copyfile(3) BSD Library Functions Manual copyfile(3)
NAME
copyfile, fcopyfile, copyfile_state_alloc, copyfile_state_free,
copyfile_state_get, copyfile_state_set -- copy a file
LIBRARY
Standard C Library (libc, -lc)
SYNOPSIS
#include <copyfile.h>
int
copyfile(const char *from, const char *to, copyfile_state_t state,
copyfile_flags_t flags);
int
fcopyfile(int from, int to, copyfile_state_t state,
copyfile_flags_t flags);
copyfile_state_t
copyfile_state_alloc(void);
int
copyfile_state_free(copyfile_state_t state);
int
copyfile_state_get(copyfile_state_t state, uint32_t flag, void * dst);
int
copyfile_state_set(copyfile_state_t state, uint32_t flag,
const void * src);
typedef int
(*copyfile_callback_t)(int what, int stage, copyfile_state_t state,
const char * src, const char * dst, void * ctx);
DESCRIPTION
These functions are used to copy a file's data and/or metadata. (Meta-
data consists of permissions, extended attributes, access control lists,
and so forth.)
The copyfile_state_alloc() function initializes a copyfile_state_t object
(which is an opaque data type). This object can be passed to copyfile()
and fcopyfile(); copyfile_state_get() and copyfile_state_set() can be
used to manipulate the state (see below). The copyfile_state_free()
function is used to deallocate the object and its contents.
The copyfile() function can copy the named from file to the named to
file; the fcopyfile() function does the same, but using the file descrip-
tors of already-opened files. If the state parameter is the return value
from copyfile_state_alloc(), then copyfile() and fcopyfile() will use the
information from the state object; if it is NULL, then both functions
will work normally, but less control will be available to the caller.
The flags parameter controls which contents are copied:
COPYFILE_ACL Copy the source file's access control lists.
COPYFILE_STAT Copy the source file's POSIX information (mode, modifica-
tion time, etc.).
COPYFILE_XATTR Copy the source file's extended attributes.
COPYFILE_DATA Copy the source file's data.
These values may be or'd together; several convenience macros are pro-
vided:
COPYFILE_SECURITY Copy the source file's POSIX and ACL information;
equivalent to (COPYFILE_STAT|COPYFILE_ACL).
COPYFILE_METADATA Copy the metadata; equivalent to
(COPYFILE_SECURITY|COPYFILE_XATTR).
COPYFILE_ALL Copy the entire file; equivalent to
(COPYFILE_METADATA|COPYFILE_DATA).
The copyfile() and fcopyfile() functions can also have their behavior
modified by the following flags:
COPYFILE_RECURSIVE Causes copyfile() to recursively copy a hierarchy.
This flag is not used by fcopyfile(); see below
for more information.
COPYFILE_CHECK Return a bitmask (corresponding to the flags argu-
ment) indicating which contents would be copied;
no data are actually copied. (E.g., if flags was
set to COPYFILE_CHECK|COPYFILE_METADATA, and the
from file had extended attributes but no ACLs, the
return value would be COPYFILE_XATTR .)
COPYFILE_PACK Serialize the from file. The to file is an Apple-
Double-format file.
COPYFILE_UNPACK Unserialize the from file. The from file is an
AppleDouble-format file; the to file will have the
extended attributes, ACLs, resource fork, and
FinderInfo data from the to file, regardless of
the flags argument passed in.
COPYFILE_EXCL Fail if the to file already exists. (This is only
applicable for the copyfile() function.)
COPYFILE_NOFOLLOW_SRC Do not follow the from file, if it is a symbolic
link. (This is only applicable for the copyfile()
function.)
COPYFILE_NOFOLLOW_DST Do not follow the to file, if it is a symbolic
link. (This is only applicable for the copyfile()
function.)
COPYFILE_MOVE Unlink (using remove(3)) the from file. (This is
only applicable for the copyfile() function.) No
error is returned if remove(3) fails. Note that
remove(3) removes a symbolic link itself, not the
target of the link.
COPYFILE_UNLINK Unlink the to file before starting. (This is only
applicable for the copyfile() function.)
COPYFILE_NOFOLLOW This is a convenience macro, equivalent to
(COPYFILE_NOFOLLOW_DST|COPYFILE_NOFOLLOW_SRC).
The copyfile_state_get() and copyfile_state_set() functions can be used
to manipulate the copyfile_state_t object returned by
copyfile_state_alloc(). In both functions, the dst parameter's type
depends on the flag parameter that is passed in.
COPYFILE_STATE_SRC_FD
COPYFILE_STATE_DST_FD Get or set the file descriptor associated
with the source (or destination) file. If
this has not been initialized yet, the value
will be -2. The dst (for
copyfile_state_get()) and src (for
copyfile_state_set()) parameters are point-
ers to int.
COPYFILE_STATE_SRC_FILENAME
COPYFILE_STATE_DST_FILENAME Get or set the filename associated with the
source (or destination) file. If it has not
been initialized yet, the value will be
NULL. For copyfile_state_set(), the src
parameter is a pointer to a C string (i.e.,
char* ); copyfile_state_set() makes a pri-
vate copy of this string. For
copyfile_state_get() function, the dst
parameter is a pointer to a pointer to a C
string (i.e., char** ); the returned value
is a pointer to the state 's copy, and must
not be modified or released.
COPYFILE_STATE_STATUS_CB Get or set the callback status function
(currently only used for recursive copies;
see below for details). The src parameter
is a pointer to a function of type
copyfile_callback_t (see above).
COPYFILE_STATE_STATUS_CTX Get or set the context parameter for the
status call-back function (see below for
details). The src parameter is a void *.
COPYFILE_STATE_QUARANTINE Get or set the quarantine information with
the source file. The src parameter is a
pointer to an opaque object (type void * ).
COPYFILE_STATE_COPIED Get the number of data bytes copied so far.
(Only valid for copyfile_state_get(); see
below for more details about callbacks.)
The dst parameter is a pointer to off_t
(type off_t * ).
COPYFILE_STATE_XATTRNAME Get the name of the extended attribute dur-
ing a callback for COPYFILE_COPY_XATTR (see
below for details). This field cannot be
set, and may be NULL.
Recursive Copies
When given the COPYFILE_RECURSIVE flag, copyfile() (but not fcopyfile())
will use the fts(3) functions to recursively descend into the source
file-system object. It then calls copyfile() on each of the entries it
finds that way. If a call-back function is given (using
copyfile_state_set() and COPYFILE_STATE_STATUS_CB ), the call-back func-
tion will be called four times for each directory object, and twice for
all other objects. (Each directory will be examined twice, once on entry
-- before copying each of the objects contained in the directory -- and
once on exit -- after copying each object contained in the directory, in
order to perform some final cleanup.)
The call-back function will have one of the following values as the first
argument, indicating what is being copied:
COPYFILE_RECURSE_FILE The object being copied is a file (or,
rather, something other than a directory).
COPYFILE_RECURSE_DIR The object being copied is a directory, and
is being entered. (That is, none of the
filesystem objects contained within the
directory have been copied yet.)
COPYFILE_RECURSE_DIR_CLEANUP The object being copied is a directory, and
all of the objects contained have been
copied. At this stage, the destination
directory being copied will have any extra
permissions that were added to allow the
copying will be removed.
COPYFILE_RECURSE_ERROR There was an error in processing an element
of the source hierarchy; this happens when
fts(3) returns an error or unknown file
type. (Currently, the second argument to
the call-back function will always be
COPYFILE_ERR in this case.)
The second argument to the call-back function will indicate the stage of
the copy, and will be one of the following values:
COPYFILE_START Before copying has begun. The third parameter will be a
newly-created copyfile_state_t object with the call-back
function and context pre-loaded.
COPYFILE_FINISH After copying has successfully finished.
COPYFILE_ERR Indicates an error has happened at some stage. If the
first argument to the call-back function is
COPYFILE_RECURSE_ERROR, then an error occurred while
processing the source hierarchy; otherwise, it will
indicate what type of object was being copied, and errno
will be set to indicate the error.
The fourth and fifth parameters are the source and destination paths that
are to be copied (or have been copied, or failed to copy, depending on
the second argument).
The last argument to the call-back function will be the value set by
COPYFILE_STATE_STATUS_CTX, if any.
The call-back function is required to return one of the following values:
COPYFILE_CONTINUE The copy will continue as expected.
COPYFILE_SKIP This object will be skipped, and the next object will
be processed. (Note that, when entering a directory.
returning COPYFILE_SKIP from the call-back function
will prevent the contents of the directory from being
copied.)
COPYFILE_QUIT The entire copy is aborted at this stage. Any
filesystem objects created up to this point will
remain. copyfile() will return -1, but errno will be
unmodified.
The call-back function must always return one of the values listed above;
if not, the results are undefined.
The call-back function will be called twice for each object (and an addi-
tional two times for directory cleanup); the first call will have a stage
parameter of COPYFILE_START; the second time, that value will be either
COPYFILE_FINISH or COPYFILE_ERR to indicate a successful completion, or
an error during processing. In the event of an error, the errno value
will be set appropriately.
The COPYFILE_PACK, COPYFILE_UNPACK, COPYFILE_MOVE, and COPYFILE_UNLINK
flags are not used during a recursive copy, and will result in an error
being returned.
Progress Callback
In addition to the recursive callbacks described above, copyfile() and
fcopyfile() will also use a callback to report data (e.g., COPYFILE_DATA)
progress. If given, the callback will be invoked on each write(2) call.
The first argument to the callback function will be COPYFILE_COPY_DATA.
The second argument will either be COPYFILE_PROGRESS (indicating that the
write was successful), or COPYFILE_ERR (indicating that there was an
error of some sort).
The amount of data bytes copied so far can be retrieved using
copyfile_state_get(), with the COPYFILE_STATE_COPIED requestor (the argu-
ment type is a pointer to off_t ).
When copying extended attributes, the first argument to the callback
function will be COPYFILE_COPY_XATTR. The other arguments will be as
described for COPYFILE_COPY_DATA; the name of the extended attribute
being copied may be retrieved using copyfile_state_get() and the parame-
ter COPYFILE_STATE_XATTRNAME. When using COPYFILE_PACK, the callback may
be called with COPYFILE_START for each of the extended attributes first,
followed by COPYFILE_PROGRESS before getting and packing the data for
each individual attribute, and then COPYFILE_FINISH when finished with
each individual attribute. (That is, COPYFILE_START may be called for
all of the extended attributes, before the first callback with
COPYFILE_PROGRESS is invoked.) Any attribute skipped by returning
COPYFILE_SKIP from the COPYFILE_START callback will not be placed into
the packed output file.
The return value for the data callback must be one of
COPYFILE_CONTINUE The copy will continue as expected. (In the case of
error, it will attempt to write the data again.)
COPYFILE_SKIP The data copy will be aborted, but without error.
COPYFILE_QUIT The data copy will be aborted; in the case of
COPYFILE_PROGRESS, errno will be set to ECANCELED.
While the src and dst parameters will be passed in, they may be NULL in
the case of fcopyfile().
RETURN VALUES
Except when given the COPYFILE_CHECK flag, copyfile() and fcopyfile()
return less than 0 on error, and 0 on success. All of the other func-
tions return 0 on success, and less than 0 on error.
WARNING
Both copyfile() and fcopyfile() can copy symbolic links; there is a gap
between when the source link is examined and the actual copy is started,
and this can be a potential security risk, especially if the process has
elevated privileges.
When performing a recursive copy, if the source hierarchy changes while
the copy is occurring, the results are undefined.
fcopyfile() does not reset the seek position for either source or desti-
nation. This can result in the destination file being a different size
than the source file.
ERRORS
copyfile() and fcopyfile() will fail if:
[EINVAL] An invalid flag was passed in with COPYFILE_RECURSIVE.
[EINVAL] The from or to parameter to copyfile() was a NULL
pointer.
[EINVAL] The from or to parameter to copyfile() was a negative
number.
[ENOMEM] A memory allocation failed.
[ENOTSUP] The source file was not a directory, symbolic link, or
regular file.
[ECANCELED] The copy was cancelled by callback.
In addition, both functions may set errno via an underlying library or
system call.
EXAMPLES
/* Initialize a state variable */
copyfile_state_t s;
s = copyfile_state_alloc();
/* Copy the data and extended attributes of one file to another */
copyfile("/tmp/f1", "/tmp/f2", s, COPYFILE_DATA | COPYFILE_XATTR);
/* Convert a file to an AppleDouble file for serialization */
copyfile("/tmp/f2", "/tmp/tmpfile", NULL, COPYFILE_ALL | COPYFILE_PACK);
/* Release the state variable */
copyfile_state_free(s);
/* A more complex way to call copyfile() */
s = copyfile_state_alloc();
copyfile_state_set(s, COPYFILE_STATE_SRC_FILENAME, "/tmp/foo");
/* One of src or dst must be set... rest can come from the state */
copyfile(NULL, "/tmp/bar", s, COPYFILE_ALL);
/* Now copy the same source file to another destination file */
copyfile(NULL, "/tmp/car", s, COPYFILE_ALL);
copyfile_state_free(s);
/* Remove extended attributes from a file */
copyfile("/dev/null", "/tmp/bar", NULL, COPYFILE_XATTR);
SEE ALSO
listxattr(2), getxattr(2), setxattr(2), acl(3)
BUGS
Both copyfile() functions lack a way to set the input or output block
size.
Recursive copies do not honor hard links.
HISTORY
The copyfile() API was introduced in Mac OS X 10.5.
BSD April 27, 2006 BSD
Mac OS X 10.8 - Generated Mon Aug 27 16:33:41 CDT 2012