bin/85712: uncompress(1) program emits bogus "overwrite?" prompt

[Giorgos Keramidas]

The following reply was made to PR bin/85712; it has been noted by GNATS.

From: Giorgos Keramidas <keramida at freebsd.org>
To: "Gary W. Swearingen" <garys at freebsd.org>
Cc: bug-followup at freebsd.org
Subject: Re: bin/85712: uncompress(1) program emits bogus "overwrite?" prompt
Date: Wed, 7 Sep 2005 02:20:19 +0300

 On 2005-09-04 09:47, "Gary W. Swearingen" <garys at freebsd.org> wrote:
 > The uncompress(1) program, when given a filename without a .Z
 > extension, prompts the user for confirmation and if given "y", it then
 > ignores the reply and then complains about the missing .Z extension.
 
 I can confirm this bug exists in CURRENT too.
 
 > This PR should be suspended immediately for the "lack of resources"
 > reason, because it is an unimportant bug that only wastes a little
 > users' time.
 
 Unless we get it fixed by committing the following:
 
 %%%
 Index: compress.c
 ===================================================================
 RCS file: /home/ncvs/src/usr.bin/compress/compress.c,v
 retrieving revision 1.21
 diff -u -r1.21 compress.c
 --- compress.c	14 Jun 2003 13:41:31 -0000	1.21
 +++ compress.c	6 Sep 2005 23:04:44 -0000
 @@ -204,7 +204,7 @@
  	int exists, isreg, oreg;
  	u_char buf[1024];
  
 -	exists = !stat(out, &sb);
 +	exists = (stat(in, &sb) == 0 && stat(out, &sb) == 0);
  	if (!force && exists && S_ISREG(sb.st_mode) && !permission(out))
  		return;
  	isreg = oreg = !exists || S_ISREG(sb.st_mode);
 @@ -294,7 +294,7 @@
  	int exists, isreg, oreg;
  	u_char buf[1024];
  
 -	exists = !stat(out, &sb);
 +	exists = (stat(in, &sb) == 0 && stat(out, &sb) == 0);
  	if (!force && exists && S_ISREG(sb.st_mode) && !permission(out))
  		return;
  	isreg = oreg = !exists || S_ISREG(sb.st_mode);
 %%%
 
 With this patch, the behavior of both compress and uncompress makes more
 sense, since they warn about missing input files *before* the permission()
 function checks for overwrite access.
 
 IMHO, it's ok to use stat() on both the input and output file here, since
 the checks for success and/or failure later on protect against files going
 away under compress(1) or uncompress(1) between the time the stat() and
 permission() calls run and the time the files are really opened.