arnold@emory.UUCP (Arnold D. Robbins {EUCC}) (10/17/86)
Subject: rcp can clobber a file; does not understand host.user:file notation
Index: /usr/src/bin/rcp.c 4.3BSD
Description:
There are two problems with rcp. First, the man page says that rcp
understands the 4.2 "host.user:file" notation, for compatibility.
In fact, it does not; it only knows about "user@host:file".
Secondly, rcp can clobber a file by attempting to copy it onto
itself, when a "remote" file is actually a local file. See the
example below. (Admittedly, this is a hole more than a "bug", but
it can be a problem in many environments, particularly where there
are shorthand names. E.g., we have two machines, "emoryu1" and
"emoryu2", with nicknames of "u1" and "u2". I clobbered files a
number of times until I learned to be more careful.)
Repeat-By:
Script started on Fri Oct 17 11:40:47 1986
emory> echo this is a file > foo
emory> rcp foo emoryu1.osadr:
emoryu1.osadr: unknown host
emory> rcp foo emory:
rcp: foo: file changed size
emory> cat foo
emory> lf -l foo
-rw-r--r-- 1 arnold eucc 15 Oct 17 11:41 foo
emory> od -c foo
0000000 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0
0000017
emory>
script done on Fri Oct 17 11:42:14 1986
Fix:
Apply the following patch:
*** rcp.c Sun Feb 9 22:36:06 1986
--- /usr4/arnold/rcp.c Fri Oct 17 10:16:28 1986
***************
*** 44,49 ****
--- 44,50 ----
struct passwd *getpwuid();
int userid;
int port;
+ struct hostent me;
struct buffer {
int cnt;
***************
*** 64,70 ****
--- 65,74 ----
int i;
char buf[BUFSIZ], cmd[16];
struct servent *sp;
+ int dot = 0; /* use old style host.user:file */
+ int junk;
+ setmyhost ();
sp = getservbyname("shell", "tcp");
if (sp == NULL) {
fprintf(stderr, "rcp: shell/tcp: unknown service\n");
***************
*** 125,142 ****
*targ++ = 0;
if (*targ == 0)
targ = ".";
! thost = index(argv[argc - 1], '@');
! if (thost) {
! *thost++ = 0;
! tuser = argv[argc - 1];
! if (*tuser == '\0')
! tuser = NULL;
! else if (!okname(tuser))
! exit(1);
! } else {
! thost = argv[argc - 1];
! tuser = NULL;
! }
for (i = 0; i < argc - 1; i++) {
src = colon(argv[i]);
if (src) { /* remote to remote */
--- 129,135 ----
*targ++ = 0;
if (*targ == 0)
targ = ".";
! sethostuser (argv[argc - 1], & thost, & tuser, NULL, & dot);
for (i = 0; i < argc - 1; i++) {
src = colon(argv[i]);
if (src) { /* remote to remote */
***************
*** 143,167 ****
*src++ = 0;
if (*src == 0)
src = ".";
! host = index(argv[i], '@');
! if (host) {
! *host++ = 0;
! suser = argv[i];
! if (*suser == '\0')
! suser = pwd->pw_name;
! else if (!okname(suser))
! continue;
(void) sprintf(buf, "rsh %s -l %s -n %s %s '%s%s%s:%s'",
host, suser, cmd, src, tuser,
tuser ? "@" : "",
thost, targ);
! } else
! (void) sprintf(buf, "rsh %s -n %s %s '%s%s%s:%s'",
! argv[i], cmd, src, tuser,
! tuser ? "@" : "",
! thost, targ);
(void) susystem(buf);
} else { /* local to remote */
if (rem == -1) {
(void) sprintf(buf, "%s -t %s",
cmd, targ);
--- 136,168 ----
*src++ = 0;
if (*src == 0)
src = ".";
! sethostuser (argv[i], & host,
! & suser, pwd->pw_name, & junk);
! if (suser && !okname(suser))
! continue;
! /*
! * this always passes the user name,
! * but big deal.
! */
! if (dot) /* set only for dest */
(void) sprintf(buf, "rsh %s -l %s -n %s %s '%s%s%s:%s'",
+ host, suser, cmd, src,
+ thost,
+ tuser ? "." : "",
+ tuser,
+ targ);
+ else
+ (void) sprintf(buf, "rsh %s -l %s -n %s %s '%s%s%s:%s'",
host, suser, cmd, src, tuser,
tuser ? "@" : "",
thost, targ);
! if (sourceistarget (host, src, thost, targ))
! continue;
(void) susystem(buf);
} else { /* local to remote */
+ if (sourceistarget (me.h_name, argv[i],
+ thost, targ))
+ continue;
if (rem == -1) {
(void) sprintf(buf, "%s -t %s",
cmd, targ);
***************
*** 184,189 ****
--- 185,194 ----
for (i = 0; i < argc - 1; i++) {
src = colon(argv[i]);
if (src == 0) { /* local to local */
+ /*
+ * cp will make sure not to copy
+ * a file onto itself.
+ */
(void) sprintf(buf, "/bin/cp%s%s %s %s",
iamrecursive ? " -r" : "",
pflag ? " -p" : "",
***************
*** 193,211 ****
*src++ = 0;
if (*src == 0)
src = ".";
! host = index(argv[i], '@');
! if (host) {
! *host++ = 0;
! suser = argv[i];
! if (*suser == '\0')
! suser = pwd->pw_name;
! else if (!okname(suser))
! continue;
! } else {
! host = argv[i];
! suser = pwd->pw_name;
! }
(void) sprintf(buf, "%s -f %s", cmd, src);
rem = rcmd(&host, port, pwd->pw_name, suser,
buf, 0);
if (rem < 0)
--- 198,211 ----
*src++ = 0;
if (*src == 0)
src = ".";
! sethostuser (argv[i], & host, & suser,
! pwd->pw_name, & junk);
! if (suser && !okname(suser))
! continue;
(void) sprintf(buf, "%s -f %s", cmd, src);
+ if (sourceistarget (host, src, me.h_name,
+ argv[argc-1]))
+ continue;
rem = rcmd(&host, port, pwd->pw_name, suser,
buf, 0);
if (rem < 0)
***************
*** 704,707 ****
--- 704,852 ----
(void) write(rem, buf, strlen(buf));
if (iamremote == 0)
(void) write(2, buf+1, strlen(buf+1));
+ }
+
+ /*
+ * sethostuser
+ *
+ * info is string containing "host", "host.user", or "user@host",
+ * set host to host part, user to user part, or to defuser if no
+ * user is available. Set dot if name was old style dotted name.
+ */
+
+ sethostuser (info, host, user, defuser, dot)
+ register char *info, **host, **user, *defuser;
+ int *dot;
+ {
+ register char *cp = info;
+
+ while (*cp && *cp != '@' && *cp != '.')
+ cp++;
+
+ if (! *cp)
+ {
+ *host = info;
+ *user = defuser;
+ }
+ else if (*cp == '@')
+ {
+ *cp++ = '\0';
+ *host = cp;
+ *user = info;
+ }
+ else /* *cp == '.' */
+ {
+ *cp++ = '\0';
+ *user = cp;
+ *host = info;
+ *dot = 1;
+ }
+ return 0;
+ }
+
+ setmyhost ()
+ {
+ struct hostent *h;
+ char buf[BUFSIZ];
+
+ if (gethostname (buf, sizeof buf) < 0)
+ {
+ error ("rcp: gethostname: %s\n", sys_errlist[errno]);
+ exit (1);
+ }
+
+ sethostent (0);
+ if ((h = gethostbyname (buf)) == NULL)
+ {
+ error ("rcp: gethostbyname (\"%s\") failed.\n", buf);
+ endhostent ();
+ exit (1);
+ }
+
+ me = *h;
+ endhostent ();
+ }
+
+ /*
+ * sourceistarget
+ *
+ * attempt to prevent rcp from copying a file onto itself by seeing
+ * if both hosts are really the current host, and if so, if the files
+ * are identical.
+ */
+
+ sourceistarget (shost, sfile, dhost, dfile)
+ char *shost, *sfile, *dhost, *dfile;
+ {
+ static char localhost[] = "localhost";
+ struct stat sbuf1, sbuf2;
+ int i;
+ char buf[BUFSIZ], *cp, *rindex ();
+
+ if (strcmp (shost, me.h_name) == 0 || strcmp (shost, localhost) == 0)
+ goto out1;
+ else
+ for (i = 0; me.h_aliases[i]; i++)
+ if (strcmp (shost, me.h_aliases[i]) == 0)
+ goto out1;
+ return 0;
+
+ out1:
+ /* source host is local, check destination host */
+ if (strcmp (dhost, me.h_name) == 0 || strcmp (dhost, localhost) == 0)
+ goto out2;
+ else
+ for (i = 0; me.h_aliases[i]; i++)
+ if (strcmp (dhost, me.h_aliases[i]) == 0)
+ goto out2;
+ return 0;
+
+ out2:
+ /*
+ * At this point, the two hosts are the same, and
+ * they are actually the local host.
+ * See if the files are the same.
+ *
+ * This gets complicated because the destination could
+ * be a directory, so if it is, get file name part of the
+ * source, tack it onto the directory, and check that.
+ *
+ * If the stat call fails on the source file, play it safe
+ * and return 1, forcing the code which checks the status to skip
+ * copying this particular file. If it fails on the destination
+ * file, it does not exist yet, so the source and target are
+ * not the same file.
+ */
+
+ if (stat (sfile, & sbuf1) < 0)
+ {
+ error ("rcp: %s: %s\n", sfile, sys_errlist[errno]);
+ return 1;
+ }
+
+ if (stat (dfile, & sbuf2) < 0) /* destination does not exist */
+ return 0;
+ else if ((sbuf2.st_mode & S_IFMT) == S_IFDIR &&
+ (sbuf1.st_mode & S_IFMT) != S_IFDIR) /* file to directory */
+ {
+ cp = rindex (sfile, '/');
+ if (cp)
+ cp++;
+ else
+ cp = sfile;
+ sprintf (buf, "%s/%s", dfile, cp);
+ if (stat (buf, & sbuf2) < 0) /* target does not exist */
+ return 0;
+ else
+ dfile = buf; /* for error message, below */
+ }
+
+ if (sbuf1.st_dev == sbuf2.st_dev && sbuf1.st_ino == sbuf2.st_ino)
+ {
+ error ("rcp: %s:%s is the same file as %s:%s.\n",
+ shost, sfile, dhost, dfile);
+ return 1;
+ }
+ else
+ return 0;
}ron@brl-sem.ARPA (Ron Natalie <ron>) (10/23/86)
In article <1721@emory.UUCP>, arnold@emory.UUCP (Arnold D. Robbins {EUCC}) writes: > Subject: rcp can clobber a file; does not understand host.user:file notation > Index: /usr/src/bin/rcp.c 4.3BSD > > Description: > Secondly, rcp can clobber a file by attempting to copy it onto > itself, when a "remote" file is actually a local file. See the > example below. (Admittedly, this is a hole more than a "bug", but > it can be a problem in many environments, particularly where there > are shorthand names. E.g., we have two machines, "emoryu1" and > "emoryu2", with nicknames of "u1" and "u2". I clobbered files a > number of times until I learned to be more careful.) The better solution, is what we did. Rather than trying to assure that we are not doing a copy to the source file, which is very difficult to get right. We just fixed it so doing such a copy is not destructive (albeit not very efficient either). The way to do this is to not do a creat first if there already exists a file there. Then after the copy is done, do a TRUNCATE to make the file the right length. This has the effect of just reading and writing all the blocks in place. I'll send the code diffs in the normal bug format. -Ron
ron@brl-sem.ARPA (Ron Natalie <ron>) (10/23/86)
Subject: RCP clobbers files. Index: bin/rcp.c 4.3BSD Description: Rcp will silently make a file zero lenght if it is specified as both the source and destination of a copy. It is difficult to predict when this will happen as there is no sure way to verify that two CPU's are in fact using the same filesystem. In addiiton, when rcp is called with one argument it just silently exit without saying anything. Repeat-By: 1. create a file with non-zero lenght called foo on machine host issue command on host: rcp host:foo foo the file will now be zero length. 2. type "rcp foo" Fix: Make rcp non-destructive in it's copies. Rather than doing an initial creat, just open the file. Then copy all the blocks. When the files are the same, each block will be read and written back into the same place it was read. Then do an ftruncate to fix up the file length. Add usage message when too few arguments. *** 118,123 **** --- 114,125 ---- } } rem = -1; + + if(argc <= 1){ + fprintf(stderr,"Usage: rcp [-p] f1 f2; or: rcp [-rp] f1...fn d2\n"); + exit(1); + } + if (argc > 2) targetshouldbedirectory = 1; (void) sprintf(cmd, "rcp%s%s%s", *************** *** 605,611 **** } continue; } ! if ((of = creat(nambuf, mode)) < 0) { bad: error("rcp: %s: %s\n", nambuf, sys_errlist[errno]); continue; --- 607,613 ---- } continue; } ! if ((of = open(nambuf, O_WRONLY|O_CREAT, mode)) < 0) { bad: error("rcp: %s: %s\n", nambuf, sys_errlist[errno]); continue; *************** *** 649,654 **** --- 651,657 ---- if (count != 0 && wrerr == 0 && write(of, bp->buf, count) != count) wrerr++; + ftruncate(of, size); (void) close(of); (void) response(); if (setimes) {