NAME
zip_file_extra_field_get,
  
zip_file_extra_field_get_by_id — 
get
  extra field for file in zip
LIBRARY
libzip (-lzip)
SYNOPSIS
#include <zip.h>
const zip_uint8_t *
zip_file_extra_field_get(
zip_t
  *archive, 
zip_uint64_t
  index, 
zip_uint16_t
  extra_field_index,
  
zip_uint16_t *idp,
  
zip_uint16_t *lenp,
  
zip_flags_t flags);
const zip_uint8_t *
zip_file_extra_field_get_by_id(
zip_t
  *archive, 
zip_uint64_t
  index, 
zip_uint16_t
  extra_field_id,
  
zip_uint16_t
  extra_field_index,
  
zip_uint16_t *lenp,
  
zip_flags_t flags);
DESCRIPTION
The 
zip_file_extra_field_get() function returns the extra
  field with index 
extra_field_index for the file at
  position 
index in the zip archive. This pointer should
  not be modified or 
free(3)'d, and becomes
  invalid when 
archive is closed. If
  
idp is not 
NULL, the integer to
  which it points will be set to the ID (two-byte signature) of the selected
  extra field. If 
lenp is not
  
NULL, the integer to which it points will be set to
  the length of the extra field. Generally speaking, 
lenp
  and 
idp should be passed since only the extra field data
  is returned (i.e., neither the ID nor the length, if the
  
idp and 
lenp arguments are not
  provided).
The following 
flags are supported:
  -  
-  
- ZIP_FL_CENTRAL
- Return extra fields from the archive's central
    directory.
-  
-  
- ZIP_FL_LOCAL
- Return extra fields from the local file headers.
-  
-  
- ZIP_FL_UNCHANGED
- Return the original unchanged extra fields, ignoring any
      changes made.
 
The 
zip_file_extra_field_get_by_id() function returns the
  extra field with ID (two-byte signature) 
extra_field_id
  and index 
extra_field_index (in other words, the
  
extra_field_index'th extra field
  with ID 
extra_field_id) The other arguments are the same
  as for 
zip_file_extra_field_get().
RETURN VALUES
Upon successful completion, a pointer to an extra field is returned, or
  
NULL if there is no extra field with that
  
extra_field_index for the file with index
  
index. In case of an error, 
NULL
  is returned and the error code in 
archive is set to
  indicate the error.
ERRORS
zip_file_extra_field_get() and
  
zip_file_extra_field_get_by_id() fail if:
  -  
-  
- [ZIP_ER_NOENT]
- index is not a valid file index in
      archive, or extra_field_index
      is not a valid extra file index (for ID
      extra_field_id).
SEE ALSO
libzip(3),
  
zip_file_extra_field_delete(3),
  
zip_file_extra_field_set(3),
  
zip_file_extra_fields_count(3)
HISTORY
zip_file_extra_field_get() and
  
zip_file_extra_field_get_by_id() were added in libzip 0.11.
AUTHORS
Dieter Baron
  <
dillo@nih.at> and
  
Thomas Klausner
  <
tk@giga.or.at>
CAVEATS
Please note that the extra field IDs 0x0001 (ZIP64 extension), 0x6375 (Infozip
  UTF-8 comment), and 0x7075 (Infozip UTF-8 file name) can not be read using
  
zip_file_extra_field_get() since they are used by
  
libzip(3) internally.