consistently use NULL for null pointers

makes the code noisier, but also somewhat more expressive.

src/common.h

@@ -191,7 +191,7 @@ int map_name( const char *arg, char **result, uint reserve, const char *in, cons
 	}
 
 #define ARRAY_INIT(arr) \
-	do { (arr)->array.data = 0; (arr)->array.size = (arr)->alloc = 0; } while (0)
+	do { (arr)->array.data = NULL; (arr)->array.size = (arr)->alloc = 0; } while (0)
 
 #define ARRAY_SQUEEZE(arr) \
 	do { \
@@ -245,7 +245,7 @@ typedef struct {
 void init_wakeup( wakeup_t *tmr, void (*cb)( void * ), void *aux );
 void conf_wakeup( wakeup_t *tmr, int timeout );
 void wipe_wakeup( wakeup_t *tmr );
-static INLINE int ATTR_UNUSED pending_wakeup( wakeup_t *tmr ) { return tmr->links.next != 0; }
+static INLINE int ATTR_UNUSED pending_wakeup( wakeup_t *tmr ) { return tmr->links.next != NULL; }
 
 void main_loop( void );
 

src/config.c

@@ -54,7 +54,7 @@ get_arg( conffile_t *cfile, int required, int *comment )
 			error( "%s:%d: parameter missing\n", cfile->file, cfile->line );
 			cfile->err = 1;
 		}
-		ret = 0;
+		ret = NULL;
 	} else {
 		for (escaped = 0, quoted = 0, ret = t = p; c; c = *p) {
 			p++;
@@ -74,12 +74,12 @@ get_arg( conffile_t *cfile, int required, int *comment )
 		if (escaped) {
 			error( "%s:%d: unterminated escape sequence\n", cfile->file, cfile->line );
 			cfile->err = 1;
-			ret = 0;
+			ret = NULL;
 		}
 		if (quoted) {
 			error( "%s:%d: missing closing quote\n", cfile->file, cfile->line );
 			cfile->err = 1;
-			ret = 0;
+			ret = NULL;
 		}
 	}
 	cfile->rest = p;
@@ -196,7 +196,7 @@ getopt_helper( conffile_t *cfile, int *cops, channel_conf_t *conf )
 				       cfile->file, cfile->line, arg );
 				cfile->err = 1;
 			}
-		while ((arg = get_arg( cfile, ARG_OPTIONAL, 0 )));
+		while ((arg = get_arg( cfile, ARG_OPTIONAL, NULL )));
 		conf->ops[M] |= XOP_HAVE_TYPE;
 	} else if (!strcasecmp( "SyncState", cfile->cmd ))
 		conf->sync_state = expand_strdup( cfile->val );
@@ -223,7 +223,7 @@ getopt_helper( conffile_t *cfile, int *cops, channel_conf_t *conf )
 						       cfile->file, cfile->line, boxOps[i].name, arg );
 						cfile->err = 1;
 					}
-				} while ((arg = get_arg( cfile, ARG_OPTIONAL, 0 )));
+				} while ((arg = get_arg( cfile, ARG_OPTIONAL, NULL )));
 				conf->ops[M] |= op * (XOP_HAVE_EXPUNGE / OP_EXPUNGE);
 				return 1;
 			}
@@ -239,7 +239,7 @@ getcline( conffile_t *cfile )
 	char *arg;
 	int comment;
 
-	if (cfile->rest && (arg = get_arg( cfile, ARG_OPTIONAL, 0 ))) {
+	if (cfile->rest && (arg = get_arg( cfile, ARG_OPTIONAL, NULL ))) {
 		error( "%s:%d: excess token '%s'\n", cfile->file, cfile->line, arg );
 		cfile->err = 1;
 	}
@@ -251,7 +251,7 @@ getcline( conffile_t *cfile )
 				continue;
 			return 1;
 		}
-		if (!(cfile->val = get_arg( cfile, ARG_REQUIRED, 0 )))
+		if (!(cfile->val = get_arg( cfile, ARG_REQUIRED, NULL )))
 			continue;
 		return 1;
 	}
@@ -343,7 +343,7 @@ load_config( const char *where, int pseudo )
 	cfile.bufl = sizeof(buf) - 1;
 	cfile.line = 0;
 	cfile.err = 0;
-	cfile.rest = 0;
+	cfile.rest = NULL;
 
 	gcops = 0;
 	global_conf.expire_unread = -1;
@@ -360,7 +360,7 @@ load_config( const char *where, int pseudo )
 						store->flat_delim = "";
 					*storeapp = store;
 					storeapp = &store->next;
-					*storeapp = 0;
+					*storeapp = NULL;
 				}
 				goto reloop;
 			}
@@ -382,7 +382,7 @@ load_config( const char *where, int pseudo )
 					arg = cfile.val;
 					do
 						add_string_list( &channel->patterns, arg );
-					while ((arg = get_arg( &cfile, ARG_OPTIONAL, 0 )));
+					while ((arg = get_arg( &cfile, ARG_OPTIONAL, NULL )));
 				}
 				else if (!strcasecmp( "Master", cfile.cmd )) {
 					ms = M;
@@ -438,17 +438,17 @@ load_config( const char *where, int pseudo )
 			group->name = nfstrdup( cfile.val );
 			*groupapp = group;
 			groupapp = &group->next;
-			*groupapp = 0;
+			*groupapp = NULL;
 			chanlistapp = &group->channels;
-			*chanlistapp = 0;
-			while ((arg = get_arg( &cfile, ARG_OPTIONAL, 0 ))) {
+			*chanlistapp = NULL;
+			while ((arg = get_arg( &cfile, ARG_OPTIONAL, NULL ))) {
 			  addone:
 				len = strlen( arg );
 				chanlist = nfmalloc( sizeof(*chanlist) + len );
 				memcpy( chanlist->string, arg, len + 1 );
 				*chanlistapp = chanlist;
 				chanlistapp = &chanlist->next;
-				*chanlistapp = 0;
+				*chanlistapp = NULL;
 			}
 			while (getcline( &cfile )) {
 				if (!cfile.cmd)

src/drv_imap.c

@@ -336,7 +336,7 @@ DIAG_POP
 		iov[1].buf = cmd->param.data;
 		iov[1].len = cmd->param.data_len;
 		iov[1].takeOwn = GiveOwn;
-		cmd->param.data = 0;
+		cmd->param.data = NULL;
 		ctx->buffer_mem -= cmd->param.data_len;
 		iov[2].buf = "\r\n";
 		iov[2].len = 2;
@@ -346,7 +346,7 @@ DIAG_POP
 	socket_write( &ctx->conn, iov, iovcnt );
 	if (cmd->param.to_trash && ctx->trashnc == TrashUnknown)
 		ctx->trashnc = TrashChecking;
-	cmd->next = 0;
+	cmd->next = NULL;
 	*ctx->in_progress_append = cmd;
 	ctx->in_progress_append = &cmd->next;
 	ctx->num_in_progress++;
@@ -435,7 +435,7 @@ submit_imap_cmd( imap_store_t *ctx, imap_cmd_t *cmd )
 			cmd->next = ctx->pending;
 			ctx->pending = cmd;
 		} else {
-			cmd->next = 0;
+			cmd->next = NULL;
 			*ctx->pending_append = cmd;
 			ctx->pending_append = &cmd->next;
 		}
@@ -649,7 +649,7 @@ imap_strchr( const char *s, char tc )
 		if (c == '\\')
 			c = *++s;
 		if (!c)
-			return 0;
+			return NULL;
 		if (c == tc)
 			return s;
 	}
@@ -664,12 +664,12 @@ next_arg( char **ps )
 	assert( ps );
 	s = *ps;
 	if (!s)
-		return 0;
+		return NULL;
 	while (isspace( (uchar)*s ))
 		s++;
 	if (!*s) {
-		*ps = 0;
-		return 0;
+		*ps = NULL;
+		return NULL;
 	}
 	if (*s == '"') {
 		s++;
@@ -678,8 +678,8 @@ next_arg( char **ps )
 			if (c == '\\')
 				c = *s++;
 			if (!c) {
-				*ps = 0;
-				return 0;
+				*ps = NULL;
+				return NULL;
 			}
 			*d++ = c;
 		}
@@ -695,7 +695,7 @@ next_arg( char **ps )
 		}
 	}
 	if (!*s)
-		s = 0;
+		s = NULL;
 
 	*ps = s;
 	return ret;
@@ -772,9 +772,9 @@ parse_imap_list( imap_store_t *ctx, char **sp, parse_list_state_t *sts )
 			goto next;
 		}
 		*curp = cur = nfmalloc( sizeof(*cur) );
-		cur->val = 0; /* for clean bail */
+		cur->val = NULL; /* for clean bail */
 		curp = &cur->next;
-		*curp = 0; /* ditto */
+		*curp = NULL; /* ditto */
 		if (*s == '(') {
 			/* sublist */
 			if (sts->level == MAX_LIST_DEPTH)
@@ -783,7 +783,7 @@ parse_imap_list( imap_store_t *ctx, char **sp, parse_list_state_t *sts )
 			cur->val = LIST;
 			sts->stack[sts->level++] = curp;
 			curp = &cur->child;
-			*curp = 0; /* for clean bail */
+			*curp = NULL; /* for clean bail */
 			goto next2;
 		} else if (ctx && *s == '{') {
 			/* literal */
@@ -873,7 +873,7 @@ parse_list_init( parse_list_state_t *sts )
 {
 	sts->need_bytes = -1;
 	sts->level = 1;
-	sts->head = 0;
+	sts->head = NULL;
 	sts->stack[0] = &sts->head;
 }
 
@@ -883,8 +883,8 @@ parse_list_continue( imap_store_t *ctx, char *s )
 	list_t *list;
 	int resp;
 	if ((resp = parse_imap_list( ctx, &s, &ctx->parse_list_sts )) != LIST_PARTIAL) {
-		list = (resp == LIST_BAD) ? 0 : ctx->parse_list_sts.head;
-		ctx->parse_list_sts.head = 0;
+		list = (resp == LIST_BAD) ? NULL : ctx->parse_list_sts.head;
+		ctx->parse_list_sts.head = NULL;
 		resp = ctx->parse_list_sts.callback( ctx, list, s );
 	}
 	return resp;
@@ -971,7 +971,7 @@ static int
 parse_fetch_rsp( imap_store_t *ctx, list_t *list, char *s ATTR_UNUSED )
 {
 	list_t *tmp, *flags;
-	char *body = 0, *tuid = 0, *msgid = 0, *ep;
+	char *body = NULL, *tuid = NULL, *msgid = NULL, *ep;
 	imap_message_t *cur;
 	msg_data_t *msgdata;
 	imap_cmd_t *cmdp;
@@ -1034,7 +1034,7 @@ parse_fetch_rsp( imap_store_t *ctx, list_t *list, char *s ATTR_UNUSED )
 				tmp = tmp->next;
 				if (is_atom( tmp )) {
 					body = tmp->val;
-					tmp->val = 0;       /* don't free together with list */
+					tmp->val = NULL;       /* don't free together with list */
 					size = tmp->len;
 				} else
 					error( "IMAP error: unable to parse BODY[]\n" );
@@ -1117,12 +1117,12 @@ parse_fetch_rsp( imap_store_t *ctx, list_t *list, char *s ATTR_UNUSED )
 		cur = nfcalloc( sizeof(*cur) );
 		*ctx->msgapp = &cur->gen;
 		ctx->msgapp = &cur->gen.next;
-		cur->gen.next = 0;
+		cur->gen.next = NULL;
 		cur->gen.uid = uid;
 		cur->gen.flags = mask;
 		cur->gen.status = status;
 		cur->gen.size = size;
-		cur->gen.srec = 0;
+		cur->gen.srec = NULL;
 		cur->gen.msgid = msgid;
 		if (tuid)
 			memcpy( cur->gen.tuid, tuid, TUIDL );
@@ -1141,7 +1141,7 @@ parse_capability( imap_store_t *ctx, char *cmd )
 	uint i;
 
 	free_string_list( ctx->auth_mechs );
-	ctx->auth_mechs = 0;
+	ctx->auth_mechs = NULL;
 	ctx->caps = 0x80000000;
 	while ((arg = next_arg( &cmd ))) {
 		if (starts_with( arg, -1, "AUTH=", 5 )) {
@@ -1393,7 +1393,7 @@ imap_socket_read( void *aux )
 
 	for (;;) {
 		if (ctx->parse_list_sts.level) {
-			resp = parse_list_continue( ctx, 0 );
+			resp = parse_list_continue( ctx, NULL );
 		  listret:
 			if (resp == LIST_PARTIAL)
 				return;
@@ -1427,7 +1427,7 @@ imap_socket_read( void *aux )
 			}
 
 			if (ctx->greeting == GreetingPending && !strcmp( "PREAUTH", arg )) {
-				parse_response_code( ctx, 0, cmd );
+				parse_response_code( ctx, NULL, cmd );
 				ctx->greeting = GreetingPreauth;
 			  dogreet:
 				imap_ref( ctx );
@@ -1435,7 +1435,7 @@ imap_socket_read( void *aux )
 				if (imap_deref( ctx ))
 					return;
 			} else if (!strcmp( "OK", arg )) {
-				parse_response_code( ctx, 0, cmd );
+				parse_response_code( ctx, NULL, cmd );
 				if (ctx->greeting == GreetingPending) {
 					ctx->greeting = GreetingOk;
 					goto dogreet;
@@ -1499,7 +1499,7 @@ imap_socket_read( void *aux )
 				iov[0].buf = cmdp->param.data;
 				iov[0].len = cmdp->param.data_len;
 				iov[0].takeOwn = GiveOwn;
-				cmdp->param.data = 0;
+				cmdp->param.data = NULL;
 				ctx->buffer_mem -= cmdp->param.data_len;
 				iov[1].buf = "\r\n";
 				iov[1].len = 2;
@@ -1667,7 +1667,7 @@ imap_free_store( store_t *gctx )
 	imap_store_t *ctx = (imap_store_t *)gctx;
 
 	free_generic_messages( ctx->msgs );
-	ctx->msgs = 0;
+	ctx->msgs = NULL;
 	imap_set_bad_callback( gctx, imap_cancel_unowned, gctx );
 	gctx->next = unowned;
 	unowned = gctx;
@@ -1687,7 +1687,7 @@ imap_cleanup( void )
 		imap_set_bad_callback( ctx, (void (*)(void *))imap_cancel_store, ctx );
 		if (((imap_store_t *)ctx)->state != SST_BAD) {
 			((imap_store_t *)ctx)->expectBYE = 1;
-			imap_exec( (imap_store_t *)ctx, 0, imap_cleanup_p2, "LOGOUT" );
+			imap_exec( (imap_store_t *)ctx, NULL, imap_cleanup_p2, "LOGOUT" );
 		} else {
 			imap_cancel_store( ctx );
 		}
@@ -1832,7 +1832,7 @@ imap_open_store_greeted( imap_store_t *ctx )
 {
 	socket_expect_activity( &ctx->conn, 0 );
 	if (!ctx->caps)
-		imap_exec( ctx, 0, imap_open_store_p2, "CAPABILITY" );
+		imap_exec( ctx, NULL, imap_open_store_p2, "CAPABILITY" );
 	else
 		imap_open_store_authenticate( ctx );
 }
@@ -1858,7 +1858,7 @@ imap_open_store_authenticate( imap_store_t *ctx )
 #ifdef HAVE_LIBSSL
 		if (srvc->ssl_type == SSL_STARTTLS) {
 			if (CAP(STARTTLS)) {
-				imap_exec( ctx, 0, imap_open_store_authenticate_p2, "STARTTLS" );
+				imap_exec( ctx, NULL, imap_open_store_authenticate_p2, "STARTTLS" );
 				return;
 			} else {
 				error( "IMAP error: SSL support not available\n" );
@@ -1898,7 +1898,7 @@ imap_open_store_tlsstarted2( int ok, void *aux )
 	if (!ok)
 		imap_open_store_ssl_bail( ctx );
 	else
-		imap_exec( ctx, 0, imap_open_store_authenticate_p3, "CAPABILITY" );
+		imap_exec( ctx, NULL, imap_open_store_authenticate_p3, "CAPABILITY" );
 }
 
 static void
@@ -1916,7 +1916,7 @@ ensure_user( imap_server_conf_t *srvc )
 {
 	if (!srvc->user) {
 		error( "Skipping account %s, no user\n", srvc->name );
-		return 0;
+		return NULL;
 	}
 	return srvc->user;
 }
@@ -1938,7 +1938,7 @@ ensure_password( imap_server_conf_t *srvc )
 		if (!(fp = popen( cmd, "r" ))) {
 		  pipeerr:
 			sys_error( "Skipping account %s, password command failed", srvc->name );
-			return 0;
+			return NULL;
 		}
 		if (!fgets( buffer, sizeof(buffer), fp ))
 			buffer[0] = 0;
@@ -1949,11 +1949,11 @@ ensure_password( imap_server_conf_t *srvc )
 				error( "Skipping account %s, password command crashed\n", srvc->name );
 			else
 				error( "Skipping account %s, password command exited with status %d\n", srvc->name, WEXITSTATUS( ret ) );
-			return 0;
+			return NULL;
 		}
 		if (!buffer[0]) {
 			error( "Skipping account %s, password command produced no output\n", srvc->name );
-			return 0;
+			return NULL;
 		}
 		buffer[strcspn( buffer, "\n" )] = 0; /* Strip trailing newline */
 		free( srvc->pass ); /* From previous runs */
@@ -1970,7 +1970,7 @@ ensure_password( imap_server_conf_t *srvc )
 		}
 		if (!*pass) {
 			error( "Skipping account %s, no password\n", srvc->name );
-			return 0;
+			return NULL;
 		}
 		/* getpass() returns a pointer to a static buffer. Make a copy for long term storage. */
 		srvc->pass = nfstrdup( pass );
@@ -2254,7 +2254,7 @@ imap_open_store_authenticate2( imap_store_t *ctx )
 		if (!ctx->conn.ssl)
 #endif
 			warn( "*** IMAP Warning *** Password is being sent in the clear\n" );
-		imap_exec( ctx, 0, imap_open_store_authenticate2_p2,
+		imap_exec( ctx, NULL, imap_open_store_authenticate2_p2,
 		           "LOGIN \"%\\s\" \"%\\s\"", srvc->user, srvc->pass );
 		return;
 	}
@@ -2284,7 +2284,7 @@ imap_open_store_compress( imap_store_t *ctx )
 {
 #ifdef HAVE_LIBZ
 	if (CAP(COMPRESS_DEFLATE)) {
-		imap_exec( ctx, 0, imap_open_store_compress_p2, "COMPRESS DEFLATE" );
+		imap_exec( ctx, NULL, imap_open_store_compress_p2, "COMPRESS DEFLATE" );
 		return;
 	}
 #endif
@@ -2316,7 +2316,7 @@ imap_open_store_namespace( imap_store_t *ctx )
 	if (((!ctx->prefix && cfg->use_namespace) || !cfg->delimiter) && CAP(NAMESPACE)) {
 		/* get NAMESPACE info */
 		if (!ctx->got_namespace)
-			imap_exec( ctx, 0, imap_open_store_namespace_p2, "NAMESPACE" );
+			imap_exec( ctx, NULL, imap_open_store_namespace_p2, "NAMESPACE" );
 		else
 			imap_open_store_namespace2( ctx );
 		return;
@@ -2390,7 +2390,7 @@ imap_select_box( store_t *gctx, const char *name )
 	imap_store_t *ctx = (imap_store_t *)gctx;
 
 	free_generic_messages( ctx->msgs );
-	ctx->msgs = 0;
+	ctx->msgs = NULL;
 	ctx->msgapp = &ctx->msgs;
 
 	ctx->name = name;
@@ -2400,7 +2400,7 @@ imap_select_box( store_t *gctx, const char *name )
 static const char *
 imap_get_box_path( store_t *gctx ATTR_UNUSED )
 {
-	return 0;
+	return NULL;
 }
 
 typedef struct {
@@ -2623,7 +2623,7 @@ imap_load_box( store_t *gctx, uint minuid, uint maxuid, uint newuid, uint seenui
 
 	if (!ctx->total_msgs) {
 		free( excs.data );
-		cb( DRV_OK, 0, 0, 0, aux );
+		cb( DRV_OK, NULL, 0, 0, aux );
 	} else {
 		INIT_REFCOUNTED_STATE(imap_load_box_state_t, sts, cb, aux)
 		for (uint i = 0; i < excs.size; ) {
@@ -2751,7 +2751,7 @@ imap_fetch_msg( store_t *ctx, message_t *msg, msg_data_t *data,
 	INIT_IMAP_CMD_X(imap_cmd_fetch_msg_t, cmd, cb, aux)
 	cmd->gen.gen.param.uid = msg->uid;
 	cmd->msg_data = data;
-	data->data = 0;
+	data->data = NULL;
 	imap_exec( (imap_store_t *)ctx, &cmd->gen.gen, imap_fetch_msg_p2,
 	           "UID FETCH %u (%s%sBODY.PEEK[])", msg->uid,
 	           !(msg->status & M_FLAGS) ? "FLAGS " : "",
@@ -3208,8 +3208,8 @@ imap_parse_store( conffile_t *cfg, store_conf_t **storep )
 		server->name = nfstrdup( cfg->val );
 		*serverapp = server;
 		serverapp = &server->next;
-		store = 0;
-		*storep = 0;
+		store = NULL;
+		*storep = NULL;
 	} else if (!strcasecmp( "IMAPStore", cfg->cmd )) {
 		store = nfcalloc( sizeof(*store) );
 		store->gen.driver = &imap_driver;
@@ -3283,7 +3283,7 @@ imap_parse_store( conffile_t *cfg, store_conf_t **storep )
 				error( "%s:%d: Unrecognized IMAP extension '%s'\n", cfg->file, cfg->line, arg );
 				cfg->err = 1;
 			  gotcap: ;
-			} while ((arg = get_arg( cfg, ARG_OPTIONAL, 0 )));
+			} while ((arg = get_arg( cfg, ARG_OPTIONAL, NULL )));
 		}
 #ifdef HAVE_LIBSSL
 		else if (!strcasecmp( "CertificateFile", cfg->cmd )) {
@@ -3343,7 +3343,7 @@ imap_parse_store( conffile_t *cfg, store_conf_t **storep )
 					error( "%s:%d: Unrecognized SSL version\n", cfg->file, cfg->line );
 					cfg->err = 1;
 				}
-			} while ((arg = get_arg( cfg, ARG_OPTIONAL, 0 )));
+			} while ((arg = get_arg( cfg, ARG_OPTIONAL, NULL )));
 		} else if (!strcasecmp( "RequireSSL", cfg->cmd ))
 			require_ssl = parse_bool( cfg );
 		else if (!strcasecmp( "UseIMAPS", cfg->cmd ))
@@ -3366,7 +3366,7 @@ imap_parse_store( conffile_t *cfg, store_conf_t **storep )
 			arg = cfg->val;
 			do
 				add_string_list( &server->auth_mechs, arg );
-			while ((arg = get_arg( cfg, ARG_OPTIONAL, 0 )));
+			while ((arg = get_arg( cfg, ARG_OPTIONAL, NULL )));
 		} else if (!strcasecmp( "RequireCRAM", cfg->cmd ))
 			require_cram = parse_bool( cfg );
 		else if (!strcasecmp( "Tunnel", cfg->cmd ))

src/drv_maildir.c

@@ -152,7 +152,7 @@ maildir_join_path( maildir_store_conf_t *conf, int in_inbox, const char *box )
 		prefix = conf->inbox;
 	} else {
 		if (maildir_ensure_path( conf ) < 0)
-			return 0;
+			return NULL;
 		prefix = conf->gen.path;
 	}
 	pl = strlen( prefix );
@@ -161,13 +161,13 @@ maildir_join_path( maildir_store_conf_t *conf, int in_inbox, const char *box )
 			if (conf->sub_style == SUB_UNSET) {
 				error( "Maildir error: accessing subfolder '%s', but store '%s' does not specify SubFolders style\n",
 				       box, conf->gen.name );
-				return 0;
+				return NULL;
 			}
 			n++;
 		} else if (c == '.' && conf->sub_style == SUB_MAILDIRPP) {
 			error( "Maildir error: store '%s', folder '%s': SubFolders style Maildir++ does not support dots in mailbox names\n",
 			       conf->gen.name, box );
-			return 0;
+			return NULL;
 		}
 	switch (conf->sub_style) {
 	case SUB_VERBATIM:
@@ -419,13 +419,13 @@ maildir_list_recurse( maildir_store_t *ctx, int isBox, int flags,
 		pl += pathLen;
 		if (inbox && equals( path, pl, inbox, inboxLen )) {
 			// Inbox nested into Path.
-			if (maildir_list_inbox( ctx, flags, 0 ) < 0) {
+			if (maildir_list_inbox( ctx, flags, NULL ) < 0) {
 				closedir( dir );
 				return -1;
 			}
 		} else if (basePath && equals( path, pl, basePath, basePathLen )) {
 			// Path nested into Inbox.
-			if (maildir_list_path( ctx, flags, 0 ) < 0) {
+			if (maildir_list_path( ctx, flags, NULL ) < 0) {
 				closedir( dir );
 				return -1;
 			}
@@ -477,7 +477,7 @@ maildir_list_inbox( maildir_store_t *ctx, int flags, const char *basePath )
 
 	add_string_list( &ctx->boxes, "INBOX" );
 	return maildir_list_recurse(
-	        ctx, 1, flags, 0, 0, basePath, basePath ? strlen( basePath ) - 1 : 0,
+	        ctx, 1, flags, NULL, 0, basePath, basePath ? strlen( basePath ) - 1 : 0,
 	        path, nfsnprintf( path, _POSIX_PATH_MAX, "%s/", ((maildir_store_conf_t *)ctx->gen.conf)->inbox ),
 	        name, nfsnprintf( name, _POSIX_PATH_MAX, "INBOX/" ) );
 }
@@ -494,7 +494,7 @@ maildir_list_path( maildir_store_t *ctx, int flags, const char *inbox )
 	if (maildir_ensure_path( (maildir_store_conf_t *)ctx->gen.conf ) < 0)
 		return -1;
 	return maildir_list_recurse(
-	        ctx, 0, flags, inbox, inbox ? strlen( inbox ) : 0, 0, 0,
+	        ctx, 0, flags, inbox, inbox ? strlen( inbox ) : 0, NULL, 0,
 	        path, nfsnprintf( path, _POSIX_PATH_MAX, "%s", ctx->gen.conf->path ),
 	        name, 0 );
 }
@@ -513,7 +513,7 @@ maildir_list_store( store_t *gctx, int flags,
 	           ((flags & LIST_INBOX)
 	            && maildir_list_inbox( ctx, flags, gctx->conf->path ) < 0))) {
 		maildir_invoke_bad_callback( ctx );
-		cb( DRV_CANCELED, 0, aux );
+		cb( DRV_CANCELED, NULL, aux );
 	} else {
 		cb( DRV_OK, ctx->boxes, aux );
 	}
@@ -674,7 +674,7 @@ maildir_store_uidval( maildir_store_t *ctx )
 		uv[1] = ctx->nuid;
 		value.data = uv;
 		value.size = sizeof(uv);
-		if ((ret = ctx->db->put( ctx->db, 0, &key, &value, 0 ))) {
+		if ((ret = ctx->db->put( ctx->db, NULL, &key, &value, 0 ))) {
 			ctx->db->err( ctx->db, ret, "Maildir error: db->put()" );
 			return DRV_BOX_BAD;
 		}
@@ -699,13 +699,13 @@ maildir_store_uidval( maildir_store_t *ctx )
 static int
 maildir_init_uidval( maildir_store_t *ctx )
 {
-	ctx->uidvalidity = (uint)time( 0 );
+	ctx->uidvalidity = (uint)time( NULL );
 	ctx->nuid = 0;
 	ctx->uvok = 0;
 #ifdef USE_DB
 	if (ctx->db) {
 		u_int32_t count;
-		ctx->db->truncate( ctx->db, 0, &count, 0 );
+		ctx->db->truncate( ctx->db, NULL, &count, 0 );
 	}
 #endif /* USE_DB */
 	return maildir_store_uidval( ctx );
@@ -749,18 +749,18 @@ maildir_uidval_lock( maildir_store_t *ctx )
 			sys_error( "Maildir error: cannot fstat UID database" );
 			return DRV_BOX_BAD;
 		}
-		if (db_create( &ctx->db, 0, 0 )) {
+		if (db_create( &ctx->db, NULL, 0 )) {
 			fputs( "Maildir error: db_create() failed\n", stderr );
 			return DRV_BOX_BAD;
 		}
-		if ((ret = (ctx->db->open)( ctx->db, 0, ctx->usedb, 0, DB_HASH,
+		if ((ret = (ctx->db->open)( ctx->db, NULL, ctx->usedb, NULL, DB_HASH,
 		                            st.st_size ? 0 : DB_CREATE | DB_TRUNCATE, 0 ))) {
 			ctx->db->err( ctx->db, ret, "Maildir error: db->open(%s)", ctx->usedb );
 			return DRV_BOX_BAD;
 		}
 		key.data = (void *)"UIDVALIDITY";
 		key.size = 11;
-		if ((ret = ctx->db->get( ctx->db, 0, &key, &value, 0 ))) {
+		if ((ret = ctx->db->get( ctx->db, NULL, &key, &value, 0 ))) {
 			if (ret != DB_NOTFOUND) {
 				ctx->db->err( ctx->db, ret, "Maildir error: db->get()" );
 				return DRV_BOX_BAD;
@@ -798,7 +798,7 @@ maildir_uidval_unlock( maildir_store_t *ctx )
 #ifdef USE_DB
 	if (ctx->db) {
 		ctx->db->close( ctx->db, 0 );
-		ctx->db = 0;
+		ctx->db = NULL;
 	}
 #endif /* USE_DB */
 	lck.l_type = F_UNLCK;
@@ -835,7 +835,7 @@ maildir_set_uid( maildir_store_t *ctx, const char *name, uint *uid )
 	make_key( ((maildir_store_conf_t *)ctx->gen.conf)->info_stop, &key, name );
 	value.data = uid;
 	value.size = sizeof(*uid);
-	if ((ret = ctx->db->put( ctx->db, 0, &key, &value, 0 ))) {
+	if ((ret = ctx->db->put( ctx->db, NULL, &key, &value, 0 ))) {
 		ctx->db->err( ctx->db, ret, "Maildir error: db->put()" );
 		return DRV_BOX_BAD;
 	}
@@ -932,11 +932,11 @@ maildir_scan( maildir_store_t *ctx, msg_t_array_alloc_t *msglist )
 	if (ctx->uvok || ctx->maxuid == UINT_MAX) {
 #ifdef USE_DB
 		if (ctx->usedb) {
-			if (db_create( &tdb, 0, 0 )) {
+			if (db_create( &tdb, NULL, 0 )) {
 				fputs( "Maildir error: db_create() failed\n", stderr );
 				return DRV_BOX_BAD;
 			}
-			if ((tdb->open)( tdb, 0, 0, 0, DB_HASH, DB_CREATE, 0 )) {
+			if ((tdb->open)( tdb, NULL, NULL, NULL, DB_HASH, DB_CREATE, 0 )) {
 				fputs( "Maildir error: tdb->open() failed\n", stderr );
 			  bork:
 				tdb->close( tdb, 0 );
@@ -946,7 +946,7 @@ maildir_scan( maildir_store_t *ctx, msg_t_array_alloc_t *msglist )
 #endif /* USE_DB */
 		bl = nfsnprintf( buf, sizeof(buf) - 4, "%s/", ctx->path );
 	  restat:
-		now = time( 0 );
+		now = time( NULL );
 		for (i = 0; i < 2; i++) {
 			memcpy( buf + bl, subdirs[i], 4 );
 			if (stat( buf, &st )) {
@@ -987,7 +987,7 @@ maildir_scan( maildir_store_t *ctx, msg_t_array_alloc_t *msglist )
 					if (maildir_uidval_lock( ctx ) != DRV_OK)
 						goto mbork;
 					make_key( conf->info_stop, &key, e->d_name );
-					if ((ret = ctx->db->get( ctx->db, 0, &key, &value, 0 ))) {
+					if ((ret = ctx->db->get( ctx->db, NULL, &key, &value, 0 ))) {
 						if (ret != DB_NOTFOUND) {
 							ctx->db->err( ctx->db, ret, "Maildir error: db->get()" );
 						  mbork:
@@ -998,7 +998,7 @@ maildir_scan( maildir_store_t *ctx, msg_t_array_alloc_t *msglist )
 						uid = UINT_MAX;
 					} else {
 						value.size = 0;
-						if ((ret = tdb->put( tdb, 0, &key, &value, 0 ))) {
+						if ((ret = tdb->put( tdb, NULL, &key, &value, 0 ))) {
 							tdb->err( tdb, ret, "Maildir error: tdb->put()" );
 							goto mbork;
 						}
@@ -1016,7 +1016,7 @@ maildir_scan( maildir_store_t *ctx, msg_t_array_alloc_t *msglist )
 						continue;
 					entry = msg_t_array_append( msglist );
 					entry->base = nfstrdup( e->d_name );
-					entry->msgid = 0;
+					entry->msgid = NULL;
 					entry->uid = uid;
 					entry->recent = (uchar)i;
 					entry->size = 0;
@@ -1045,7 +1045,7 @@ maildir_scan( maildir_store_t *ctx, msg_t_array_alloc_t *msglist )
 		if (ctx->usedb) {
 			if (maildir_uidval_lock( ctx ) != DRV_OK)
 				;
-			else if ((ret = ctx->db->cursor( ctx->db, 0, &dbc, 0 )))
+			else if ((ret = ctx->db->cursor( ctx->db, NULL, &dbc, 0 )))
 				ctx->db->err( ctx->db, ret, "Maildir error: db->cursor()" );
 			else {
 				for (;;) {
@@ -1055,7 +1055,7 @@ maildir_scan( maildir_store_t *ctx, msg_t_array_alloc_t *msglist )
 						break;
 					}
 					if (!equals( key.data, (int)key.size, "UIDVALIDITY", 11 ) &&
-					    (ret = tdb->get( tdb, 0, &key, &value, 0 ))) {
+					    (ret = tdb->get( tdb, NULL, &key, &value, 0 ))) {
 						if (ret != DB_NOTFOUND) {
 							tdb->err( tdb, ret, "Maildir error: tdb->get()" );
 							break;
@@ -1217,11 +1217,11 @@ static void
 maildir_init_msg( maildir_store_t *ctx, maildir_message_t *msg, msg_t *entry )
 {
 	msg->base = entry->base;
-	entry->base = 0; /* prevent deletion */
+	entry->base = NULL; /* prevent deletion */
 	msg->gen.msgid = entry->msgid;
-	entry->msgid = 0; /* prevent deletion */
+	entry->msgid = NULL; /* prevent deletion */
 	msg->gen.size = entry->size;
-	msg->gen.srec = 0;
+	msg->gen.srec = NULL;
 	memcpy( msg->gen.tuid, entry->tuid, TUIDL );
 	if (entry->recent)
 		msg->gen.status |= M_RECENT;
@@ -1251,12 +1251,12 @@ maildir_select_box( store_t *gctx, const char *name )
 	maildir_store_t *ctx = (maildir_store_t *)gctx;
 
 	maildir_cleanup( gctx );
-	ctx->msgs = 0;
-	ctx->excs.data = 0;
+	ctx->msgs = NULL;
+	ctx->excs.data = NULL;
 	ctx->uvfd = -1;
 #ifdef USE_DB
-	ctx->db = 0;
-	ctx->usedb = 0;
+	ctx->db = NULL;
+	ctx->usedb = NULL;
 #endif /* USE_DB */
 	ctx->fresh[0] = ctx->fresh[1] = 0;
 	if (starts_with( name, -1, "INBOX", 5 ) && (!name[5] || name[5] == '/')) {
@@ -1300,7 +1300,7 @@ maildir_open_box( store_t *gctx,
 		return;
 	}
 #else
-	ctx->usedb = 0;
+	ctx->usedb = NULL;
 	if ((ctx->uvfd = open( uvpath, O_RDWR, 0600 )) < 0) {
 		nfsnprintf( uvpath, sizeof(uvpath), "%s/.isyncuidmap.db", ctx->path );
 		if ((ctx->uvfd = open( uvpath, O_RDWR, 0600 )) < 0) {
@@ -1451,7 +1451,7 @@ maildir_load_box( store_t *gctx, uint minuid, uint maxuid, uint newuid, uint see
 	ctx->excs = excs;
 
 	if (maildir_scan( ctx, &msglist ) != DRV_OK) {
-		cb( DRV_BOX_BAD, 0, 0, 0, aux );
+		cb( DRV_BOX_BAD, NULL, 0, 0, aux );
 		return;
 	}
 	msgapp = &ctx->msgs;
@@ -1592,7 +1592,7 @@ maildir_store_msg( store_t *gctx, msg_data_t *data, int to_trash,
 	uint uid;
 	char buf[_POSIX_PATH_MAX], nbuf[_POSIX_PATH_MAX], fbuf[NUM_FLAGS + 3], base[128];
 
-	bl = nfsnprintf( base, sizeof(base), "%lld.%d_%d.%s", (long long)time( 0 ), Pid, ++MaildirCount, Hostname );
+	bl = nfsnprintf( base, sizeof(base), "%lld.%d_%d.%s", (long long)time( NULL ), Pid, ++MaildirCount, Hostname );
 	if (!to_trash) {
 #ifdef USE_DB
 		if (ctx->usedb) {
@@ -1744,7 +1744,7 @@ maildir_purge_msg( maildir_store_t *ctx, const char *name )
 	if ((ret = maildir_uidval_lock( ctx )) != DRV_OK)
 		return ret;
 	make_key( ((maildir_store_conf_t *)ctx->gen.conf)->info_stop, &key, name );
-	if ((ret = ctx->db->del( ctx->db, 0, &key, 0 ))) {
+	if ((ret = ctx->db->del( ctx->db, NULL, &key, 0 ))) {
 		ctx->db->err( ctx->db, ret, "Maildir error: db->del()" );
 		return DRV_BOX_BAD;
 	}
@@ -1767,7 +1767,7 @@ maildir_trash_msg( store_t *gctx, message_t *gmsg,
 		nfsnprintf( buf, sizeof(buf), "%s/%s/%s", ctx->path, subdirs[gmsg->status & M_RECENT], msg->base );
 		s = strstr( msg->base, ((maildir_store_conf_t *)gctx->conf)->info_prefix );
 		nfsnprintf( nbuf, sizeof(nbuf), "%s/%s/%lld.%d_%d.%s%s", ctx->trash,
-		            subdirs[gmsg->status & M_RECENT], (long long)time( 0 ), Pid, ++MaildirCount, Hostname, s ? s : "" );
+		            subdirs[gmsg->status & M_RECENT], (long long)time( NULL ), Pid, ++MaildirCount, Hostname, s ? s : "" );
 		if (!rename( buf, nbuf ))
 			break;
 		if (!stat( buf, &st )) {

src/drv_proxy_gen.pl

@@ -128,7 +128,7 @@ for (@ptypes) {
 	/^([\w* ]+)\(\*(\w+)\)\( (.*) \)$/ or die("Cannot parse prototype '$_'\n");
 	my ($cmd_type, $cmd_name, $cmd_args) = ($1, $2, $3);
 	if (defined($excluded{$cmd_name})) {
-		push @cmd_table, "0";
+		push @cmd_table, "NULL";
 		next;
 	}
 	push @cmd_table, "proxy_$cmd_name";

src/main.c

@@ -175,7 +175,7 @@ crashHandler( int n )
 		close( pip[1] );
 		close( pip[0] );
 #endif
-		waitpid( dpid, 0, 0 );
+		waitpid( dpid, NULL, 0 );
 		break;
 	}
 	exit( 3 );
@@ -262,7 +262,7 @@ static char **
 filter_boxes( string_list_t *boxes, const char *prefix, string_list_t *patterns )
 {
 	string_list_t *cpat;
-	char **boxarr = 0;
+	char **boxarr = NULL;
 	const char *ps;
 	uint not, fnot, pfxl, num = 0, rnum = 0;
 
@@ -287,7 +287,7 @@ filter_boxes( string_list_t *boxes, const char *prefix, string_list_t *patterns
 			if (num + 1 >= rnum)
 				boxarr = nfrealloc( boxarr, (rnum = (rnum + 10) * 2) * sizeof(*boxarr) );
 			boxarr[num++] = nfstrdup( boxes->string + pfxl );
-			boxarr[num] = 0;
+			boxarr[num] = NULL;
 		}
 	}
 	qsort( boxarr, num, sizeof(*boxarr), cmp_box_names );
@@ -348,7 +348,7 @@ add_named_channel( chan_ent_t ***chanapp, char *channame, int ops[] )
 {
 	channel_conf_t *chan;
 	chan_ent_t *ce;
-	box_ent_t *boxes = 0, **mboxapp = &boxes, *mbox;
+	box_ent_t *boxes = NULL, **mboxapp = &boxes, *mbox;
 	char *boxp, *nboxp;
 	size_t boxl;
 	char boxlist = 0;
@@ -359,12 +359,12 @@ add_named_channel( chan_ent_t ***chanapp, char *channame, int ops[] )
 		if (!strcmp( chan->name, channame ))
 			goto gotchan;
 	error( "No channel or group named '%s' defined.\n", channame );
-	return 0;
+	return NULL;
   gotchan:
 	if (boxp) {
 		if (!chan->patterns) {
 			error( "Cannot override mailbox in channel '%s' - no Patterns.\n", channame );
-			return 0;
+			return NULL;
 		}
 		boxlist = 1;
 		do {
@@ -381,7 +381,7 @@ add_named_channel( chan_ent_t ***chanapp, char *channame, int ops[] )
 			else
 				mbox->name = nfstrndup( "INBOX", 5 );
 			mbox->present[M] = mbox->present[S] = BOX_POSSIBLE;
-			mbox->next = 0;
+			mbox->next = NULL;
 			*mboxapp = mbox;
 			mboxapp = &mbox->next;
 			boxes_total++;
@@ -426,11 +426,11 @@ int
 main( int argc, char **argv )
 {
 	main_vars_t mvars[1];
-	chan_ent_t *chans = 0, **chanapp = &chans;
+	chan_ent_t *chans = NULL, **chanapp = &chans;
 	group_conf_t *group;
 	channel_conf_t *chan;
 	string_list_t *channame;
-	char *config = 0, *opt, *ochar;
+	char *config = NULL, *opt, *ochar;
 	int oind, cops = 0, op, ops[2] = { 0, 0 }, pseudo = 0;
 
 	tzset();
@@ -447,7 +447,7 @@ main( int argc, char **argv )
 	memset( mvars, 0, sizeof(*mvars) );
 	mvars->t[1] = 1;
 
-	for (oind = 1, ochar = 0; ; ) {
+	for (oind = 1, ochar = NULL; ; ) {
 		if (!ochar || !*ochar) {
 			if (oind >= argc)
 				break;
@@ -846,7 +846,7 @@ sync_chans( main_vars_t *mvars, int ent )
 		if (mvars->skip)
 			goto next2;
 		mvars->state[M] = mvars->state[S] = ST_FRESH;
-		if ((DFlags & DEBUG_DRV) || (mvars->chan->stores[M]->driver->get_caps( 0 ) & mvars->chan->stores[S]->driver->get_caps( 0 ) & DRV_VERBOSE))
+		if ((DFlags & DEBUG_DRV) || (mvars->chan->stores[M]->driver->get_caps( NULL ) & mvars->chan->stores[S]->driver->get_caps( NULL ) & DRV_VERBOSE))
 			labels[M] = "M: ", labels[S] = "S: ";
 		else
 			labels[M] = labels[S] = "";
@@ -881,8 +881,8 @@ sync_chans( main_vars_t *mvars, int ent )
 			boxes[S] = filter_boxes( mvars->boxes[S], mvars->chan->boxes[S], mvars->chan->patterns );
 			mboxapp = &mvars->chanptr->boxes;
 			for (mb = sb = 0; ; ) {
-				char *mname = boxes[M] ? boxes[M][mb] : 0;
-				char *sname = boxes[S] ? boxes[S][sb] : 0;
+				char *mname = boxes[M] ? boxes[M][mb] : NULL;
+				char *sname = boxes[S] ? boxes[S][sb] : NULL;
 				if (!mname && !sname)
 					break;
 				mbox = nfmalloc( sizeof(*mbox) );
@@ -903,7 +903,7 @@ sync_chans( main_vars_t *mvars, int ent )
 					mbox->present[S] = BOX_PRESENT;
 					sb++;
 				}
-				mbox->next = 0;
+				mbox->next = NULL;
 				*mboxapp = mbox;
 				mboxapp = &mbox->next;
 				boxes_total++;
@@ -945,7 +945,7 @@ sync_chans( main_vars_t *mvars, int ent )
 		mvars->cben = 0;
 		for (t = 0; t < 2; t++) {
 			free_string_list( mvars->boxes[t] );
-			mvars->boxes[t] = 0;
+			mvars->boxes[t] = NULL;
 			if (mvars->state[t] == ST_FRESH) {
 				/* An unconnected store may be only cancelled. */
 				mvars->state[t] = ST_CLOSED;
@@ -966,7 +966,7 @@ sync_chans( main_vars_t *mvars, int ent )
 				free( mbox->name );
 				free( mbox );
 			}
-			mvars->chanptr->boxes = 0;
+			mvars->chanptr->boxes = NULL;
 			mvars->chanptr->boxlist = 0;
 		}
 	  next2:

src/mdconvert.c

@@ -117,11 +117,11 @@ convert( const char *box, int altmap )
 		sys_error( "Cannot create %s", tdpath );
 		goto sbork;
 	}
-	if (db_create( &db, 0, 0 )) {
+	if (db_create( &db, NULL, 0 )) {
 		fputs( "Error: db_create() failed\n", stderr );
 		goto tbork;
 	}
-	if ((ret = (db->open)( db, 0, dbpath, 0, DB_HASH, altmap ? DB_CREATE|DB_TRUNCATE : 0, 0 ))) {
+	if ((ret = (db->open)( db, NULL, dbpath, NULL, DB_HASH, altmap ? DB_CREATE|DB_TRUNCATE : 0, 0 ))) {
 		db->err( db, ret, "Error: db->open(%s)", dbpath );
 	  dbork:
 		db->close( db, 0 );
@@ -143,12 +143,12 @@ convert( const char *box, int altmap )
 		}
 		value.data = uv;
 		value.size = sizeof(uv);
-		if ((ret = db->put( db, 0, &key, &value, 0 ))) {
+		if ((ret = db->put( db, NULL, &key, &value, 0 ))) {
 			db->err( db, ret, "Error: cannot write UIDVALIDITY for '%s'", box );
 			goto dbork;
 		}
 	} else {
-		if ((ret = db->get( db, 0, &key, &value, 0 ))) {
+		if ((ret = db->get( db, NULL, &key, &value, 0 ))) {
 			db->err( db, ret, "Error: cannot read UIDVALIDITY of '%s'", box );
 			goto dbork;
 		}
@@ -188,7 +188,7 @@ convert( const char *box, int altmap )
 				uid = atoi( p + 3 );
 				value.data = &uid;
 				value.size = sizeof(uid);
-				if ((ret = db->put( db, 0, &key, &value, 0 ))) {
+				if ((ret = db->put( db, NULL, &key, &value, 0 ))) {
 					db->err( db, ret, "Error: cannot write UID for '%s'", box );
 					goto ebork;
 				}
@@ -197,7 +197,7 @@ convert( const char *box, int altmap )
 				s = strpbrk( e->d_name, ",:" );
 				key.data = e->d_name;
 				key.size = s ? (size_t)(s - e->d_name) : strlen( e->d_name );
-				if ((ret = db->get( db, 0, &key, &value, 0 ))) {
+				if ((ret = db->get( db, NULL, &key, &value, 0 ))) {
 					if (ret != DB_NOTFOUND) {
 						db->err( db, ret, "Error: cannot read UID for '%s'", box );
 						goto ebork;

src/socket.c

@@ -74,7 +74,7 @@ print_ssl_errors( const char *fmt, ... )
 	nfvasprintf( &action, fmt, va );
 	va_end( va );
 	while ((err = ERR_get_error()))
-		error( "Error while %s: %s\n", action, ERR_error_string( err, 0 ) );
+		error( "Error while %s: %s\n", action, ERR_error_string( err, NULL ) );
 	free( action );
 }
 
@@ -85,7 +85,7 @@ print_ssl_socket_errors( const char *func, conn_t *conn )
 	int num = 0;
 
 	while ((err = ERR_get_error())) {
-		error( "Socket error: secure %s %s: %s\n", func, conn->name, ERR_error_string( err, 0 ) );
+		error( "Socket error: secure %s %s: %s\n", func, conn->name, ERR_error_string( err, NULL ) );
 		num++;
 	}
 	return num;
@@ -273,7 +273,7 @@ DIAG_POP
 		return 0;
 	}
 
-	if (conf->cert_file && !SSL_CTX_load_verify_locations( mconf->SSLContext, conf->cert_file, 0 )) {
+	if (conf->cert_file && !SSL_CTX_load_verify_locations( mconf->SSLContext, conf->cert_file, NULL )) {
 		print_ssl_errors( "loading certificate file '%s'", conf->cert_file );
 		return 0;
 	}
@@ -281,7 +281,7 @@ DIAG_POP
 	if (mconf->system_certs && !SSL_CTX_set_default_verify_paths( mconf->SSLContext )) {
 		ulong err;
 		while ((err = ERR_get_error()))
-			warn( "Warning: Unable to load default certificate files: %s\n", ERR_error_string( err, 0 ) );
+			warn( "Warning: Unable to load default certificate files: %s\n", ERR_error_string( err, NULL ) );
 	}
 
 	SSL_CTX_set_verify( mconf->SSLContext, SSL_VERIFY_NONE, NULL );
@@ -602,7 +602,7 @@ socket_connect_next( conn_t *conn )
 {
 	sys_error( "Cannot connect to %s", conn->name );
 	free( conn->name );
-	conn->name = 0;
+	conn->name = NULL;
 	conn->curr_addr = conn->curr_addr->ai_next;
 	socket_connect_one( conn );
 }
@@ -619,7 +619,7 @@ socket_connected( conn_t *conn )
 {
 	if (conn->addrs) {
 		freeaddrinfo( conn->addrs );
-		conn->addrs = 0;
+		conn->addrs = NULL;
 	}
 	conf_notifier( &conn->notify, 0, POLLIN );
 	socket_expect_activity( conn, 0 );
@@ -632,10 +632,10 @@ socket_cleanup_names( conn_t *conn )
 {
 	if (conn->addrs) {
 		freeaddrinfo( conn->addrs );
-		conn->addrs = 0;
+		conn->addrs = NULL;
 	}
 	free( conn->name );
-	conn->name = 0;
+	conn->name = NULL;
 }
 
 static void
@@ -656,7 +656,7 @@ socket_close( conn_t *sock )
 #ifdef HAVE_LIBSSL
 	if (sock->ssl) {
 		SSL_free( sock->ssl );
-		sock->ssl = 0;
+		sock->ssl = NULL;
 		wipe_wakeup( &sock->ssl_fake );
 	}
 #endif
@@ -664,17 +664,17 @@ socket_close( conn_t *sock )
 	if (sock->in_z) {
 		inflateEnd( sock->in_z );
 		free( sock->in_z );
-		sock->in_z = 0;
+		sock->in_z = NULL;
 		deflateEnd( sock->out_z );
 		free( sock->out_z );
-		sock->out_z = 0;
+		sock->out_z = NULL;
 		wipe_wakeup( &sock->z_fake );
 	}
 #endif
 	while (sock->write_buf)
 		dispose_chunk( sock );
 	free( sock->append_buf );
-	sock->append_buf = 0;
+	sock->append_buf = NULL;
 }
 
 static int
@@ -822,7 +822,7 @@ socket_read_line( conn_t *b )
 		}
 		if (b->state == SCK_EOF)
 			return (void *)~0;
-		return 0;
+		return NULL;
 	}
 	n = (uint)(p + 1 - s);
 	b->offset += n;
@@ -902,7 +902,7 @@ do_queued_write( conn_t *conn )
 static void
 do_append( conn_t *conn, buff_chunk_t *bc )
 {
-	bc->next = 0;
+	bc->next = NULL;
 	conn->buffer_mem += bc->len;
 	*conn->write_buf_append = bc;
 	conn->write_buf_append = &bc->next;
@@ -942,7 +942,7 @@ do_flush( conn_t *conn )
 			bc->len = (uint)((char *)conn->out_z->next_out - bc->data);
 			if (bc->len) {
 				do_append( conn, bc );
-				bc = 0;
+				bc = NULL;
 				buf_avail = 0;
 			} else {
 				buf_avail = conn->out_z->avail_out;
@@ -955,7 +955,7 @@ do_flush( conn_t *conn )
 #endif
 	if (bc) {
 		do_append( conn, bc );
-		conn->append_buf = 0;
+		conn->append_buf = NULL;
 #ifdef HAVE_LIBZ
 		conn->append_avail = 0;
 #endif
@@ -1033,7 +1033,7 @@ socket_write( conn_t *conn, conn_iovec_t *iov, int iovcnt )
 			}
 			if (!buf_avail) {
 				do_append( conn, bc );
-				bc = 0;
+				bc = NULL;
 				break;
 			}
 		}

src/socket.h

@@ -134,7 +134,7 @@ static INLINE void socket_init( conn_t *conn,
 	conn->write_callback = write_callback;
 	conn->callback_aux = aux;
 	conn->fd = -1;
-	conn->name = 0;
+	conn->name = NULL;
 	conn->write_buf_append = &conn->write_buf;
 }
 void socket_connect( conn_t *conn, void (*cb)( int ok, void *aux ) );

src/sync.c

@@ -237,7 +237,7 @@ static void
 match_tuids( sync_vars_t *svars, int t, message_t *msgs )
 {
 	sync_rec_t *srec;
-	message_t *tmsg, *ntmsg = 0;
+	message_t *tmsg, *ntmsg = NULL;
 	const char *diag;
 	int num_lost = 0;
 
@@ -870,7 +870,7 @@ load_state( sync_vars_t *svars )
 				                 "(got %s, expected " JOURNAL_VERSION ")\n", buf );
 				goto jbail;
 			}
-			srec = 0;
+			srec = NULL;
 			line = 1;
 			while (fgets( buf, sizeof(buf), jfp )) {
 				line++;
@@ -1330,7 +1330,7 @@ box_opened2( sync_vars_t *svars, int t )
 	sync_ref( svars );
 	load_box( svars, M, minwuid, mexcs.array );
 	if (!check_cancel( svars ))
-		load_box( svars, S, (svars->opts[S] & OPEN_OLD) ? 1 : UINT_MAX, (uint_array_t){ 0, 0 } );
+		load_box( svars, S, (svars->opts[S] & OPEN_OLD) ? 1 : UINT_MAX, (uint_array_t){ NULL, 0 } );
 	sync_deref( svars );
 }
 
@@ -1748,7 +1748,7 @@ box_loaded( int sts, message_t *msgs, int total_msgs, int recent_msgs, void *aux
 					// but some are still propagated because they are important, we need to
 					// ensure explicitly that the bulk fetch limit is upped.
 					svars->mmaxxuid = srec->uid[M];
-					srec->msg[M]->srec = 0;
+					srec->msg[M]->srec = NULL;
 					srec->status = S_DEAD;
 				}
 			}
@@ -2063,7 +2063,7 @@ msgs_flags_set( sync_vars_t *svars, int t )
 							cv = nfmalloc( sizeof(*cv) );
 							cv->cb = msg_rtrashed;
 							cv->aux = INV_AUX;
-							cv->srec = 0;
+							cv->srec = NULL;
 							cv->msg = tmsg;
 							copy_msg( cv );
 							if (check_cancel( svars ))

src/util.c

@@ -455,7 +455,7 @@ expand_strdup( const char *s )
 	if (*s == '~') {
 		s++;
 		if (!*s) {
-			p = 0;
+			p = NULL;
 			q = Home;
 		} else if (*s == '/') {
 			p = s;
@@ -468,7 +468,7 @@ expand_strdup( const char *s )
 			} else
 				pw = getpwnam( s );
 			if (!pw)
-				return 0;
+				return NULL;
 			q = pw->pw_dir;
 		}
 		nfasprintf( &r, "%s%s", q, p ? p : "" );
@@ -656,7 +656,7 @@ list_unlink( list_head_t *head )
 	assert( head->prev->next == head);
 	head->next->prev = head->prev;
 	head->prev->next = head->next;
-	head->next = head->prev = 0;
+	head->next = head->prev = NULL;
 }
 
 static notifier_t *notifiers;
@@ -714,7 +714,7 @@ wipe_notifier( notifier_t *sn )
 	for (snp = &notifiers; *snp != sn; snp = &(*snp)->next)
 		assert( *snp );
 	*snp = sn->next;
-	sn->next = 0;
+	sn->next = NULL;
 	changed = 1;
 
 #ifdef HAVE_SYS_POLL_H
@@ -730,7 +730,7 @@ wipe_notifier( notifier_t *sn )
 static time_t
 get_now( void )
 {
-	return time( 0 );
+	return time( NULL );
 }
 
 static list_head_t timers = { &timers, &timers };
@@ -740,7 +740,7 @@ init_wakeup( wakeup_t *tmr, void (*cb)( void * ), void *aux )
 {
 	tmr->cb = cb;
 	tmr->aux = aux;
-	tmr->links.next = tmr->links.prev = 0;
+	tmr->links.next = tmr->links.prev = NULL;
 }
 
 void