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Diffstat (limited to 'Doc/library/os.rst')
| -rw-r--r-- | Doc/library/os.rst | 22 |
1 files changed, 22 insertions, 0 deletions
diff --git a/Doc/library/os.rst b/Doc/library/os.rst index b53fd71e65..107764ba4d 100644 --- a/Doc/library/os.rst +++ b/Doc/library/os.rst @@ -707,6 +707,28 @@ as internal buffering of data. pass +.. function:: copy_file_range(src, dst, count, offset_src=None, offset_dst=None) + + Copy *count* bytes from file descriptor *src*, starting from offset + *offset_src*, to file descriptor *dst*, starting from offset *offset_dst*. + If *offset_src* is None, then *src* is read from the current position; + respectively for *offset_dst*. The files pointed by *src* and *dst* + must reside in the same filesystem, otherwise an :exc:`OSError` is + raised with :attr:`~OSError.errno` set to :data:`errno.EXDEV`. + + This copy is done without the additional cost of transferring data + from the kernel to user space and then back into the kernel. Additionally, + some filesystems could implement extra optimizations. The copy is done as if + both files are opened as binary. + + The return value is the amount of bytes copied. This could be less than the + amount requested. + + .. availability:: Linux kernel >= 4.5 or glibc >= 2.27. + + .. versionadded:: 3.8 + + .. function:: device_encoding(fd) Return a string describing the encoding of the device associated with *fd* |