* ext/socket/raddrinfo.c (rsock_unixpath_len, init_unix_addrinfo),

  ext/socket/unixsocket.c (unixsock_connect_internal,
  rsock_init_unixsock): calculate the correct address length of
  an abstract socket.  Without this fix, sizeof(struct sockaddr_un)
  is specified as the length of an abstract socket for bind(2) or
  connect(2), so the address of the socket is filled with extra NUL
  characters.  See unix(7) for details.

* ext/socket/lib/socket.rb (unix_server_socket): don't access the
  file system if the platform is Linux and path starts with NUL,
  which means that the socket is an abstract socket.

* test/socket/test_unix.rb: related test.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@38939 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

4 files changed, 46 insertions, 10 deletions

diff --git a/ext/socket/lib/socket.rb b/ext/socket/lib/socket.rb
index 10ab13b953..981b937329 100644
--- a/ext/socket/lib/socket.rb
+++ b/ext/socket/lib/socket.rb
@@ -791,12 +791,14 @@ class Socket < BasicSocket
   #   }
   #
   def self.unix_server_socket(path)
-    begin
-      st = File.lstat(path)
-    rescue Errno::ENOENT
-    end
-    if st && st.socket? && st.owned?
-      File.unlink path
+    if !unix_socket_abstract_name?(path)
+      begin
+        st = File.lstat(path)
+      rescue Errno::ENOENT
+      end
+      if st && st.socket? && st.owned?
+        File.unlink path
+      end
     end
     s = Addrinfo.unix(path).listen
     if block_given?
@@ -804,13 +806,23 @@ class Socket < BasicSocket
         yield s
       ensure
         s.close if !s.closed?
-        File.unlink path
+        if !unix_socket_abstract_name?(path)
+          File.unlink path
+        end
       end
     else
       s
     end
   end
 
+  class << self
+    private
+
+    def unix_socket_abstract_name?(path)
+      /linux/ =~ RUBY_PLATFORM && /\A\0/ =~ path
+    end
+  end
+
   # creates a UNIX socket server on _path_.
   # It calls the block for each socket accepted.
   #
diff --git a/ext/socket/raddrinfo.c b/ext/socket/raddrinfo.c
index 6a5129efa8..fdc3d4e61c 100644
--- a/ext/socket/raddrinfo.c
+++ b/ext/socket/raddrinfo.c
@@ -441,6 +441,23 @@ rsock_unixaddr(struct sockaddr_un *sockaddr, socklen_t len)
     return rb_assoc_new(rb_str_new2("AF_UNIX"),
                         rsock_unixpath_str(sockaddr, len));
 }
+
+socklen_t
+rsock_unixpath_len(VALUE path)
+{
+#ifdef __linux__
+    if (RSTRING_PTR(path)[0] == '\0') {
+	/* abstract namespace; see unix(7) for details. */
+	return (socklen_t) offsetof(struct sockaddr_un, sun_path) +
+	    RSTRING_LEN(path);
+    }
+    else {
+#endif
+	return (socklen_t) sizeof(struct sockaddr_un);
+#ifdef __linux__
+    }
+#endif
+}
 #endif
 
 struct hostent_arg {
@@ -769,6 +786,7 @@ static void
 init_unix_addrinfo(rb_addrinfo_t *rai, VALUE path, int socktype)
 {
     struct sockaddr_un un;
+    socklen_t len;
 
     StringValue(path);
 
@@ -782,7 +800,8 @@ init_unix_addrinfo(rb_addrinfo_t *rai, VALUE path, int socktype)
     un.sun_family = AF_UNIX;
     memcpy((void*)&un.sun_path, RSTRING_PTR(path), RSTRING_LEN(path));
 
-    init_addrinfo(rai, (struct sockaddr *)&un, (socklen_t)sizeof(un),
+    len = rsock_unixpath_len(path);
+    init_addrinfo(rai, (struct sockaddr *)&un, len,
 		  PF_UNIX, socktype, 0, Qnil, Qnil);
 }
 #endif
diff --git a/ext/socket/rubysocket.h b/ext/socket/rubysocket.h
index 33cb51a5c9..c27b164188 100644
--- a/ext/socket/rubysocket.h
+++ b/ext/socket/rubysocket.h
@@ -240,6 +240,7 @@ int rsock_revlookup_flag(VALUE revlookup, int *norevlookup);
 #ifdef HAVE_SYS_UN_H
 VALUE rsock_unixpath_str(struct sockaddr_un *sockaddr, socklen_t len);
 VALUE rsock_unixaddr(struct sockaddr_un *sockaddr, socklen_t len);
+socklen_t rsock_unixpath_len(VALUE path);
 #endif
 
 int rsock_socket(int domain, int type, int proto);
diff --git a/ext/socket/unixsocket.c b/ext/socket/unixsocket.c
index c8557cb4c9..e7693356b5 100644
--- a/ext/socket/unixsocket.c
+++ b/ext/socket/unixsocket.c
@@ -13,6 +13,7 @@
 #ifdef HAVE_SYS_UN_H
 struct unixsock_arg {
     struct sockaddr_un *sockaddr;
+    socklen_t sockaddrlen;
     int fd;
 };
 
@@ -21,13 +22,14 @@ unixsock_connect_internal(VALUE a)
 {
     struct unixsock_arg *arg = (struct unixsock_arg *)a;
     return (VALUE)rsock_connect(arg->fd, (struct sockaddr*)arg->sockaddr,
-			        (socklen_t)sizeof(*arg->sockaddr), 0);
+			        arg->sockaddrlen, 0);
 }
 
 VALUE
 rsock_init_unixsock(VALUE sock, VALUE path, int server)
 {
     struct sockaddr_un sockaddr;
+    socklen_t sockaddrlen;
     int fd, status;
     rb_io_t *fptr;
 
@@ -44,14 +46,16 @@ rsock_init_unixsock(VALUE sock, VALUE path, int server)
             RSTRING_LEN(path), (int)sizeof(sockaddr.sun_path));
     }
     memcpy(sockaddr.sun_path, RSTRING_PTR(path), RSTRING_LEN(path));
+    sockaddrlen = rsock_unixpath_len(path);
 
     if (server) {
-        status = bind(fd, (struct sockaddr*)&sockaddr, (socklen_t)sizeof(sockaddr));
+        status = bind(fd, (struct sockaddr*)&sockaddr, sockaddrlen);
     }
     else {
 	int prot;
 	struct unixsock_arg arg;
 	arg.sockaddr = &sockaddr;
+	arg.sockaddrlen = sockaddrlen;
 	arg.fd = fd;
         status = (int)rb_protect(unixsock_connect_internal, (VALUE)&arg, &prot);
 	if (prot) {