patch-id: tighten code to detect the patch header

[alt-git.git] / midx.c

#include "git-compat-util.h"
#include "config.h"
#include "dir.h"
#include "hex.h"
#include "packfile.h"
#include "object-file.h"
#include "hash-lookup.h"
#include "midx.h"
#include "progress.h"
#include "trace2.h"
#include "chunk-format.h"
#include "pack-bitmap.h"
#include "pack-revindex.h"

int midx_checksum_valid(struct multi_pack_index *m);
void clear_midx_files_ext(const char *object_dir, const char *ext,
                          unsigned char *keep_hash);
int cmp_idx_or_pack_name(const char *idx_or_pack_name,
                         const char *idx_name);

const unsigned char *get_midx_checksum(struct multi_pack_index *m)
{
        return m->data + m->data_len - the_hash_algo->rawsz;
}

void get_midx_filename(struct strbuf *out, const char *object_dir)
{
        strbuf_addf(out, "%s/pack/multi-pack-index", object_dir);
}

void get_midx_rev_filename(struct strbuf *out, struct multi_pack_index *m)
{
        get_midx_filename(out, m->object_dir);
        strbuf_addf(out, "-%s.rev", hash_to_hex(get_midx_checksum(m)));
}

static int midx_read_oid_fanout(const unsigned char *chunk_start,
                                size_t chunk_size, void *data)
{
        int i;
        struct multi_pack_index *m = data;
        m->chunk_oid_fanout = (uint32_t *)chunk_start;

        if (chunk_size != 4 * 256) {
                error(_("multi-pack-index OID fanout is of the wrong size"));
                return 1;
        }
        for (i = 0; i < 255; i++) {
                uint32_t oid_fanout1 = ntohl(m->chunk_oid_fanout[i]);
                uint32_t oid_fanout2 = ntohl(m->chunk_oid_fanout[i+1]);

                if (oid_fanout1 > oid_fanout2) {
                        error(_("oid fanout out of order: fanout[%d] = %"PRIx32" > %"PRIx32" = fanout[%d]"),
                              i, oid_fanout1, oid_fanout2, i + 1);
                        return 1;
                }
        }
        m->num_objects = ntohl(m->chunk_oid_fanout[255]);
        return 0;
}

static int midx_read_oid_lookup(const unsigned char *chunk_start,
                                size_t chunk_size, void *data)
{
        struct multi_pack_index *m = data;
        m->chunk_oid_lookup = chunk_start;

        if (chunk_size != st_mult(m->hash_len, m->num_objects)) {
                error(_("multi-pack-index OID lookup chunk is the wrong size"));
                return 1;
        }
        return 0;
}

static int midx_read_object_offsets(const unsigned char *chunk_start,
                                    size_t chunk_size, void *data)
{
        struct multi_pack_index *m = data;
        m->chunk_object_offsets = chunk_start;

        if (chunk_size != st_mult(m->num_objects, MIDX_CHUNK_OFFSET_WIDTH)) {
                error(_("multi-pack-index object offset chunk is the wrong size"));
                return 1;
        }
        return 0;
}

#define MIDX_MIN_SIZE (MIDX_HEADER_SIZE + the_hash_algo->rawsz)

struct multi_pack_index *load_multi_pack_index(const char *object_dir, int local)
{
        struct multi_pack_index *m = NULL;
        int fd;
        struct stat st;
        size_t midx_size;
        void *midx_map = NULL;
        uint32_t hash_version;
        struct strbuf midx_name = STRBUF_INIT;
        uint32_t i;
        const char *cur_pack_name;
        struct chunkfile *cf = NULL;

        get_midx_filename(&midx_name, object_dir);

        fd = git_open(midx_name.buf);

        if (fd < 0)
                goto cleanup_fail;
        if (fstat(fd, &st)) {
                error_errno(_("failed to read %s"), midx_name.buf);
                goto cleanup_fail;
        }

        midx_size = xsize_t(st.st_size);

        if (midx_size < MIDX_MIN_SIZE) {
                error(_("multi-pack-index file %s is too small"), midx_name.buf);
                goto cleanup_fail;
        }

        strbuf_release(&midx_name);

        midx_map = xmmap(NULL, midx_size, PROT_READ, MAP_PRIVATE, fd, 0);
        close(fd);

        FLEX_ALLOC_STR(m, object_dir, object_dir);
        m->data = midx_map;
        m->data_len = midx_size;
        m->local = local;

        m->signature = get_be32(m->data);
        if (m->signature != MIDX_SIGNATURE)
                die(_("multi-pack-index signature 0x%08x does not match signature 0x%08x"),
                      m->signature, MIDX_SIGNATURE);

        m->version = m->data[MIDX_BYTE_FILE_VERSION];
        if (m->version != MIDX_VERSION)
                die(_("multi-pack-index version %d not recognized"),
                      m->version);

        hash_version = m->data[MIDX_BYTE_HASH_VERSION];
        if (hash_version != oid_version(the_hash_algo)) {
                error(_("multi-pack-index hash version %u does not match version %u"),
                      hash_version, oid_version(the_hash_algo));
                goto cleanup_fail;
        }
        m->hash_len = the_hash_algo->rawsz;

        m->num_chunks = m->data[MIDX_BYTE_NUM_CHUNKS];

        m->num_packs = get_be32(m->data + MIDX_BYTE_NUM_PACKS);

        m->preferred_pack_idx = -1;

        cf = init_chunkfile(NULL);

        if (read_table_of_contents(cf, m->data, midx_size,
                                   MIDX_HEADER_SIZE, m->num_chunks,
                                   MIDX_CHUNK_ALIGNMENT))
                goto cleanup_fail;

        if (pair_chunk(cf, MIDX_CHUNKID_PACKNAMES, &m->chunk_pack_names, &m->chunk_pack_names_len))
                die(_("multi-pack-index required pack-name chunk missing or corrupted"));
        if (read_chunk(cf, MIDX_CHUNKID_OIDFANOUT, midx_read_oid_fanout, m))
                die(_("multi-pack-index required OID fanout chunk missing or corrupted"));
        if (read_chunk(cf, MIDX_CHUNKID_OIDLOOKUP, midx_read_oid_lookup, m))
                die(_("multi-pack-index required OID lookup chunk missing or corrupted"));
        if (read_chunk(cf, MIDX_CHUNKID_OBJECTOFFSETS, midx_read_object_offsets, m))
                die(_("multi-pack-index required object offsets chunk missing or corrupted"));

        pair_chunk(cf, MIDX_CHUNKID_LARGEOFFSETS, &m->chunk_large_offsets,
                   &m->chunk_large_offsets_len);
        if (git_env_bool("GIT_TEST_MIDX_READ_BTMP", 1))
                pair_chunk(cf, MIDX_CHUNKID_BITMAPPEDPACKS,
                           (const unsigned char **)&m->chunk_bitmapped_packs,
                           &m->chunk_bitmapped_packs_len);

        if (git_env_bool("GIT_TEST_MIDX_READ_RIDX", 1))
                pair_chunk(cf, MIDX_CHUNKID_REVINDEX, &m->chunk_revindex,
                           &m->chunk_revindex_len);

        CALLOC_ARRAY(m->pack_names, m->num_packs);
        CALLOC_ARRAY(m->packs, m->num_packs);

        cur_pack_name = (const char *)m->chunk_pack_names;
        for (i = 0; i < m->num_packs; i++) {
                const char *end;
                size_t avail = m->chunk_pack_names_len -
                                (cur_pack_name - (const char *)m->chunk_pack_names);

                m->pack_names[i] = cur_pack_name;

                end = memchr(cur_pack_name, '\0', avail);
                if (!end)
                        die(_("multi-pack-index pack-name chunk is too short"));
                cur_pack_name = end + 1;

                if (i && strcmp(m->pack_names[i], m->pack_names[i - 1]) <= 0)
                        die(_("multi-pack-index pack names out of order: '%s' before '%s'"),
                              m->pack_names[i - 1],
                              m->pack_names[i]);
        }

        trace2_data_intmax("midx", the_repository, "load/num_packs", m->num_packs);
        trace2_data_intmax("midx", the_repository, "load/num_objects", m->num_objects);

        free_chunkfile(cf);
        return m;

cleanup_fail:
        free(m);
        strbuf_release(&midx_name);
        free_chunkfile(cf);
        if (midx_map)
                munmap(midx_map, midx_size);
        if (0 <= fd)
                close(fd);
        return NULL;
}

void close_midx(struct multi_pack_index *m)
{
        uint32_t i;

        if (!m)
                return;

        close_midx(m->next);

        munmap((unsigned char *)m->data, m->data_len);

        for (i = 0; i < m->num_packs; i++) {
                if (m->packs[i])
                        m->packs[i]->multi_pack_index = 0;
        }
        FREE_AND_NULL(m->packs);
        FREE_AND_NULL(m->pack_names);
        free(m);
}

int prepare_midx_pack(struct repository *r, struct multi_pack_index *m, uint32_t pack_int_id)
{
        struct strbuf pack_name = STRBUF_INIT;
        struct packed_git *p;

        if (pack_int_id >= m->num_packs)
                die(_("bad pack-int-id: %u (%u total packs)"),
                    pack_int_id, m->num_packs);

        if (m->packs[pack_int_id])
                return 0;

        strbuf_addf(&pack_name, "%s/pack/%s", m->object_dir,
                    m->pack_names[pack_int_id]);

        p = add_packed_git(pack_name.buf, pack_name.len, m->local);
        strbuf_release(&pack_name);

        if (!p)
                return 1;

        p->multi_pack_index = 1;
        m->packs[pack_int_id] = p;
        install_packed_git(r, p);
        list_add_tail(&p->mru, &r->objects->packed_git_mru);

        return 0;
}

#define MIDX_CHUNK_BITMAPPED_PACKS_WIDTH (2 * sizeof(uint32_t))

int nth_bitmapped_pack(struct repository *r, struct multi_pack_index *m,
                       struct bitmapped_pack *bp, uint32_t pack_int_id)
{
        if (!m->chunk_bitmapped_packs)
                return error(_("MIDX does not contain the BTMP chunk"));

        if (prepare_midx_pack(r, m, pack_int_id))
                return error(_("could not load bitmapped pack %"PRIu32), pack_int_id);

        bp->p = m->packs[pack_int_id];
        bp->bitmap_pos = get_be32((char *)m->chunk_bitmapped_packs +
                                  MIDX_CHUNK_BITMAPPED_PACKS_WIDTH * pack_int_id);
        bp->bitmap_nr = get_be32((char *)m->chunk_bitmapped_packs +
                                 MIDX_CHUNK_BITMAPPED_PACKS_WIDTH * pack_int_id +
                                 sizeof(uint32_t));
        bp->pack_int_id = pack_int_id;

        return 0;
}

int bsearch_midx(const struct object_id *oid, struct multi_pack_index *m, uint32_t *result)
{
        return bsearch_hash(oid->hash, m->chunk_oid_fanout, m->chunk_oid_lookup,
                            the_hash_algo->rawsz, result);
}

struct object_id *nth_midxed_object_oid(struct object_id *oid,
                                        struct multi_pack_index *m,
                                        uint32_t n)
{
        if (n >= m->num_objects)
                return NULL;

        oidread(oid, m->chunk_oid_lookup + st_mult(m->hash_len, n));
        return oid;
}

off_t nth_midxed_offset(struct multi_pack_index *m, uint32_t pos)
{
        const unsigned char *offset_data;
        uint32_t offset32;

        offset_data = m->chunk_object_offsets + (off_t)pos * MIDX_CHUNK_OFFSET_WIDTH;
        offset32 = get_be32(offset_data + sizeof(uint32_t));

        if (m->chunk_large_offsets && offset32 & MIDX_LARGE_OFFSET_NEEDED) {
                if (sizeof(off_t) < sizeof(uint64_t))
                        die(_("multi-pack-index stores a 64-bit offset, but off_t is too small"));

                offset32 ^= MIDX_LARGE_OFFSET_NEEDED;
                if (offset32 >= m->chunk_large_offsets_len / sizeof(uint64_t))
                        die(_("multi-pack-index large offset out of bounds"));
                return get_be64(m->chunk_large_offsets + sizeof(uint64_t) * offset32);
        }

        return offset32;
}

uint32_t nth_midxed_pack_int_id(struct multi_pack_index *m, uint32_t pos)
{
        return get_be32(m->chunk_object_offsets +
                        (off_t)pos * MIDX_CHUNK_OFFSET_WIDTH);
}

int fill_midx_entry(struct repository *r,
                    const struct object_id *oid,
                    struct pack_entry *e,
                    struct multi_pack_index *m)
{
        uint32_t pos;
        uint32_t pack_int_id;
        struct packed_git *p;

        if (!bsearch_midx(oid, m, &pos))
                return 0;

        if (pos >= m->num_objects)
                return 0;

        pack_int_id = nth_midxed_pack_int_id(m, pos);

        if (prepare_midx_pack(r, m, pack_int_id))
                return 0;
        p = m->packs[pack_int_id];

        /*
        * We are about to tell the caller where they can locate the
        * requested object.  We better make sure the packfile is
        * still here and can be accessed before supplying that
        * answer, as it may have been deleted since the MIDX was
        * loaded!
        */
        if (!is_pack_valid(p))
                return 0;

        if (oidset_size(&p->bad_objects) &&
            oidset_contains(&p->bad_objects, oid))
                return 0;

        e->offset = nth_midxed_offset(m, pos);
        e->p = p;

        return 1;
}

/* Match "foo.idx" against either "foo.pack" _or_ "foo.idx". */
int cmp_idx_or_pack_name(const char *idx_or_pack_name,
                         const char *idx_name)
{
        /* Skip past any initial matching prefix. */
        while (*idx_name && *idx_name == *idx_or_pack_name) {
                idx_name++;
                idx_or_pack_name++;
        }

        /*
         * If we didn't match completely, we may have matched "pack-1234." and
         * be left with "idx" and "pack" respectively, which is also OK. We do
         * not have to check for "idx" and "idx", because that would have been
         * a complete match (and in that case these strcmps will be false, but
         * we'll correctly return 0 from the final strcmp() below.
         *
         * Technically this matches "fooidx" and "foopack", but we'd never have
         * such names in the first place.
         */
        if (!strcmp(idx_name, "idx") && !strcmp(idx_or_pack_name, "pack"))
                return 0;

        /*
         * This not only checks for a complete match, but also orders based on
         * the first non-identical character, which means our ordering will
         * match a raw strcmp(). That makes it OK to use this to binary search
         * a naively-sorted list.
         */
        return strcmp(idx_or_pack_name, idx_name);
}

int midx_locate_pack(struct multi_pack_index *m, const char *idx_or_pack_name,
                     uint32_t *pos)
{
        uint32_t first = 0, last = m->num_packs;

        while (first < last) {
                uint32_t mid = first + (last - first) / 2;
                const char *current;
                int cmp;

                current = m->pack_names[mid];
                cmp = cmp_idx_or_pack_name(idx_or_pack_name, current);
                if (!cmp) {
                        if (pos)
                                *pos = mid;
                        return 1;
                }
                if (cmp > 0) {
                        first = mid + 1;
                        continue;
                }
                last = mid;
        }

        return 0;
}

int midx_contains_pack(struct multi_pack_index *m, const char *idx_or_pack_name)
{
        return midx_locate_pack(m, idx_or_pack_name, NULL);
}

int midx_preferred_pack(struct multi_pack_index *m, uint32_t *pack_int_id)
{
        if (m->preferred_pack_idx == -1) {
                if (load_midx_revindex(m) < 0) {
                        m->preferred_pack_idx = -2;
                        return -1;
                }

                m->preferred_pack_idx =
                        nth_midxed_pack_int_id(m, pack_pos_to_midx(m, 0));
        } else if (m->preferred_pack_idx == -2)
                return -1; /* no revindex */

        *pack_int_id = m->preferred_pack_idx;
        return 0;
}

int prepare_multi_pack_index_one(struct repository *r, const char *object_dir, int local)
{
        struct multi_pack_index *m;
        struct multi_pack_index *m_search;

        prepare_repo_settings(r);
        if (!r->settings.core_multi_pack_index)
                return 0;

        for (m_search = r->objects->multi_pack_index; m_search; m_search = m_search->next)
                if (!strcmp(object_dir, m_search->object_dir))
                        return 1;

        m = load_multi_pack_index(object_dir, local);

        if (m) {
                struct multi_pack_index *mp = r->objects->multi_pack_index;
                if (mp) {
                        m->next = mp->next;
                        mp->next = m;
                } else
                        r->objects->multi_pack_index = m;
                return 1;
        }

        return 0;
}

int midx_checksum_valid(struct multi_pack_index *m)
{
        return hashfile_checksum_valid(m->data, m->data_len);
}

struct clear_midx_data {
        char *keep;
        const char *ext;
};

static void clear_midx_file_ext(const char *full_path, size_t full_path_len UNUSED,
                                const char *file_name, void *_data)
{
        struct clear_midx_data *data = _data;

        if (!(starts_with(file_name, "multi-pack-index-") &&
              ends_with(file_name, data->ext)))
                return;
        if (data->keep && !strcmp(data->keep, file_name))
                return;

        if (unlink(full_path))
                die_errno(_("failed to remove %s"), full_path);
}

void clear_midx_files_ext(const char *object_dir, const char *ext,
                          unsigned char *keep_hash)
{
        struct clear_midx_data data;
        memset(&data, 0, sizeof(struct clear_midx_data));

        if (keep_hash)
                data.keep = xstrfmt("multi-pack-index-%s%s",
                                    hash_to_hex(keep_hash), ext);
        data.ext = ext;

        for_each_file_in_pack_dir(object_dir,
                                  clear_midx_file_ext,
                                  &data);

        free(data.keep);
}

void clear_midx_file(struct repository *r)
{
        struct strbuf midx = STRBUF_INIT;

        get_midx_filename(&midx, r->objects->odb->path);

        if (r->objects && r->objects->multi_pack_index) {
                close_midx(r->objects->multi_pack_index);
                r->objects->multi_pack_index = NULL;
        }

        if (remove_path(midx.buf))
                die(_("failed to clear multi-pack-index at %s"), midx.buf);

        clear_midx_files_ext(r->objects->odb->path, ".bitmap", NULL);
        clear_midx_files_ext(r->objects->odb->path, ".rev", NULL);

        strbuf_release(&midx);
}

static int verify_midx_error;

__attribute__((format (printf, 1, 2)))
static void midx_report(const char *fmt, ...)
{
        va_list ap;
        verify_midx_error = 1;
        va_start(ap, fmt);
        vfprintf(stderr, fmt, ap);
        fprintf(stderr, "\n");
        va_end(ap);
}

struct pair_pos_vs_id
{
        uint32_t pos;
        uint32_t pack_int_id;
};

static int compare_pair_pos_vs_id(const void *_a, const void *_b)
{
        struct pair_pos_vs_id *a = (struct pair_pos_vs_id *)_a;
        struct pair_pos_vs_id *b = (struct pair_pos_vs_id *)_b;

        return b->pack_int_id - a->pack_int_id;
}

/*
 * Limit calls to display_progress() for performance reasons.
 * The interval here was arbitrarily chosen.
 */
#define SPARSE_PROGRESS_INTERVAL (1 << 12)
#define midx_display_sparse_progress(progress, n) \
        do { \
                uint64_t _n = (n); \
                if ((_n & (SPARSE_PROGRESS_INTERVAL - 1)) == 0) \
                        display_progress(progress, _n); \
        } while (0)

int verify_midx_file(struct repository *r, const char *object_dir, unsigned flags)
{
        struct pair_pos_vs_id *pairs = NULL;
        uint32_t i;
        struct progress *progress = NULL;
        struct multi_pack_index *m = load_multi_pack_index(object_dir, 1);
        verify_midx_error = 0;

        if (!m) {
                int result = 0;
                struct stat sb;
                struct strbuf filename = STRBUF_INIT;

                get_midx_filename(&filename, object_dir);

                if (!stat(filename.buf, &sb)) {
                        error(_("multi-pack-index file exists, but failed to parse"));
                        result = 1;
                }
                strbuf_release(&filename);
                return result;
        }

        if (!midx_checksum_valid(m))
                midx_report(_("incorrect checksum"));

        if (flags & MIDX_PROGRESS)
                progress = start_delayed_progress(_("Looking for referenced packfiles"),
                                          m->num_packs);
        for (i = 0; i < m->num_packs; i++) {
                if (prepare_midx_pack(r, m, i))
                        midx_report("failed to load pack in position %d", i);

                display_progress(progress, i + 1);
        }
        stop_progress(&progress);

        if (m->num_objects == 0) {
                midx_report(_("the midx contains no oid"));
                /*
                 * Remaining tests assume that we have objects, so we can
                 * return here.
                 */
                goto cleanup;
        }

        if (flags & MIDX_PROGRESS)
                progress = start_sparse_progress(_("Verifying OID order in multi-pack-index"),
                                                 m->num_objects - 1);
        for (i = 0; i < m->num_objects - 1; i++) {
                struct object_id oid1, oid2;

                nth_midxed_object_oid(&oid1, m, i);
                nth_midxed_object_oid(&oid2, m, i + 1);

                if (oidcmp(&oid1, &oid2) >= 0)
                        midx_report(_("oid lookup out of order: oid[%d] = %s >= %s = oid[%d]"),
                                    i, oid_to_hex(&oid1), oid_to_hex(&oid2), i + 1);

                midx_display_sparse_progress(progress, i + 1);
        }
        stop_progress(&progress);

        /*
         * Create an array mapping each object to its packfile id.  Sort it
         * to group the objects by packfile.  Use this permutation to visit
         * each of the objects and only require 1 packfile to be open at a
         * time.
         */
        ALLOC_ARRAY(pairs, m->num_objects);
        for (i = 0; i < m->num_objects; i++) {
                pairs[i].pos = i;
                pairs[i].pack_int_id = nth_midxed_pack_int_id(m, i);
        }

        if (flags & MIDX_PROGRESS)
                progress = start_sparse_progress(_("Sorting objects by packfile"),
                                                 m->num_objects);
        display_progress(progress, 0); /* TODO: Measure QSORT() progress */
        QSORT(pairs, m->num_objects, compare_pair_pos_vs_id);
        stop_progress(&progress);

        if (flags & MIDX_PROGRESS)
                progress = start_sparse_progress(_("Verifying object offsets"), m->num_objects);
        for (i = 0; i < m->num_objects; i++) {
                struct object_id oid;
                struct pack_entry e;
                off_t m_offset, p_offset;

                if (i > 0 && pairs[i-1].pack_int_id != pairs[i].pack_int_id &&
                    m->packs[pairs[i-1].pack_int_id])
                {
                        close_pack_fd(m->packs[pairs[i-1].pack_int_id]);
                        close_pack_index(m->packs[pairs[i-1].pack_int_id]);
                }

                nth_midxed_object_oid(&oid, m, pairs[i].pos);

                if (!fill_midx_entry(r, &oid, &e, m)) {
                        midx_report(_("failed to load pack entry for oid[%d] = %s"),
                                    pairs[i].pos, oid_to_hex(&oid));
                        continue;
                }

                if (open_pack_index(e.p)) {
                        midx_report(_("failed to load pack-index for packfile %s"),
                                    e.p->pack_name);
                        break;
                }

                m_offset = e.offset;
                p_offset = find_pack_entry_one(oid.hash, e.p);

                if (m_offset != p_offset)
                        midx_report(_("incorrect object offset for oid[%d] = %s: %"PRIx64" != %"PRIx64),
                                    pairs[i].pos, oid_to_hex(&oid), m_offset, p_offset);

                midx_display_sparse_progress(progress, i + 1);
        }
        stop_progress(&progress);

cleanup:
        free(pairs);
        close_midx(m);

        return verify_midx_error;
}