +		} while (cnt != 0);
 +
  		if ((out.dbcnt -= n) < out.dbsz)
  			break;
  	}
 _______________________________________________
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 http://lists.freebsd.org/mailman/listinfo/svn-src-all
 To unsubscribe, send any mail to "svn-src-all-unsubscribe@freebsd.org"
 

From: dfilter@FreeBSD.ORG (dfilter service)
To: bug-followup@FreeBSD.org
Cc:  
Subject: Re: bin/189284: commit references a PR
Date: Wed, 21 May 2014 07:42:48 +0000 (UTC)

 Author: thomas
 Date: Wed May 21 07:42:42 2014
 New Revision: 266489
 URL: http://svnweb.freebsd.org/changeset/base/266489
 
 Log:
   MFC rev. 265593:
   (dd_out): Fix handling of all-zeroes block at end of input with
   conv=sparse.
   
   PR:		bin/189174
   PR:		bin/189284
   Reviewed by:	kib
 
 Modified:
   stable/9/bin/dd/dd.c
 Directory Properties:
   stable/9/   (props changed)
   stable/9/bin/   (props changed)
   stable/9/bin/dd/   (props changed)
 
 Modified: stable/9/bin/dd/dd.c
 ==============================================================================
 --- stable/9/bin/dd/dd.c	Wed May 21 07:21:36 2014	(r266488)
 +++ stable/9/bin/dd/dd.c	Wed May 21 07:42:42 2014	(r266489)
 @@ -52,6 +52,7 @@ __FBSDID("$FreeBSD$");
  #include <sys/filio.h>
  #include <sys/time.h>
  
 +#include <assert.h>
  #include <ctype.h>
  #include <err.h>
  #include <errno.h>
 @@ -76,6 +77,7 @@ STAT	st;			/* statistics */
  void	(*cfunc)(void);		/* conversion function */
  uintmax_t cpy_cnt;		/* # of blocks to copy */
  static off_t	pending = 0;	/* pending seek if sparse */
 +static off_t	last_sp = 0;	/* size of last added sparse block */
  u_int	ddflags = 0;		/* conversion options */
  size_t	cbsz;			/* conversion block size */
  uintmax_t files_cnt = 1;	/* # of files to copy */
 @@ -173,6 +175,8 @@ setup(void)
  	} else if ((in.db = malloc(MAX(in.dbsz, cbsz) + cbsz)) == NULL ||
  	    (out.db = malloc(out.dbsz + cbsz)) == NULL)
  		err(1, "output buffer");
 +
 +	/* dbp is the first free position in each buffer. */
  	in.dbp = in.db;
  	out.dbp = out.db;
  
 @@ -434,8 +438,15 @@ dd_out(int force)
  	 * we play games with the buffer size, and it's usually a partial write.
  	 */
  	outp = out.db;
 +
 +	/*
 +	 * If force, first try to write all pending data, else try to write
 +	 * just one block. Subsequently always write data one full block at
 +	 * a time at most.
 +	 */
  	for (n = force ? out.dbcnt : out.dbsz;; n = out.dbsz) {
 -		for (cnt = n;; cnt -= nw) {
 +		cnt = n;
 +		do {
  			sparse = 0;
  			if (ddflags & C_SPARSE) {
  				sparse = 1;	/* Is buffer sparse? */
 @@ -447,18 +458,24 @@ dd_out(int force)
  			}
  			if (sparse && !force) {
  				pending += cnt;
 +				last_sp = cnt;
  				nw = cnt;
  			} else {
  				if (pending != 0) {
 -					if (force)
 -						pending--;
 +					/* If forced to write, and we have no
 +					 * data left, we need to write the last
 +					 * sparse block explicitly.
 +					 */
 +					if (force && cnt == 0) {
 +						pending -= last_sp;
 +						assert(outp == out.db);
 +						memset(outp, 0, cnt);
 +					}
  					if (lseek(out.fd, pending, SEEK_CUR) ==
  					    -1)
  						err(2, "%s: seek error creating sparse file",
  						    out.name);
 -					if (force)
 -						write(out.fd, outp, 1);
 -					pending = 0;
 +					pending = last_sp = 0;
  				}
  				if (cnt)
  					nw = write(out.fd, outp, cnt);
 @@ -473,27 +490,29 @@ dd_out(int force)
  					err(1, "%s", out.name);
  				nw = 0;
  			}
 +
  			outp += nw;
  			st.bytes += nw;
 -			if ((size_t)nw == n) {
 -				if (n != out.dbsz)
 -					++st.out_part;
 -				else
 -					++st.out_full;
 -				break;
 -			}
 -			++st.out_part;
 -			if ((size_t)nw == cnt)
 -				break;
 -			if (out.flags & ISTAPE)
 -				errx(1, "%s: short write on tape device",
 -				    out.name);
 -			if (out.flags & ISCHR && !warned) {
 -				warned = 1;
 -				warnx("%s: short write on character device",
 -				    out.name);
 +
 +			if ((size_t)nw == n && n == out.dbsz)
 +				++st.out_full;
 +			else
 +				++st.out_part;
 +
 +			if ((size_t) nw != cnt) {
 +				if (out.flags & ISTAPE)
 +					errx(1, "%s: short write on tape device",
 +				    	out.name);
 +				if (out.flags & ISCHR && !warned) {
 +					warned = 1;
 +					warnx("%s: short write on character device",
 +				    	out.name);
 +				}
  			}
 -		}
 +
 +			cnt -= nw;
 +		} while (cnt != 0);
 +
  		if ((out.dbcnt -= n) < out.dbsz)
  			break;
  	}
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>Unformatted:
