4mARCHIVE_READ_DISK24m(3)	 Library Functions Manual      4mARCHIVE_READ_DISK24m(3)

1mNAME0m
       archive_read_disk_new,			       archive_read_disk_open,
       archive_read_disk_open_w,	       archive_read_disk_set_behavior,
       archive_read_disk_set_symlink_logical,
       archive_read_disk_set_symlink_physical,
       archive_read_disk_set_symlink_hybrid,
       archive_read_disk_entry_from_file,	      archive_read_disk_gname,
       archive_read_disk_uname,		   archive_read_disk_set_uname_lookup,
       archive_read_disk_set_gname_lookup,
       archive_read_disk_set_standard_lookup,	    archive_read_disk_descend,
       archive_read_disk_can_descend,	 archive_read_disk_current_filesystem,
       archive_read_disk_current_filesystem_is_synthetic,
       archive_read_disk_current_filesystem_is_remote,
       archive_read_disk_set_matching,
       archive_read_disk_set_metadata_filter_callback, — functions for reading
       objects from disk

1mLIBRARY0m
       Streaming Archive Library (libarchive, -larchive)

1mSYNOPSIS0m
       1m#include <archive.h>0m

       4mstruct24m 4marchive24m 4m*0m
       1marchive_read_disk_new22m(4mvoid24m);

       4mint0m
       1marchive_read_disk_open22m(4mstruct24m 4marchive24m 4m*24m, 4mconst24m 4mchar24m 4m*24m);

       4mint0m
       1marchive_read_disk_open_w22m(4mstruct24m 4marchive24m 4m*24m, 4mconst24m 4mwchar_t24m 4m*24m);

       4mint0m
       1marchive_read_disk_set_behavior22m(4mstruct24m 4marchive24m 4m*24m, 4mint24m);

       4mint0m
       1marchive_read_disk_set_symlink_logical22m(4mstruct24m 4marchive24m 4m*24m);

       4mint0m
       1marchive_read_disk_set_symlink_physical22m(4mstruct24m 4marchive24m 4m*24m);

       4mint0m
       1marchive_read_disk_set_symlink_hybrid22m(4mstruct24m 4marchive24m 4m*24m);

       4mconst24m 4mchar24m 4m*0m
       1marchive_read_disk_gname22m(4mstruct24m 4marchive24m 4m*24m, 4mgid_t24m);

       4mconst24m 4mchar24m 4m*0m
       1marchive_read_disk_uname22m(4mstruct24m 4marchive24m 4m*24m, 4muid_t24m);

       4mint0m
       1marchive_read_disk_set_gname_lookup22m(4mstruct24m 4marchive24m 4m*24m,		   4mvoid24m 4m*24m,
	   4mconst24m 4mchar24m 4m*(*lookup)(void24m 4m*,24m 4mgid_t)24m, 4mvoid24m 4m(*cleanup)(void24m 4m*)24m);

       4mint0m
       1marchive_read_disk_set_uname_lookup22m(4mstruct24m 4marchive24m 4m*24m,		   4mvoid24m 4m*24m,
	   4mconst24m 4mchar24m 4m*(*lookup)(void24m 4m*,24m 4muid_t)24m, 4mvoid24m 4m(*cleanup)(void24m 4m*)24m);

       4mint0m
       1marchive_read_disk_set_standard_lookup22m(4mstruct24m 4marchive24m 4m*24m);

       4mint0m
       1marchive_read_disk_entry_from_file22m(4mstruct24m 4marchive24m 4m*24m,
	   4mstruct24m 4marchive_entry24m 4m*24m, 4mint24m 4mfd24m, 4mconst24m 4mstruct24m 4mstat24m 4m*24m);

       4mint0m
       1marchive_read_disk_descend22m(4mstruct24m 4marchive24m 4m*24m);

       4mint0m
       1marchive_read_disk_can_descend22m(4mstruct24m 4marchive24m 4m*24m);

       4mint0m
       1marchive_read_disk_current_filesystem22m(4mstruct24m 4marchive24m 4m*24m);

       4mint0m
       1marchive_read_disk_current_filesystem_is_synthetic22m(4mstruct24m 4marchive24m 4m*24m);

       4mint0m
       1marchive_read_disk_current_filesystem_is_remote22m(4mstruct24m 4marchive24m 4m*24m);

       4mint0m
       1marchive_read_disk_set_matching22m(4mstruct24m 4marchive24m 4m*24m,	 4mstruct24m 4marchive24m 4m*24m,
	   4mvoid24m 4m(*excluded_func)(struct24m 4marchive24m 4m*,24m 4mvoid24m 4m*,24m 4mstruct24m 4marchive24m 4mentry24m 4m*)24m,
	   4mvoid24m 4m*24m);

       4mint0m
       1marchive_read_disk_set_metadata_filter_callback22m(4mstruct24m 4marchive24m 4m*24m,
	   4mint24m 4m(*metadata_filter_func)(struct24m 4marchive24m 4m*,24m 4mvoid*,24m 4mstruct24m 4marchive_entry24m 4m*)24m,
	   4mvoid24m 4m*24m);

1mDESCRIPTION0m
       These functions provide an API for reading information about objects on
       disk.  In particular, they provide an interface for  populating	struct
       archive_entry objects.

       1marchive_read_disk_new22m()
	       Allocates  and initializes a struct archive object suitable for
	       reading object information from disk.

       1marchive_read_disk_open22m()
	       Opens the file or directory from the given  path	 and  prepares
	       the struct archive to read it from disk.

       1marchive_read_disk_open_w22m()
	       Opens the file or directory from the given path as a wide char‐
	       acter  string  and  prepares the struct archive to read it from
	       disk.

       1marchive_read_disk_set_behavior22m()
	       Configures various behavior options when reading	 entries  from
	       disk.   The flags field consists of a bitwise OR of one or more
	       of the following values:
	       1mARCHIVE_READDISK_HONOR_NODUMP0m
		       Skip files and directories with	the  nodump  file  at‐
		       tribute	(file  flag) set.  By default, the nodump file
		       attribute is ignored.
	       1mARCHIVE_READDISK_MAC_COPYFILE0m
		       Mac OS X specific.  Read metadata  (ACLs	 and  extended
		       attributes)  with 4mcopyfile24m(3).  By default, metadata is
		       read using 4mcopyfile24m(3).
	       1mARCHIVE_READDISK_NO_ACL0m
		       Do not read Access Control Lists.  By default, ACLs are
		       read from disk.
	       1mARCHIVE_READDISK_NO_FFLAGS0m
		       Do not read file attributes (file flags).  By  default,
		       file  attributes	 are  read  from  disk.	 See 4mchattr24m(1)
		       (Linux) or 4mchflags24m(1) (FreeBSD, Mac OS X) for more	in‐
		       formation on file attributes.
	       1mARCHIVE_READDISK_NO_TRAVERSE_MOUNTS0m
		       Do not traverse mount points.  By default, mount points
		       are traversed.
	       1mARCHIVE_READDISK_NO_XATTR0m
		       Do  not read extended file attributes (xattrs).	By de‐
		       fault, extended file attributes	are  read  from	 disk.
		       See   4mxattr24m(7)   (Linux),	4mxattr24m(2)  (Mac  OS	 X),  or
		       4mgetextattr24m(8) (FreeBSD) for	 more  information  on	ex‐
		       tended file attributes.
	       1mARCHIVE_READDISK_RESTORE_ATIME0m
		       Restore	access	time  of traversed files.  By default,
		       access time of traversed files is not restored.
	       1mARCHIVE_READDISK_NO_SPARSE0m
		       Do not  read  sparse  file  information.	  By  default,
		       sparse file information is read from disk.

       1marchive_read_disk_set_symlink_logical22m(),
	       1marchive_read_disk_set_symlink_physical22m(),
	       1marchive_read_disk_set_symlink_hybrid22m()
	       This  sets  the	mode  used  for	 handling symbolic links.  The
	       “logical” mode follows all symbolic links, except that  a  sym‐
	       bolic link whose target is an ancestor directory of the link is
	       archived	 as  a	symbolic  link	rather than being followed, to
	       avoid loops.  The “physical” mode does not follow any  symbolic
	       links.	The  “hybrid” mode follows symbolic links specified as
	       the	target	    of	     1marchive_read_disk_open22m()	 or
	       1marchive_read_disk_open_w22m()	but  does not follow symbolic links
	       anywhere else.

       1marchive_read_disk_gname22m(), 1marchive_read_disk_uname22m()
	       Returns a user or group name given a gid or uid value.  By  de‐
	       fault, these always return a NULL string.

       1marchive_read_disk_set_gname_lookup22m(),
	       1marchive_read_disk_set_uname_lookup22m()
	       These  allow  you  to  override the functions used for user and
	       group name lookups.  You may also provide a void * pointer to a
	       private data structure and a cleanup function  for  that	 data.
	       The  cleanup  function  will be invoked when the struct archive
	       object is destroyed or when new	lookup	functions  are	regis‐
	       tered.

       1marchive_read_disk_set_standard_lookup22m()
	       This  convenience  function installs a standard set of user and
	       group name lookup functions.  These functions  use  4mgetpwuid24m(3)
	       and  4mgetgrgid24m(3) to convert ids to names, defaulting to NULL if
	       the names cannot be looked up.  These functions also  implement
	       a  simple  memory  cache	 to  reduce  the  number  of  calls to
	       4mgetpwuid24m(3) and 4mgetgrgid24m(3).

       1marchive_read_disk_entry_from_file22m()
	       Populates a struct archive_entry object with information	 about
	       a  particular file.  The archive_entry object must have already
	       been created with 4marchive_entry_new24m(3) and at least one of	the
	       source  path  or path fields must already be set.  (If both are
	       set, the source path will be used.)

	       Information is read from disk using  the	 path  name  from  the
	       struct archive_entry object.  If a file descriptor is provided,
	       some  information  will be obtained using that file descriptor,
	       on platforms that support the appropriate system calls.

	       If a pointer to a struct stat  is  provided,  information  from
	       that  structure	will  be used instead of reading from the disk
	       where appropriate.  This can provide  performance  benefits  in
	       scenarios  where	 struct stat information has already been read
	       from the disk as a side effect of some other  operation.	  (For
	       example,	 directory  traversal libraries often provide this in‐
	       formation.)

	       Where necessary, user and group ids are converted to  user  and
	       group  names  using  the	 currently-registered lookup functions
	       above.  This affects the file ownership fields and  ACL	values
	       in the struct archive_entry object.

       1marchive_read_disk_descend22m()
	       If  the current entry can be descended, this function will mark
	       the directory as the next entry for  4marchive_read_header24m(3)	 to
	       visit.

       1marchive_read_disk_can_descend22m()
	       Returns	1 if the current entry is an unvisited directory and 0
	       otherwise.

       1marchive_read_disk_current_filesystem22m()
	       Returns the index of the most recent filesystem entry that  has
	       been visited through archive_read_disk.

       1marchive_read_disk_current_filesystem_is_synthetic22m()
	       Returns	1  if  the current filesystem is a virtual filesystem.
	       Returns 0 if the current filesystem is not a  virtual  filesys‐
	       tem. Returns -1 if it is unknown.

       1marchive_read_disk_current_filesystem_is_remote22m()
	       Returns 1 if the current filesystem is a remote filesystem. Re‐
	       turns  0	 if the current filesystem is not a remote filesystem.
	       Returns -1 if it is unknown.

       1marchive_read_disk_set_matching22m()
	       Allows the caller to set struct archive *_ma  to	 compare  each
	       entry  during 4marchive_read_header24m(3) calls. If matched based on
	       calls		  to		  archive_match_path_excluded,
	       archive_match_time_excluded,  or	 archive_match_owner_excluded,
	       then the callback function specified by the _excluded_func  pa‐
	       rameter	will execute. This function will receive data provided
	       to the fourth parameter, void *_client_data.

       1marchive_read_disk_set_metadata_filter_callback22m()
	       Allows the caller to set a callback function  during  calls  to
	       4marchive_read_header24m(3)  to	filter out metadata for each entry.
	       The callback function receives the struct archive object, void*
	       custom filter data, and the struct archive_entry.  If the call‐
	       back function returns an error, ARCHIVE_RETRY will be  returned
	       and the entry will not be further processed.
       More information about the 4mstruct24m 4marchive24m object and the overall design
       of the library can be found in the 4mlibarchive24m(3) overview.

1mEXAMPLES0m
       The  following illustrates basic usage of the library by showing how to
       use it to copy an item on disk into an archive.

	     void
	     file_to_archive(struct archive *a, const char *name)
	     {
	       char buff[8192];
	       size_t bytes_read;
	       struct archive *ard;
	       struct archive_entry *entry;
	       int fd;

	       fd = open(name, O_RDONLY);
	       if (fd < 0)
		 return;
	       ard = archive_read_disk_new();
	       archive_read_disk_set_standard_lookup(ard);
	       entry = archive_entry_new();
	       archive_entry_copy_pathname(entry, name);
	       archive_read_disk_entry_from_file(ard, entry, fd, NULL);
	       archive_write_header(a, entry);
	       while ((bytes_read = read(fd, buff, sizeof(buff))) > 0)
		 archive_write_data(a, buff, bytes_read);
	       archive_write_finish_entry(a);
	       archive_read_free(ard);
	       archive_entry_free(entry);
	     }

1mRETURN VALUES0m
       Most functions return 1mARCHIVE_OK 22m(zero) on success, or one	of  several
       negative	 error	codes  for  errors.   Specific	error  codes  include:
       1mARCHIVE_RETRY	22mfor	operations   that   might   succeed   if   retried,
       1mARCHIVE_WARN  22mfor unusual conditions that do not prevent further opera‐
       tions, and 1mARCHIVE_FATAL 22mfor serious errors that make remaining  opera‐
       tions impossible.

       1marchive_read_disk_new22m()  returns  a pointer to a newly-allocated struct
       archive object or NULL if the allocation failed for any reason.

       1marchive_read_disk_gname22m() and  1marchive_read_disk_uname22m()  return  const
       char  *	pointers  to the textual name or NULL if the lookup failed for
       any reason.  The returned pointer points to internal storage  that  may
       be reused on the next call to either of these functions; callers should
       copy the string if they need to continue accessing it.

1mERRORS0m
       Detailed	 error	codes  and textual descriptions are available from the
       1marchive_errno22m() and 1marchive_error_string22m() functions.

1mSEE ALSO0m
       4mtar24m(1),	4marchive_read24m(3),	  4marchive_util24m(3),	    4marchive_write24m(3),
       4marchive_write_disk24m(3), 4mlibarchive24m(3)

1mHISTORY0m
       The   1mlibarchive   22mlibrary	 first	 appeared   in	FreeBSD	 5.3.	The
       1marchive_read_disk 22minterface was added to 1mlibarchive 2.6 22mand  first  ap‐
       peared in FreeBSD 8.0.

1mAUTHORS0m
       The    1mlibarchive    22mlibrary    was	   written    by    Tim	   Kientzle
       <kientzle@FreeBSD.org>.

1mBUGS0m
       The “standard” user name and group name lookup functions	 are  not  the
       defaults	 because  4mgetgrgid24m(3)  and 4mgetpwuid24m(3) are sometimes too large
       for particular applications.  The current design allows the application
       author to use a more compact implementation when appropriate.

       The    full    list    of    metadata	 read	  from	   disk	    by
       1marchive_read_disk_entry_from_file22m() is necessarily system-dependent.

       The 1marchive_read_disk_entry_from_file22m() function reads as much informa‐
       tion as it can from disk.  Some method should be provided to limit this
       so that clients who do not need ACLs, for instance, can avoid the extra
       work needed to look up such information.

       This  API should provide a set of methods for walking a directory tree.
       That would make it a direct parallel of the 4marchive_read24m(3) API.   When
       such methods are implemented, the “hybrid” symbolic link mode will make
       sense.

Debian				 April 3, 2017		  4mARCHIVE_READ_DISK24m(3)
