copyfile-173.40.2.tar.gz

[apple/copyfile.git] / copyfile.3

.\"
.\" Copyright (c) 2002 Apple Computer, Inc.  All rights reserved.
.\"
.Dd July 22, 2019
.Dt COPYFILE 3
.Os
.Sh NAME
.Nm copyfile , fcopyfile ,
.Nm copyfile_state_alloc , copyfile_state_free ,
.Nm copyfile_state_get , copyfile_state_set
.Nd copy a file
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.In copyfile.h
.Ft int
.Fn copyfile "const char *from" "const char *to" "copyfile_state_t state" "copyfile_flags_t flags"
.Ft int
.Fn fcopyfile "int from" "int to" "copyfile_state_t state" "copyfile_flags_t flags"
.Ft copyfile_state_t
.Fn copyfile_state_alloc "void"
.Ft int
.Fn copyfile_state_free "copyfile_state_t state"
.Ft int
.Fn copyfile_state_get "copyfile_state_t state" "uint32_t flag" "void * dst"
.Ft int
.Fn copyfile_state_set "copyfile_state_t state" "uint32_t flag" "const void * src"
.Ft typedef int
.Fn (*copyfile_callback_t) "int what" "int stage" "copyfile_state_t state" "const char * src" "const char * dst" "void * ctx"
.Sh DESCRIPTION
These functions are used to copy a file's data and/or metadata.  (Metadata
consists of permissions, extended attributes, access control lists, and so
forth.)
.Pp
The
.Fn copyfile_state_alloc
function initializes a
.Vt copyfile_state_t
object (which is an opaque data type).
This object can be passed to
.Fn copyfile
and
.Fn fcopyfile ;
.Fn copyfile_state_get
and
.Fn copyfile_state_set
can be used to manipulate the state (see below).
The
.Fn copyfile_state_free
function is used to deallocate the object and its contents.
.Pp
The
.Fn copyfile
function can copy the named
.Va from
file to the named
.Va to
file; the
.Fn fcopyfile
function does the same, but using the file descriptors of already-opened
files.
If the
.Va state
parameter is the return value from
.Fn copyfile_state_alloc ,
then
.Fn copyfile
and
.Fn fcopyfile
will use the information from the state object; if it is
.Dv NULL ,
then both functions will work normally, but less control will be available to the caller.
The
.Va flags
parameter controls which contents are copied:
.Bl -tag -width COPYFILE_XATTR
.It Dv COPYFILE_ACL
Copy the source file's access control lists.
.It Dv COPYFILE_STAT
Copy the source file's POSIX information (mode, modification time, etc.).
.It Dv COPYFILE_XATTR
Copy the source file's extended attributes.
.It Dv COPYFILE_DATA
Copy the source file's data.
.El
.Pp
These values may be or'd together; several convenience macros are provided:
.Bl -tag -width COPYFILE_SECURITY
.It Dv COPYFILE_SECURITY
Copy the source file's POSIX and ACL information; equivalent to
.Dv (COPYFILE_STAT|COPYFILE_ACL) .
.It Dv COPYFILE_METADATA
Copy the metadata; equivalent to
.Dv (COPYFILE_SECURITY|COPYFILE_XATTR) .
.It Dv COPYFILE_ALL
Copy the entire file; equivalent to
.Dv (COPYFILE_METADATA|COPYFILE_DATA) .
.El
.Pp
The
.Fn copyfile
and
.Fn fcopyfile
functions can also have their behavior modified by the following flags:
.Bl -tag -width COPYFILE_NOFOLLOW_SRC
.It Dv COPYFILE_RECURSIVE
Causes
.Fn copyfile
to recursively copy a hierarchy.
This flag is not used by
.Fn fcopyfile ;
see below for more information.
.It Dv COPYFILE_CHECK
Return a bitmask (corresponding to the
.Va flags
argument) indicating which contents would be copied; no data are actually
copied.  (E.g., if
.Va flags
was set to
.Dv COPYFILE_CHECK|COPYFILE_METADATA ,
and the
.Va from
file had extended attributes but no ACLs, the return value would be
.Dv COPYFILE_XATTR .)
.It Dv COPYFILE_PACK
Serialize the
.Va from
file.
The
.Va to
file is an AppleDouble-format file.
.It Dv COPYFILE_UNPACK
Unserialize the
.Va from
file.
The
.Va from
file is an AppleDouble-format file; the
.Va to
file will have the extended attributes, ACLs, resource fork, and
FinderInfo data from the
.Va to
file, regardless of the
.Va flags
argument passed in.
.It Dv COPYFILE_EXCL
Fail if the
.Va to
file already exists.  (This is only applicable for the
.Fn copyfile
function.)
.It Dv COPYFILE_NOFOLLOW_SRC
Do not follow the
.Va from
file, if it is a symbolic link.  (This is only applicable for the
.Fn copyfile
function.)
.It Dv COPYFILE_NOFOLLOW_DST
Do not follow the
.Va to
file, if it is a symbolic link.  (This is only applicable for the
.Fn copyfile
function.)
.It Dv COPYFILE_MOVE
Unlink (using 
.Xr remove 3 )
the
.Fa from
file.  (This is only applicable for the
.Fn copyfile
function.)  No error is returned if
.Xr remove 3
fails.
Note that
.Xr remove 3
removes a symbolic link itself, not the
target of the link.
.It Dv COPYFILE_UNLINK
Unlink the
.Va to
file before starting.  (This is only applicable for the
.Fn copyfile
function.)
.It Dv COPYFILE_CLONE_FORCE
Clone the file instead.
This is a force flag i.e. if cloning fails, an error is returned.
This flag is equivalent to (COPYFILE_EXCL | COPYFILE_ACL | COPYFILE_STAT | COPYFILE_XATTR | COPYFILE_DATA
| COPYFILE_NOFOLLOW_SRC).
Note that if cloning is successful, progress callbacks will not be invoked.
Note also that there is no support for cloning directories: if a directory is provided as the source,
an error will be returned.
Since this flag implies COPYFILE_NOFOLLOW_SRC, symbolic links themselves will be cloned instead of their targets.
(This is only applicable for the
.Fn copyfile
function.)
.It Dv COPYFILE_CLONE
Try to clone the file instead.
This is a best try flag i.e. if cloning fails, fallback to copying the file.
This flag is equivalent to (COPYFILE_EXCL | COPYFILE_ACL | COPYFILE_STAT | COPYFILE_XATTR | COPYFILE_DATA
| COPYFILE_NOFOLLOW_SRC).
Note that if cloning is successful, progress callbacks will not be invoked.
Note also that there is no support for cloning directories: if a directory is provided as the source and
COPYFILE_CLONE_FORCE is not passed, this will instead copy the directory.
Since this flag implies COPYFILE_NOFOLLOW_SRC, symbolic links themselves will be cloned instead of their targets.
Recursive copying however is supported, see below for more information.
(This is only applicable for the
.Fn copyfile
function.)
.It Dv COPYFILE_DATA_SPARSE
Copy a file sparsely.
This requires that the source and destination file systems support sparse files with hole sizes
at least as large as their block sizes.
This also requires that the source file is sparse, and for
.Fn fcopyfile
the source file descriptor's offset be a multiple of the minimum hole size.
If COPYFILE_DATA is also specified, this will fall back to a full copy
if sparse copying cannot be performed for any reason; otherwise, an error is returned.
.It Dv COPYFILE_NOFOLLOW
This is a convenience macro, equivalent to
.Dv (COPYFILE_NOFOLLOW_DST | COPYFILE_NOFOLLOW_SRC) .
.It Dv COPYFILE_RUN_IN_PLACE
If the src file has quarantine information, add the QTN_FLAG_DO_NOT_TRANSLOCATE flag to the quarantine information of the dst file.
This allows a bundle to run in place instead of being translocated.
.It Dv COPYFILE_PRESERVE_DST_TRACKED
Preserve the UF_TRACKED flag at
.Va to
when copying metadata, regardless of whether
.Va from
has it set.
This flag is used in conjunction with COPYFILE_STAT, or COPYFILE_CLONE (for its fallback case).
.El
.Pp
Copying files into a directory is supported.
If
.Va to
is a directory,
.Va from
will be copied into
.Va to
(if
.Va from
is a directory,
copying its contents requires use of the COPYFILE_RECURSIVE parameter,
which is documented below).
.Pp
The
.Fn copyfile_state_get
and
.Fn copyfile_state_set
functions can be used to manipulate the
.Ft copyfile_state_t
object returned by
.Fn copyfile_state_alloc .
In both functions, the
.Va dst
parameter's type depends on the
.Va flag
parameter that is passed in.
.Bl -tag -width COPYFILE_STATE_DST_FILENAME
.It Dv COPYFILE_STATE_SRC_FD
.It Dv 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
.Va dst
(for
.Fn copyfile_state_get )
and
.Va src
(for
.Fn copyfile_state_set )
parameters are pointers to
.Vt int .
.It Dv COPYFILE_STATE_SRC_FILENAME
.It Dv 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
.Dv NULL .
For
.Fn copyfile_state_set ,
the
.Va src
parameter is a pointer to a C string
(i.e.,
.Vt char* );
.Fn copyfile_state_set
makes a private copy of this string.
For
.Fn copyfile_state_get
function, the
.Va dst
parameter is a pointer to a pointer to a C string
(i.e.,
.Vt char** );
the returned value is a pointer to the
.Va state 's
copy, and must not be modified or released.
.It Dv COPYFILE_STATE_STATUS_CB
Get or set the callback status function (currently
only used for recursive copies; see below for details).
The
.Va src
parameter is a pointer to a function of type
.Vt copyfile_callback_t
(see above).
.It Dv COPYFILE_STATE_STATUS_CTX
Get or set the context parameter for the status
call-back function (see below for details).
The
.Va src
parameter is a
.Vt void\ * .
.It Dv COPYFILE_STATE_QUARANTINE
Get or set the quarantine information with the source file.
The
.Va src
parameter is a pointer to an opaque
object (type
.Vt void\ *
).
.It Dv COPYFILE_STATE_COPIED
Get the number of data bytes copied so far.
(Only valid for
.Fn copyfile_state_get ;
see below for more details about callbacks.)
If a
.Dv COPYFILE_CLONE
or
.Dv COPYFILE_CLONE_FORCE
operation successfully cloned the requested objects, then this value will be 0.
The
.Va dst
parameter is a pointer to
.Vt off_t
(type
.Vt off_t\ * ).
.It Dv COPYFILE_STATE_XATTRNAME
Get the name of the extended attribute during a callback
for
.Dv COPYFILE_COPY_XATTR
(see below for details).  This field cannot be set,
and may be
.Dv NULL .
.It Dv COPYFILE_STATE_WAS_CLONED
True if a
.Dv COPYFILE_CLONE
or
.Dv COPYFILE_CLONE_FORCE
operation successfully cloned the requested objects.
The
.Va dst
parameter is a pointer to
.Vt bool
(type
.Vt bool\ * ).
.El
.Sh Recursive Copies
When given the
.Dv COPYFILE_RECURSIVE
flag,
.Fn copyfile
(but not
.Fn fcopyfile )
will use the 
.Xr fts 3
functions to recursively descend into the source file-system object.
It then calls
.Fn copyfile
on each of the entries it finds that way.
If a call-back function is given (using
.Fn copyfile_state_set
and
.Dv COPYFILE_STATE_STATUS_CB ),
the call-back function 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.)
.Pp
The call-back function will have one of the following values
as the first argument, indicating what is being copied:
.Bl -tag -width COPYFILE_RECURSE_DIR_CLEANUP
.It Dv COPYFILE_RECURSE_FILE
The object being copied is a file (or, rather,
something other than a directory).
.It Dv 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.)
.It Dv 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.
.It Dv COPYFILE_RECURSE_ERROR
There was an error in processing an element of the source hierarchy;
this happens when
.Xr fts 3
returns an error or unknown file type.
(Currently, the second argument to the call-back function will always
be
.Dv COPYFILE_ERR
in this case.)
.El
.Pp
The second argument to the call-back function will indicate
the stage of the copy, and will be one of the following values:
.Bl -tag -width COPYFILE_FINISH
.It Dv COPYFILE_START
Before copying has begun.
The third parameter will be a newly-created
.Vt copyfile_state_t
object with the call-back function and context pre-loaded.
.It Dv COPYFILE_FINISH
After copying has successfully finished.
.It Dv COPYFILE_ERR
Indicates an error has happened at some stage.
If the first argument to the call-back function is
.Dv COPYFILE_RECURSE_ERROR ,
then an error occurred while processing the source hierarchy;
otherwise, it will indicate what type of object was being copied,
and
.Dv errno
will be set to indicate the error.
.El
.Pp
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).
.Pp
The last argument to the call-back function will be the value
set by
.Dv COPYFILE_STATE_STATUS_CTX ,
if any.
.Pp
The call-back function is required to return one of the following
values:
.Bl -tag -width COPYFILE_CONTINUE
.It Dv COPYFILE_CONTINUE
The copy will continue as expected.
.It Dv COPYFILE_SKIP
This object will be skipped, and the next object will
be processed.
(Note that, when entering a directory, returning
.Dv COPYFILE_SKIP
from the call-back function will prevent the contents
of the directory from being copied.)
.It Dv COPYFILE_QUIT
The entire copy is aborted at this stage.
Any filesystem
objects created up to this point will remain.
.Fn copyfile
will return -1, but
.Dv errno
will be unmodified.
.El
.Pp
The call-back function must always return one of the values listed
above; if not, the results are undefined.
.Pp
The call-back function will be called twice for each object
(and an additional two times for directory cleanup); the first
call will have a
.Ar stage
parameter of
.Dv COPYFILE_START ;
the second time, that value will be either
.Dv COPYFILE_FINISH
or
.Dv COPYFILE_ERR
to indicate a successful completion, or an error during
processing.
In the event of an error, the
.Dv errno
value will be set appropriately.
.Pp
Note that recursive cloning is also supported with the
.Dv COPYFILE_CLONE
flag (but not the
.Dv COPYFILE_CLONE_FORCE
flag).
A recursive clone operation invokes
.Fn copyfile
with
.Dv COPYFILE_CLONE
on every entry found in the source file-system object.
Because
.Fn copyfile
does not allow the cloning of directories, a recursive clone will
instead copy any directory it finds (while cloning its contents).
As symbolic links may point to directories, they are not followed
during recursive clones even if the source is a symbolic link.
Additionally, because the
.Dv COPYFILE_CLONE
flag implies the
.Dv COPYFILE_EXCL
flag, recursive clones require a nonexistent destination.
.Pp
The
.Dv COPYFILE_PACK ,
.Dv COPYFILE_UNPACK ,
.Dv COPYFILE_MOVE ,
and
.Dv COPYFILE_UNLINK
flags are not used during a recursive copy, and will result
in an error being returned.
.Pp
Note that if the source path ends in a
.Va /
its contents are copied rather than the directory itself (like cp(1)).
The behavior of a recursive copy on a directory hierarchy also depends
on the contents of the destination.
If the destination is a directory, the source directory (or its contents,
if the source path ends in a
.Va /
) will be copied into it.
If the destination exists but is not a
directory, and the source is a non-empty directory, the copy will fail;
the exact error set depends on the flags provided to
.Fn copyfile
initially.
.Sh Progress Callback
In addition to the recursive callbacks described above,
.Fn copyfile
and
.Fn fcopyfile
will also use a callback to report data (e.g.,
.Dv COPYFILE_DATA )
progress.
If given, the callback will be invoked on each
.Xr write 2
call.
The first argument to the callback function will be
.Dv COPYFILE_COPY_DATA .
The second argument will either be
.Dv COPYFILE_PROGRESS
(indicating that the write was successful), or
.Dv COPYFILE_ERR
(indicating that there was an error of some sort).
.Pp
The amount of data bytes copied so far can be retrieved using
.Fn copyfile_state_get ,
with the
.Dv COPYFILE_STATE_COPIED
requestor (the argument type is a pointer to
.Vt off_t ).
.Pp
When copying extended attributes, the first argument to the
callback function will be
.Dv COPYFILE_COPY_XATTR .
The other arguments will be as described for
.Dv COPYFILE_COPY_DATA ;
the name of the extended attribute being copied may be
retrieved using
.Fn copyfile_state_get
and the parameter
.Dv COPYFILE_STATE_XATTRNAME .
When using
.Dv COPYFILE_PACK ,
the callback may be called with
.Dv COPYFILE_START
for each of the extended attributes first, followed by
.Dv COPYFILE_PROGRESS
before getting and packing the data for each
individual attribute, and then
.Dv COPYFILE_FINISH
when finished with each individual attribute.
(That is,
.Dv COPYFILE_START
may be called for all of the extended attributes, before
the first callback with
.Dv COPYFILE_PROGRESS
is invoked.)
Any attribute skipped by returning
.Dv COPYFILE_SKIP
from the
.Dv COPYFILE_START
callback will not be placed into the packed output file.
.Pp
The return value for the data callback must be one of
.Bl -tag -width COPYFILE_CONTINUE
.It Dv COPYFILE_CONTINUE
The copy will continue as expected.
(In the case of error, it will attempt to write the data again.)
.It Dv COPYFILE_SKIP
The data copy will be aborted, but without error.
.It Dv COPYFILE_QUIT
The data copy will be aborted; in the case of
.Dv COPYFILE_PROGRESS ,
.Dv errno
will be set to
.Dv ECANCELED .
.El
.Pp
While the
.Va src
and
.Va dst
parameters will be passed in, they may be
.Dv NULL
in the case of
.Fn fcopyfile .
.Pp
Note that progress callbacks are not invoked when a clone is requested
(e.g.
.Dv COPYFILE_CLONE )
unless the clone cannot be performed and a copy is performed instead.
.Sh RETURN VALUES
Except when given the
.Dv COPYFILE_CHECK
flag,
.Fn copyfile
and
.Fn fcopyfile
return less than 0 on error, and 0 on success.
All of the other functions return 0 on success, and less than 0
on error.
.Sh WARNING
Both
.Fn copyfile
and
.Fn 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.
.Pp
When performing a recursive copy, if the source hierarchy
changes while the copy is occurring, the results are undefined.
.Pp
.Fn fcopyfile
does not reset the seek position for either source or destination.
This can result in the destination file being a different size
than the source file.
.Sh EXAMPLES
.Bd -literal -offset indent
/* 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);
.Ed
.Sh ERRORS
.Fn copyfile
and
.Fn fcopyfile
will fail if:
.Bl -tag -width Er
.It Bq Er EINVAL
An invalid flag was passed in with
.Dv COPYFILE_RECURSIVE .
.It Bq Er EINVAL
The
.Va from
or
.Va to
parameter to
.Fn copyfile
was a
.Dv NULL
pointer.
.It Bq Er EINVAL
The
.Va from
or
.Va to
parameter to
.Fn fcopyfile
was a negative number.
.It Bq Er ENOMEM
A memory allocation failed.
.It Bq Er ENOTSUP
The source file was not a directory, symbolic link, or regular file.
.It Bq Er ENOTSUP
COPYFILE_CLONE_FORCE was specified and file cloning is not supported.
.It Bq Er ENOTSUP
COPYFILE_DATA_SPARSE was specified, sparse copying is not supported,
and COPYFILE_DATA was not specified.
.It Bq Er ECANCELED
The copy was cancelled by callback.
.It Bq Er EEXIST
The
.Va to
parameter to
.Fn copyfile
already existed and was passed in with
.Dv COPYFILE_EXCL .
.It Bq Er ENOENT
The
.Va from
parameter to
.Fn copyfile
did not exist.
.It Bq Er EACCES
Search permission is denied for a component of the path prefix for
the
.Va from
or
.Va to
parameters.
.It Bq Er EACCES
Write permission is denied for a component of the path prefix for the
.Va to
parameter.
.El
.Pp
In addition, both functions may set
.Dv errno
via an underlying library or system call.
.Sh SEE ALSO
.Xr getxattr 2 ,
.Xr listxattr 2 ,
.Xr setxattr 2 ,
.Xr acl 3
.Sh HISTORY
The
.Fn copyfile
API was introduced in Mac OS X 10.5.
.Sh BUGS
Both
.Fn copyfile
functions lack a way to set the input or output block size.
.Pp
Recursive copies do not honor hard links.