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Implement blocking file locking API for windows

master
LeRoyce Pearson 2020-03-09 20:48:00 -06:00
parent 9af0590a28
commit e1868029e9
4 changed files with 80 additions and 59 deletions
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132
lib/std/fs.zig
View File

@ -708,7 +708,12 @@ pub const Dir = struct {
const access_mask = w.SYNCHRONIZE |
(if (flags.read) @as(u32, w.GENERIC_READ) else 0) |
(if (flags.write) @as(u32, w.GENERIC_WRITE) else 0);
return self.openFileWindows(sub_path_w, access_mask, w.FILE_OPEN);
const share_access = if (flags.lock)
w.FILE_SHARE_DELETE |
(if (flags.write) @as(os.windows.ULONG, 0) else w.FILE_SHARE_READ)
else
null;
return self.openFileWindows(sub_path_w, access_mask, share_access, w.FILE_OPEN);
}
/// Creates, opens, or overwrites a file with write access.
@ -753,7 +758,7 @@ pub const Dir = struct {
@as(u32, w.FILE_OVERWRITE_IF)
else
@as(u32, w.FILE_OPEN_IF);
return self.openFileWindows(sub_path_w, access_mask, creation);
return self.openFileWindows(sub_path_w, access_mask, null, creation);
}
/// Deprecated; call `openFile` directly.
@ -775,65 +780,80 @@ pub const Dir = struct {
self: Dir,
sub_path_w: [*:0]const u16,
access_mask: os.windows.ACCESS_MASK,
share_access_opt: ?os.windows.ULONG,
creation: os.windows.ULONG,
) File.OpenError!File {
const w = os.windows;
var delay: usize = 1;
while (true) {
const w = os.windows;
if (sub_path_w[0] == '.' and sub_path_w[1] == 0) {
return error.IsDir;
}
if (sub_path_w[0] == '.' and sub_path_w[1] == '.' and sub_path_w[2] == 0) {
return error.IsDir;
}
if (sub_path_w[0] == '.' and sub_path_w[1] == 0) {
return error.IsDir;
}
if (sub_path_w[0] == '.' and sub_path_w[1] == '.' and sub_path_w[2] == 0) {
return error.IsDir;
}
var result = File{
.handle = undefined,
.io_mode = .blocking,
};
var result = File{
.handle = undefined,
.io_mode = .blocking,
};
const path_len_bytes = math.cast(u16, mem.toSliceConst(u16, sub_path_w).len * 2) catch |err| switch (err) {
error.Overflow => return error.NameTooLong,
};
var nt_name = w.UNICODE_STRING{
.Length = path_len_bytes,
.MaximumLength = path_len_bytes,
.Buffer = @intToPtr([*]u16, @ptrToInt(sub_path_w)),
};
var attr = w.OBJECT_ATTRIBUTES{
.Length = @sizeOf(w.OBJECT_ATTRIBUTES),
.RootDirectory = if (path.isAbsoluteWindowsW(sub_path_w)) null else self.fd,
.Attributes = 0, // Note we do not use OBJ_CASE_INSENSITIVE here.
.ObjectName = &nt_name,
.SecurityDescriptor = null,
.SecurityQualityOfService = null,
};
var io: w.IO_STATUS_BLOCK = undefined;
const rc = w.ntdll.NtCreateFile(
&result.handle,
access_mask,
&attr,
&io,
null,
w.FILE_ATTRIBUTE_NORMAL,
w.FILE_SHARE_WRITE | w.FILE_SHARE_READ | w.FILE_SHARE_DELETE,
creation,
w.FILE_NON_DIRECTORY_FILE | w.FILE_SYNCHRONOUS_IO_NONALERT,
null,
0,
);
switch (rc) {
.SUCCESS => return result,
.OBJECT_NAME_INVALID => unreachable,
.OBJECT_NAME_NOT_FOUND => return error.FileNotFound,
.OBJECT_PATH_NOT_FOUND => return error.FileNotFound,
.NO_MEDIA_IN_DEVICE => return error.NoDevice,
.INVALID_PARAMETER => unreachable,
.SHARING_VIOLATION => return error.SharingViolation,
.ACCESS_DENIED => return error.AccessDenied,
.PIPE_BUSY => return error.PipeBusy,
.OBJECT_PATH_SYNTAX_BAD => unreachable,
.OBJECT_NAME_COLLISION => return error.PathAlreadyExists,
else => return w.unexpectedStatus(rc),
const path_len_bytes = math.cast(u16, mem.toSliceConst(u16, sub_path_w).len * 2) catch |err| switch (err) {
error.Overflow => return error.NameTooLong,
};
var nt_name = w.UNICODE_STRING{
.Length = path_len_bytes,
.MaximumLength = path_len_bytes,
.Buffer = @intToPtr([*]u16, @ptrToInt(sub_path_w)),
};
var attr = w.OBJECT_ATTRIBUTES{
.Length = @sizeOf(w.OBJECT_ATTRIBUTES),
.RootDirectory = if (path.isAbsoluteWindowsW(sub_path_w)) null else self.fd,
.Attributes = 0, // Note we do not use OBJ_CASE_INSENSITIVE here.
.ObjectName = &nt_name,
.SecurityDescriptor = null,
.SecurityQualityOfService = null,
};
var io: w.IO_STATUS_BLOCK = undefined;
const share_access = share_access_opt orelse w.FILE_SHARE_WRITE | w.FILE_SHARE_READ | w.FILE_SHARE_DELETE;
const rc = w.ntdll.NtCreateFile(
&result.handle,
access_mask,
&attr,
&io,
null,
w.FILE_ATTRIBUTE_NORMAL,
share_access,
creation,
w.FILE_NON_DIRECTORY_FILE | w.FILE_SYNCHRONOUS_IO_NONALERT,
null,
0,
);
switch (rc) {
.SUCCESS => return result,
.OBJECT_NAME_INVALID => unreachable,
.OBJECT_NAME_NOT_FOUND => return error.FileNotFound,
.OBJECT_PATH_NOT_FOUND => return error.FileNotFound,
.NO_MEDIA_IN_DEVICE => return error.NoDevice,
.INVALID_PARAMETER => unreachable,
.SHARING_VIOLATION => {
// TODO: check if async or blocking
//return error.SharingViolation
// Sleep so we don't consume a ton of CPU waiting to get lock on file
std.time.sleep(delay);
// Increase sleep time as long as it is less than 5 seconds
if (delay < 5 * std.time.ns_per_s) {
delay *= 2;
}
continue;
},
.ACCESS_DENIED => return error.AccessDenied,
.PIPE_BUSY => return error.PipeBusy,
.OBJECT_PATH_SYNTAX_BAD => unreachable,
.OBJECT_NAME_COLLISION => return error.PathAlreadyExists,
else => return w.unexpectedStatus(rc),
}
}
}

4
lib/std/os.zig
View File

@ -1141,8 +1141,8 @@ pub fn freeNullDelimitedEnvMap(allocator: *mem.Allocator, envp_buf: []?[*:0]u8)
}
/// Attempts to get lock the file, blocking if the file is locked.
pub fn fcntlFlockBlocking(fd: fd_t, flock_p: *flock) OpenError!void {
const rc = system.fcntlFlock(fd, F_SETLKW, flock_p);
pub fn fcntlFlockBlocking(fd: fd_t, flock_p: *const flock) OpenError!void {
const rc = system.fcntl(fd, F_SETLKW, flock_p);
if (rc < 0) {
std.debug.panic("fcntl error: {}\n", .{rc});
}

1
lib/std/os/bits/linux/i386.zig
View File

@ -8,6 +8,7 @@ const iovec = linux.iovec;
const iovec_const = linux.iovec_const;
const uid_t = linux.uid_t;
const gid_t = linux.gid_t;
const pid_t = linux.pid_t;
const stack_t = linux.stack_t;
const sigset_t = linux.sigset_t;

2
lib/std/os/linux.zig
View File

@ -219,7 +219,7 @@ pub fn mmap(address: ?[*]u8, length: usize, prot: usize, flags: u32, fd: i32, of
}
}
pub fn fcntlFlock(fd: fd_t, cmd: i32, flock_p: *flock) usize {
pub fn fcntl(fd: fd_t, cmd: i32, flock_p: *const c_void) usize {
return syscall3(SYS_fcntl, @bitCast(usize, @as(isize, fd)), @bitCast(usize, @as(isize, cmd)), @ptrToInt(flock_p));
}