Merge pull request #6516 from LemonBoy/fastfilecopy
std: Make file copy ops use zero-copy mechanismsmaster
commit
76a195473d
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@ -18,6 +18,14 @@ pub extern "c" fn _dyld_get_image_header(image_index: u32) ?*mach_header;
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pub extern "c" fn _dyld_get_image_vmaddr_slide(image_index: u32) usize;
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pub extern "c" fn _dyld_get_image_name(image_index: u32) [*:0]const u8;
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pub const COPYFILE_ACL = 1 << 0;
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pub const COPYFILE_STAT = 1 << 1;
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pub const COPYFILE_XATTR = 1 << 2;
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pub const COPYFILE_DATA = 1 << 3;
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pub const copyfile_state_t = *@Type(.Opaque);
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pub extern "c" fn fcopyfile(from: fd_t, to: fd_t, state: ?copyfile_state_t, flags: u32) c_int;
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pub extern "c" fn @"realpath$DARWIN_EXTSN"(noalias file_name: [*:0]const u8, noalias resolved_name: [*]u8) ?[*:0]u8;
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pub extern "c" fn __getdirentries64(fd: c_int, buf_ptr: [*]u8, buf_len: usize, basep: *i64) isize;
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@ -1823,7 +1823,7 @@ pub const Dir = struct {
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var atomic_file = try dest_dir.atomicFile(dest_path, .{ .mode = mode });
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defer atomic_file.deinit();
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try atomic_file.file.writeFileAll(in_file, .{ .in_len = size });
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try copy_file(in_file.handle, atomic_file.file.handle);
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return atomic_file.finish();
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}
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@ -2271,6 +2271,53 @@ pub fn realpathAlloc(allocator: *Allocator, pathname: []const u8) ![]u8 {
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return allocator.dupe(u8, try os.realpath(pathname, &buf));
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}
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const CopyFileError = error{SystemResources} || os.CopyFileRangeError || os.SendFileError;
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// Transfer all the data between two file descriptors in the most efficient way.
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// The copy starts at offset 0, the initial offsets are preserved.
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// No metadata is transferred over.
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fn copy_file(fd_in: os.fd_t, fd_out: os.fd_t) CopyFileError!void {
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if (comptime std.Target.current.isDarwin()) {
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const rc = os.system.fcopyfile(fd_in, fd_out, null, os.system.COPYFILE_DATA);
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switch (os.errno(rc)) {
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0 => return,
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os.EINVAL => unreachable,
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os.ENOMEM => return error.SystemResources,
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// The source file is not a directory, symbolic link, or regular file.
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// Try with the fallback path before giving up.
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os.ENOTSUP => {},
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else => |err| return os.unexpectedErrno(err),
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}
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}
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if (std.Target.current.os.tag == .linux) {
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// Try copy_file_range first as that works at the FS level and is the
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// most efficient method (if available).
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var offset: u64 = 0;
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cfr_loop: while (true) {
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// The kernel checks the u64 value `offset+count` for overflow, use
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// a 32 bit value so that the syscall won't return EINVAL except for
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// impossibly large files (> 2^64-1 - 2^32-1).
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const amt = try os.copy_file_range(fd_in, offset, fd_out, offset, math.maxInt(u32), 0);
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// Terminate when no data was copied
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if (amt == 0) break :cfr_loop;
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offset += amt;
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}
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return;
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}
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// Sendfile is a zero-copy mechanism iff the OS supports it, otherwise the
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// fallback code will copy the contents chunk by chunk.
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const empty_iovec = [0]os.iovec_const{};
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var offset: u64 = 0;
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sendfile_loop: while (true) {
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const amt = try os.sendfile(fd_out, fd_in, offset, 0, &empty_iovec, &empty_iovec, 0);
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// Terminate when no data was copied
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if (amt == 0) break :sendfile_loop;
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offset += amt;
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}
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}
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test "" {
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if (builtin.os.tag != .wasi) {
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_ = makeDirAbsolute;
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@ -4945,6 +4945,9 @@ pub fn sendfile(
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pub const CopyFileRangeError = error{
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FileTooBig,
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InputOutput,
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/// `fd_in` is not open for reading; or `fd_out` is not open for writing;
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/// or the `O_APPEND` flag is set for `fd_out`.
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FilesOpenedWithWrongFlags,
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IsDir,
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OutOfMemory,
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NoSpaceLeft,
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@ -4953,6 +4956,11 @@ pub const CopyFileRangeError = error{
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FileBusy,
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} || PReadError || PWriteError || UnexpectedError;
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var has_copy_file_range_syscall = init: {
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const kernel_has_syscall = std.Target.current.os.isAtLeast(.linux, .{ .major = 4, .minor = 5 }) orelse true;
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break :init std.atomic.Int(bool).init(kernel_has_syscall);
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};
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/// Transfer data between file descriptors at specified offsets.
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/// Returns the number of bytes written, which can less than requested.
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///
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@ -4981,22 +4989,18 @@ pub const CopyFileRangeError = error{
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pub fn copy_file_range(fd_in: fd_t, off_in: u64, fd_out: fd_t, off_out: u64, len: usize, flags: u32) CopyFileRangeError!usize {
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const use_c = std.c.versionCheck(.{ .major = 2, .minor = 27, .patch = 0 }).ok;
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// TODO support for other systems than linux
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const try_syscall = comptime std.Target.current.os.isAtLeast(.linux, .{ .major = 4, .minor = 5 }) != false;
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if (use_c or try_syscall) {
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if (std.Target.current.os.tag == .linux and
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(use_c or has_copy_file_range_syscall.get()))
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{
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const sys = if (use_c) std.c else linux;
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var off_in_copy = @bitCast(i64, off_in);
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var off_out_copy = @bitCast(i64, off_out);
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const rc = sys.copy_file_range(fd_in, &off_in_copy, fd_out, &off_out_copy, len, flags);
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// TODO avoid wasting a syscall every time if kernel is too old and returns ENOSYS https://github.com/ziglang/zig/issues/1018
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switch (sys.getErrno(rc)) {
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0 => return @intCast(usize, rc),
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EBADF => unreachable,
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EBADF => return error.FilesOpenedWithWrongFlags,
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EFBIG => return error.FileTooBig,
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EIO => return error.InputOutput,
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EISDIR => return error.IsDir,
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@ -5005,9 +5009,14 @@ pub fn copy_file_range(fd_in: fd_t, off_in: u64, fd_out: fd_t, off_out: u64, len
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EOVERFLOW => return error.Unseekable,
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EPERM => return error.PermissionDenied,
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ETXTBSY => return error.FileBusy,
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EINVAL => {}, // these may not be regular files, try fallback
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EXDEV => {}, // support for cross-filesystem copy added in Linux 5.3, use fallback
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ENOSYS => {}, // syscall added in Linux 4.5, use fallback
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// these may not be regular files, try fallback
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EINVAL => {},
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// support for cross-filesystem copy added in Linux 5.3, use fallback
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EXDEV => {},
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// syscall added in Linux 4.5, use fallback
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ENOSYS => {
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has_copy_file_range_syscall.set(false);
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},
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else => |err| return unexpectedErrno(err),
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}
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}
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