feat: shorten paths that exceed the device's limit

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3 Commits

Author	SHA1	Message	Date
Emma Thorpe	ece79515c0	fix: cost the device prefix exactly rather than approximately Build and publish container / build (pull_request) Successful in 3m54s Details The budget subtracted the prefix length plus two, on the assumption of a leading and a trailing slash. That is right for /Music and wrong for an empty prefix, where there is only one slash -- losing a character at the card root, which is exactly where the longest paths sit. Computed from the prefix as it will actually appear instead: /Music/ costs seven characters and gives a mirror-relative budget of 253, the root costs one and gives 259. Worth being exact about because the reverse error is worse. A checker comparing mirror-relative paths against the flat 260 passes everything between 253 and 260, and those are precisely the paths closest to the edge.	2026-08-25 11:52:03 +01:00
Emma Thorpe	46435feebd	fix: cut long names from the middle, not the end Build and publish container / build (pull_request) Canceled after 1m18s Details The shortening fitted the path and destroyed its meaning. Lidarr writes "Artist - Album - 07 - Flamethrower.mp3" inside a directory already named for that artist and album, so a long album title occurs three times in one path and everything that distinguishes one track from another sits at the very end. Cutting from the end removed precisely that: King Gizzard & the Lizard Wizard - PetroDragonic Apocalypse; or, Dawn of Eter~c526.mp3 All seven tracks on that record reduced to the same string bar the hash. The path fitted; the result was seven files nobody could tell apart on the device, which is a worse outcome than the failure it replaced. Cut from the middle instead, giving two thirds of the remaining room to the tail because the head is generally a restatement of the directory the file already sits in: King Gizzard & the Lizard~c526~ginning of Merciless Damnation - 07 - Flamethrower.mp3 The eight real paths that prompted this are now regression tests: every track on that album keeps its number and title, all seven names stay distinct, and The Beatles' "The Long One" -- whose length is the title itself rather than a repeated album name -- keeps both ends.	2026-08-25 11:50:42 +01:00
Emma Thorpe	d5f67c6de5	feat: shorten paths that exceed the device's limit Build and publish container / build (pull_request) Successful in 2m16s Details Rockbox's MAX_PATH is 260, defined in firmware/include/fs_defines.h and used to size the directory entry buffer in dir.h. It bounds the path as the device sees it, so the directory the mirror is copied into spends part of the same budget; --device-prefix accounts for that and defaults to /Music. Over-budget paths are shortened from the deepest component outward. The track name carries the least navigational value and the artist directory the most, so the filename is cut first and the artist only if nothing else will serve. A shortened component keeps its extension and gains four hex digits of the original name: two long titles sharing a prefix cut to the same string otherwise, and a silent collision between two tracks is a worse outcome than an ugly filename. The result is stable. The same source always yields the same shortened name, so one pass does not rename what the last one wrote -- an unstable scheme would churn the whole mirror every six hours. A path too deeply nested to fit without reducing every component to nonsense is left alone and reported rather than mangled. Migration now tries more than one previous naming, because there is more than one. A mirror already running with --fat32-safe holds sanitised but unshortened paths, and matching only the original unsanitised name would have re-encoded every one of them instead of moving it. The checker gains the same two options, since it was measuring the mirror-relative path against a limit that applies to the device-absolute one, and so under-reported by the length of the destination directory.	2026-08-25 11:46:26 +01:00

Author

SHA1

Message

Date

Emma Thorpe

ece79515c0

fix: cost the device prefix exactly rather than approximately

Build and publish container / build (pull_request) Successful in 3m54s

Details

The budget subtracted the prefix length plus two, on the assumption of a
leading and a trailing slash. That is right for /Music and wrong for an empty
prefix, where there is only one slash -- losing a character at the card root,
which is exactly where the longest paths sit.

Computed from the prefix as it will actually appear instead: /Music/ costs
seven characters and gives a mirror-relative budget of 253, the root costs one
and gives 259.

Worth being exact about because the reverse error is worse. A checker
comparing mirror-relative paths against the flat 260 passes everything between
253 and 260, and those are precisely the paths closest to the edge.

2026-08-25 11:52:03 +01:00

Emma Thorpe

46435feebd

fix: cut long names from the middle, not the end

Build and publish container / build (pull_request) Canceled after 1m18s

Details

The shortening fitted the path and destroyed its meaning. Lidarr writes
"Artist - Album - 07 - Flamethrower.mp3" inside a directory already named for
that artist and album, so a long album title occurs three times in one path and
everything that distinguishes one track from another sits at the very end.
Cutting from the end removed precisely that:

  King Gizzard & the Lizard Wizard - PetroDragonic Apocalypse; or, Dawn of Eter~c526.mp3

All seven tracks on that record reduced to the same string bar the hash. The
path fitted; the result was seven files nobody could tell apart on the device,
which is a worse outcome than the failure it replaced.

Cut from the middle instead, giving two thirds of the remaining room to the
tail because the head is generally a restatement of the directory the file
already sits in:

  King Gizzard & the Lizard~c526~ginning of Merciless Damnation - 07 - Flamethrower.mp3

The eight real paths that prompted this are now regression tests: every track
on that album keeps its number and title, all seven names stay distinct, and
The Beatles' "The Long One" -- whose length is the title itself rather than a
repeated album name -- keeps both ends.

2026-08-25 11:50:42 +01:00

Emma Thorpe

d5f67c6de5

feat: shorten paths that exceed the device's limit

Build and publish container / build (pull_request) Successful in 2m16s

Details

Rockbox's MAX_PATH is 260, defined in firmware/include/fs_defines.h and used to
size the directory entry buffer in dir.h. It bounds the path as the device sees
it, so the directory the mirror is copied into spends part of the same budget;
--device-prefix accounts for that and defaults to /Music.

Over-budget paths are shortened from the deepest component outward. The track
name carries the least navigational value and the artist directory the most, so
the filename is cut first and the artist only if nothing else will serve. A
shortened component keeps its extension and gains four hex digits of the
original name: two long titles sharing a prefix cut to the same string
otherwise, and a silent collision between two tracks is a worse outcome than an
ugly filename.

The result is stable. The same source always yields the same shortened name, so
one pass does not rename what the last one wrote -- an unstable scheme would
churn the whole mirror every six hours. A path too deeply nested to fit without
reducing every component to nonsense is left alone and reported rather than
mangled.

Migration now tries more than one previous naming, because there is more than
one. A mirror already running with --fat32-safe holds sanitised but unshortened
paths, and matching only the original unsanitised name would have re-encoded
every one of them instead of moving it.

The checker gains the same two options, since it was measuring the
mirror-relative path against a limit that applies to the device-absolute one,
and so under-reported by the length of the destination directory.

2026-08-25 11:46:26 +01:00

feat: shorten paths that exceed the device's limit #8