Overwrites the extra-field data of the gz-header from xfield.
if xfield is empty xf_len returns the size of the extra-field otherwise xfield returns the no. of bytes written.
Returns Z_STREAM_ERROR on errors or Z_OK.
To use this vi the file must be opened with Mode:
"r+b", "wb" or "w+b"
file/in "gz" filehandle from xzopen. |
xfield If xfield is empty, xf_len returns the size of the extra-field in the gz-header, otherwise xfield will be copiied into the extra-field and xf_len returns the no. of bytes written. |
Result |
file/out |
xf_len If xfield is empty, xf_len returns the size of the extra-field in the gz-header, otherwise xfield will be copiied into the extra-field and xf_len returns the no. of bytes written. |