feature_reindex_readonly.py

#!/usr/bin/env python3
# Copyright (c) 2023-present The Bitcoin Core developers
# Distributed under the MIT software license, see the accompanying
# file COPYING or http://www.opensource.org/licenses/mit-license.php.
"""Test running bitcoind with -reindex from a read-only blockstore
- Start a node, generate blocks, then restart with -reindex after setting blk files to read-only
"""

import os
import stat
import subprocess
from test_framework.test_framework import BitcoinTestFramework


class BlockstoreReindexTest(BitcoinTestFramework):
    def set_test_params(self):
        self.setup_clean_chain = True
        self.num_nodes = 1
        self.extra_args = [["-fastprune"]]

    def reindex_readonly(self):
        self.log.debug("Generate block big enough to start second block file")
        fastprune_blockfile_size = 0x10000
        opreturn = "6a"
        nulldata = fastprune_blockfile_size * "ff"
        self.generateblock(self.nodes[0], output=f"raw({opreturn}{nulldata})", transactions=[])
        block_count = self.nodes[0].getblockcount()
        self.stop_node(0)

        assert (self.nodes[0].chain_path / "blocks" / "blk00000.dat").exists()
        assert (self.nodes[0].chain_path / "blocks" / "blk00001.dat").exists()

        self.log.debug("Make the first block file read-only")
        filename = self.nodes[0].chain_path / "blocks" / "blk00000.dat"
        filename.chmod(stat.S_IREAD)

        undo_immutable = lambda: None
        # Linux
        try:
            subprocess.run(['chattr'], stdout=subprocess.DEVNULL, stderr=subprocess.DEVNULL)
            try:
                subprocess.run(['chattr', '+i', filename], capture_output=True, check=True)
                undo_immutable = lambda: subprocess.check_call(['chattr', '-i', filename])
                self.log.info("Made file immutable with chattr")
            except subprocess.CalledProcessError as e:
                self.log.warning(str(e))
                if e.stdout:
                    self.log.warning(f"stdout: {e.stdout}")
                if e.stderr:
                    self.log.warning(f"stderr: {e.stderr}")
                if os.getuid() == 0:
                    self.log.warning("Return early on Linux under root, because chattr failed.")
                    self.log.warning("This should only happen due to missing capabilities in a container.")
                    self.log.warning("Make sure to --cap-add LINUX_IMMUTABLE if you want to run this test.")
                    undo_immutable = False
        except Exception:
            # macOS, and *BSD
            try:
                subprocess.run(['chflags'], stdout=subprocess.DEVNULL, stderr=subprocess.DEVNULL)
                try:
                    subprocess.run(['chflags', 'uchg', filename], capture_output=True, check=True)
                    undo_immutable = lambda: subprocess.check_call(['chflags', 'nouchg', filename])
                    self.log.info("Made file immutable with chflags")
                except subprocess.CalledProcessError as e:
                    self.log.warning(str(e))
                    if e.stdout:
                        self.log.warning(f"stdout: {e.stdout}")
                    if e.stderr:
                        self.log.warning(f"stderr: {e.stderr}")
                    if os.getuid() == 0:
                        self.log.warning("Return early on BSD under root, because chflags failed.")
                        undo_immutable = False
            except Exception:
                pass

        if undo_immutable:
            self.log.debug("Attempt to restart and reindex the node with the unwritable block file")
            with self.nodes[0].wait_for_debug_log([b"Reindexing finished"]):
                self.start_node(0, extra_args=['-reindex', '-fastprune'])
            assert block_count == self.nodes[0].getblockcount()
            undo_immutable()

        filename.chmod(0o777)

    def run_test(self):
        self.reindex_readonly()


if __name__ == '__main__':
    BlockstoreReindexTest().main()