/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 2022 The FreeBSD Foundation
 *
 * This software was developed by Mark Johnston under sponsorship from
 * the FreeBSD Foundation.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <sys/param.h>
#include <sys/endian.h>

#include <assert.h>
#include <stddef.h>
#include <stdint.h>
#include <stdlib.h>
#include <string.h>

#include <util.h>

#include "makefs.h"
#include "zfs.h"

typedef struct zfs_zap_entry {
        char            *name;          /* entry key, private copy */
        uint64_t        hash;           /* key hash */
        union {
                uint8_t  *valp;
                uint16_t *val16p;
                uint32_t *val32p;
                uint64_t *val64p;
        };                              /* entry value, an integer array */
        uint64_t        val64;          /* embedded value for a common case */
        size_t          intsz;          /* array element size; 1, 2, 4 or 8 */
        size_t          intcnt;         /* array size */
        STAILQ_ENTRY(zfs_zap_entry) next;
} zfs_zap_entry_t;

struct zfs_zap {
        STAILQ_HEAD(, zfs_zap_entry) kvps;
        uint64_t        hashsalt;       /* key hash input */
        unsigned long   kvpcnt;         /* number of key-value pairs */
        unsigned long   chunks;         /* count of chunks needed for fat ZAP */
        bool            micro;          /* can this be a micro ZAP? */

        dnode_phys_t    *dnode;         /* backpointer */
        zfs_objset_t    *os;            /* backpointer */
};

static uint16_t
zap_entry_chunks(zfs_zap_entry_t *ent)
{
        return (1 + howmany(strlen(ent->name) + 1, ZAP_LEAF_ARRAY_BYTES) +
            howmany(ent->intsz * ent->intcnt, ZAP_LEAF_ARRAY_BYTES));
}

static uint64_t
zap_hash(uint64_t salt, const char *name)
{
        static uint64_t crc64_table[256];
        const uint64_t crc64_poly = 0xC96C5795D7870F42UL;
        const uint8_t *cp;
        uint64_t crc;
        uint8_t c;

        assert(salt != 0);
        if (crc64_table[128] == 0) {
                for (int i = 0; i < 256; i++) {
                        uint64_t *t;

                        t = crc64_table + i;
                        *t = i;
                        for (int j = 8; j > 0; j--)
                                *t = (*t >> 1) ^ (-(*t & 1) & crc64_poly);
                }
        }
        assert(crc64_table[128] == crc64_poly);

        for (cp = (const uint8_t *)name, crc = salt; (c = *cp) != '\0'; cp++)
                crc = (crc >> 8) ^ crc64_table[(crc ^ c) & 0xFF];

        /*
         * Only use 28 bits, since we need 4 bits in the cookie for the
         * collision differentiator.  We MUST use the high bits, since
         * those are the ones that we first pay attention to when
         * choosing the bucket.
         */
        crc &= ~((1ULL << (64 - ZAP_HASHBITS)) - 1);

        return (crc);
}

zfs_zap_t *
zap_alloc(zfs_objset_t *os, dnode_phys_t *dnode)
{
        zfs_zap_t *zap;

        zap = ecalloc(1, sizeof(*zap));
        STAILQ_INIT(&zap->kvps);
        zap->hashsalt = ((uint64_t)random() << 32) | random();
        zap->micro = true;
        zap->kvpcnt = 0;
        zap->chunks = 0;
        zap->dnode = dnode;
        zap->os = os;
        return (zap);
}

void
zap_add(zfs_zap_t *zap, const char *name, size_t intsz, size_t intcnt,
    const uint8_t *val)
{
        zfs_zap_entry_t *ent;

        assert(intsz == 1 || intsz == 2 || intsz == 4 || intsz == 8);
        assert(strlen(name) + 1 <= ZAP_MAXNAMELEN);
        assert(intcnt <= ZAP_MAXVALUELEN && intcnt * intsz <= ZAP_MAXVALUELEN);

        ent = ecalloc(1, sizeof(*ent));
        ent->name = estrdup(name);
        ent->hash = zap_hash(zap->hashsalt, ent->name);
        ent->intsz = intsz;
        ent->intcnt = intcnt;
        if (intsz == sizeof(uint64_t) && intcnt == 1) {
                /*
                 * Micro-optimization to elide a memory allocation in that most
                 * common case where this is a directory entry.
                 */
                ent->val64p = &ent->val64;
        } else {
                ent->valp = ecalloc(intcnt, intsz);
        }
        memcpy(ent->valp, val, intcnt * intsz);
        zap->kvpcnt++;
        zap->chunks += zap_entry_chunks(ent);
        STAILQ_INSERT_TAIL(&zap->kvps, ent, next);

        if (zap->micro && (intcnt != 1 || intsz != sizeof(uint64_t) ||
            strlen(name) + 1 > MZAP_NAME_LEN || zap->kvpcnt > MZAP_ENT_MAX))
                zap->micro = false;
}

void
zap_add_uint64(zfs_zap_t *zap, const char *name, uint64_t val)
{
        zap_add(zap, name, sizeof(uint64_t), 1, (uint8_t *)&val);
}

void
zap_add_uint64_self(zfs_zap_t *zap, uint64_t val)
{
        char name[32];

        (void)snprintf(name, sizeof(name), "%jx", (uintmax_t)val);
        zap_add(zap, name, sizeof(uint64_t), 1, (uint8_t *)&val);
}

void
zap_add_string(zfs_zap_t *zap, const char *name, const char *val)
{
        zap_add(zap, name, 1, strlen(val) + 1, (const uint8_t *)val);
}

bool
zap_entry_exists(zfs_zap_t *zap, const char *name)
{
        zfs_zap_entry_t *ent;

        STAILQ_FOREACH(ent, &zap->kvps, next) {
                if (strcmp(ent->name, name) == 0)
                        return (true);
        }
        return (false);
}

static void
zap_micro_write(zfs_opt_t *zfs, zfs_zap_t *zap)
{
        dnode_phys_t *dnode;
        zfs_zap_entry_t *ent;
        mzap_phys_t *mzap;
        mzap_ent_phys_t *ment;
        off_t bytes, loc;
        uint16_t cd;

        _Static_assert(MZAP_ENT_MAX <= UINT16_MAX,
            "micro ZAP collision differentiator must fit in 16 bits");

        memset(zfs->filebuf, 0, sizeof(zfs->filebuf));
        mzap = (mzap_phys_t *)&zfs->filebuf[0];
        mzap->mz_block_type = ZBT_MICRO;
        mzap->mz_salt = zap->hashsalt;
        mzap->mz_normflags = 0;

        bytes = sizeof(*mzap) + (zap->kvpcnt - 1) * sizeof(*ment);
        assert(bytes <= (off_t)MZAP_MAX_BLKSZ);

        cd = 0;
        ment = &mzap->mz_chunk[0];
        STAILQ_FOREACH(ent, &zap->kvps, next) {
                memcpy(&ment->mze_value, ent->valp, ent->intsz * ent->intcnt);
                ment->mze_cd = cd++;
                (void)strlcpy(ment->mze_name, ent->name,
                    sizeof(ment->mze_name));
                ment++;
        }

        loc = objset_space_alloc(zfs, zap->os, &bytes);

        dnode = zap->dnode;
        dnode->dn_maxblkid = 0;
        dnode->dn_datablkszsec = bytes >> MINBLOCKSHIFT;

        vdev_pwrite_dnode_data(zfs, dnode, zfs->filebuf, bytes, loc);
}

/*
 * Write some data to the fat ZAP leaf chunk starting at index "li".
 *
 * Note that individual integers in the value may be split among consecutive
 * leaves.
 */
static void
zap_fat_write_array_chunk(zap_leaf_t *l, uint16_t li, size_t sz,
    const uint8_t *val)
{
        struct zap_leaf_array *la;

        assert(sz <= ZAP_MAXVALUELEN);
        assert(sz > 0);

        for (uint16_t n, resid = sz; resid > 0; resid -= n, val += n, li++) {
                n = MIN(resid, ZAP_LEAF_ARRAY_BYTES);

                la = &ZAP_LEAF_CHUNK(l, li).l_array;
                assert(la->la_type == ZAP_CHUNK_FREE);
                la->la_type = ZAP_CHUNK_ARRAY;
                memcpy(la->la_array, val, n);
                la->la_next = li + 1;
        }
        la->la_next = 0xffff;
}

/*
 * Find the shortest hash prefix length which lets us distribute keys without
 * overflowing a leaf block.  This is not (space) optimal, but is simple, and
 * directories large enough to overflow a single 128KB leaf block are uncommon.
 */
static unsigned int
zap_fat_write_prefixlen(zfs_zap_t *zap, zap_leaf_t *l)
{
        zfs_zap_entry_t *ent;
        unsigned int prefixlen;

        if (zap->chunks <= ZAP_LEAF_NUMCHUNKS(l)) {
                /*
                 * All chunks will fit in a single leaf block.
                 */
                return (0);
        }

        for (prefixlen = 1; prefixlen < (unsigned int)l->l_bs; prefixlen++) {
                uint32_t *leafchunks;

                leafchunks = ecalloc(1u << prefixlen, sizeof(*leafchunks));
                STAILQ_FOREACH(ent, &zap->kvps, next) {
                        uint64_t li;
                        uint16_t chunks;

                        li = ZAP_HASH_IDX(ent->hash, prefixlen);

                        chunks = zap_entry_chunks(ent);
                        if (ZAP_LEAF_NUMCHUNKS(l) - leafchunks[li] < chunks) {
                                /*
                                 * Not enough space, grow the prefix and retry.
                                 */
                                break;
                        }
                        leafchunks[li] += chunks;
                }
                free(leafchunks);

                if (ent == NULL) {
                        /*
                         * Everything fits, we're done.
                         */
                        break;
                }
        }

        /*
         * If this fails, then we need to expand the pointer table.  For now
         * this situation is unhandled since it is hard to trigger.
         */
        assert(prefixlen < (unsigned int)l->l_bs);

        return (prefixlen);
}

/*
 * Initialize a fat ZAP leaf block.
 */
static void
zap_fat_write_leaf_init(zap_leaf_t *l, uint64_t prefix, int prefixlen)
{
        zap_leaf_phys_t *leaf;

        leaf = l->l_phys;

        leaf->l_hdr.lh_block_type = ZBT_LEAF;
        leaf->l_hdr.lh_magic = ZAP_LEAF_MAGIC;
        leaf->l_hdr.lh_nfree = ZAP_LEAF_NUMCHUNKS(l);
        leaf->l_hdr.lh_prefix = prefix;
        leaf->l_hdr.lh_prefix_len = prefixlen;

        /* Initialize the leaf hash table. */
        assert(leaf->l_hdr.lh_nfree < 0xffff);
        memset(leaf->l_hash, 0xff,
            ZAP_LEAF_HASH_NUMENTRIES(l) * sizeof(*leaf->l_hash));

        /* Initialize the leaf chunks. */
        for (uint16_t i = 0; i < ZAP_LEAF_NUMCHUNKS(l); i++) {
                struct zap_leaf_free *lf;

                lf = &ZAP_LEAF_CHUNK(l, i).l_free;
                lf->lf_type = ZAP_CHUNK_FREE;
                if (i + 1 == ZAP_LEAF_NUMCHUNKS(l))
                        lf->lf_next = 0xffff;
                else
                        lf->lf_next = i + 1;
        }
}

static void
zap_fat_write(zfs_opt_t *zfs, zfs_zap_t *zap)
{
        struct dnode_cursor *c;
        zap_leaf_t l;
        zap_phys_t *zaphdr;
        struct zap_table_phys *zt;
        zfs_zap_entry_t *ent;
        dnode_phys_t *dnode;
        uint8_t *leafblks;
        uint64_t lblkcnt, *ptrhasht;
        off_t loc, blksz;
        size_t blkshift;
        unsigned int prefixlen;
        int ptrcnt;

        /*
         * For simplicity, always use the largest block size.  This should be ok
         * since most directories will be micro ZAPs, but it's space inefficient
         * for small ZAPs and might need to be revisited.
         */
        blkshift = MAXBLOCKSHIFT;
        blksz = (off_t)1 << blkshift;

        /*
         * Embedded pointer tables give up to 8192 entries.  This ought to be
         * enough for anything except massive directories.
         */
        ptrcnt = (blksz / 2) / sizeof(uint64_t);

        memset(zfs->filebuf, 0, sizeof(zfs->filebuf));
        zaphdr = (zap_phys_t *)&zfs->filebuf[0];
        zaphdr->zap_block_type = ZBT_HEADER;
        zaphdr->zap_magic = ZAP_MAGIC;
        zaphdr->zap_num_entries = zap->kvpcnt;
        zaphdr->zap_salt = zap->hashsalt;

        l.l_bs = blkshift;
        l.l_phys = NULL;

        zt = &zaphdr->zap_ptrtbl;
        zt->zt_blk = 0;
        zt->zt_numblks = 0;
        zt->zt_shift = flsll(ptrcnt) - 1;
        zt->zt_nextblk = 0;
        zt->zt_blks_copied = 0;

        /*
         * How many leaf blocks do we need?  Initialize them and update the
         * header.
         */
        prefixlen = zap_fat_write_prefixlen(zap, &l);
        lblkcnt = (uint64_t)1 << prefixlen;
        leafblks = ecalloc(lblkcnt, blksz);
        for (unsigned int li = 0; li < lblkcnt; li++) {
                l.l_phys = (zap_leaf_phys_t *)(leafblks + li * blksz);
                zap_fat_write_leaf_init(&l, li, prefixlen);
        }
        zaphdr->zap_num_leafs = lblkcnt;
        zaphdr->zap_freeblk = lblkcnt + 1;

        /*
         * For each entry, figure out which leaf block it belongs to based on
         * the upper bits of its hash, allocate chunks from that leaf, and fill
         * them out.
         */
        ptrhasht = (uint64_t *)(&zfs->filebuf[0] + blksz / 2);
        STAILQ_FOREACH(ent, &zap->kvps, next) {
                struct zap_leaf_entry *le;
                uint16_t *lptr;
                uint64_t hi, li;
                uint16_t namelen, nchunks, nnamechunks, nvalchunks;

                hi = ZAP_HASH_IDX(ent->hash, zt->zt_shift);
                li = ZAP_HASH_IDX(ent->hash, prefixlen);
                assert(ptrhasht[hi] == 0 || ptrhasht[hi] == li + 1);
                ptrhasht[hi] = li + 1;
                l.l_phys = (zap_leaf_phys_t *)(leafblks + li * blksz);

                namelen = strlen(ent->name) + 1;

                /*
                 * How many leaf chunks do we need for this entry?
                 */
                nnamechunks = howmany(namelen, ZAP_LEAF_ARRAY_BYTES);
                nvalchunks = howmany(ent->intcnt,
                    ZAP_LEAF_ARRAY_BYTES / ent->intsz);
                nchunks = 1 + nnamechunks + nvalchunks;

                /*
                 * Allocate a run of free leaf chunks for this entry,
                 * potentially extending a hash chain.
                 */
                assert(l.l_phys->l_hdr.lh_nfree >= nchunks);
                l.l_phys->l_hdr.lh_nfree -= nchunks;
                l.l_phys->l_hdr.lh_nentries++;
                lptr = ZAP_LEAF_HASH_ENTPTR(&l, ent->hash);
                while (*lptr != 0xffff) {
                        assert(*lptr < ZAP_LEAF_NUMCHUNKS(&l));
                        le = ZAP_LEAF_ENTRY(&l, *lptr);
                        assert(le->le_type == ZAP_CHUNK_ENTRY);
                        le->le_cd++;
                        lptr = &le->le_next;
                }
                *lptr = l.l_phys->l_hdr.lh_freelist;
                l.l_phys->l_hdr.lh_freelist += nchunks;
                assert(l.l_phys->l_hdr.lh_freelist <=
                    ZAP_LEAF_NUMCHUNKS(&l));
                if (l.l_phys->l_hdr.lh_freelist ==
                    ZAP_LEAF_NUMCHUNKS(&l))
                        l.l_phys->l_hdr.lh_freelist = 0xffff;

                /*
                 * Integer values must be stored in big-endian format.
                 */
                switch (ent->intsz) {
                case 1:
                        break;
                case 2:
                        for (uint16_t *v = ent->val16p;
                            v - ent->val16p < (ptrdiff_t)ent->intcnt;
                            v++)
                                *v = htobe16(*v);
                        break;
                case 4:
                        for (uint32_t *v = ent->val32p;
                            v - ent->val32p < (ptrdiff_t)ent->intcnt;
                            v++)
                                *v = htobe32(*v);
                        break;
                case 8:
                        for (uint64_t *v = ent->val64p;
                            v - ent->val64p < (ptrdiff_t)ent->intcnt;
                            v++)
                                *v = htobe64(*v);
                        break;
                default:
                        assert(0);
                }

                /*
                 * Finally, write out the leaf chunks for this entry.
                 */
                le = ZAP_LEAF_ENTRY(&l, *lptr);
                assert(le->le_type == ZAP_CHUNK_FREE);
                le->le_type = ZAP_CHUNK_ENTRY;
                le->le_next = 0xffff;
                le->le_name_chunk = *lptr + 1;
                le->le_name_numints = namelen;
                le->le_value_chunk = *lptr + 1 + nnamechunks;
                le->le_value_intlen = ent->intsz;
                le->le_value_numints = ent->intcnt;
                le->le_hash = ent->hash;
                zap_fat_write_array_chunk(&l, *lptr + 1, namelen,
                    (uint8_t *)ent->name);
                zap_fat_write_array_chunk(&l, *lptr + 1 + nnamechunks,
                    ent->intcnt * ent->intsz, ent->valp);
        }

        /*
         * Initialize unused slots of the pointer table.
         */
        for (int i = 0; i < ptrcnt; i++)
                if (ptrhasht[i] == 0)
                        ptrhasht[i] = (i >> (zt->zt_shift - prefixlen)) + 1;

        /*
         * Write the whole thing to disk.
         */
        dnode = zap->dnode;
        dnode->dn_datablkszsec = blksz >> MINBLOCKSHIFT;
        dnode->dn_maxblkid = lblkcnt + 1;

        c = dnode_cursor_init(zfs, zap->os, zap->dnode,
            (lblkcnt + 1) * blksz, blksz);

        loc = objset_space_alloc(zfs, zap->os, &blksz);
        vdev_pwrite_dnode_indir(zfs, dnode, 0, 1, zfs->filebuf, blksz, loc,
            dnode_cursor_next(zfs, c, 0));

        for (uint64_t i = 0; i < lblkcnt; i++) {
                loc = objset_space_alloc(zfs, zap->os, &blksz);
                vdev_pwrite_dnode_indir(zfs, dnode, 0, 1, leafblks + i * blksz,
                    blksz, loc, dnode_cursor_next(zfs, c, (i + 1) * blksz));
        }

        dnode_cursor_finish(zfs, c);

        free(leafblks);
}

void
zap_write(zfs_opt_t *zfs, zfs_zap_t *zap)
{
        zfs_zap_entry_t *ent;

        if (zap->micro) {
                zap_micro_write(zfs, zap);
        } else {
                assert(!STAILQ_EMPTY(&zap->kvps));
                assert(zap->kvpcnt > 0);
                zap_fat_write(zfs, zap);
        }

        while ((ent = STAILQ_FIRST(&zap->kvps)) != NULL) {
                STAILQ_REMOVE_HEAD(&zap->kvps, next);
                if (ent->val64p != &ent->val64)
                        free(ent->valp);
                free(ent->name);
                free(ent);
        }
        free(zap);
}