hfs-556.41.1.tar.gz

[apple/hfs.git] / fsck_hfs / dfalib / fsck_journal.c

/*
 * Copyright (c) 2010-2012 Apple Inc. All rights reserved.
 *
 * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
 * 
 * This file contains Original Code and/or Modifications of Original Code
 * as defined in and that are subject to the Apple Public Source License
 * Version 2.0 (the 'License'). You may not use this file except in
 * compliance with the License. The rights granted to you under the License
 * may not be used to create, or enable the creation or redistribution of,
 * unlawful or unlicensed copies of an Apple operating system, or to
 * circumvent, violate, or enable the circumvention or violation of, any
 * terms of an Apple operating system software license agreement.
 * 
 * Please obtain a copy of the License at
 * http://www.opensource.apple.com/apsl/ and read it before using this file.
 * 
 * The Original Code and all software distributed under the License are
 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
 * Please see the License for the specific language governing rights and
 * limitations under the License.
 * 
 * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
 */

#include <stdio.h>
#include <stddef.h>
#include <stdlib.h>
#include <string.h>
#include <limits.h>
#include <err.h>
#include <errno.h>
#include <fcntl.h>
#include <unistd.h>
#include <stdarg.h>
#include <sys/types.h>
#include <sys/param.h>
#include <sys/stat.h>
#include <sys/ioctl.h>
#include <sys/disk.h>
#include <sys/param.h>

#include "../fsck_hfs.h"
#include "fsck_journal.h"

#define DEBUG_JOURNAL 0

extern char debug;

#include <hfs/hfs_format.h>
#include <libkern/OSByteOrder.h>

typedef struct SwapType {
        const char *name;
        uint16_t (^swap16)(uint16_t);
        uint32_t (^swap32)(uint32_t);
        uint64_t (^swap64)(uint64_t);
} swapper_t;

static swapper_t nativeEndian = {
        "native endian",
        ^(uint16_t x) { return x; },
        ^(uint32_t x) { return x; },
        ^(uint64_t x) { return x; }
};

static swapper_t swappedEndian = {
        "swapped endian",
        ^(uint16_t x) { return OSSwapInt16(x); },
        ^(uint32_t x) { return OSSwapInt32(x); },
        ^(uint64_t x) { return OSSwapInt64(x); }
};

typedef int (^journal_write_block_t)(off_t, void *, size_t);

//
// this isn't a great checksum routine but it will do for now.
// we use it to checksum the journal header and the block list
// headers that are at the start of each transaction.
//
static uint32_t
calc_checksum(char *ptr, int len)
{
        int i;
        uint32_t cksum = 0;

        // this is a lame checksum but for now it'll do
        for(i = 0; i < len; i++, ptr++) {
                cksum = (cksum << 8) ^ (cksum + *(unsigned char *)ptr);
        }

        return (~cksum);
}

typedef struct JournalIOInfo {
        int             jfd;    // File descriptor for journal buffer
        int             wrapCount;      // Incremented when it wraps around.
        size_t          bSize;  // Block size.  I/O needs to be done in that amount.
        uint64_t        base;   // Base offset of journal buffer, past the header
        uint64_t        size;   // Size of the journal, minus the header size
        uint64_t        end;    // End of the journal (initially the "end" field from the journal header)
        uint64_t        current;        // Current offset; starts at "start"
} JournalIOInfo_t;

/*
 * Attempt to read <length> bytes from the journal buffer.
 * Since this is a wrapped buffer, it may have to start at the
 * beginning.  info->{base, size, end} are read-only; info->current
 * is updated with the current offset.  It returns the number of bytes
 * it read, or -1 on error.
 */
static ssize_t
journalRead(JournalIOInfo_t *info, uint8_t *buffer, size_t length)
{
        size_t nread = 0;
        uint8_t *ptr = buffer;

//      fprintf(stderr, "%s(%p, %p, %zu)\n", __FUNCTION__, info, buffer, length);
        if (info->wrapCount > 1) {
                fplog(stderr, "%s(%p, %p, %zu):  journal buffer wrap count = %d\n", __FUNCTION__, info, buffer, length, info->wrapCount);
                return -1;
        }
        while (nread < length) {
                off_t end;
                size_t amt;
                ssize_t n;

                if (info->end < info->current) {
                        // It wraps, so we max out at bse+size
                        end = info->base + info->size;
                } else {
                        end = info->end;
                }
                amt = MIN((length - nread), (end - info->current));
                if (amt == 0) {
                        if (debug) {
                                fplog(stderr, "Journal read amount is 0, is that right?\n");
                        }
                        goto done;
                }

                n = pread(info->jfd, ptr, amt, info->current);
                if (n == -1) {
                        warn("pread(%d, %p, %zu, %llu)", info->jfd, ptr, amt, info->current);
                        goto done;
                }
                if (n != amt) {
                        if (debug) {
                                fplog(stderr, "%s(%d):  Wanted to read %zu, but only read %zd\n", __FUNCTION__, __LINE__, amt, n);
                        }
                }
                nread += n;
                ptr += n;
                info->current += n;
                if (info->current == (info->base + info->size)) {
                        info->current = info->base;
                        info->wrapCount++;
                }
        }
done:
        return nread;
}

/*
 * Read a transaction from the journal buffer.
 * A transaction is a list of block_list_headers, and their
 * associated data.  It needs to read all of the block_lists in
 * a transaction, or it fails.  It returns NULL if there are
 * no transactions, and on error.  (Maybe that should change?)
 */
static block_list_header *
getJournalTransaction(JournalIOInfo_t *jinfo, swapper_t *swap)
{
        block_list_header *retval = NULL;
        uint8_t block[jinfo->bSize];
        block_list_header *hdr = (void*)&block;
        ssize_t nread;
        ssize_t amt;

        memset(block, 0, sizeof(block));
        nread = journalRead(jinfo, block, sizeof(block));
        if (nread == -1 ||
            (size_t)nread != sizeof(block)) {
                if (debug)
                        plog("%s:  wanted %zd, got %zd\n", __FUNCTION__, sizeof(block), nread);
                return NULL;
        }
        if (swap->swap32(hdr->num_blocks) == 0) {
                /*
                 * Either there really are no blocks, or this is not a valid
                 * transaction.  Either way, there's nothing for us to do here.
                 */
#if DEBUG_JOURNAL
                if (debug)
                        fplog(stderr, "%s(%d):  hdr->num_blocks == 0\n", __FUNCTION__, __LINE__);
#endif
                return NULL;
        }
        /*
         * Now we check the checksum to see if this is a valid header.
         * Note that we verify the checksum before reading any more -- if
         * it's not a valid header, we don't want to read more than a block
         * size.
         */
        uint32_t tmpChecksum = swap->swap32(hdr->checksum);
        uint32_t compChecksum;
        hdr->checksum = 0;
        compChecksum = calc_checksum((void*)hdr, sizeof(*hdr));
        hdr->checksum = swap->swap32(tmpChecksum);

        if (compChecksum != tmpChecksum) {
                if (debug)
                        fplog(stderr, "%s(%d):  hdr has bad checksum, returning NULL\n", __FUNCTION__, __LINE__);
                return NULL;
        }

        if (swap->swap32(hdr->bytes_used) < sizeof(block)) {
#if DEBUG_JOURNAL
                if (debug) {
                        fplog(stderr, "%s(%d):  hdr has bytes_used (%u) less than sizeof block (%zd)\n",
                              __FUNCTION__, __LINE__, swap->swap32(hdr->bytes_used), sizeof(block));
                }
#endif
                return NULL;
        }

        retval = malloc(swap->swap32(hdr->bytes_used));
        if (retval == NULL)
                return NULL;

        memset(retval, 0, swap->swap32(hdr->bytes_used));
        memcpy(retval, block, sizeof(block));
        amt = swap->swap32(hdr->bytes_used) - sizeof(block);
        nread = journalRead(jinfo, ((uint8_t*)retval) + sizeof(block), amt);
        if (nread != amt) {
                free(retval);
                return NULL;
        }

        return retval;
}

/*
 * Replay a transaction.
 * Transactions have a blockListSize amount of block_list_header, and
 * are then followed by data.  We read it in, verify the checksum, and
 * if it's good, we call the block that was passed in to do something
 * with it.  Maybe write it out.  Maybe laugh about it.
 *
 * It returns -1 if there was an error before it wrote anything out,
 * and -2 if there was an error after it wrote something out.
 *
 * The arguments are:
 * txn  -- a block_list_header pointer, which has the description and data
 *      to be replayed.
 * blSize       -- the size of the block_list for this journal.  (The data
 *              are after the block_list, but part of the same buffer.)
 * blkSize      -- The block size used to convert block numbers to offsets.  This
 *              is defined to be the size of the journal header.
 * swap -- A pointer to a swapper_t used to swap journal data structure elements.
 * writer       -- A block-of-code that does writing.
 *
 * "writer" should return -1 to stop the replay (this propagates an error up).
 */
static int
replayTransaction(block_list_header *txn, size_t blSize, size_t blkSize, swapper_t *swap, journal_write_block_t writer)
{
        uint32_t i;
        uint8_t *endPtr = ((uint8_t*)txn) + swap->swap32(txn->bytes_used);
        uint8_t *dataPtr = ((uint8_t*)txn) + blSize;
        int retval = -1;
        for (i = 1; i < swap->swap32(txn->num_blocks); i++) {
#if DEBUG_JOURNAL
                if (debug)
                        plog("\tBlock %d:  blkNum %llu, size %u, data offset = %zd\n", i, swap->swap64(txn->binfo[i].bnum), swap->swap32(txn->binfo[i].bsize), dataPtr - (uint8_t*)txn);
#endif
                /*
                 * XXX
                 * Check with security types on these checks.  Need to ensure
                 * that the fields don't take us off into the dark scary woods.
                 * It's mostly the second one that I am unsure about.
                 */
                if (dataPtr > endPtr) {
                        if (debug)
                                plog("\tData out of range for block_list_header\n");
                        return retval;
                }
                if ((endPtr - dataPtr) < swap->swap32(txn->binfo[i].bsize)) {
                        if (debug)
                                plog("\tData size for block %d out of range for block_list_header\n", i);
                        return retval;
                }
                if ((dataPtr + swap->swap32(txn->binfo[i].bsize)) > endPtr) {
                        if (debug)
                                plog("\tData end out of range for block_list_header\n");
                        return retval;
                }
#if DEBUG_JOURNAL
                // Just for debugging
                if (debug) {
                        if (swap->swap64(txn->binfo[i].bnum) == 2) {
                                HFSPlusVolumeHeader *vp = (void*)dataPtr;
                                plog("vp->signature = %#x, version = %#x\n", vp->signature, vp->version);
                        }
                }
#endif
                // It's in the spec, and I saw it come up once on a live volume.
                if (swap->swap64(txn->binfo[i].bnum) == ~(uint64_t)0) {
#if DEBUG_JOURNAL
                        if (debug)
                                plog("\tSkipping this block due to magic skip number\n");
#endif
                } else {
                        // Should we set retval to -2 here?
                        if (writer) {
                                if ((writer)(swap->swap64(txn->binfo[i].bnum) * blkSize, dataPtr, swap->swap32(txn->binfo[i].bsize)) == -1)
                                        return retval;
                        }
                }
                dataPtr += swap->swap32(txn->binfo[i].bsize);
                retval = -2;
        }
        return 0;
}

/*
 * Read a journal header in from the journal device.
 */
static int
loadJournalHeader(int jfd, off_t offset, size_t blockSize, journal_header *jhp)
{
        uint8_t buffer[blockSize];
        ssize_t nread;

        nread = pread(jfd, buffer, sizeof(buffer), offset);
        if (nread == -1 ||
            (size_t)nread != sizeof(buffer)) {
                warn("tried to read %zu for journal header buffer, got %zd", sizeof(buffer), nread);
                return -1;
        }
        *jhp = *(journal_header*)buffer;
        return 0;
}

/*
 * Replay a journal (called "journal_open" because you have to
 * to replay it as part of opening it).  At this point, all it
 * is useful for is replaying the journal.
 *
 * It is passed in:
 *     jfd      -- file descriptor for the journal device
 *     offset   -- offset (in bytes) of the journal on the journal device
 *     journal_size     -- size of the jorunal (in bytes)
 *     min_fs_blksize   -- Blocksize of the data filesystem
 *     flags    -- unused for now
 *     jdev_name        -- string name for the journal device.  used for logging.
 *     do_write_b       -- a block which does the actual writing.
 *
 * Currently, for fsck_hfs, the do_write_b block writes to the cache.  It could also
 * just print out the block numbers, or just check their integrity, as much as is
 * possible.
 * 
 * The function works by loading the journal header.  From there, it then starts
 * loading transactions, via block_list_header groups.  When it gets to the end
 * of the journal, it tries continuing, in case there were transactions that
 * didn't get updated in the header (this apparently happens).
 * 
 * It returns 0 on success, and -1 on error.  Note that there's not a lot
 * fsck_hfs can probably do in the event of error.
 *
 */
int
journal_open(int jfd,
             off_t      offset,         // Offset of journal
             off_t      journal_size,   // Size, in bytes, of the entire journal
             size_t     min_fs_blksize, // Blocksize of the data filesystem, journal blocksize must be at least this size
             uint32_t   flags __unused, // Not used in this implementation
             const char *jdev_name,     // The name of the journal device, for logging
             int (^do_write_b)(off_t, void*, size_t))
{
        journal_header jhdr = { 0 };
        swapper_t       *jnlSwap;       // Used to swap fields of the journal
        uint32_t        tempCksum;      // Temporary checksum value
        uint32_t        jBlkSize = 0;

        if (ioctl(jfd, DKIOCGETBLOCKSIZE, &jBlkSize) == -1) {
                jBlkSize = (uint32_t)min_fs_blksize;
        } else {
                if (jBlkSize < min_fs_blksize) {
                        fplog(stderr, "%s:  journal block size %u < min block size %zu for %s\n", __FUNCTION__, jBlkSize, min_fs_blksize, jdev_name);
                        return -1;
                }
                if ((jBlkSize % min_fs_blksize) != 0) {
                        fplog(stderr, "%s:  journal block size %u is not a multiple of fs block size %zu for %s\n", __FUNCTION__, jBlkSize, min_fs_blksize, jdev_name);
                        return -1;
                }
        }
        if (loadJournalHeader(jfd, offset, jBlkSize, &jhdr) != 0) {
                fplog(stderr, "%s:  unable to load journal header from %s\n", __FUNCTION__, jdev_name);
                return -1;
        }

        /*
         * Unlike the rest of the filesystem, the journal can be in native or
         * non-native byte order.  Barring moving a filesystem from one host
         * to another, it'll almost always be in native byte order.
         */
        if (jhdr.endian == ENDIAN_MAGIC) {
                jnlSwap = &nativeEndian;
        } else if (OSSwapInt32(jhdr.endian) == ENDIAN_MAGIC) {
                jnlSwap = &swappedEndian;
        } else {
                fplog(stderr, "%s:  Unknown journal endian magic number %#x from %s\n", __FUNCTION__, jhdr.endian, jdev_name);
                return -1;
        }
        /*
         * Two different magic numbers are valid.
         * Do they mean different thigs, though?
         */
        if (jnlSwap->swap32(jhdr.magic) != JOURNAL_HEADER_MAGIC &&
            jnlSwap->swap32(jhdr.magic) != OLD_JOURNAL_HEADER_MAGIC) {
                fplog(stderr, "%s:  Unknown journal header magic number %#x from %s\n", __FUNCTION__, jhdr.magic, jdev_name);
                return -1;
        }

        /*
         * Checksums have to be done with the checksum field set to 0.
         * So we have to stash it aside for a bit, and set the field to
         * 0, before we can compare.  Afterwards, if it compares correctly,
         * we put the original (swapped, if necessary) value back, just
         * in case.
         */
        tempCksum = jnlSwap->swap32(jhdr.checksum);
        jhdr.checksum = 0;
        if (jnlSwap->swap32(jhdr.magic) == JOURNAL_HEADER_MAGIC &&
            (calc_checksum((void*)&jhdr, JOURNAL_HEADER_CKSUM_SIZE) != tempCksum)) {
                fplog(stderr, "%s:  Invalid journal checksum from %s\n", __FUNCTION__, jdev_name);
                return -1;
        }
        jhdr.checksum = jnlSwap->swap32(tempCksum);

        /*
         * Set up information about the journal which we use to do the I/O.
         * The journal is a circular buffer.  However, the start of the journal
         * buffer is past the journal header.  See the JournalIOInfo structure above.
         */
        off_t startOffset = jnlSwap->swap64(jhdr.start);
        off_t endOffset =jnlSwap->swap64(jhdr.end);
        off_t journalStart = offset + jnlSwap->swap32(jhdr.jhdr_size);

        /*
         * The journal code was updated to be able to read past the "end" of the journal,
         * to see if there were any valid transactions there.  If we are peeking past the
         * end, we don't care if we have checksum errors -- that just means they're not
         * valid transactions.
         *
         */
        int into_the_weeds = 0;
        uint32_t last_sequence_number = 0;

        JournalIOInfo_t jinfo = { 0 };

#if DEBUG_JOURNAL
        if (debug)
                plog("Journal start sequence number = %u\n", jnlSwap->swap32(jhdr.sequence_num));
#endif

        /*
         * Now set up the JournalIOInfo object with the file descriptor,
         * the block size, start and end of the journal buffer, and where
         * the journal pointer currently is.
         */
        jinfo.jfd = jfd;
        jinfo.bSize = jnlSwap->swap32(jhdr.jhdr_size);
        jinfo.base = journalStart;
        jinfo.size = journal_size - jinfo.bSize;
        jinfo.end = offset + endOffset;
        jinfo.current = offset + startOffset;

        const char *state = "";
        int bad_journal = 0;
        block_list_header *txn = NULL;

        /*
         * Loop while getting transactions.  We exit when we hit a checksum
         * error, or when the sequence number for a transaction doesn't match
         * what we expect it to.  (That's the trickiest part -- the into_the_weeds
         * portion of the code.  It doesn't match the TN11150 documentation, so
         * I've had to go by both my experience with real-world journals and by
         * looking at the kernel code.)
         */
        while (1) {
                int rv;

                if (jinfo.current == jinfo.end && into_the_weeds == 0) {
                        /*
                         * This is a bit weird, but it works:  if current == end, but gone_into_weeds is 1,
                         * then this code will not execute.  If it does execute, it'll go to get a transaction.
                         * That will put the pointer past end.
                         */
                        if (jhdr.sequence_num == 0) {
                                /*
                                 * XXX
                                 * I am not sure about this; this behaviour is not in TN1150 at all,
                                 * but I _think_ this is what the kernel is doing.
                 */
#if DEBUG_JOURNAL
                if (debug)
                    plog("Journal sequence number is 0, is going into the end okay?\n");
#endif
                        }
                        into_the_weeds = 1;
#if DEBUG_JOURNAL
                        if (debug)
                                plog("Attempting to read past stated end of journal\n");
#endif
                        state = "tentative ";
                        jinfo.end = (jinfo.base + startOffset - jinfo.bSize);
                        continue;
                }
#if DEBUG_JOURNAL
                if (debug)
                        plog("Before getting %stransaction:  jinfo.current = %llu\n", state, jinfo.current);
#endif
                /*
                 * Note that getJournalTransaction verifies the checksum on the block_list_header, so
                 * if it's bad, it'll return NULL.
                 */
                txn = getJournalTransaction(&jinfo, jnlSwap);
                if (txn == NULL) {
#if DEBUG_JOURNAL
                        if (debug)
                                plog("txn is NULL, jinfo.current = %llu\n", jinfo.current);
#endif
                        if (into_the_weeds) {
#if DEBUG_JOURNAL
                                if (debug)
                                        plog("\tBut we do not care, since it is past the end of the journal\n");
#endif
                        } else {
                                bad_journal = 1;
                        }
                        break;
                }
#if DEBUG_JOURNAL
                if (debug) {
                        plog("After getting %stransaction:  jinfo.current = %llu\n", state, jinfo.current);
                        plog("%stxn = { %u max_blocks, %u num_blocks, %u bytes_used, binfo[0].next = %u }\n", state, jnlSwap->swap32(txn->max_blocks), jnlSwap->swap32(txn->num_blocks), jnlSwap->swap32(txn->bytes_used), jnlSwap->swap32(txn->binfo[0].next));
                }
#endif
                if (into_the_weeds) {
                        /*
                         * This seems to be what the kernel was checking:  if the
                         * last_sequence_number was set, and the txn sequence number
                         * is set, and the txn sequence number doesn't match either
                         * last_sequence_number _or_ an incremented version of it, then
                         * the transaction isn't worth looking at, and we've reached
                         * the end of the journal.
                         */
                        if (last_sequence_number != 0 &&
                            txn->binfo[0].next != 0 &&
                            jnlSwap->swap32(txn->binfo[0].next) != last_sequence_number &&
                            jnlSwap->swap32(txn->binfo[0].next) != (last_sequence_number + 1)) {
                                // Probably not a valid transaction
#if DEBUG_JOURNAL
                                if (debug)
                                        plog("\tTentative txn sequence %u is not expected %u, stopping journal replay\n", jnlSwap->swap32(txn->binfo[0].next), last_sequence_number + 1);
#endif
                                break;
                        }
                }
                /*
                 * If we've got a valid transaction, then we replay it.
                 * If there was an error, we're done with the journal replay.
                 * (If the error occurred after the "end," then we don't care,
                 * and it's not a bad journal.)
                 */
                rv = replayTransaction(txn,
                                       jnlSwap->swap32(jhdr.blhdr_size),
                                       jnlSwap->swap32(jhdr.jhdr_size),
                                       jnlSwap,
                                       do_write_b);

                if (rv < 0) {
                        if (debug)
                                plog("\tTransaction replay failed, returned %d\n", rv);
                        if (into_the_weeds) {
                                if (debug)
                                        plog("\t\tAnd we don't care\n");
                        } else {
                                bad_journal = 1;
                        }
                        break;
                }
                last_sequence_number = jnlSwap->swap32(txn->binfo[0].next);
                free(txn);
                txn = NULL;
        }
        if (txn)
                free(txn);
        if (bad_journal) {
                if (debug)
                        plog("Journal was bad, stopped replaying\n");
                return -1;
        }

        return 0;
}