From: Tomi Ollila <tomi.ollila@iki.fi>
Date: Sat, 27 Apr 2013 13:22:01 +0000 (+0300)
Subject: Re: [PATCH] don't store temporary value returned from c_str()
X-Git-Url: http://git.tremily.us/?a=commitdiff_plain;h=6abc9b27e545ffda5b9aaebb464f4b99af261b9d;p=notmuch-archives.git

Re: [PATCH] don't store temporary value returned from c_str()
---

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+From: Tomi Ollila <tomi.ollila@iki.fi>
+To: Jani Nikula <jani@nikula.org>, Vladimir.Marek@oracle.com,
+	notmuch@notmuchmail.org
+Subject: Re: [PATCH] don't store temporary value returned from c_str()
+In-Reply-To: <878v44qhop.fsf@nikula.org>
+References: <1366405933-17223-1-git-send-email-Vladimir.Marek@oracle.com>
+	<878v44qhop.fsf@nikula.org>
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+Date: Sat, 27 Apr 2013 16:22:01 +0300
+Message-ID: <m261z8hzwm.fsf@guru.guru-group.fi>
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+Content-Type: text/plain
+Cc: Vladimir Marek <vlmarek@volny.cz>
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+
+On Sat, Apr 27 2013, Jani Nikula <jani@nikula.org> wrote:
+
+> On Sat, 20 Apr 2013, Vladimir.Marek@oracle.com wrote:
+>> From: Vladimir Marek <vlmarek@volny.cz>
+>>
+>> This is causing problems when compiled by Oracle Studio. Memory pointed
+>> by (const char*)term was already changed once talloc_strdup was called.
+>>
+>> Signed-off-by: Vladimir Marek <vlmarek@volny.cz>
+>> ---
+>>  lib/message.cc |    9 ++++-----
+>>  1 files changed, 4 insertions(+), 5 deletions(-)
+>>
+>> diff --git a/lib/message.cc b/lib/message.cc
+>> index 8720c1b..8d329d1 100644
+>> --- a/lib/message.cc
+>> +++ b/lib/message.cc
+>> @@ -266,18 +266,17 @@ _notmuch_message_get_term (notmuch_message_t *message,
+>>  			   const char *prefix)
+>>  {
+>>      int prefix_len = strlen (prefix);
+>> -    const char *term = NULL;
+>>      char *value;
+>>  
+>>      i.skip_to (prefix);
+>>  
+>> -    if (i != end)
+>> -	term = (*i).c_str ();
+>
+> It's okay to use the result of .c_str() as long as the string object
+> stays in scope, and none of the non-const member functions are
+> called. Here, I think the problem is that TermIterator's overloaded
+> operator*() returns a string object within the if block's scope, and it
+> goes immediately out of scope. You could check this by adding
+>
+> 	string s = *i;
+>
+> in function scope, and replacing (*i) with s in the if block. This might
+> also be more obvious than the presented patch, but I think the patch is
+> fine too.
+
+Thanks, now I understand. I'd like to see updated patch using Jani's
+example but I also think that the current patch is fine too.
+
+>
+> BR,
+> Jani.
+
+Tomi
+
+>
+>
+>> +    if (i == end)
+>> +	return NULL;
+>>  
+>> -    if (!term || strncmp (term, prefix, prefix_len))
+>> +    if (strncmp ((*i).c_str(), prefix, prefix_len))
+>>  	return NULL;
+>>  
+>> -    value = talloc_strdup (message, term + prefix_len);
+>> +    value = talloc_strdup (message, (*i).c_str() + prefix_len);
+>>  
+>>  #if DEBUG_DATABASE_SANITY
+>>      i++;
+>> -- 
+>> 1.7.3.2
+>>
+>> _______________________________________________
+>> notmuch mailing list
+>> notmuch@notmuchmail.org
+>> http://notmuchmail.org/mailman/listinfo/notmuch
+> _______________________________________________
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