From patchwork Wed Jan 22 14:08:18 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Shahab Vahedi X-Patchwork-Id: 37464 Received: (qmail 66657 invoked by alias); 22 Jan 2020 14:08:36 -0000 Mailing-List: contact gdb-patches-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Unsubscribe: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: gdb-patches-owner@sourceware.org Delivered-To: mailing list gdb-patches@sourceware.org Received: (qmail 66648 invoked by uid 89); 22 Jan 2020 14:08:35 -0000 Authentication-Results: sourceware.org; auth=none X-Spam-SWARE-Status: No, score=-26.1 required=5.0 tests=BAYES_00, FREEMAIL_FROM, GIT_PATCH_0, GIT_PATCH_1, GIT_PATCH_2, GIT_PATCH_3, KAM_ASCII_DIVIDERS, RCVD_IN_DNSWL_NONE, SPF_PASS autolearn=ham version=3.3.1 spammy= X-HELO: mail-lj1-f195.google.com Received: from mail-lj1-f195.google.com (HELO mail-lj1-f195.google.com) (209.85.208.195) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with ESMTP; Wed, 22 Jan 2020 14:08:33 +0000 Received: by mail-lj1-f195.google.com with SMTP id a13so6928164ljm.10 for ; Wed, 22 Jan 2020 06:08:33 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=eivU/g0jP7rgA1kAglYGmPbnnJJoYb/H7/qyZP01+ck=; b=pNtx2uwyJ8oPfUGTbnieawIBjukbRYlf5v3as5VAmX9ERxnsoMpUY32gFxUPGOrSfQ O4BralSIafexxNE8C8D2P6L4TDRoIH3l2t3eQyETgRNrNxcjkvUk0Mt+PVacdYuAdLOg qfIslTvAC5ZJlHzsLkVcQeXuYorTmx+TWNyDKU6TYiLeFbGK3uFc1D4jjSLUAOSyxdDD rtjEifV4Fjqp/VVieNhFHbgTXIHhwm/KGA8v1RaOCJOsUQB9j37X2S2WqajTjQJ1NPZE zyJpay8VtvTS7PBxC0uKveKE/4n/So8TrEkDIatVLabjEuqRKlSMLuHvfKDwN+A14yI8 e1rA== Return-Path: Received: from archie.internal.synopsys.com ([2a03:1b20:6:f011::2d]) by smtp.gmail.com with ESMTPSA id f11sm8045762lfm.12.2020.01.22.06.08.28 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 22 Jan 2020 06:08:30 -0800 (PST) From: Shahab Vahedi To: gdb-patches@sourceware.org Cc: Shahab Vahedi , Shahab Vahedi , Andrew Burgess , Tom Tromey , Claudiu Zissulescu , Francois Bedard Subject: [PATCH] gdb: Catch exceptions if the source file is not found Date: Wed, 22 Jan 2020 15:08:18 +0100 Message-Id: <20200122140818.84308-1-shahab.vahedi@gmail.com> MIME-Version: 1.0 From: Shahab Vahedi The source_cache::ensure method may throw an exception through the invocation of source_cache::get_plain_source_lines. This happens when the source file is not found. The expected behaviour of "ensure" is only returning "true" or "false" according to the documentation in the header file. So far, if gdb is in source layout and a file is missing, you see some outputs like below: ,---------------------------------------------. | test.c file is loaded in the source window. | | | | int main() | | ... | |---------------------------------------------| | Remote debugging using :1234 | | __start () at /path/to/crt0.S:141 | | /path/to/crt0.S: No such file or directory. | | (gdb) p/x $pc | | $1 = 0x124 | | (gdb) n | | /path/to/crt0.S: No such file or directory. | | (gdb) p/x $pc | | $2 = 0x128 | | (gdb) [pressing arrow-down key] | | (gdb) terminate called after throwing an | | instance of 'gdb_exception_error' | `---------------------------------------------' Other issues have been encountered as well [2]. The patch from Pedro [1] which is about preventing exceptions from crossing the "readline" mitigates the situation by not causing gdb crash, but still there are lots of errors printed: ,---------------------------------------------. | test.c file is loaded in the source window. | | | | int main() | | ... | |---------------------------------------------| | Remote debugging using :1234 | | __start () at /path/to/crt0.S:141 | | /path/to/crt0.S: No such file or directory. | | (gdb) [pressing arrow-down key] | | /path/to/crt0.S: No such file or directory. | | (gdb) [pressing arrow-down key] | | /path/to/crt0.S: No such file or directory. | | (gdb) [pressing arrow-up key] | | /path/to/crt0.S: No such file or directory. | `---------------------------------------------' With the changes of this patch, the behavior is like: ,---------------------------------------------. | initially, source window is empty because | | crt0.S is not found and according to the | | program counter that is the piece of code | | being executed. | | | | later, when we break at main (see commands | | below), this window will be filled with the | | the contents of test.c file. | |---------------------------------------------| | Remote debugging using :1234 | | __start () at /path/to/crt0.S:141 | | (gdb) p/x $pc | | $1 = 0x124 | | (gdb) n | | (gdb) p/x $pc | | $2 = 0x128 | | (gdb) b main | | Breakpoint 1 at 0x334: file test.c, line 8. | | (gdb) cont | | Continuing. | | Breakpoint 1, main () at hello.c:8 | | (gdb) n | | (gdb) | `---------------------------------------------' There is no crash and the error message is completely gone. Maybe it is good practice that the error is shown inside the source window. I tested this change against gdb.base/list-missing-source.exp and there was no regression. [1] https://sourceware.org/ml/gdb-patches/2020-01/msg00440.html [2] It has also been observed in the past that the register values are not transferred from qemu's gdb stub, see: https://github.com/foss-for-synopsys-dwc-arc-processors/toolchain/issues/226 gdb/ChangeLog: 2020-01-22 Shahab Vahedi * source-cache.c (source_cache::ensure): Surround get_plain_source_lines with a try/catch. (source_cache::get_line_charpos): Get rid of try/catch and only check for the return value of "ensure". --- gdb/source-cache.c | 39 +++++++++++++++++++++------------------ 1 file changed, 21 insertions(+), 18 deletions(-) diff --git a/gdb/source-cache.c b/gdb/source-cache.c index 71277ecc9b3..9196e3a19e3 100644 --- a/gdb/source-cache.c +++ b/gdb/source-cache.c @@ -176,7 +176,16 @@ source_cache::ensure (struct symtab *s) } } - std::string contents = get_plain_source_lines (s, fullname); + std::string contents; + try + { + contents = get_plain_source_lines (s, fullname); + } + catch (const gdb_exception_error &e) + { + /* If 's' is not found, an exception is thrown. */ + return false; + } if (source_styling && gdb_stdout->can_emit_style_escape ()) { @@ -241,26 +250,20 @@ bool source_cache::get_line_charpos (struct symtab *s, const std::vector **offsets) { - try - { - std::string fullname = symtab_to_fullname (s); - - auto iter = m_offset_cache.find (fullname); - if (iter == m_offset_cache.end ()) - { - ensure (s); - iter = m_offset_cache.find (fullname); - /* cache_source_text ensured this was entered. */ - gdb_assert (iter != m_offset_cache.end ()); - } + std::string fullname = symtab_to_fullname (s); - *offsets = &iter->second; - return true; - } - catch (const gdb_exception_error &e) + auto iter = m_offset_cache.find (fullname); + if (iter == m_offset_cache.end ()) { - return false; + if (!ensure (s)) + return false; + iter = m_offset_cache.find (fullname); + /* cache_source_text ensured this was entered. */ + gdb_assert (iter != m_offset_cache.end ()); } + + *offsets = &iter->second; + return true; } /* A helper function that extracts the desired source lines from TEXT,