From: Dave Chinner <dchinner@xxxxxxxxxx> Update with all the missing errors the syscall can return, the behaviour the syscall should have w.r.t. to copies within single files, etc. Signed-off-by: Dave Chinner <dchinner@xxxxxxxxxx> --- man2/copy_file_range.2 | 94 +++++++++++++++++++++++++++++++++++++++++--------- 1 file changed, 77 insertions(+), 17 deletions(-) diff --git a/man2/copy_file_range.2 b/man2/copy_file_range.2 index 20374abb21f0..23b00c2f3fea 100644 --- a/man2/copy_file_range.2 +++ b/man2/copy_file_range.2 @@ -42,9 +42,9 @@ without the additional cost of transferring data from the kernel to user space and then back into the kernel. It copies up to .I len -bytes of data from file descriptor +bytes of data from the source file descriptor .I fd_in -to file descriptor +to target file descriptor .IR fd_out , overwriting any data that exists within the requested range of the target file. .PP @@ -74,6 +74,11 @@ is not changed, but .I off_in is adjusted appropriately. .PP +.I fd_in +and +.I fd_out +can refer to the same file. If they refer to the same file, then the source and +target ranges are not allowed to overlap. .PP The .I flags @@ -93,34 +98,73 @@ is set to indicate the error. .SH ERRORS .TP .B EBADF -One or more file descriptors are not valid; or +One or more file descriptors are not valid. +.TP +.B EBADF .I fd_in is not open for reading; or .I fd_out -is not open for writing; or -the +is not open for writing. +.TP +.B EBADF +The .B O_APPEND flag is set for the open file description referred to by .IR fd_out . .TP .B EFBIG -An attempt was made to write a file that exceeds the implementation-defined -maximum file size or the process's file size limit, -or to write at a position past the maximum allowed offset. +An attempt was made to write at a position past the maximum file offset the +kernel supports. +.TP +.B EFBIG +An attempt was made to write a range that exceeds the allowed maximum file size. +The maximum file size differs between filesystem implemenations and can be +different to the maximum allowed file offset. +.TP +.B EFBIG +An attempt was made to write beyond the process's file size resource +limit. This may also result in the process receiving a +.I SIGXFSZ +signal. .TP .B EINVAL -Requested range extends beyond the end of the source file; or the -.I flags -argument is not 0. +.I (off_in + len) +spans the end of the source file. .TP -.B EIO -A low-level I/O error occurred while copying. +.B EINVAL +.I fd_in +and +.I fd_out +refer to the same file and the source and target ranges overlap. +.TP +.B EINVAL +.I fd_in +or +.I fd_out +is not a regular file. .TP .B EISDIR .I fd_in or .I fd_out refers to a directory. +.B EINVAL +The +.I flags +argument is not 0. +.TP +.B EINVAL +.I off_in +or +.I (off_in + len) +is beyond the maximum valid file offset. +.TP +.B EOVERFLOW +The requested source or destination range is too large to represent in the +specified data types. +.TP +.B EIO +A low-level I/O error occurred while copying. .TP .B ENOMEM Out of memory. @@ -128,16 +172,32 @@ Out of memory. .B ENOSPC There is not enough space on the target filesystem to complete the copy. .TP -.B EXDEV -The files referred to by -.IR file_in " and " file_out -are not on the same mounted filesystem. +.B TXTBSY +.I fd_in +or +.I fd_out +refers to an active swap file. +.TP +.B EPERM +.I fd_out +refers to an immutable file. +.TP +.B EACCES +The user does not have write permissions for the destination file. .SH VERSIONS The .BR copy_file_range () system call first appeared in Linux 4.5, but glibc 2.27 provides a user-space emulation when it is not available. .\" https://sourceware.org/git/?p=glibc.git;a=commit;f=posix/unistd.h;h=bad7a0c81f501fbbcc79af9eaa4b8254441c4a1f +.PP +A major rework of the kernel implementation occurred in 4.21. Areas of the API +that weren't clearly defined were clarified and the API bounds are much more +strictly checked than on earlier kernels. Applications should target the +behaviour and requirements of 4.21 kernels. +.PP +First support for cross-filesystem copies was introduced in Linux 4.21. Older +kernels will return -EXDEV when cross-filesystem copies are attempted. .SH CONFORMING TO The .BR copy_file_range ()
