Silence spurious clang warnings

Silence clang warnings under --enable-expensive-hardening, including:
  + implicit truncation of 64 bit values to 32 bit;
  + const char assignment to self;
  + tautological compare; and
  + additional parentheses around equality tests. (gcc uses these to
    silence assignment, so clang warns when they're present in an
    equality test. But we need to use extra parentheses in macros to
    isolate them from other code).

changes/spurious-clang-warnings

@@ -0,0 +1,10 @@
+  o Minor bugfixes:
+    - Silence clang warnings under --enable-expensive-hardening, including:
+        + implicit truncation of 64 bit values to 32 bit;
+        + const char assignment to self;
+        + tautological compare; and
+        + additional parentheses around equality tests. (gcc uses these to
+          silence assignment, so clang warns when they're present in an
+          equality test. But we need to use extra parentheses in macros to
+          isolate them from other code).
+      Fixes bug 13577.

src/common/compat.c

@@ -138,9 +138,10 @@ int
 tor_open_cloexec(const char *path, int flags, unsigned mode)
 {
   int fd;
+  const char *p = path;
 #ifdef O_CLOEXEC
-  path = sandbox_intern_string(path);
-  fd = open(path, flags|O_CLOEXEC, mode);
+  p = sandbox_intern_string(path);
+  fd = open(p, flags|O_CLOEXEC, mode);
   if (fd >= 0)
     return fd;
   /* If we got an error, see if it is EINVAL. EINVAL might indicate that,
@@ -150,8 +151,8 @@ tor_open_cloexec(const char *path, int flags, unsigned mode)
     return -1;
 #endif
 
-  log_debug(LD_FS, "Opening %s with flags %x", path, flags);
-  fd = open(path, flags, mode);
+  log_debug(LD_FS, "Opening %s with flags %x", p, flags);
+  fd = open(p, flags, mode);
 #ifdef FD_CLOEXEC
   if (fd >= 0) {
     if (fcntl(fd, F_SETFD, FD_CLOEXEC) == -1) {

src/common/compat.h

@@ -562,17 +562,18 @@ const char *tor_socket_strerror(int e);
 #else
 #define SOCK_ERRNO(e) e
 #if EAGAIN == EWOULDBLOCK
-#define ERRNO_IS_EAGAIN(e)           ((e) == EAGAIN)
+/* || 0 is for -Wparentheses-equality (-Wall?) appeasement under clang */
+#define ERRNO_IS_EAGAIN(e)           ((e) == EAGAIN || 0)
 #else
 #define ERRNO_IS_EAGAIN(e)           ((e) == EAGAIN || (e) == EWOULDBLOCK)
 #endif
-#define ERRNO_IS_EINPROGRESS(e)      ((e) == EINPROGRESS)
-#define ERRNO_IS_CONN_EINPROGRESS(e) ((e) == EINPROGRESS)
+#define ERRNO_IS_EINPROGRESS(e)      ((e) == EINPROGRESS || 0)
+#define ERRNO_IS_CONN_EINPROGRESS(e) ((e) == EINPROGRESS || 0)
 #define ERRNO_IS_ACCEPT_EAGAIN(e) \
   (ERRNO_IS_EAGAIN(e) || (e) == ECONNABORTED)
 #define ERRNO_IS_ACCEPT_RESOURCE_LIMIT(e) \
   ((e) == EMFILE || (e) == ENFILE || (e) == ENOBUFS || (e) == ENOMEM)
-#define ERRNO_IS_EADDRINUSE(e)       ((e) == EADDRINUSE)
+#define ERRNO_IS_EADDRINUSE(e)       (((e) == EADDRINUSE) || 0)
 #define tor_socket_errno(sock)       (errno)
 #define tor_socket_strerror(e)       strerror(e)
 #endif

src/common/crypto_pwbox.c

@@ -62,7 +62,7 @@ crypto_pwbox(uint8_t **out, size_t *outlen_out,
   pwbox_encoded_setlen_data(enc, encrypted_len);
   encrypted_portion = pwbox_encoded_getarray_data(enc);
 
-  set_uint32(encrypted_portion, htonl(input_len));
+  set_uint32(encrypted_portion, htonl((uint32_t)input_len));
   memcpy(encrypted_portion+4, input, input_len);
 
   /* Now that all the data is in position, derive some keys, encrypt, and

src/ext/ht.h

@@ -38,8 +38,9 @@
   }
 #endif
 
+/* || 0 is for -Wparentheses-equality (-Wall?) appeasement under clang */
 #define HT_EMPTY(head)                          \
-  ((head)->hth_n_entries == 0)
+  (((head)->hth_n_entries == 0) || 0)
 
 /* How many elements in 'head'? */
 #define HT_SIZE(head)                           \

src/ext/tor_queue.h

@@ -109,7 +109,8 @@ struct {								\
  */
 #define	TOR_SLIST_FIRST(head)	((head)->slh_first)
 #define	TOR_SLIST_END(head)		NULL
-#define	TOR_SLIST_EMPTY(head)	(SLIST_FIRST(head) == TOR_SLIST_END(head))
+/* || 0 is for -Wparentheses-equality (-Wall?) appeasement under clang */
+#define	TOR_SLIST_EMPTY(head)	((SLIST_FIRST(head) == TOR_SLIST_END(head)) || 0)
 #define	TOR_SLIST_NEXT(elm, field)	((elm)->field.sle_next)
 
 #define	TOR_SLIST_FOREACH(var, head, field)					\
@@ -181,9 +182,11 @@ struct {								\
 /*
  * List access methods
  */
-#define	TOR_LIST_FIRST(head)		((head)->lh_first)
-#define	TOR_LIST_END(head)			NULL
-#define	TOR_LIST_EMPTY(head)		(TOR_LIST_FIRST(head) == TOR_LIST_END(head))
+#define	TOR_LIST_FIRST(head)    ((head)->lh_first)
+#define	TOR_LIST_END(head)		  NULL
+/* || 0 is for -Wparentheses-equality (-Wall?) appeasement under clang */
+#define	TOR_LIST_EMPTY(head)	  \
+          ((TOR_LIST_FIRST(head) == TOR_LIST_END(head)) || 0)
 #define	TOR_LIST_NEXT(elm, field)		((elm)->field.le_next)
 
 #define TOR_LIST_FOREACH(var, head, field)					\
@@ -265,8 +268,10 @@ struct {								\
  * Simple queue access methods.
  */
 #define	TOR_SIMPLEQ_FIRST(head)	    ((head)->sqh_first)
-#define	TOR_SIMPLEQ_END(head)	    NULL
-#define	TOR_SIMPLEQ_EMPTY(head)	    (TOR_SIMPLEQ_FIRST(head) == TOR_SIMPLEQ_END(head))
+#define	TOR_SIMPLEQ_END(head)	      NULL
+/* || 0 is for -Wparentheses-equality (-Wall?) appeasement under clang */
+#define	TOR_SIMPLEQ_EMPTY(head)	    \
+          ((TOR_SIMPLEQ_FIRST(head) == TOR_SIMPLEQ_END(head)) || 0)
 #define	TOR_SIMPLEQ_NEXT(elm, field)    ((elm)->field.sqe_next)
 
 #define TOR_SIMPLEQ_FOREACH(var, head, field)				\
@@ -345,8 +350,9 @@ struct {								\
 /* XXX */
 #define TOR_TAILQ_PREV(elm, headname, field)				\
 	(*(((struct headname *)((elm)->field.tqe_prev))->tqh_last))
+/* || 0 is for -Wparentheses-equality (-Wall?) appeasement under clang */
 #define	TOR_TAILQ_EMPTY(head)						\
-	(TOR_TAILQ_FIRST(head) == TOR_TAILQ_END(head))
+	((TOR_TAILQ_FIRST(head) == TOR_TAILQ_END(head)) || 0)
 
 #define TOR_TAILQ_FOREACH(var, head, field)					\
 	for((var) = TOR_TAILQ_FIRST(head);					\
@@ -462,8 +468,9 @@ struct {								\
 #define	TOR_CIRCLEQ_END(head)		((void *)(head))
 #define	TOR_CIRCLEQ_NEXT(elm, field)	((elm)->field.cqe_next)
 #define	TOR_CIRCLEQ_PREV(elm, field)	((elm)->field.cqe_prev)
+/* || 0 is for -Wparentheses-equality (-Wall?) appeasement under clang */
 #define	TOR_CIRCLEQ_EMPTY(head)						\
-	(TOR_CIRCLEQ_FIRST(head) == TOR_CIRCLEQ_END(head))
+	((TOR_CIRCLEQ_FIRST(head) == TOR_CIRCLEQ_END(head)) || 0)
 
 #define TOR_CIRCLEQ_FOREACH(var, head, field)				\
 	for((var) = TOR_CIRCLEQ_FIRST(head);				\

src/or/channeltls.c

@@ -847,8 +847,8 @@ channel_tls_handle_state_change_on_orconn(channel_tls_t *chan,
   tor_assert(conn);
   tor_assert(conn->chan == chan);
   tor_assert(chan->conn == conn);
-  /* -Werror appeasement */
-  tor_assert(old_state == old_state);
+  /* Shut the compiler up without triggering -Wtautological-compare */
+  (void)old_state;
 
   base_chan = TLS_CHAN_TO_BASE(chan);
 

src/or/circuitmux_ewma.c

@@ -273,8 +273,8 @@ ewma_alloc_circ_data(circuitmux_t *cmux,
   tor_assert(circ);
   tor_assert(direction == CELL_DIRECTION_OUT ||
              direction == CELL_DIRECTION_IN);
-  /* Shut the compiler up */
-  tor_assert(cell_count == cell_count);
+  /* Shut the compiler up without triggering -Wtautological-compare */
+  (void)cell_count;
 
   cdata = tor_malloc_zero(sizeof(*cdata));
   cdata->base_.magic = EWMA_POL_CIRC_DATA_MAGIC;

src/or/connection.h

@@ -189,7 +189,8 @@ dir_connection_t *connection_dir_get_by_purpose_and_resource(
 
 int any_other_active_or_conns(const or_connection_t *this_conn);
 
-#define connection_speaks_cells(conn) ((conn)->type == CONN_TYPE_OR)
+/* || 0 is for -Wparentheses-equality (-Wall?) appeasement under clang */
+#define connection_speaks_cells(conn) (((conn)->type == CONN_TYPE_OR) || 0)
 int connection_is_listener(connection_t *conn);
 int connection_state_is_open(connection_t *conn);
 int connection_state_is_connecting(connection_t *conn);

src/or/or.h

@@ -241,7 +241,7 @@ typedef enum {
 #define PROXY_CONNECT 1
 #define PROXY_SOCKS4 2
 #define PROXY_SOCKS5 3
-/* !!!! If there is ever a PROXY_* type over 2, we must grow the proxy_type
+/* !!!! If there is ever a PROXY_* type over 3, we must grow the proxy_type
  * field in or_connection_t */
 
 /* Pluggable transport proxy type. Don't use this in or_connection_t,
@@ -4317,7 +4317,8 @@ static INLINE void or_state_mark_dirty(or_state_t *state, time_t when)
 /** Please turn this IP address into an FQDN, privately. */
 #define SOCKS_COMMAND_RESOLVE_PTR   0xF1
 
-#define SOCKS_COMMAND_IS_CONNECT(c) ((c)==SOCKS_COMMAND_CONNECT)
+/* || 0 is for -Wparentheses-equality (-Wall?) appeasement under clang */
+#define SOCKS_COMMAND_IS_CONNECT(c) (((c)==SOCKS_COMMAND_CONNECT) || 0)
 #define SOCKS_COMMAND_IS_RESOLVE(c) ((c)==SOCKS_COMMAND_RESOLVE || \
                                      (c)==SOCKS_COMMAND_RESOLVE_PTR)