cidata: fix virtiofs mounts with a space in the path

[ekalinin]

Problem

A vz + virtiofs mount whose host path contains a space (e.g. /Volumes/External HD, /tmp/lima space test) is never mounted in the guest, and no error is reported — the mount silently does not appear. External drives on macOS commonly contain spaces, so this affects a common setup. Surfaced downstream in Colima (abiosoft/colima#1471).

Root cause

cloud-init's cc_mounts writes each mount into /etc/fstab with a bare "\t".join(fields) and does not octal-escape the mount point (canonical/cloud-init#3603). A space/tab in the path produces an unparsable fstab line that mount(8) silently skips because of the nofail option, so the mount never appears:

lima-9661e8fd74e6c9ad /tmp/lima space test    virtiofs        rw,nofail,comment=cloudconfig   0       0

(findmnt --verify reports parse error at line N -- ignored.)

Fix

cc_mounts already creates the mount-point directory from the unescaped value, so only the fstab line needs repair. The escape/decode logic lives in two small, self-tested helper scripts under pkg/cidata/cidata.TEMPLATE.d/util/, following the compare_version.sh convention:

• util/escape_fstab.sh — octal-escapes the mount-point field of cloud-config virtiofs entries read on stdin. Parsing with -F'\t' isolates the field reliably and makes the pass idempotent (an already-escaped path has no literal space/tab), so it is also forward-compatible with a fixed cloud-init.
• util/unescape_fstab.sh — the inverse decode, used by the SELinux remount in 05-lima-mounts.sh and (replacing an identical inline sed) by 04-persistent-data-volume.sh.

boot.Linux/05-lima-mounts.sh now repairs the fstab via escape_fstab.sh, runs mount -t virtiofs -a, and decodes via unescape_fstab.sh before the SELinux remount. Both helpers are unit-tested via an embedded SELFTEST block (SELFTEST=1 ./util/escape_fstab.sh), like compare_version.sh; .ls-lint.yml carries the snake_case exceptions.

No Go/template changes. The fix is scoped to vz + virtiofs; it complements, but does not depend on, the upstream cloud-init fix canonical/cloud-init#6911 (distros will ship that only years from now).

Verified

Built limactl and booted a vz + virtiofs instance mounting /tmp/lima space test:

• findmnt --verify → 0 parse errors (was parse error at line 4)
• mount present; test file reads/writes round-trip host ↔ guest
• idempotent across reboot — a single \040-escaped fstab line, no duplicate
• no-space mounts unaffected; no literal \040 directory created
• SELFTEST=1 passes for both helpers, and escape → unescape round-trips

Fixes: #5136
Link: abiosoft/colima#1471

[Copilot]

Pull request overview

This PR addresses a vz + virtiofs mount failure when the host path contains whitespace by repairing cloud-init–generated /etc/fstab entries and ensuring mount points are correctly (un)escaped when remounting under SELinux. It also factors out fstab unescaping into a reusable utility script.

Changes:

• Add util/escape_fstab.sh to octal-escape the mount-point field for affected cloud-config virtiofs fstab entries, and trigger a mount -t virtiofs -a pass for vz+virtiofs.
• Add util/unescape_fstab.sh and use it where mount points must be decoded before being passed to mount(8).
• Update .ls-lint.yml ignores for the new util scripts.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
pkg/cidata/cidata.TEMPLATE.d/util/unescape_fstab.sh	New helper to decode fstab/proc-style octal escapes, with selftest.
pkg/cidata/cidata.TEMPLATE.d/util/escape_fstab.sh	New helper to rewrite fstab so virtiofs mount points with whitespace are parseable.
pkg/cidata/cidata.TEMPLATE.d/boot.Linux/05-lima-mounts.sh	Repairs fstab and remounts virtiofs; decodes escaped mount points for SELinux remount path.
pkg/cidata/cidata.TEMPLATE.d/boot.Linux/04-persistent-data-volume.sh	Reuses unescape_fstab.sh for mount-point decoding from /proc/mounts.
.ls-lint.yml	Adds ignores for the newly introduced util scripts.

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[ekalinin]

@AkihiroSuda thanks for the reviews! I think everything is addressed now:

• the awk/sed are split into self-tested util/escape_fstab.sh and util/unescape_fstab.sh, following the compare_version.sh convention (SELFTEST=1 ./… runs the unit tests)
• issue references are full URLs
• the unescape helper also de-duplicates the identical snippet in 04-persistent-data-volume.sh

All review threads are resolved and CI is green. Whenever you have a moment, could you take another look? 🙏

[AkihiroSuda]

Please squash the commits

[ekalinin]

@AkihiroSuda sorry to bother you again, could you help me with this problem?