Reads the extra-field of the gz-header into xfield.
If len=0 xf_len returns the size of the extra-field without any data. If len not 0 xf_len returns the no. of bytes copiied into xfield.
Returns Z_STREAM_ERROR on errors or Z_OK.
To use this vi the file must be opened with Mode:
"rb", "r+b" or "w+b"
file/in "gz" filehandle from xzopen. |
len No. of bytes to read. If len is 0, xf_len returns the size of the extra-field and no data are returned. |
Result |
file/out |
xfield Data of extra-field. |
xf_len Returns the no. of bytes read or, if len was 0, the size of the extra-field. |