From patchwork Thu May 4 14:17:07 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Pedro Alves X-Patchwork-Id: 20273 Received: (qmail 7110 invoked by alias); 4 May 2017 14:17:12 -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 7099 invoked by uid 89); 4 May 2017 14:17:11 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-24.2 required=5.0 tests=AWL, BAYES_00, GIT_PATCH_0, GIT_PATCH_1, GIT_PATCH_2, GIT_PATCH_3, KAM_LAZY_DOMAIN_SECURITY, RCVD_IN_DNSWL_NONE autolearn=ham version=3.3.2 spammy=worries X-HELO: mail-wm0-f46.google.com Received: from mail-wm0-f46.google.com (HELO mail-wm0-f46.google.com) (74.125.82.46) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with ESMTP; Thu, 04 May 2017 14:17:09 +0000 Received: by mail-wm0-f46.google.com with SMTP id u65so2763113wmu.1 for ; Thu, 04 May 2017 07:17:11 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:references:cc:from:message-id:date :user-agent:mime-version:in-reply-to:content-transfer-encoding; bh=I+x80UEMiFl/CH12ywnLJ7Niz53Enj6zTzFnlKvgREc=; b=WGSVSE3KDoPckaHGC6M76+hR7Pk7j+XxRJNh+Vhu7ldfNZFjUJZ6zqwwIRhNwaW/N+ pctesgzi4IWSVYgao61bAdmPVQmZtNgXgXKF5uqKX1hL0pIuILsvbWRVldSiWZSDN+/W EsTzgwyhOvjJ0bu+FjXuvXyvRUFu8LYK32JAR+WLXnur4Z6dfscLxCjTx1IvIsQlAwUl 5Xxo5ay6Ai4coy+Q7Q3B7aTj6k3nLgBULdaRgOkgeJKsCbXhUQZ/okPM6zvuNQd39lWX PqialuYYrVxmmibPE2AXRU9KVSAYKlko1rU1kGy6n5tXkQHN9UlXK6VgLJZU5WoCDEiO h/oA== X-Gm-Message-State: AN3rC/62I/LCAjLA8G0CxNW0psGS3oWDSCVYu/anPXTysXn00f2ucS1A XaMGEcdzxRVR6ODm X-Received: by 10.28.213.72 with SMTP id m69mr2011245wmg.9.1493907429332; Thu, 04 May 2017 07:17:09 -0700 (PDT) Received: from [192.168.0.102] ([37.189.166.198]) by smtp.gmail.com with ESMTPSA id w10sm1947082wmw.14.2017.05.04.07.17.07 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 04 May 2017 07:17:08 -0700 (PDT) Subject: Re: [PATCH obv] Remove some superfluous code in corelow.c To: Andreas Arnez References: Cc: gdb-patches@sourceware.org From: Pedro Alves Message-ID: Date: Thu, 4 May 2017 15:17:07 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.4.0 MIME-Version: 1.0 In-Reply-To: On 05/04/2017 12:58 PM, Andreas Arnez wrote: > Oh my, you're right, of course. Sorry for that. No worries. >> The easiest to fix that nowadays is to use a std::string. >> >> I don't see a need to xstrdup the section name in the single-threaded >> case though, and also there's more than one place that computes >> a multi-threaded section name in the same way, so how about the >> patch below? > > Yeah, looks OK to me. Tested on x86_64 GNU/Linux and pushed now. From 3c3ae77e68a9032ef9f174bf6b1cc992b6a4cb35 Mon Sep 17 00:00:00 2001 From: Pedro Alves Date: Thu, 4 May 2017 15:14:37 +0100 Subject: [PATCH] Fix get_core_register_section leak, introduce thread_section_name This plugs a leak introduced in the previous change to get_core_register_section, which removed an xfree call that is actually necessary because the 'section_name' local is static. From [1] it looks like the reason the variable was made static to begin with, was just "laziness" to avoid having to think about freeing it on every function return path: https://sourceware.org/ml/gdb-patches/2005-03/msg00237.html The easiest to fix that nowadays is to use a std::string. I don't see a need to xstrdup the section name in the single-threaded case though, and also there's more than one place that computes a multi-threaded section name in the same way. So put the section name computation in a wrapper class with state. gdb/ChangeLog: 2017-05-04 Pedro Alves * corelow.c (thread_section_name): New class. (get_core_register_section, get_core_siginfo): Use it. --- gdb/ChangeLog | 5 ++++ gdb/corelow.c | 76 +++++++++++++++++++++++++++++++++++++++++------------------ 2 files changed, 58 insertions(+), 23 deletions(-) diff --git a/gdb/ChangeLog b/gdb/ChangeLog index de4d90f..aeb83dd 100644 --- a/gdb/ChangeLog +++ b/gdb/ChangeLog @@ -1,3 +1,8 @@ +2017-05-04 Pedro Alves + + * corelow.c (thread_section_name): New class. + (get_core_register_section, get_core_siginfo): Use it. + 2017-05-04 Andreas Arnez * corelow.c (sniff_core_bfd): Remove extra semicolon. diff --git a/gdb/corelow.c b/gdb/corelow.c index 2266f24..0aff02d 100644 --- a/gdb/corelow.c +++ b/gdb/corelow.c @@ -485,6 +485,51 @@ core_detach (struct target_ops *ops, const char *args, int from_tty) printf_filtered (_("No core file now.\n")); } +/* Build either a single-thread or multi-threaded section name for + PTID. + + If ptid's lwp member is zero, we want to do the single-threaded + thing: look for a section named NAME (as passed to the + constructor). If ptid's lwp member is non-zero, we'll want do the + multi-threaded thing: look for a section named "NAME/LWP", where + LWP is the shortest ASCII decimal representation of ptid's lwp + member. */ + +class thread_section_name +{ +public: + /* NAME is the single-threaded section name. If PTID represents an + LWP, then the build section name is "NAME/LWP", otherwise it's + just "NAME" unmodified. */ + thread_section_name (const char *name, ptid_t ptid) + { + if (ptid.lwp_p ()) + { + m_storage = string_printf ("%s/%ld", name, ptid.lwp ()); + m_section_name = m_storage.c_str (); + } + else + m_section_name = name; + } + + /* Return the computed section name. The result is valid as long as + this thread_section_name object is live. */ + const char *c_str () const + { return m_section_name; } + + /* Disable copy. */ + thread_section_name (const thread_section_name &) = delete; + void operator= (const thread_section_name &) = delete; + +private: + /* Either a pointer into M_STORAGE, or a pointer to the name passed + as parameter to the constructor. */ + const char *m_section_name; + /* If we need to build a new section name, this is where we store + it. */ + std::string m_storage; +}; + /* Try to retrieve registers from a section in core_bfd, and supply them to core_vec->core_read_registers, as the register set numbered WHICH. @@ -511,21 +556,15 @@ get_core_register_section (struct regcache *regcache, const char *human_name, int required) { - static char *section_name; struct bfd_section *section; bfd_size_type size; char *contents; bool variable_size_section = (regset != NULL && regset->flags & REGSET_VARIABLE_SIZE); - ptid_t ptid = regcache_get_ptid (regcache); - if (ptid_get_lwp (ptid)) - section_name = xstrprintf ("%s/%ld", name, - ptid_get_lwp (ptid)); - else - section_name = xstrdup (name); + thread_section_name section_name (name, regcache->ptid ()); - section = bfd_get_section_by_name (core_bfd, section_name); + section = bfd_get_section_by_name (core_bfd, section_name.c_str ()); if (! section) { if (required) @@ -537,13 +576,14 @@ get_core_register_section (struct regcache *regcache, size = bfd_section_size (core_bfd, section); if (size < min_size) { - warning (_("Section `%s' in core file too small."), section_name); + warning (_("Section `%s' in core file too small."), + section_name.c_str ()); return; } if (size != min_size && !variable_size_section) { warning (_("Unexpected size of section `%s' in core file."), - section_name); + section_name.c_str ()); } contents = (char *) alloca (size); @@ -551,7 +591,7 @@ get_core_register_section (struct regcache *regcache, (file_ptr) 0, size)) { warning (_("Couldn't read %s registers from `%s' section in core file."), - human_name, name); + human_name, section_name.c_str ()); return; } @@ -681,18 +721,8 @@ add_to_spuid_list (bfd *abfd, asection *asect, void *list_p) static LONGEST get_core_siginfo (bfd *abfd, gdb_byte *readbuf, ULONGEST offset, ULONGEST len) { - asection *section; - char *section_name; - const char *name = ".note.linuxcore.siginfo"; - - if (ptid_get_lwp (inferior_ptid)) - section_name = xstrprintf ("%s/%ld", name, - ptid_get_lwp (inferior_ptid)); - else - section_name = xstrdup (name); - - section = bfd_get_section_by_name (abfd, section_name); - xfree (section_name); + thread_section_name section_name (".note.linuxcore.siginfo", inferior_ptid); + asection *section = bfd_get_section_by_name (abfd, section_name.c_str ()); if (section == NULL) return -1;