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dosforge 0.9.55

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@github-actions github-actions released this 14 Jun 02:38
· 8 commits to main since this release
v0.9.55
eaf0e90

dosforge v0.9.55

Fix: _effective_size_cap_bytes drift -- COMPAQ3, DRDOS6, DRDOS7

User-reported follow-up to v0.9.54: same "16M means 16M" bug for
compaq3 (Microsoft MS-DOS 3.00 Compaq OEM) -- 16M is rejected,
15M works.

Root cause

v0.9.54 added branches in _effective_size_cap_bytes for PCDOS3
and COMPAQ2 to mirror formlogic's max_mb constraints, but
missed three other modes that formlogic also pins below the FAT
format hard cap:

BootMode formlogic max_mb v0.9.54 disk-side cap Bug?
COMPAQ3 16 none (used FAT12 32 MiB cap) yes -- same 16M-rejected as PCDOS3
DRDOS6 32 none (used FAT16 2 GiB cap) yes -- bumps past 32 MiB on XT-IDE
DRDOS7 2048 none (matches FAT16 cap) no, but added for symmetry

When formlogic's advertised cap is tighter than the FAT format
cap, the disk-side _effective_size_cap_bytes must mirror it or
_xtide_geometry will bump past the cap and the create gets
rejected by downstream validation.

Fix

Three new branches in _effective_size_cap_bytes:

  • COMPAQ3 -> 16 MiB (same 1985-era partition cap as PCDOS3).
  • DRDOS6 -> 32 MiB (IBM-3.3-class BPB, no FAT16B in DR-DOS 6.0).
  • DRDOS7 -> 2 GiB (FAT16B BIGDOS; identical to FAT16 hard cap
    but added explicitly for symmetry with formlogic's max_mb).

Drift-prevention test

New TestFormDiskCapParity.test_every_formlogic_max_mb_has_disk_side_mirror
iterates formlogic._BOOT_MODE_MEDIA_RULES, builds a probe request
for every rule with an explicit max_mb tighter than the FAT format
cap, and asserts that _effective_size_cap_bytes returns the same
number of bytes the form advertised. Going forward, adding a new
max_mb cap in formlogic without mirroring it in disk.py will
fail this test instead of silently breaking create.

Verified end-to-end on Windows

Direct repro of the COMPAQ3 bug:

$ dosforge create --path test.vhd --media-type vhd --format fat12 \
    --size 16M --boot-mode compaq3 --disk-controller xtide
Created and prepared test.vhd
VHD size: 16,294,400 bytes (15.54 MiB)

(Picks the (306, 4, 26) whitelist geometry under the 16 MiB cap,
identical to PCDOS3 behavior after v0.9.54.)

Tests

16 tests in tests/test_size_cap_snap.py (up from 12 in v0.9.54):

  • 3 new _effective_size_cap_bytes cases for COMPAQ3 / DRDOS6 / DRDOS7.
  • 1 new TestFormDiskCapParity that catches any future drift between
    formlogic and disk.py automatically.

Files changed

  • src/dosforge/disk.py -- added COMPAQ3 / DRDOS6 / DRDOS7 branches
    in _effective_size_cap_bytes.
  • tests/test_size_cap_snap.py -- 3 new per-mode tests + 1 parity test.
  • pyproject.toml + src/dosforge/__init__.py -- 0.9.54 -> 0.9.55.

Carried forward

  • v0.9.54 16M means 16M (PCDOS3 / COMPAQ2 + XT-IDE)
  • v0.9.53 Show log grows window
  • v0.9.52 Windows-path ECHS-doubling fix
Assets 7
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