authorgravatar for squeek502@hotmail.comRyan Liptak <squeek502@hotmail.com> 2022-07-25 06:14:25-07:00
committergravatar for noreply@github.comGitHub <noreply@github.com> 2022-07-25 16:14:25+03:00
log75e5b38410e81ddf21ba37a874ee2bb13dea7477
tree86bc98c9bf81d13ca30e676e533d58c956196b72
parent8f3ab96b0e8cd22dc98f9fe352c5d4fff491dd0e
signaturebadge-question-mark Signed by PGP key 4AEE18F83AFDEB23

std.fs: End iteration on Linux/WASI during Iterator.next when hitting `ENOENT`

`getdents` on Linux can return `ENOENT` if the directory referred to by the fd is deleted during iteration. Returning null when this happens makes sense because: - `ENOENT` is specific to the Linux implementation of `getdents` - On other platforms like FreeBSD, `getdents` returns `0` in this scenario, which is functionally equivalent to the `.NOENT => return null` handling on Linux - In all the usage sites of `Iterator.next` throughout the standard library, translating `ENOENT` returned from `next` as null was the best way to handle it, so the use-case for handling the exact `ENOENT` scenario specifically may not exist to a relevant extent Previously, ENOENT being returned would trigger `os.unexpectedErrno`. Closes #12211

2 files changed, 26 insertions(+), 0 deletions(-)

lib/std/fs.zig+2
......@@ -607,6 +607,7 @@ pub const IterableDir = struct {
607607 .BADF => unreachable, // Dir is invalid or was opened without iteration ability
608608 .FAULT => unreachable,
609609 .NOTDIR => unreachable,
610 .NOENT => return null, // The directory being iterated was deleted during iteration.
610611 .INVAL => return error.Unexpected, // Linux may in some cases return EINVAL when reading /proc/$PID/net.
611612 else => |err| return os.unexpectedErrno(err),
612613 }
......@@ -741,6 +742,7 @@ pub const IterableDir = struct {
741742 .FAULT => unreachable,
742743 .NOTDIR => unreachable,
743744 .INVAL => unreachable,
745 .NOENT => return null, // The directory being iterated was deleted during iteration.
744746 .NOTCAPABLE => return error.AccessDenied,
745747 else => |err| return os.unexpectedErrno(err),
746748 }
lib/std/fs/test.zig+24
......@@ -219,6 +219,30 @@ test "Dir.Iterator twice" {
219219 }
220220}
221221
222test "Dir.Iterator but dir is deleted during iteration" {
223 var tmp = std.testing.tmpDir(.{});
224 defer tmp.cleanup();
225
226 // Create directory and setup an iterator for it
227 var iterable_subdir = try tmp.dir.makeOpenPathIterable("subdir", .{});
228 defer iterable_subdir.close();
229
230 var iterator = iterable_subdir.iterate();
231
232 // Create something to iterate over within the subdir
233 try tmp.dir.makePath("subdir/b");
234
235 // Then, before iterating, delete the directory that we're iterating.
236 // This is a contrived reproduction, but this could happen outside of the program, in another thread, etc.
237 // If we get an error while trying to delete, we can skip this test (this will happen on platforms
238 // like Windows which will give FileBusy if the directory is currently open for iteration).
239 tmp.dir.deleteTree("subdir") catch return error.SkipZigTest;
240
241 // Now, when we try to iterate, the next call should return null immediately.
242 const entry = try iterator.next();
243 try std.testing.expect(entry == null);
244}
245
222246fn entryEql(lhs: IterableDir.Entry, rhs: IterableDir.Entry) bool {
223247 return mem.eql(u8, lhs.name, rhs.name) and lhs.kind == rhs.kind;
224248}