From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx2.suse.de (mx2.suse.de [195.135.220.15]) by sourceware.org (Postfix) with ESMTPS id 850BF3858D38 for ; Sun, 5 Jul 2020 21:40:52 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.3.2 sourceware.org 850BF3858D38 Authentication-Results: sourceware.org; dmarc=none (p=none dis=none) header.from=suse.de Authentication-Results: sourceware.org; spf=pass smtp.mailfrom=tdevries@suse.de X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id A6506ADF7; Sun, 5 Jul 2020 21:40:51 +0000 (UTC) Date: Sun, 5 Jul 2020 23:40:49 +0200 From: Tom de Vries To: gdb-patches@sourceware.org Cc: Tom Tromey Subject: [PATCH][gdb/tui,c++17] Fix NULL string_view in tui_partial_win_by_name Message-ID: <20200705214048.GA21240@delia> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.10.1 (2018-07-13) X-Spam-Status: No, score=-11.2 required=5.0 tests=BAYES_00, GIT_PATCH_0, KAM_DMARC_STATUS, RCVD_IN_MSPIKE_H3, RCVD_IN_MSPIKE_WL, SPF_HELO_NONE, SPF_PASS, TXREP autolearn=ham autolearn_force=no version=3.4.2 X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on server2.sourceware.org X-BeenThere: gdb-patches@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Gdb-patches mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 05 Jul 2020 21:40:54 -0000 Hi, When building gdb with CFLAGS=-std=gnu17 and CXXFLAGS=-std=gnu++17 and running test-case gdb.tui/new-layout.exp, we run into: ... UNRESOLVED: gdb.tui/new-layout.exp: left window box after shrink (ll corner) FAIL: gdb.tui/new-layout.exp: right window box after shrink (ll corner) ... In a minimal form, we run into an abort when issuing a winheight command: ... $ gdb -tui -ex "winheight src - 5" Aborted (core dumped) $ ... with this backtrace at the abort: ... \#0 0x0000000000438db0 in std::char_traits::length (__s=0x0) at /usr/include/c++/9/bits/char_traits.h:335 \#1 0x000000000043b72e in std::basic_string_view >::basic_string_view (this=0x7fffffffd4f0, \ __str=0x0) at /usr/include/c++/9/string_view:124 \#2 0x000000000094971b in tui_partial_win_by_name (name="src") at src/gdb/tui/tui-win.c:663 ... due to a NULL comparison which constructs a string_view object from NULL: ... 657 /* Answer the window represented by name. */ 658 static struct tui_win_info * 659 tui_partial_win_by_name (gdb::string_view name) 660 { 661 struct tui_win_info *best = nullptr; 662 663 if (name != NULL) ... In gdbsupport/gdb_string_view.h, we either use: - gdb's copy of libstdc++-v3/include/experimental/string_view, or - the standard implementation of string_view, when built with C++17 or later (which in gcc's case comes from libstdc++-v3/include/std/string_view) In the first case, there's support for constructing a string_view from a NULL pointer: ... /*constexpr*/ basic_string_view(const _CharT* __str) : _M_len{__str == nullptr ? 0 : traits_type::length(__str)}, _M_str{__str} { } ... but in the second case, there's not: ... __attribute__((__nonnull__)) constexpr basic_string_view(const _CharT* __str) noexcept : _M_len{traits_type::length(__str)}, _M_str{__str} { } ... Fix this by removing the NULL comparison altogether. Build on x86_64-linux with CFLAGS=-std=gnu17 and CXXFLAGS=-std=gnu++17, and tested. Any comments? Thanks, - Tom [gdb/tui,c++17] Fix NULL string_view in tui_partial_win_by_name gdb/ChangeLog: 2020-07-05 Tom de Vries PR tui/26205 * tui/tui-win.c (tui_partial_win_by_name): Don't test for NULL name. --- gdb/tui/tui-win.c | 23 ++++++++++------------- 1 file changed, 10 insertions(+), 13 deletions(-) diff --git a/gdb/tui/tui-win.c b/gdb/tui/tui-win.c index 336571f158..f906b0dc4f 100644 --- a/gdb/tui/tui-win.c +++ b/gdb/tui/tui-win.c @@ -660,21 +660,18 @@ tui_partial_win_by_name (gdb::string_view name) { struct tui_win_info *best = nullptr; - if (name != NULL) + for (tui_win_info *item : all_tui_windows ()) { - for (tui_win_info *item : all_tui_windows ()) - { - const char *cur_name = item->name (); + const char *cur_name = item->name (); - if (name == cur_name) - return item; - if (startswith (cur_name, name)) - { - if (best != nullptr) - error (_("Window name \"%*s\" is ambiguous"), - (int) name.size (), name.data ()); - best = item; - } + if (name == cur_name) + return item; + if (startswith (cur_name, name)) + { + if (best != nullptr) + error (_("Window name \"%*s\" is ambiguous"), + (int) name.size (), name.data ()); + best = item; } }