when UNIX-LISTEN was applied to an existing file it failed as expected but removed the file

CHANGES

@@ -30,6 +30,10 @@ corrections:
 	endian systems due to wrong byte order (thanks to Peter M. Galbavy for
 	bug report and patch)
 
+	when UNIX-LISTEN was applied to an existing file it failed as expected
+	but removed the file. Thanks to Bjoern Bosselmann for reporting this
+	problem
+
 	fixed a bug where socat might crash when connecting to a unix domain
 	socket using address GOPEN. Thanks to Martin Forssen for bug report and
 	patch.

test.sh

@@ -10755,6 +10755,37 @@ esac
 N=$((N+1))
 
 
+# test if socat keeps an existing file where it wanted to create a UNIX socket
+NAME=UNIXLISTEN_KEEPFILE
+case "$TESTS" in
+*%functions%*|*%bugs%*|*%unix%*|*%socket%*|*%$NAME%*)
+TEST="$NAME: socat keeps an existing file where it wanted to create a UNIX socket"
+# we create a file and start socat with UNIX-LISTEN on this file. expected
+# behaviour: socat exits immediately with error, but keeps the file
+# up to 1.7.1.3, it removed the file
+if ! eval $NUMCOND; then :; else
+tf="$td/test$N.file"
+te="$td/test$N.stderr"
+CMD0="$SOCAT $opts -u UNIX-LISTEN:$tf /dev/null"
+printf "test $F_n $TEST... " $N
+rm -f "$tf"; touch "$tf"
+$CMD0 >/dev/null 2>"${te}0"
+rc0=$?
+if [ $rc0 -ne 0 -a -f "$tf" ]; then
+    $PRINTF "$OK\n"
+    numOK=$((numOK+1))
+else
+    $PRINTF "$FAILED\n"
+    echo "$CMD0"
+    cat "${te}0"
+    numFAIL=$((numFAIL+1))
+fi
+fi # NUMCOND
+ ;;
+esac
+N=$((N+1))
+
+
 # socat up to 1.7.2.0 and  2.0.0-b4 had a bug in xioscan_readline() that could
 # be exploited 
 # to overflow a heap based buffer (socat security advisory 3)

xio-listen.c

@@ -308,12 +308,6 @@ int _xioopen_listen(struct single *xfd, int xioflags, struct sockaddr *us, sockl
 	    level = E_ERROR;
 #endif /* WITH_RETRY */
 
-#if WITH_UNIX
-	    /* with UNIX sockets: only listening parent is allowed to remove
-	       the socket file */
-	    xfd->opt_unlink_close = false;
-#endif /* WITH_UNIX */
-
 	    break;
 	 }
 

xio-unix.c

@@ -1,5 +1,5 @@
 /* source: xio-unix.c */
-/* Copyright Gerhard Rieger 2001-2009 */
+/* Copyright Gerhard Rieger 2001-2012 */
 /* Published under the GNU General Public License V.2, see file COPYING */
 
 /* this file contains the source for opening addresses of UNIX socket type */
@@ -142,6 +142,7 @@ static int xioopen_unix_listen(int argc, const char *argv[], struct opt *opts, i
    socklen_t uslen;
    bool tight = true;
    struct opt *opts0 = NULL;
+   pid_t pid = Getpid();
    bool opt_unlink_early = false;
    bool opt_unlink_close = true;
    int result;
@@ -161,12 +162,6 @@ static int xioopen_unix_listen(int argc, const char *argv[], struct opt *opts, i
       /* only for non abstract because abstract do not work in file system */
       retropt_bool(opts, OPT_UNLINK_EARLY, &opt_unlink_early);
       retropt_bool(opts, OPT_UNLINK_CLOSE, &opt_unlink_close);
-      if (opt_unlink_close) {
-	 if ((xfd->unlink_close = strdup(name)) == NULL) {
-	    Error1("strdup(\"%s\"): out of memory", name);
-	 }
-	 xfd->opt_unlink_close = true;
-      }
    }
 
    if (applyopts_single(xfd, opts, PH_INIT) < 0) return STAT_NORETRY;
@@ -197,6 +192,19 @@ static int xioopen_unix_listen(int argc, const char *argv[], struct opt *opts, i
 		       opts, opts0, pf, socktype, protocol))
        != 0)
       return result;
+
+   /* we set this option as late as now because we should not remove an
+      existing entry when bind() failed */
+   if (!(ABSTRACT && abstract)) {
+      if (opt_unlink_close) {
+	 if (pid == Getpid()) {
+	    if ((xfd->unlink_close = strdup(name)) == NULL) {
+	       Error1("strdup(\"%s\"): out of memory", name);
+	    }
+	    xfd->opt_unlink_close = true;
+	 }
+      }
+   }
    return 0;
 }
 #endif /* WITH_LISTEN */