[PATCH 1/4] erofs-utils: lib: refactor erofs compressors init

[Guo Xuenan]

Hi Xiang,

On 2023/6/9 17:38, Gao Xiang wrote:
>
>
> On 2023/6/9 16:50, Guo Xuenan via Linux-erofs wrote:
>> refactor compressor code using constructor.
>>
>> Signed-off-by: Guo Xuenan <guoxuenan at huawei.com>
>> ---
>>   lib/compressor.c         | 49 ++++++++++++++++++++++++++++++++++++++++
>>   lib/compressor.h         | 15 ++++++++++++
>>   lib/compressor_liblzma.c |  5 ++++
>>   lib/compressor_lz4.c     |  5 ++++
>>   lib/compressor_lz4hc.c   |  5 ++++
>>   5 files changed, 79 insertions(+)
>>
>> diff --git a/lib/compressor.c b/lib/compressor.c
>> index 52eb761..0fa7105 100644
>> --- a/lib/compressor.c
>> +++ b/lib/compressor.c
>> @@ -22,6 +22,40 @@ static const struct erofs_compressor 
>> *compressors[] = {
>>   #endif
>>   };
>>   +/* compressing configuration specified by users */
>> +static struct erofs_supported_algothrim {
>> +    int algtype;
>> +    const char *name;
>> +} erofs_supported_algothrims[] = {
>> +    { Z_EROFS_COMPRESSION_LZ4, "lz4"},
>> +    { Z_EROFS_COMPRESSION_LZ4, "lz4hc"},
>> +    { Z_EROFS_COMPRESSION_LZMA, "lzma"},
>> +};
>> +
>> +static struct erofs_compressors_cfg erofs_ccfg;
>> +
>> +int erofs_compressor_num(void)
>> +{
>> +    return erofs_ccfg.erofs_ccfg_num;
>
>
>
>> +}
>> +
>> +void erofs_compressor_register(const char *name, const struct 
>> erofs_compressor *alg)
>> +{
>> +    int i;
>> +
>> +    for (i = 0; i < erofs_compressor_num(); i++) {
>> +        if (!strcmp(erofs_ccfg.compressors[i].name, name)) {
>> +            erofs_ccfg.compressors[i].handle.alg = alg;
>
> should we return error?  and also, why we need dynamicly
> register algorithms? liberofs expects to have given
> algorithms all the time...
>
>> +            return;
>> +        }
>> +    }
>> +
>> +    erofs_ccfg.compressors[i].name = name;
>> +    erofs_ccfg.compressors[i].handle.alg = alg;
>> +    erofs_ccfg.compressors[i].algorithmtype = 
>> erofs_supported_algothrims[i].algtype;
>> +    erofs_ccfg.erofs_ccfg_num = ++i;
>> +}
>> +
>>   int erofs_compress_destsize(const struct erofs_compress *c,
>>                   const void *src, unsigned int *srcsize,
>>                   void *dst, unsigned int dstsize, bool inblocks)
>> @@ -106,3 +140,18 @@ int erofs_compressor_exit(struct erofs_compress *c)
>>           return c->alg->exit(c);
>>       return 0;
>>   }
>> +
>> +void __attribute__((constructor(101))) __erofs_compressor_init(void)
>
>
> Honestly I don't like __attribute__((constructor)) and
> __attribute__((destructor)) which could causes unexpected behaviors and
> not good at compatiability.
>
OK,  will dorp them next version.
> Thanks,
> Gao Xiang

-- 
Best regards
Guo Xuenan