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Re: [PATCH 2/2] remote.c, QCatchSyscalls: Build std::string instead of unique_xmalloc_ptr (Re: [RFA 4/6] Simple cleanup removals in remote.c)
On 10/19/2017 04:17 AM, Simon Marchi wrote:
> On 2017-10-16 19:38, Pedro Alves wrote:
>> diff --git a/gdb/remote.c b/gdb/remote.c
>> index 6b77a9f..a6cb724 100644
>> --- a/gdb/remote.c
>> +++ b/gdb/remote.c
>> @@ -2086,40 +2086,32 @@ remote_set_syscall_catchpoint (struct
>> target_ops *self,
>> pid, needed, any_count, n_sysno);
>> }
>>
>> - gdb::unique_xmalloc_ptr<char> built_packet;
>> + std::string built_packet;
>> if (needed)
>> {
>> /* Prepare a packet with the sysno list, assuming max 8+1
>> characters for a sysno. If the resulting packet size is too
>> big, fallback on the non-selective packet. */
>> const int maxpktsz = strlen ("QCatchSyscalls:1") + n_sysno * 9
>> + 1;
>> -
>> - built_packet.reset ((char *) xmalloc (maxpktsz));
>> - strcpy (built_packet.get (), "QCatchSyscalls:1");
>> + built_packet.reserve (maxpktsz);
>> + built_packet = "QCatchSyscalls:1";
>> if (!any_count)
>> {
>> - int i;
>> - char *p;
>> -
>> - p = built_packet.get ();
>> - p += strlen (p);
>> -
>> /* Add in catch_packet each syscall to be caught (table[i] !=
>> 0). */
>> - for (i = 0; i < table_size; i++)
>> + for (int i = 0; i < table_size; i++)
>> {
>> if (table[i] != 0)
>> - p += xsnprintf (p, built_packet.get () + maxpktsz - p,
>> - ";%x", i);
>> + string_appendf (built_packet, ";%x", i);
>> }
>> }
>> - if (strlen (built_packet.get ()) > get_remote_packet_size ())
>> + if (built_packet.size () > get_remote_packet_size ())
>> {
>> /* catch_packet too big. Fallback to less efficient
>> non selective mode, with GDB doing the filtering. */
>> catch_packet = "QCatchSyscalls:1";
>> }
>> else
>> - catch_packet = built_packet.get ();
>> + catch_packet = built_packet.c_str ();
>
> You can get rid of built_packet, and make catch_packet the std::string.
> And then this last else branch can be removed.
The reason I didn't do that is because that'd introduce an
allocation + one deep string copy in the '!needed' case:
else
catch_packet = "QCatchSyscalls:0";
when it's very easy to avoid.
So I pushed the patch in as is.
Thanks,
Pedro Alves