Re: [PATCH v4 5/8] migration: converts exec backend to accept MigrateAddress struct.

[Het Gala <het.gala@nutanix.com>]

On 15/05/23 3:59 pm, Daniel P. Berrangé wrote:
> On Fri, May 12, 2023 at 02:32:37PM +0000, Het Gala wrote:
>> Exec transport backend for 'migrate'/'migrate-incoming' QAPIs accept
>> new wire protocol of MigrateAddress struct.
>>
>> It is achived by parsing 'uri' string and storing migration parameters
>> required for exec connection into strList struct.
>>
>> Suggested-by: Aravind Retnakaran <aravind.retnakaran@nutanix.com>
>> Signed-off-by: Het Gala <het.gala@nutanix.com>
>> ---
>>   migration/exec.c      | 58 ++++++++++++++++++++++++++++++++-----------
>>   migration/exec.h      |  4 +--
>>   migration/migration.c | 10 +++-----
>>   3 files changed, 50 insertions(+), 22 deletions(-)
>>
>> diff --git a/migration/exec.c b/migration/exec.c
>> index c4a3293246..210f4e9400 100644
>> --- a/migration/exec.c
>> +++ b/migration/exec.c
>> @@ -39,22 +39,51 @@ const char *exec_get_cmd_path(void)
>>   }
>>   #endif
>>   
>> -void exec_start_outgoing_migration(MigrationState *s, const char *command,
>> +/* provides the length of strList */
>> +static int
>> +str_list_length(strList *list)
>> +{
>> +    int len = 0;
>> +    strList *elem;
>> +
>> +    for (elem = list; elem != NULL; elem = elem->next) {
>> +        len++;
>> +    }
>> +
>> +    return len;
>> +}
>> +

Juan for your comment : "I can't believe tat we have a list type and we 
don't have a length() function for that type."

I had seen come patches regarding adding utility for finding length of a 
strList in util.h file as a MACRO, but I think the patches have still 
not gone in.

>> +static void
>> +init_exec_array(strList *command, const char **argv, Error **errp)
>> +{
>> +    int i = 0;
>> +    strList *lst;
>> +
>> +    for (lst = command; lst; lst = lst->next) {
>> +        argv[i++] = lst->value;
>> +    }
>> +
>> +    argv[i] = NULL;
>> +    return;
>> +}
>> +
>> +void exec_start_outgoing_migration(MigrationState *s, strList *command,
>>                                      Error **errp)
>>   {
>>       QIOChannel *ioc;
>>   
>> -#ifdef WIN32
>> -    const char *argv[] = { exec_get_cmd_path(), "/c", command, NULL };
>> -#else
>> -    const char *argv[] = { "/bin/sh", "-c", command, NULL };
>> -#endif
>> +    int length = str_list_length(command);
>> +    const char **argv = g_malloc0(length * sizeof(const char *));
> g_malloc0 is almost never desirable to use, instead:
>
>          g_new0(const char *, length);
Ack. Will change that.
>>   
>> -    trace_migration_exec_outgoing(command);
>> +    init_exec_array(command, argv, errp);
>> +    char *new_command = g_strjoinv(" ", (char **)argv);
> Never freed - use
>
>     g_autofree char *new_command...
Ack.
>> +    trace_migration_exec_outgoing(new_command);
>>
>>       ioc = QIO_CHANNEL(qio_channel_command_new_spawn(argv,
>>                                                       O_RDWR,
>>                                                       errp));
>>       if (!ioc) {
>> +        g_free(argv);
>>           return;
>>       }
> argv needs freeing in success too. Simpler to declare it
> with
>
>      g_auto(GStrv) argv = .....
Yes, Ack.
>>   
>> @@ -72,21 +101,22 @@ static gboolean exec_accept_incoming_migration(QIOChannel *ioc,
>>       return G_SOURCE_REMOVE;
>>   }
>>   
>> -void exec_start_incoming_migration(const char *command, Error **errp)
>> +void exec_start_incoming_migration(strList *command, Error **errp)
>>   {
>>       QIOChannel *ioc;
>>   
>> -#ifdef WIN32
>> -    const char *argv[] = { exec_get_cmd_path(), "/c", command, NULL };
>> -#else
>> -    const char *argv[] = { "/bin/sh", "-c", command, NULL };
>> -#endif
>> +    int length = str_list_length(command);
>> +    const char **argv = g_malloc0(length * sizeof(const char *));
>> +
>> +    init_exec_array(command, argv, errp);
>> +    char *new_command = g_strjoinv(" ", (char **)argv);
>>   
>> -    trace_migration_exec_incoming(command);
>> +    trace_migration_exec_incoming(new_command);
>>       ioc = QIO_CHANNEL(qio_channel_command_new_spawn(argv,
>>                                                       O_RDWR,
>>                                                       errp));
>>       if (!ioc) {
>> +        g_free(argv);
>>           return;
>>       }
> All the same comments as the outgoing case.
Ack. Thanks Daniel for the inputs.
> With regards,
> Daniel
Regards,
Het Gala