update

2026-08-18 09:20:44 +02:00
commit b826cd721a
522 changed files with 93730 additions and 0 deletions
@@ -0,0 +1,199 @@
+#!/bin/sh
+set -eu
+
+script_dir=$(CDPATH= cd -- "$(dirname -- "$0")" && pwd)
+fixture_dir="$script_dir/fixture"
+artifact_dir="$script_dir/artifacts"
+
+mkdir -p \
+	"$fixture_dir/alpha/bravo/charlie" \
+	"$fixture_dir/alpha/sibling" \
+	"$fixture_dir/wide" \
+	"$artifact_dir"
+
+printf '%s\n' 'cold nested lookup payload' > \
+	"$fixture_dir/alpha/bravo/charlie/payload.txt"
+printf '%s\n' 'repeat lookup payload' > \
+	"$fixture_dir/alpha/bravo/repeat.txt"
+printf '%s\n' 'sibling marker' > \
+	"$fixture_dir/alpha/sibling/marker.txt"
+
+index=0
+while [ "$index" -lt 320 ]; do
+	name=$(printf 'entry-%03d-abcdefghijklmnopqrstuvwxyz.txt' "$index")
+	printf 'wide entry %03d\n' "$index" > "$fixture_dir/wide/$name"
+	index=$((index + 1))
+done
+
+find "$fixture_dir" -exec touch -h -t 197001010000.00 {} +
+
+build_image()
+{
+	image=$1
+	mkfs.erofs -d0 -x-1 -T0 --all-time --all-root --workers=1 \
+		-U 11111111-2222-3333-4444-555555555555 \
+		"$image" "$fixture_dir"
+}
+
+build_image "$artifact_dir/nested.erofs"
+build_image "$artifact_dir/nested-repeat.erofs"
+cmp "$artifact_dir/nested.erofs" "$artifact_dir/nested-repeat.erofs"
+
+ARTIFACT_DIR="$artifact_dir" python3 <<'PY'
+import hashlib
+import os
+import shutil
+import struct
+
+artifact_dir = os.environ["ARTIFACT_DIR"]
+base_path = os.path.join(artifact_dir, "nested.erofs")
+
+
+def u16(image, offset):
+    return struct.unpack_from("<H", image, offset)[0]
+
+
+def u32(image, offset):
+    return struct.unpack_from("<I", image, offset)[0]
+
+
+def put_u16(image, offset, value):
+    struct.pack_into("<H", image, offset, value)
+
+
+def put_u32(image, offset, value):
+    struct.pack_into("<I", image, offset, value)
+
+
+def update_superblock_checksum(image):
+    polynomial = 0x82F63B78
+    checksum = 0xFFFFFFFF
+    put_u32(image, 1024 + 4, 0)
+    for byte in image[1024:4096]:
+        checksum ^= byte
+        for _ in range(8):
+            checksum = (checksum >> 1) ^ (polynomial if checksum & 1 else 0)
+    put_u32(image, 1024 + 4, checksum & 0xFFFFFFFF)
+
+
+def inode_offset(nid):
+    return nid << 5
+
+
+def compact_inline_dir(image, nid):
+    offset = inode_offset(nid)
+    inode_format = u16(image, offset)
+    layout = (inode_format >> 1) & 0x7
+    assert (inode_format & 0x1) == 0
+    assert layout == 2
+    assert u16(image, offset + 2) == 0
+    return offset, offset + 32, u32(image, offset + 8)
+
+
+def dir_entries(image, data_offset, size):
+    first_nameoff = u16(image, data_offset + 8)
+    assert first_nameoff >= 12
+    assert first_nameoff % 12 == 0
+    assert first_nameoff < size
+    count = first_nameoff // 12
+    entries = []
+    for index in range(count):
+        entry_offset = data_offset + index * 12
+        nid, nameoff, file_type, reserved = struct.unpack_from(
+            "<QHBB", image, entry_offset
+        )
+        endoff = (
+            u16(image, data_offset + (index + 1) * 12 + 8)
+            if index + 1 < count
+            else size
+        )
+        assert first_nameoff <= nameoff < endoff <= size
+        slot = bytes(image[data_offset + nameoff : data_offset + endoff])
+        name = slot.split(b"\0", 1)[0]
+        assert name
+        entries.append((nid, nameoff, file_type, reserved, name))
+    return entries
+
+
+with open(base_path, "rb") as source:
+    base = bytearray(source.read())
+
+assert u32(base, 1024) == 0xE0F5E1E2
+assert base[1024 + 12] == 12
+assert u16(base, 1024 + 14) == 36
+root_nid = 36
+root_inode, root_data, root_size = compact_inline_dir(base, root_nid)
+root_entries = dir_entries(base, root_data, root_size)
+assert [entry[4] for entry in root_entries] == [b".", b"..", b"alpha", b"wide"]
+
+dot_omitted = bytearray(base)
+removed = 13
+new_size = root_size - removed
+new_entries = root_entries[1:]
+new_first_nameoff = len(new_entries) * 12
+for index, entry in enumerate(new_entries):
+    nid, nameoff, file_type, reserved, _ = entry
+    struct.pack_into(
+        "<QHBB",
+        dot_omitted,
+        root_data + index * 12,
+        nid,
+        nameoff - removed,
+        file_type,
+        reserved,
+    )
+names = b"".join(entry[4] for entry in new_entries)
+dot_omitted[root_data + new_first_nameoff : root_data + new_size] = names
+dot_omitted[root_data + new_size : root_data + root_size] = b"\0" * (
+    root_size - new_size
+)
+put_u16(dot_omitted, root_inode, u16(dot_omitted, root_inode) | (1 << 4))
+put_u32(dot_omitted, root_inode + 8, new_size)
+assert [entry[4] for entry in dir_entries(dot_omitted, root_data, new_size)] == [
+    b"..",
+    b"alpha",
+    b"wide",
+]
+
+short_block = bytearray(base)
+put_u32(short_block, root_inode + 8, 8)
+
+nonmonotonic = bytearray(base)
+first_nameoff = u16(nonmonotonic, root_data + 8)
+put_u16(nonmonotonic, root_data + 12 + 8, first_nameoff)
+
+wide_nid = next(entry[0] for entry in root_entries if entry[4] == b"wide")
+wide_inode = inode_offset(wide_nid)
+assert ((u16(base, wide_inode) >> 1) & 0x7) == 2
+wide_startblk = u32(base, wide_inode + 16)
+wide_block = wide_startblk << 12
+wide_first_nameoff = u16(base, wide_block + 8)
+wide_count = wide_first_nameoff // 12
+wide_last_nameoff = u16(base, wide_block + (wide_count - 1) * 12 + 8)
+padding_nul = base.index(0, wide_block + wide_last_nameoff, wide_block + 4096)
+assert padding_nul + 1 < wide_block + 4096
+assert base[padding_nul + 1] == 0
+bad_padding = bytearray(base)
+bad_padding[padding_nul + 1] = ord("X")
+
+outputs = {
+    "dot-omitted.erofs": dot_omitted,
+    "corrupt-short-block.erofs": short_block,
+    "corrupt-nameoff.erofs": nonmonotonic,
+    "corrupt-padding.erofs": bad_padding,
+}
+for filename, image in outputs.items():
+    update_superblock_checksum(image)
+    path = os.path.join(artifact_dir, filename)
+    with open(path, "wb") as output:
+        output.write(image)
+
+with open(os.path.join(artifact_dir, "SHA256SUMS"), "w", encoding="ascii") as sums:
+    for filename in sorted(["nested.erofs", "nested-repeat.erofs", *outputs]):
+        path = os.path.join(artifact_dir, filename)
+        with open(path, "rb") as image_file:
+            digest = hashlib.sha256(image_file.read()).hexdigest()
+        sums.write(f"{digest}  {filename}\n")
+PY
+
+cat "$artifact_dir/SHA256SUMS"