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Path: utzoo!watmath!clyde!caip!rutgers!princeton!allegra!ulysses!bellcore!whuxcc!lcuxlm!akgua!emory!arnold
From: arnold@emory.UUCP (Arnold D. Robbins {EUCC})
Newsgroups: net.bugs.4bsd
Subject: 4.3 rcp can clobber a source file; does not understand host.user:file
Message-ID: <1721@emory.UUCP>
Date: Fri, 17-Oct-86 11:56:59 EDT
Article-I.D.: emory.1721
Posted: Fri Oct 17 11:56:59 1986
Date-Received: Wed, 22-Oct-86 05:49:21 EDT
Organization: Math & Computer Science, Emory University, Atlanta
Lines: 349
Keywords: remote copy, bugs, file clobbering

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;
  }