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Differential D11620

dirstate-v2: Swap the order of size and mtime on disk
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Authored by SimonSapin on Oct 8 2021, 8:06 AM.

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rHG6e01bcd111d2: dirstate-v2: Swap the order of size and mtime on disk
Summary

This makes the dirstate-v2 file format match dirstate-v1 for the order of
mode, size, and mtime. This order does not matter as long as these
components are handled through named fields/attributes in code, but in a few
places we still have tuples so having the same order everywhere might help
avoid a bug that might not be obvious since those components have the same type.

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rHG Mercurial
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Event Timeline

SimonSapin created this revision.Oct 8 2021, 8:06 AM
SimonSapin added a comment.Oct 8 2021, 8:07 AM

I’ve split this from D11547.

Because of how BytesCast is used, the struct definition defines the file format.

martinvonz added a subscriber: martinvonz.Oct 8 2021, 6:37 PM

This makes the dirstate-v2 file format match dirstate-v2 for the order of

Should the second "v2" be "v1?

(And I assume "Change swap" can be just "Swap".)

SimonSapin retitled this revision from dirstate-v2: Change swap the order of size and mtime on disk to dirstate-v2: Swap the order of size and mtime on disk.Oct 12 2021, 7:04 AM
SimonSapin edited the summary of this revision. (Show Details)
SimonSapin added a comment.Oct 12 2021, 7:05 AM

Ah yes. Thanks!

SimonSapin added a commit: rHG6e01bcd111d2: dirstate-v2: Swap the order of size and mtime on disk.Oct 12 2021, 2:02 PM
This revision was not accepted when it landed; it landed in state Needs Review.
Closed by commit rHG6e01bcd111d2: dirstate-v2: Swap the order of size and mtime on disk (authored by SimonSapin). · Explain Why
This revision was automatically updated to reflect the committed changes.

Revision Contents
Changeset List

Diff 30750

mercurial/helptext/internals/dirstate-v2.txt

* Offset 31: * Offset 31:
If `HAS_MODE_AND_SIZE` is unset, four zero bytes. If `HAS_MODE_AND_SIZE` is unset, four zero bytes.
Otherwise, a 32-bit integer for the Unix mode (as in `stat_result.st_mode`) Otherwise, a 32-bit integer for the Unix mode (as in `stat_result.st_mode`)
expected for this file to be considered clean. expected for this file to be considered clean.
Only the `S_IXUSR` bit (owner has execute permission) is considered. Only the `S_IXUSR` bit (owner has execute permission) is considered.
* Offset 35: * Offset 35:
If `HAS_MTIME` is unset, four zero bytes. If `HAS_MODE_AND_SIZE` is unset, four zero bytes.
Otherwise, a 32-bit integer for expected modified time of the file Otherwise, a 32-bit integer for expected size of the file
(as in `stat_result.st_mtime`),
truncated to its 31 least-significant bits. truncated to its 31 least-significant bits.
Unlike in dirstate-v1, negative values are not used. Unlike in dirstate-v1, negative values are not used.
* Offset 39: * Offset 39:
If `HAS_MODE_AND_SIZE` is unset, four zero bytes. If `HAS_MTIME` is unset, four zero bytes.
Otherwise, a 32-bit integer for expected size of the file Otherwise, a 32-bit integer for expected modified time of the file
(as in `stat_result.st_mtime`),
truncated to its 31 least-significant bits. truncated to its 31 least-significant bits.
Unlike in dirstate-v1, negative values are not used. Unlike in dirstate-v1, negative values are not used.
If an untracked node `HAS_MTIME` *unset*, this space is unused: If an untracked node `HAS_MTIME` *unset*, this space is unused:
* Offset 31: * Offset 31:
12 bytes set to zero 12 bytes set to zero

rust/hg-core/src/dirstate_tree/on_disk.rs

const HAS_MTIME = 1 << 4; const HAS_MTIME = 1 << 4;
} }
} }
#[derive(BytesCast, Copy, Clone, Debug)] #[derive(BytesCast, Copy, Clone, Debug)]
#[repr(C)] #[repr(C)]
struct Entry { struct Entry {
mode: I32Be, mode: I32Be,
mtime: I32Be,
size: I32Be, size: I32Be,
mtime: I32Be,
} }
/// Duration since the Unix epoch /// Duration since the Unix epoch
#[derive(BytesCast, Copy, Clone, PartialEq)] #[derive(BytesCast, Copy, Clone, PartialEq)]
#[repr(C)] #[repr(C)]
pub(super) struct Timestamp { pub(super) struct Timestamp {
seconds: I64Be, seconds: I64Be,