[PATCH v2 3/4] erofs-utils: add erofs_read_metadata() helper

[Jingbo Xu]

On 8/16/23 11:58 AM, Gao Xiang wrote:
> 
> 
> On 2023/8/16 11:49, Jingbo Xu wrote:
>> Add erofs_read_metadata() helper reading variable-sized metadata from
>> inode specified by @nid.  Read from meta inode if @nid is 0.
>>
>> Signed-off-by: Jingbo Xu <jefflexu at linux.alibaba.com>
>> ---
>>   include/erofs/internal.h |  2 +
>>   lib/data.c               | 84 ++++++++++++++++++++++++++++++++++++++++
>>   2 files changed, 86 insertions(+)
>>
>> diff --git a/include/erofs/internal.h b/include/erofs/internal.h
>> index a04e6a6..3e7319d 100644
>> --- a/include/erofs/internal.h
>> +++ b/include/erofs/internal.h
>> @@ -364,6 +364,8 @@ int erofs_read_one_data(struct erofs_inode *inode,
>> struct erofs_map_blocks *map,
>>   int z_erofs_read_one_data(struct erofs_inode *inode,
>>               struct erofs_map_blocks *map, char *raw, char *buffer,
>>               erofs_off_t skip, erofs_off_t length, bool trimmed);
>> +void *erofs_read_metadata(struct erofs_sb_info *sbi, erofs_nid_t nid,
>> +              erofs_off_t *offset, int *lengthp);
>>     static inline int erofs_get_occupied_size(const struct erofs_inode
>> *inode,
>>                         erofs_off_t *size)
>> diff --git a/lib/data.c b/lib/data.c
>> index a172bb5..3ec5330 100644
>> --- a/lib/data.c
>> +++ b/lib/data.c
>> @@ -372,3 +372,87 @@ int erofs_pread(struct erofs_inode *inode, char
>> *buf,
>>       }
>>       return -EINVAL;
>>   }
>> +
>> +static void *erofs_read_meta(struct erofs_sb_info *sbi, erofs_nid_t nid,
>> +                 erofs_off_t *offset, int *lengthp)
> 
> erofs_read_metadata_nid?

Okay.

> 
>> +{
>> +    struct erofs_inode vi = { .sbi = sbi, .nid = nid };
>> +    __le16 __len;
>> +    int ret, len;
>> +    char *buffer;
>> +
>> +    ret = erofs_read_inode_from_disk(&vi);
>> +    if (ret)
>> +        return ERR_PTR(ret);
>> +
>> +    *offset = round_up(*offset, 4);
>> +    ret = erofs_pread(&vi, (void *)&__len, sizeof(__le16), *offset);
>> +    if (ret)
>> +        return ERR_PTR(ret);
>> +
>> +    len = le16_to_cpu(__len);
>> +    if (!len)
>> +        return ERR_PTR(-EFSCORRUPTED);
>> +
>> +    buffer = malloc(len);
>> +    if (!buffer)
>> +        return ERR_PTR(-ENOMEM);
>> +    *offset += sizeof(__le16);
>> +    *lengthp = len;
>> +
>> +    ret = erofs_pread(&vi, buffer, len, *offset);
>> +    if (ret) {
>> +        free(buffer);
>> +        return ERR_PTR(ret);
>> +    }
>> +    *offset += len;
>> +    return buffer;
>> +}
>> +
>> +static void *erofs_read_metainode(struct erofs_sb_info *sbi,
>> +                  erofs_off_t *offset, int *lengthp)
> 
> erofs_read_metadata_bdi?

Okay.


-- 
Thanks,
Jingbo