# VFS-mutation syscalls (brintos/linux#5): mkdirat / chmod / chown / rename / fsync
# / link, plus the fd forms fchmod / fchown (brintos/linux#8).
# These returned ENOSYS before the wasm32 kernel wired them. GNU `mv` masks a
# broken rename (copy-then-delete fallback) and no shell tool calls fsync, so the
# syscalls are exercised at the C boundary by the data/vfs-probe payload, which
# prints one `VFS-<name> OK|FAIL` line each. data payloads install 0644; the wasm
# exec bit is set on a private copy (chmod itself is one of the wired syscalls).
#
# The probe runs twice, against both filesystems the image has, because they do
# not behave alike: /tmp is a tmpfs, the rootfs is the cloud virtio-fs. Only the
# tmpfs pass ran until BRINTOS-52, which is why a virtio-fs rename defect reached
# the image with this suite green.
. "$BST_LIB"

probe=${TMPDIR:-/tmp}/bst-vfs-probe.$$
cp "$BST_DATA/vfs-probe" "$probe" 2>/dev/null && chmod +x "$probe" 2>/dev/null || {
  bst_notok vfs/stage "cannot stage $BST_DATA/vfs-probe"; exit 0; }

out=$("$probe" 2>&1)

# One assertion per ticket syscall. The four wired upstream must pass; chown is a
# known upstream gap (brintos/linux#5: no ownership model on the virtio-fs backend)
# and reports its actual state so a future wiring flips this suite green.
check_out vfs/mkdirat "VFS-mkdirat OK" printf '%s\n' "$out"
check_out vfs/fsync   "VFS-fsync OK"   printf '%s\n' "$out"
check_out vfs/chmod   "VFS-chmod OK"   printf '%s\n' "$out"
check_out vfs/rename  "VFS-rename OK"  printf '%s\n' "$out"
check_out vfs/chown   "VFS-chown OK"   printf '%s\n' "$out"

# rename onto an EXISTING file — the write-.new-then-rename atomic update every
# database-ish writer uses. Covered on the tmpfs first.
check_out vfs/rename-over "VFS-rename-over OK" printf '%s\n' "$out"

# --- link(2) — the sixth linux#5 syscall, and the one this suite never covered --
# `ln` (no -s) issues link(2) directly and has no fallback, so a refusal surfaces
# as a failure here instead of being masked the way `mv`'s copy-then-delete hides
# a broken rename. The identity assertion is st_ino equality — what tar and dpkg
# use to recognise a hardlink — and deliberately NOT st_nlink, which the cloud
# store under-reports on the link source (brintos-fs PLAN-CROSS-PLATFORM.md §10).
hardlink_cases() {
  _dir=$1; _sfx=$2
  if ! command -v ln >/dev/null 2>&1 || ! command -v stat >/dev/null 2>&1; then
    bst_skip "vfs/hardlink$_sfx"         "ln or stat not installed on this image"
    bst_skip "vfs/hardlink-content$_sfx" "ln or stat not installed on this image"
    bst_skip "vfs/hardlink-ino$_sfx"     "ln or stat not installed on this image"
    return
  fi
  _src="$_dir/bst-vfs-hl.$$"; _dst="$_dir/bst-vfs-hl-link.$$"
  rm -f "$_src" "$_dst" 2>/dev/null
  printf 'hardlink-payload\n' > "$_src" 2>/dev/null
  check     "vfs/hardlink$_sfx"         ln "$_src" "$_dst"
  check_out "vfs/hardlink-content$_sfx" "hardlink-payload" cat "$_dst"
  _si=$(stat -c %i "$_src" 2>/dev/null); _di=$(stat -c %i "$_dst" 2>/dev/null)
  if [ -n "$_si" ] && [ -n "$_di" ]; then
    check_eq "vfs/hardlink-ino$_sfx" "$_si" "$_di"
  else
    bst_notok "vfs/hardlink-ino$_sfx" "stat -c %i gave src='$_si' dst='$_di'"
  fi
  rm -f "$_src" "$_dst" 2>/dev/null
}
hardlink_cases "${TMPDIR:-/tmp}" ""

# --- fchmod/fchown on an fd — brintos/linux#8 ---------------------------------
# The chmod/chown cases above are the path forms, which glibc routes through
# fchmodat/fchownat. [91] fchmod and [93] fchown are separate table entries and
# were the pair linux#8 reported: bzip2 bails after writing a valid archive
# because applySavedFileAttrToOutputFile() fchmod()s the output fd. No shell tool
# calls either on an fd, so perl drives them — chmod/chown on a filehandle ARE
# fchmod(2)/fchown(2), and each returns the count of files it changed, so a
# refusal reads as 0. The mode is read back through fstat so an accept-and-drop
# no-op cannot pass as success. fchown is issued with the file's own uid/gid and
# asserts only that the call succeeds: on virtio-fs it is the sanctioned
# accept-and-succeed no-op (that backend has no ownership model), so demanding a
# uid change would assert something the platform legitimately does not do — and
# re-setting the current owner needs no privilege, so the case does not silently
# become a root-only assertion.
fd_meta_cases() {
  _dir=$1; _sfx=$2
  if ! command -v perl >/dev/null 2>&1; then
    bst_skip "vfs/fchmod$_sfx"      "perl not installed on this image"
    bst_skip "vfs/fchmod-mode$_sfx" "perl not installed on this image"
    bst_skip "vfs/fchown$_sfx"      "perl not installed on this image"
    return
  fi
  _f="$_dir/bst-vfs-fd.$$"
  rm -f "$_f" 2>/dev/null
  _o=$(perl -e '
    my $p = shift;
    open(my $fh, ">", $p) or die "open: $!\n";
    print $fh "x";
    my $c = chmod(0640, $fh);
    my @s = stat($fh);
    my $m = $s[2] & 07777;
    my $o = chown($s[4], $s[5], $fh);
    close $fh;
    printf "FCHMOD=%d MODE=%o FCHOWN=%d\n", $c, $m, $o;
  ' "$_f" 2>&1)
  check_out "vfs/fchmod$_sfx"      "FCHMOD=1" printf '%s\n' "$_o"
  check_out "vfs/fchmod-mode$_sfx" "MODE=640" printf '%s\n' "$_o"
  check_out "vfs/fchown$_sfx"      "FCHOWN=1" printf '%s\n' "$_o"
  rm -f "$_f" 2>/dev/null
}
fd_meta_cases "${TMPDIR:-/tmp}" ""

# --- the same probe against the rootfs (cloud virtio-fs) ----------------------
# The rootfs is read-only on an anonymously-booted session, which is the normal
# case: skip rather than fail, since an absent capability is not a defect. An
# owner-authenticated session makes it writable and the cases below run for real.
vdir=/var/lib/bst-vfs
if mkdir -p "$vdir" 2>/dev/null; then
  vout=$("$probe" /var/lib -vfs 2>&1)
  hardlink_cases "$vdir" "-vfs"
  fd_meta_cases  "$vdir" "-vfs"
  rmdir "$vdir" 2>/dev/null
  check_out vfs/rename-vfs      "VFS-rename-vfs OK"      printf '%s\n' "$vout"
  check_out vfs/rename-over-vfs "VFS-rename-over-vfs OK" printf '%s\n' "$vout"
else
  bst_skip vfs/rename-vfs      "rootfs read-only (anonymous session); needs an owner-authenticated boot"
  bst_skip vfs/rename-over-vfs "rootfs read-only (anonymous session); needs an owner-authenticated boot"
  bst_skip vfs/hardlink-vfs         "rootfs read-only (anonymous session); needs an owner-authenticated boot"
  bst_skip vfs/hardlink-content-vfs "rootfs read-only (anonymous session); needs an owner-authenticated boot"
  bst_skip vfs/hardlink-ino-vfs     "rootfs read-only (anonymous session); needs an owner-authenticated boot"
  bst_skip vfs/fchmod-vfs           "rootfs read-only (anonymous session); needs an owner-authenticated boot"
  bst_skip vfs/fchmod-mode-vfs      "rootfs read-only (anonymous session); needs an owner-authenticated boot"
  bst_skip vfs/fchown-vfs           "rootfs read-only (anonymous session); needs an owner-authenticated boot"
fi

rm -f "$probe"