[vlc-devel] [PATCH 2/6] modules: check plugin version

[Rémi Denis-Courmont]

Hi,

It was a string with a string comparison before (inside vlc_dlsym). It still is a string comparison.

Of course it could be changed to an integer, but then the meta export macro won't be usable, so it will need more custom code.

Le 19 juillet 2019 10:04:48 GMT+03:00, Steve Lhomme <robux4 at ycbcr.xyz> a écrit :
>On 2019-07-18 21:29, Rémi Denis-Courmont wrote:
>> ---
>>   src/modules/bank.c | 59
>+++++++++++++++++++++++++++++++++++-----------
>>   1 file changed, 45 insertions(+), 14 deletions(-)
>> 
>> diff --git a/src/modules/bank.c b/src/modules/bank.c
>> index 0b551a91bc..f6f5ae1a85 100644
>> --- a/src/modules/bank.c
>> +++ b/src/modules/bank.c
>> @@ -193,6 +193,49 @@ static void module_InitStaticModules(void) { }
>>   #endif
>>   
>>   #ifdef HAVE_DYNAMIC_PLUGINS
>> +static const char *module_GetVersion(void *handle)
>> +{
>> +    const char *(*get_api_version)(void);
>> +
>> +    get_api_version = vlc_dlsym(handle, "vlc_entry_api_version");
>> +    if (get_api_version == NULL)
>> +        return NULL;
>> +
>> +    return get_api_version();
>> +}
>> +
>> +static void *module_Open(struct vlc_logger *log,
>> +                         const char *path, bool fast)
>> +{
>> +    void *handle = vlc_dlopen(path, fast);
>> +    if (handle == NULL)
>> +    {
>> +        char *errmsg = vlc_dlerror();
>> +
>> +        vlc_error(log, "cannot load plug-in %s: %s", path,
>> +                  errmsg ? errmsg : "unknown error");
>> +        free(errmsg);
>> +        return NULL;
>> +    }
>> +
>> +    const char *str = module_GetVersion(handle);
>> +    if (str == NULL) {
>> +        vlc_error(log, "cannot load plug-in %s: %s", path,
>> +                  "unknown version or not a plug-in");
>> +error:
>> +        vlc_dlclose(handle);
>> +        return NULL;
>> +    }
>> +
>> +    if (strcmp(str, VLC_API_VERSION_STRING)) {
>
>Couldn't we use an integer ? Speed-wise this is going backward from
>have 
>no extra check needed because the name we loaded already had the proper
>
>version, which was a feature not a bug.
>
>> +        vlc_error(log, "cannot load plug-in %s: unsupported version
>%s", path,
>> +                  str);
>> +        goto error;
>> +    }
>> +
>> +    return handle;
>> +}
>> +
>>   static const char vlc_entry_name[] = "vlc_entry" MODULE_SUFFIX;
>>   
>>   /**
>> @@ -207,15 +250,9 @@ static const char vlc_entry_name[] = "vlc_entry"
>MODULE_SUFFIX;
>>   static vlc_plugin_t *module_InitDynamic(vlc_object_t *obj, const
>char *path,
>>                                           bool fast)
>>   {
>> -    void *handle = vlc_dlopen(path, fast);
>> +    void *handle = module_Open(obj->logger, path, fast);
>>       if (handle == NULL)
>> -    {
>> -        char *errmsg = vlc_dlerror();
>> -        msg_Err(obj, "cannot load plug-in %s: %s", path,
>> -                errmsg ? errmsg : "unknown error");
>> -        free(errmsg);
>>           return NULL;
>> -    }
>>   
>>       /* Try to resolve the symbol */
>>       vlc_plugin_cb entry = vlc_dlsym(handle, vlc_entry_name);
>> @@ -507,15 +544,9 @@ int module_Map(struct vlc_logger *log,
>vlc_plugin_t *plugin)
>>       /* Try to load the plug-in (without locks, so read-only) */
>>       assert(plugin->abspath != NULL);
>>   
>> -    void *handle = vlc_dlopen(plugin->abspath, false);
>> +    void *handle = module_Open(log, plugin->abspath, false);
>>       if (handle == NULL)
>> -    {
>> -        char *errmsg = vlc_dlerror();
>> -        vlc_error(log, "cannot load plug-in %s: %s",
>> -                  plugin->abspath, errmsg ? errmsg : "unknown
>error");
>> -        free(errmsg);
>>           return -1;
>> -    }
>>   
>>       vlc_plugin_cb entry = vlc_dlsym(handle, vlc_entry_name);
>>       if (entry == NULL)
>> -- 
>> 2.22.0
>> 
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