Date: Sun, 29 Oct 2006 23:28:47 +0100 From: Romain Tartiere <romain-tartiere@astase.com> To: freebsd-hackers@freebsd.org Subject: [patch] rm can have undesired side-effects Message-ID: <20061029222847.GA68272@marvin.astase.com>
next in thread | raw e-mail | index | archive | help
--SkvwRMAIpAhPCcCJ Content-Type: multipart/mixed; boundary="9jxsPFA5p3P2qPhR" Content-Disposition: inline --9jxsPFA5p3P2qPhR Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Hello The rm utility provides a "-P" option for overwriting files before removing them. I was wondering about the behaviour of it on regular files with more than one hard link. I just wrote a few lines in a file, created an hard link to it and "rm -P" the first one. The content of the second one was just lost too. I wonder if this is a desired feature, in accordance to some standard, or just something so improbable that nobody got in trouble with it (yet) ? I guess that in some circumstances this may be an issue. As an example, for associating UIDs with user names in an anonymous FTP server, you may have to provide a copy of the /etc/passwd file... or maybe you will just think about creating a hard link to it. I guess that it can be fixed (in case it is not desired) by: - Ignoring the -P option when the link count is greater then one, or - Asking the user whether he is ready to lose data, assuming "no" if the -f option is set, or - Asking the user whether he is ready to lose data, assuming "yes" if the -f option is set. I have attached a patch that implements the first behaviour. I think here is the best place to speak about this, maybe before thinking about filling-in a problem-report? Regards, Romain --=20 Romain Tartiere <romain-tartiere@astase.com> http://romain.astase.com/ pgp: 8DAB A124 0DA4 7024 F82A E748 D8E9 A33F FF56 FF43 (ID: 0xFF56FF43) (plain text =3Dnon-HTML=3D PGP/GPG encrypted/signed e-mail much appreciated) --9jxsPFA5p3P2qPhR Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename="rm.patch" diff -ru /usr/src/bin/rm/rm.1 rm/rm.1 --- /usr/src/bin/rm/rm.1 Fri Mar 31 01:58:14 2006 +++ rm/rm.1 Sun Oct 29 22:44:17 2006 @@ -92,6 +92,8 @@ .Nm to generate an error message and exit. The file will not be removed or overwritten. +This option is silently ignored if the file link count is greater than +one and overwriting it would cause data loss. .It Fl R Attempt to remove the file hierarchy rooted in each file argument. The diff -ru /usr/src/bin/rm/rm.c rm/rm.c --- /usr/src/bin/rm/rm.c Tue May 16 18:14:51 2006 +++ rm/rm.c Sun Oct 15 22:55:05 2006 @@ -289,7 +289,7 @@ continue; /* FALLTHROUGH */ default: - if (Pflag) + if (Pflag && (1 == p->fts_statp->st_nlink)) if (!rm_overwrite(p->fts_accpath, NULL)) continue; rval = unlink(p->fts_accpath); @@ -357,7 +357,7 @@ else if (S_ISDIR(sb.st_mode)) rval = rmdir(f); else { - if (Pflag) + if (Pflag && (1 == sb.st_nlink)) if (!rm_overwrite(f, &sb)) continue; rval = unlink(f); --9jxsPFA5p3P2qPhR-- --SkvwRMAIpAhPCcCJ Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.5 (FreeBSD) iD8DBQFFRSsf2OmjP/9W/0MRAql8AJ9oIM4AIkRcGUFBYaj5C78DlHcwvQCdEWVV HpmrfzFPLYIPac6sV8VzgCw= =IuNE -----END PGP SIGNATURE----- --SkvwRMAIpAhPCcCJ--
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?20061029222847.GA68272>