[PATCH] erofs-utils: add I/O control for tarerofs stream via `erofs_vfile`

[Hongzhen Luo]

On 2024/6/11 16:00, Gao Xiang wrote:
> Hi,
>
> On 2024/6/11 15:54, Hongzhen Luo wrote:
>> This adds I/O control for tarerofs stream.
>>
>> Signed-off-by: Hongzhen Luo <hongzhen at linux.alibaba.com>
>> ---
>>   include/erofs/io.h  |  1 +
>>   include/erofs/tar.h |  2 +-
>>   lib/tar.c           | 16 ++++++++++------
>>   3 files changed, 12 insertions(+), 7 deletions(-)
>>
>> diff --git a/include/erofs/io.h b/include/erofs/io.h
>> index c82dfdf..a501685 100644
>> --- a/include/erofs/io.h
>> +++ b/include/erofs/io.h
>> @@ -26,6 +26,7 @@ struct erofs_vfile;
>>     struct erofs_vfops {
>>       int (*pread)(struct erofs_vfile *vf, void *buf, u64 offset, 
>> size_t len);
>> +    int (*read)(struct erofs_vfile *vf, void *buf, size_t len);
>
> I think you need to add both read and lseek.
>
>
>>       int (*pwrite)(struct erofs_vfile *vf, const void *buf, u64 
>> offset, size_t len);
>>       int (*fsync)(struct erofs_vfile *vf);
>>       int (*fallocate)(struct erofs_vfile *vf, u64 offset, size_t 
>> len, bool pad);
>> diff --git a/include/erofs/tar.h b/include/erofs/tar.h
>> index b5c966b..e1de0df 100644
>> --- a/include/erofs/tar.h
>> +++ b/include/erofs/tar.h
>> @@ -39,7 +39,7 @@ struct erofs_iostream_liblzma {
>>     struct erofs_iostream {
>>       union {
>> -        int fd;            /* original fd */
>> +        struct erofs_vfile vf;
>>           void *handler;
>>   #ifdef HAVE_LIBLZMA
>>           struct erofs_iostream_liblzma *lzma;
>> diff --git a/lib/tar.c b/lib/tar.c
>> index 3514381..77e09ae 100644
>> --- a/lib/tar.c
>> +++ b/lib/tar.c
>> @@ -79,7 +79,7 @@ void erofs_iostream_close(struct erofs_iostream *ios)
>>   #endif
>>           return;
>>       }
>> -    close(ios->fd);
>> +    close(ios->vf.fd);
>>   }
>>     int erofs_iostream_open(struct erofs_iostream *ios, int fd, int 
>> decoder)
>> @@ -119,7 +119,7 @@ int erofs_iostream_open(struct erofs_iostream 
>> *ios, int fd, int decoder)
>>           return -EOPNOTSUPP;
>>   #endif
>>       } else {
>> -        ios->fd = fd;
>> +        ios->vf.fd = fd;
>>           fsz = lseek(fd, 0, SEEK_END);
>>           if (fsz <= 0) {
>>               ios->feof = !fsz;
>> @@ -218,8 +218,12 @@ int erofs_iostream_read(struct erofs_iostream 
>> *ios, void **buf, u64 bytes)
>>               return -EOPNOTSUPP;
>>   #endif
>>           } else {
>> -            ret = erofs_read_from_fd(ios->fd, ios->buffer + rabytes,
>> -                         ios->bufsize - rabytes);
>> +            if (ios->vf.ops)
>> +                ret = ios->vf.ops->read(&ios->vf, ios->buffer + 
>> rabytes,
>> +                             ios->bufsize - rabytes);
>> +            else
>> +                ret = erofs_read_from_fd(ios->vf.fd, ios->buffer + 
>> rabytes,
>> +                             ios->bufsize - rabytes);
>
> I guess this could be moved into lib/io.c? and call erofs_io_read() here.
>
>>               if (ret < 0)
>>                   return ret;
>>               ios->tail += ret;
>> @@ -270,8 +274,8 @@ int erofs_iostream_lskip(struct erofs_iostream 
>> *ios, u64 sz)
>>       if (ios->feof)
>>           return sz;
>>   -    if (ios->sz && likely(ios->dumpfd < 0)) {
>> -        s64 cur = lseek(ios->fd, sz, SEEK_CUR);
>> +    if (ios->sz && likely(ios->dumpfd < 0) && !ios->vf.ops) {
>> +        s64 cur = lseek(ios->vf.fd, sz, SEEK_CUR);
>
> Same here, erofs_io_lseek is needed.
>
> Thanks,
> Gao Xiang

Ok, I will send a new version later.

---

Thanks,

Hongzhen Luo