Add FALLTHROUGH macro to silence -Wimplicit-fallthrough in GCC7

base64.c

@@ -18,6 +18,7 @@
  */
 
 #include "base64.h"
+#include "lang.h"    // for FALLTHROUGH
 #include "str.h"     // for Serval ctype
 #include <stdint.h>  // for uint8_t
 #include <stdio.h>   // for NULL
@@ -74,6 +75,7 @@ static size_t _base64_encodev(const char symbols[], char *dstBase64, const struc
   switch (place) {
     case 1:
       *dst++ = symbols[64];
+      FALLTHROUGH;
     case 2:
       *dst++ = symbols[64];
   }

config.h.in

@@ -156,6 +156,9 @@
 /* Define to 1 if you have the <stdlib.h> header file. */
 #undef HAVE_STDLIB_H
 
+/* Define to 1 if the system has the `fallthrough' statement attribute */
+#undef HAVE_STMT_ATTRIBUTE_FALLTHROUGH
+
 /* Define to 1 if you have the <strings.h> header file. */
 #undef HAVE_STRINGS_H
 

configure.ac

@@ -18,6 +18,7 @@ AX_GCC_FUNC_ATTRIBUTE(unused)
 AX_GCC_FUNC_ATTRIBUTE(used)
 AX_GCC_VAR_ATTRIBUTE(section)
 AX_GCC_VAR_ATTRIBUTE(section_seg)
+AX_GCC_STMT_ATTRIBUTE(fallthrough)
 
 dnl Init pkg-config
 PKG_PROG_PKG_CONFIG()

http_server.c

@@ -20,6 +20,7 @@ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 #include <assert.h>
 #include <inttypes.h>
 #include <time.h>
+#include "lang.h" // for FALLTHROUGH
 #include "serval_types.h"
 #include "http_server.h"
 #include "sighandlers.h"
@@ -1185,7 +1186,7 @@ static int http_request_decode_chunks(struct http_request *r){
 	  return WHY("Unexpected data");
 	return 0;
       }
-      // fall through
+      FALLTHROUGH;
     }
     case CHUNK_SIZE:{
       const char *p;
@@ -1213,7 +1214,7 @@ static int http_request_decode_chunks(struct http_request *r){
 	r->request_content_remaining = 0;
 	IDEBUGF(r->debug, "EOF Chunk");
       }
-      // fall through
+      FALLTHROUGH;
     }
     case CHUNK_DATA:{
 
@@ -1502,7 +1503,7 @@ static int http_request_form_data_start_part(struct http_request *r, int b)
 	      r->part_header.content_length
 	    );
       }
-      // fall through...
+      FALLTHROUGH;
     case HEADER:
       _INVOKE_HANDLER_VOID(handle_mime_part_end);
       break;
@@ -1542,7 +1543,7 @@ static int http_request_parse_body_form_data(struct http_request *r)
       // The logic here allows for a missing initial CRLF before the first boundary line.
       at_start = 1;
       r->form_data_state = PREAMBLE;
-      // fall through
+      FALLTHROUGH;
     case PREAMBLE: {
 	DEBUGF(http_server, "PREAMBLE");
 	char *start = r->parsed;
@@ -2138,6 +2139,7 @@ unsigned http_range_close(struct http_range *dst, const struct http_range *src,
     switch (range->type) {
       case CLOSED:
 	last = range->last < resource_length ? range->last : resource_length - 1;
+	FALLTHROUGH;
       case OPEN:
 	first = range->first < resource_length ? range->first : resource_length;
 	break;

keyring_restful.c

@@ -17,6 +17,7 @@ along with this program; if not, write to the Free Software
 Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 */
 
+#include "lang.h" // for FALLTHROUGH
 #include "serval.h"
 #include "conf.h"
 #include "httpd.h"
@@ -175,6 +176,7 @@ static int restful_keyring_identitylist_json_content_chunk(struct http_request *
       
     case LIST_ROWS:
       strbuf_putc(b, ',');
+      FALLTHROUGH;
     case LIST_FIRST:
       r->u.sidlist.phase = LIST_ROWS;
       const char *did = NULL;

lang.h

@@ -66,4 +66,13 @@ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 #   define UNUSED(x) x
 #endif
 
+// To suppress the "may fall through" warning from -Wimplicit-fallthrough.
+#ifdef HAVE_STMT_ATTRIBUTE_FALLTHROUGH
+#   define __ATTRIBUTE_fallthrough  __fallthrough__
+#   define FALLTHROUGH __attribute__((__fallthrough__))
+#else
+#   define __ATTRIBUTE_fallthrough
+#   define FALLTHROUGH
+#endif
+
 #endif // __SERVAL_DNA__LANG_H

m4/ax_gcc_stmt_attribute.m4

@@ -0,0 +1,69 @@
+# SYNOPSIS
+#
+#   AX_GCC_STMT_ATTRIBUTE(ATTRIBUTE)
+#
+# DESCRIPTION
+#
+#   This macro checks if the compiler supports one of GCC's statement
+#   attributes; many other compilers also provide statement attributes with the
+#   same syntax. Compiler warnings are used to detect supported attributes as
+#   unsupported ones are ignored by default so quieting warnings when using
+#   this macro will yield false positives.
+#
+#   The ATTRIBUTE parameter holds the name of the attribute to be checked.
+#
+#   If ATTRIBUTE is supported define HAVE_STMT_ATTRIBUTE_<ATTRIBUTE>.
+#
+#   The macro caches its result in the ax_cv_have_stmt_attribute_<attribute>
+#   variable.
+#
+#   The macro currently supports the following variable attributes:
+#
+#    fallthrough  (added 11 Sep 2017, Serval Project)
+#
+# LICENSE
+#
+#   Copyright (c) 2017 Flinders University
+#
+#   Copying and distribution of this file, with or without modification, are
+#   permitted in any medium without royalty provided the copyright notice
+#   and this notice are preserved.  This file is offered as-is, without any
+#   warranty.
+
+#serial 3
+
+AC_DEFUN([AX_GCC_STMT_ATTRIBUTE], [
+    AS_VAR_PUSHDEF([ac_var], [ax_cv_have_stmt_attribute_$1])
+
+    AC_CACHE_CHECK([for __attribute__(($1))], [ac_var], [
+        AC_LINK_IFELSE([AC_LANG_PROGRAM([], [
+            m4_case([$1],
+                [fallthrough], [
+                    int x = 1;
+                    switch (x) {
+                    case 0: __attribute__(($1));
+                    case 1: break;
+                    }
+                ], [
+                    m4_warn([syntax], [Unsupported attribute "$1", the test may fail])
+                    int x = 1;
+                    ++x __attribute__(($1));
+                ]
+            )])
+            ],
+            dnl GCC doesn't exit with an error if an unknown attribute is
+            dnl provided but only outputs a warning, so accept the attribute
+            dnl only if no warning were issued.
+            [AS_IF([test -s conftest.err],
+                [AS_VAR_SET([ac_var], [no])],
+                [AS_VAR_SET([ac_var], [yes])])],
+            [AS_VAR_SET([ac_var], [no])
+        ])
+    ])
+
+    AS_IF([test yes = AS_VAR_GET([ac_var])],
+        [AC_DEFINE_UNQUOTED(AS_TR_CPP(HAVE_STMT_ATTRIBUTE_$1), 1,
+            [Define to 1 if the system has the `$1' statement attribute])], [])
+
+    AS_VAR_POPDEF([ac_var])
+])

meshmb.c

@@ -1,3 +1,4 @@
+#include "lang.h" // for FALLTHROUGH
 #include "serval.h"
 #include "serval_types.h"
 #include "dataformats.h"
@@ -211,13 +212,14 @@ static int activity_ack(struct meshmb_feeds *feeds, struct message_ply_ack *ack)
       case RHIZOME_BUNDLE_STATUS_NEW:
 	rhizome_manifest_set_tail(m, 0);
 	rhizome_manifest_set_filesize(m, 0);
+	FALLTHROUGH;
       case RHIZOME_BUNDLE_STATUS_SAME:
       {
 	enum rhizome_payload_status pstatus = rhizome_write_open_journal(&feeds->ack_writer, m, 0, RHIZOME_SIZE_UNSET);
 	if (pstatus==RHIZOME_PAYLOAD_STATUS_NEW)
 	  break;
       }
-	// fallthrough
+	FALLTHROUGH;
       case RHIZOME_BUNDLE_STATUS_BUSY:
 	rhizome_bundle_result_free(&result);
 	rhizome_manifest_free(m);

meshmb_restful.c

@@ -1,3 +1,4 @@
+#include "lang.h" // for FALLTHROUGH
 #include "serval.h"
 #include "dataformats.h"
 #include "conf.h"
@@ -339,7 +340,7 @@ static int restful_meshmb_list_json_content_chunk(struct http_request *hr, strbu
       return 1;
 
 ROWS:
-    case LIST_ROWS:
+    case LIST_ROWS: FALLTHROUGH;
     case LIST_FIRST:
 
       if (!message_ply_is_open(&r->u.plylist.ply_reader)){
@@ -371,6 +372,7 @@ ROWS:
 
 END:
       r->u.plylist.phase = LIST_END;
+      FALLTHROUGH;
     case LIST_END:
 
       {
@@ -395,7 +397,7 @@ END:
       strbuf_puts(b, "\n]\n}\n");
       if (!strbuf_overrun(b))
 	r->u.plylist.phase = LIST_DONE;
-      // fall through...
+      FALLTHROUGH;
     case LIST_DONE:
       return 0;
   }
@@ -600,7 +602,7 @@ static int restful_meshmb_feedlist_json_content_chunk(struct http_request *hr, s
 	r->u.meshmb_feeds.phase = LIST_ROWS;
       return 1;
 
-    case LIST_ROWS:
+    case LIST_ROWS: FALLTHROUGH;
     case LIST_FIRST:
       {
 	struct enum_state state={
@@ -613,14 +615,13 @@ static int restful_meshmb_feedlist_json_content_chunk(struct http_request *hr, s
 	if (meshmb_enum(r->u.meshmb_feeds.session->feeds, &r->u.meshmb_feeds.bundle_id, restful_feedlist_enum, &state)!=0)
 	  return 0;
       }
-      // fallthrough
       r->u.meshmb_feeds.phase = LIST_END;
+      FALLTHROUGH;
     case LIST_END:
       strbuf_puts(b, "\n]\n}\n");
       if (!strbuf_overrun(b))
 	r->u.plylist.phase = LIST_DONE;
-
+      FALLTHROUGH;
-      // fall through...
     case LIST_DONE:
       return 0;
   }

rhizome_bundle.c

@@ -21,6 +21,7 @@ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 #include <stdlib.h>
 #include <assert.h>
 #include <sys/uio.h>
+#include "lang.h" // for FALLTHROUGH
 #include "serval.h"
 #include "conf.h"
 #include "crypto.h"
@@ -1397,7 +1398,7 @@ struct rhizome_bundle_result rhizome_fill_manifest(rhizome_manifest *m, const ch
     if (rhizome_manifest_createid(m) == -1) {
       return rhizome_bundle_result_static(RHIZOME_BUNDLE_STATUS_ERROR, "Could not bind manifest to an ID");
     }
-    // fall through to set the BK field...
+    FALLTHROUGH; // to set the BK field...
   case NEW_BUNDLE_ID:
     assert(m->has_id);
     // If no 'authorSidp' parameter was supplied but the manifest has a 'sender' field, then use the

rhizome_database.c

@@ -22,6 +22,7 @@ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 #include <time.h>
 #include <ctype.h>
 #include <assert.h>
+#include "lang.h" // for FALLTHROUGH
 #include "serval.h"
 #include "conf.h"
 #include "rhizome.h"
@@ -649,6 +650,7 @@ int _sqlite_vbind(struct __sourceloc __whence, int log_level, sqlite_retry_state
 	    case SQLITE_LOCKED: \
 	      if (retry && _sqlite_retry(__whence, retry, #FUNC "()")) \
 		continue; \
+	      FALLTHROUGH; \
 	    default: \
 	      LOGF(log_level, #FUNC "(%d) failed, %s: %s", index, sqlite3_errmsg(rhizome_db), sqlite3_sql(statement)); \
 	      sqlite3_finalize(statement); \

rhizome_sync_keys.c

@@ -1,4 +1,5 @@
 
+#include "lang.h" // for FALLTHROUGH
 #include "rhizome.h"
 #include "overlay_address.h"
 #include "overlay_buffer.h"
@@ -400,6 +401,7 @@ static void sync_send_peer(struct subscriber *peer, struct rhizome_sync_keys *sy
 	      DEBUGF(rhizome_sync_keys, "Can't send manifest right now, (hash %s) %s",
 		alloca_sync_key(&msg->key),
 		rhizome_bundle_status_message_nonnull(status));
+	      FALLTHROUGH;
 	    case RHIZOME_BUNDLE_STATUS_NEW:
 	      // TODO we don't have this bundle anymore!
 	      ob_rewind(payload);

sqlite-amalgamation-3140200/sqlite3.c

@@ -1,3 +1,4 @@
+#pragma GCC diagnostic ignored "-Wimplicit-fallthrough"
 /******************************************************************************
 ** This file is an amalgamation of many separate C source files from SQLite
 ** version 3.14.2.  By combining all the individual C code files into this

strbuf_helpers.c

@@ -65,6 +65,7 @@ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 #include <sys/uio.h>
 #include <sys/socket.h>
 #include <netdb.h>
+#include "lang.h" // for FALLTHROUGH
 #include "http_server.h"
 #include "strbuf_helpers.h"
 #include "str.h"
@@ -491,7 +492,7 @@ strbuf strbuf_append_sockaddr(strbuf sb, const struct sockaddr *addr, socklen_t
       }
     }
     break;
-  case AF_INET:
+  case AF_INET: FALLTHROUGH;
   case AF_INET6:{
     char name[INET6_ADDRSTRLEN];
     char service[6];
@@ -503,7 +504,7 @@ strbuf strbuf_append_sockaddr(strbuf sb, const struct sockaddr *addr, socklen_t
 	service);
       break;
     }
-    // fall through
+    FALLTHROUGH;
   }
   default: {
       strbuf_append_socket_domain(sb, addr->sa_family);

uuid.c

@@ -21,6 +21,7 @@ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 #include "config.h"
 #endif
 
+#include "lang.h" // for FALLTHROUGH
 #define __SERVAL_DNA__UUID_H_INLINE
 #include "uuid.h"
 #include "os.h"
@@ -78,6 +79,7 @@ strbuf strbuf_uuid(strbuf sb, const serval_uuid_t *uuid)
     switch (i) {
       case 4: case 6: case 8: case 10:
 	strbuf_putc(sb, '-');
+	FALLTHROUGH;
       default:
 	strbuf_putc(sb, hexdigit_lower[uuid->u.binary[i] >> 4]);
 	strbuf_putc(sb, hexdigit_lower[uuid->u.binary[i] & 0xf]);