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33 .Nd kernel copy of a byte range from one file to another
47 .Fa "unsigned int flags"
60 It may do this using a file system specific technique if
64 are on the same file system.
69 refer to the same file, the byte ranges defined by
70 the input file offset, output file offset and
75 argument must be opened for reading and the
77 argument must be opened for writing, but not
89 respectively will be used and updated by
90 the number of bytes copied.
97 the byte offset pointed to by
101 respectively will be used/updated and the file offset for
105 respectively will not be affected.
110 This system call attempts to maintain holes in the output file for
111 the byte range being copied.
112 However, this does not always work well.
113 It is recommended that sparse files be copied in a loop using
118 arguments and this system call for the
122 If it succeeds, the call returns the number of bytes copied, which can be fewer
125 Returning fewer bytes than
127 does not necessarily indicate that EOF was reached.
128 However, a return of zero for a non-zero
130 argument indicates that the offset for
134 should be used in a loop until copying of the desired byte range has been
136 If an error has occurred, a \-1 is returned and the error code is placed in
149 is not open for reading or
152 is not open for writing, or opened for writing with
158 refer to the same file.
160 If the copy exceeds the process's file size limit or the maximum file size
165 A signal interrupted the system call
166 before it could be completed.
167 This may happen for files on some NFS mounts.
168 When this happens, the values pointed to by
172 are reset to the initial values for the system call.
177 refer to the same file and the byte ranges overlap or
182 An I/O error occurred while reading/writing the files.
188 refers to a directory.
190 File system that stores
199 system call is expected to be compatible with the Linux system call of