Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!rutgers!njin!princeton!notecnirp!nfs
From: nfs@notecnirp.Princeton.EDU (Norbert Schlenker)
Newsgroups: comp.os.minix
Subject: Tee bug and fix
Keywords: tee create append bug fix
Message-ID: <18226@princeton.Princeton.EDU>
Date: 18 Jul 89 04:14:54 GMT
References: <1951@ast.cs.vu.nl>
Sender: news@princeton.Princeton.EDU
Reply-To: nfs@notecnirp.UUCP (Norbert Schlenker)
Organization: Dept. of Computer Science, Princeton University
Lines: 44

The tee command has been broken since Minix was born.  Standard
distributions up to and including v1.3 have the problem that an
invocation without the -a flag will not truncate an existing file,
potentially leaving trash at the end.  A patch to fix this problem
was included in the v1.4a cdiffs from Andy Tanenbaum; unfortunately,
that patch has resulted in a tee command which will not create a
brand new file when the -a flag IS specified.

The following is a (normal) diff from the standard v1.3 tee.c that
fixes both problems.

------------------------------ Cut here ------------------------------
3c3
< #include <minix/blocksize.h>
---
> #include <minix/const.h>
37,45c37,48
<   for (s = 1; s < MAXFD && argc > 0; --argc, argv++) {
< 	if ((fd[s] = open(*argv, 2)) < 0 &&
< 				(fd[s] = creat(*argv, 0666)) < 0) {
< 		std_err("Cannot open output file: ");
< 		std_err(*argv);
< 		std_err("\n");
< 		exit(2);
< 	}
< 	s++;
---
>   for (s = 1; s < MAXFD && argc > 0; --argc, argv++, s++) {
> 	if (aflag && (fd[s] = open(*argv, 2)) >= 0) {
> 		lseek(fd[s], 0L, 2);
> 		continue;
> 	} else {
> 		if ((fd[s] = creat(*argv, 0666)) >= 0)
> 			continue;
> 	}
> 	std_err("Cannot open output file: ");
> 	std_err(*argv);
> 	std_err("\n");
> 	exit(2);
50,53d52
<   for (i = 1; i < s; i++) {	/* Don't lseek stdout. */
< 	if (aflag)
< 		lseek(fd[i], 0L, 2);
<   }