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Move copy_file to fs namespace 

Now it is a private API.
Also handle short writes in copy_file_range fallback implementation.
master
LemonBoy 2020-10-06 09:38:59 +02:00
parent 8b4f5f039d
commit a419a1aabc
2 changed files with 69 additions and 89 deletions
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48
lib/std/fs.zig
View File

@ -1823,7 +1823,7 @@ pub const Dir = struct {
var atomic_file = try dest_dir.atomicFile(dest_path, .{ .mode = mode });
defer atomic_file.deinit();
try os.copy_file(in_file.handle, atomic_file.file.handle, .{});
try copy_file(in_file.handle, atomic_file.file.handle);
return atomic_file.finish();
}
@ -2263,6 +2263,52 @@ pub fn realpathAlloc(allocator: *Allocator, pathname: []const u8) ![]u8 {
return allocator.dupe(u8, try os.realpath(pathname, &buf));
}
const CopyFileError = error{SystemResources} || os.CopyFileRangeError || os.SendFileError;
/// Transfer all the data between two file descriptors in the most efficient way.
/// No metadata is transferred over.
fn copy_file(fd_in: os.fd_t, fd_out: os.fd_t) CopyFileError!void {
if (comptime std.Target.current.isDarwin()) {
const rc = os.system.fcopyfile(fd_in, fd_out, null, os.system.COPYFILE_DATA);
switch (errno(rc)) {
0 => return,
EINVAL => unreachable,
ENOMEM => return error.SystemResources,
// The source file was not a directory, symbolic link, or regular file.
// Try with the fallback path before giving up.
ENOTSUP => {},
else => |err| return unexpectedErrno(err),
}
}
if (std.Target.current.os.tag == .linux) {
// Try copy_file_range first as that works at the FS level and is the
// most efficient method (if available).
var offset: u64 = 0;
cfr_loop: while (true) {
// The kernel checks `offset+count` for overflow, use a 32 bit
// value so that the syscall won't return EINVAL except for
// impossibly large files.
const amt = try os.copy_file_range(fd_in, offset, fd_out, offset, math.maxInt(u32), 0);
// Terminate when no data was copied
if (amt == 0) break :cfr_loop;
offset += amt;
}
return;
}
// Sendfile is a zero-copy mechanism iff the OS supports it, otherwise the
// fallback code will copy the contents chunk by chunk.
const empty_iovec = [0]os.iovec_const{};
var offset: u64 = 0;
sendfile_loop: while (true) {
const amt = try os.sendfile(fd_out, fd_in, offset, 0, &empty_iovec, &empty_iovec, 0);
// Terminate when no data was copied
if (amt == 0) break :sendfile_loop;
offset += amt;
}
}
test "" {
if (builtin.os.tag != .wasi) {
_ = makeDirAbsolute;

110
lib/std/os.zig
View File

@ -4945,6 +4945,7 @@ pub fn sendfile(
pub const CopyFileRangeError = error{
FileTooBig,
InputOutput,
InvalidFileDescriptor,
IsDir,
OutOfMemory,
NoSpaceLeft,
@ -4978,6 +4979,11 @@ pub const CopyFileRangeError = error{
/// Other systems fall back to calling `pread` / `pwrite`.
///
/// Maximum offsets on Linux are `math.maxInt(i64)`.
var has_copy_file_range_syscall = init: {
const kernel_has_syscall = comptime std.Target.current.os.isAtLeast(.linux, .{ .major = 4, .minor = 5 }) orelse true;
break :init std.atomic.Int(u1).init(@boolToInt(kernel_has_syscall));
};
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 {
const use_c = std.c.versionCheck(.{ .major = 2, .minor = 27, .patch = 0 }).ok;
@ -4992,7 +4998,7 @@ pub fn copy_file_range(fd_in: fd_t, off_in: u64, fd_out: fd_t, off_out: u64, len
const rc = sys.copy_file_range(fd_in, &off_in_copy, fd_out, &off_out_copy, len, flags);
switch (sys.getErrno(rc)) {
0 => return @intCast(usize, rc),
EBADF => unreachable,
EBADF => return error.InvalidFileDescriptor,
EFBIG => return error.FileTooBig,
EIO => return error.InputOutput,
EISDIR => return error.IsDir,
@ -5013,96 +5019,24 @@ pub fn copy_file_range(fd_in: fd_t, off_in: u64, fd_out: fd_t, off_out: u64, len
}
}
var buf: [8 * 4096]u8 = undefined;
const adjusted_count = math.min(buf.len, len);
const amt_read = try pread(fd_in, buf[0..adjusted_count], off_in);
// TODO without @as the line below fails to compile for wasm32-wasi:
// error: integer value 0 cannot be coerced to type 'os.PWriteError!usize'
if (amt_read == 0) return @as(usize, 0);
return pwrite(fd_out, buf[0..amt_read], off_out);
}
var buf: [2 * 4096]u8 = undefined;
var has_copy_file_range_syscall = std.atomic.Int(u1).init(1);
pub const CopyFileOptions = struct {};
pub const CopyFileError = error{
BadFileHandle,
SystemResources,
FileTooBig,
InputOutput,
IsDir,
OutOfMemory,
NoSpaceLeft,
Unseekable,
PermissionDenied,
FileBusy,
} || FStatError || SendFileError;
/// Transfer all the data between two file descriptors in the most efficient way.
/// No metadata is transferred over.
pub fn copy_file(fd_in: fd_t, fd_out: fd_t, options: CopyFileOptions) CopyFileError!void {
if (comptime std.Target.current.isDarwin()) {
const rc = system.fcopyfile(fd_in, fd_out, null, system.COPYFILE_DATA);
switch (errno(rc)) {
0 => return,
EINVAL => unreachable,
ENOMEM => return error.SystemResources,
// The source file was not a directory, symbolic link, or regular file.
// Try with the fallback path before giving up.
ENOTSUP => {},
else => |err| return unexpectedErrno(err),
}
var total_copied: usize = 0;
var read_off = off_in;
var write_off = off_out;
while (total_copied < len) {
const adjusted_count = math.min(buf.len, len - total_copied);
const amt_read = try pread(fd_in, buf[0..adjusted_count], read_off);
if (amt_read == 0) break;
const amt_written = try pwrite(fd_out, buf[0..amt_read], write_off);
// pwrite may write less than the specified amount, handle the remaining
// chunk of data in the next iteration
read_off += amt_written;
write_off += amt_written;
total_copied += amt_written;
}
if (std.Target.current.os.tag == .linux) {
// Try copy_file_range first as that works at the FS level and is the
// most efficient method (if available).
if (has_copy_file_range_syscall.get() != 0) {
cfr_loop: while (true) {
// The kernel checks `file_pos+count` for overflow, use a 32 bit
// value so that the syscall won't return EINVAL except for
// impossibly large files.
const rc = linux.copy_file_range(fd_in, null, fd_out, null, math.maxInt(u32), 0);
switch (errno(rc)) {
0 => {},
EBADF => return error.BadFileHandle,
EFBIG => return error.FileTooBig,
EIO => return error.InputOutput,
EISDIR => return error.IsDir,
ENOMEM => return error.OutOfMemory,
ENOSPC => return error.NoSpaceLeft,
EOVERFLOW => return error.Unseekable,
EPERM => return error.PermissionDenied,
ETXTBSY => return error.FileBusy,
// These may not be regular files, try fallback
EINVAL => break :cfr_loop,
// Support for cross-filesystem copy added in Linux 5.3, use fallback
EXDEV => break :cfr_loop,
// Syscall added in Linux 4.5, use fallback
ENOSYS => {
has_copy_file_range_syscall.set(0);
break :cfr_loop;
},
else => |err| return unexpectedErrno(err),
}
// Terminate when no data was copied
if (rc == 0) return;
}
// This point is reached when an error occurred, hopefully no data
// was transferred yet
}
}
// Sendfile is a zero-copy mechanism iff the OS supports it, otherwise the
// fallback code will copy the contents chunk by chunk.
const empty_iovec = [0]iovec_const{};
var offset: u64 = 0;
sendfile_loop: while (true) {
const amt = try sendfile(fd_out, fd_in, offset, 0, &empty_iovec, &empty_iovec, 0);
if (amt == 0) break :sendfile_loop;
offset += amt;
}
return total_copied;
}
pub const PollError = error{