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From: sms@wlv.imsd.contel.com (Steven M. Schultz)
Newsgroups: comp.bugs.2bsd
Subject: dd exit status bug (+fix)
Message-ID: <1991May5.080445.15466@wlbr.imsd.contel.com>
Date: 5 May 91 08:04:45 GMT
Sender: news@wlbr.imsd.contel.com (news)
Organization: Contel Federal Systems
Lines: 95
Nntp-Posting-Host: wlv.imsd.contel.com

File: /usr/src/bin/dd.c

Description:
	When dd(1) is writing an archive to tape, and
	encounters a write error or even an end of tape
	mark, it returns exit status 0, which spoils error
	checking in scripts and especially if it is the last
	command in a list.

Repeat-By:
	try it; or inspect code to see that term() always
	exits with zero.

Fix:
	Apply the following patch and recompile 'dd'.

*** dd.c.old	Sun Feb  8 14:24:49 1987
--- dd.c	Sun Mar 31 00:23:49 1991
***************
*** 313,319 ****
  			perror("read");
  			if((cflag&NERR) == 0) {
  				flsh();
! 				term();
  			}
  			ibc = 0;
  			for(c=0; c<ibs; c++)
--- 313,319 ----
  			perror("read");
  			if((cflag&NERR) == 0) {
  				flsh();
! 				term(1);
  			}
  			ibc = 0;
  			for(c=0; c<ibs; c++)
***************
*** 323,329 ****
  		}
  		if(ibc == 0 && --files<=0) {
  			flsh();
! 			term();
  		}
  		if(ibc != ibs) {
  			nipr++;
--- 323,329 ----
  		}
  		if(ibc == 0 && --files<=0) {
  			flsh();
! 			term(0);
  		}
  		if(ibc != ibs) {
  			nipr++;
***************
*** 365,371 ****
  		c = write(obf, obuf, obc);
  		if(c != obc) {
  			perror("write");
! 			term();
  		}
  		obc = 0;
  	}
--- 365,371 ----
  		c = write(obf, obuf, obc);
  		if(c != obc) {
  			perror("write");
! 			term(1);
  		}
  		obc = 0;
  	}
***************
*** 592,602 ****
  		null(c);
  }
  
! term()
  {
  
  	stats();
! 	exit(0);
  }
  
  stats()
--- 592,603 ----
  		null(c);
  }
  
! term(status)
! int status;
  {
  
  	stats();
! 	exit(status);
  }
  
  stats()