src/lib-index/mail-cache-fields.c

/* Copyright (c) 2004-2018 Dovecot authors, see the included COPYING file */

#include "lib.h"
#include "ioloop.h"
#include "buffer.h"
#include "hash.h"
#include "file-cache.h"
#include "read-full.h"
#include "write-full.h"
#include "mmap-util.h"
#include "mail-cache-private.h"

#include <stddef.h>

#define CACHE_FIELD_IS_NEWLY_WANTED(cache, field_idx) \
    ((cache)->field_file_map[field_idx] == (uint32_t)-1 && \
     (cache)->fields[field_idx].used)

static bool field_has_fixed_size(enum mail_cache_field_type type)
{
    switch (type) {
    case MAIL_CACHE_FIELD_FIXED_SIZE:
    case MAIL_CACHE_FIELD_BITMASK:
        return TRUE;
    case MAIL_CACHE_FIELD_VARIABLE_SIZE:
    case MAIL_CACHE_FIELD_STRING:
    case MAIL_CACHE_FIELD_HEADER:
        return FALSE;

    case MAIL_CACHE_FIELD_COUNT:
        break;
    }

    i_unreached();
    return FALSE;
}

static bool field_decision_is_valid(enum mail_cache_decision_type type)
{
    switch (type & ~MAIL_CACHE_DECISION_FORCED) {
    case MAIL_CACHE_DECISION_NO:
    case MAIL_CACHE_DECISION_TEMP:
    case MAIL_CACHE_DECISION_YES:
        return TRUE;
    default:
        return FALSE;
    }
}

static int field_type_verify(struct mail_cache *cache, unsigned int idx,
                 enum mail_cache_field_type type, unsigned int size)
{
    const struct mail_cache_field *field = &cache->fields[idx].field;

    if (field->type != type) {
        mail_cache_set_corrupted(cache,
            "registered field %s type changed", field->name);
        return -1;
    }
    if (field->field_size != size && field_has_fixed_size(type)) {
        mail_cache_set_corrupted(cache,
            "registered field %s size changed", field->name);
        return -1;
    }
    return 0;
}

static void
mail_cache_field_update(struct mail_cache *cache,
            const struct mail_cache_field *newfield)
{
    struct mail_cache_field_private *orig;
    bool initial_registering;

    i_assert(newfield->type < MAIL_CACHE_FIELD_COUNT);

    /* are we still doing the initial cache field registering for
       internal fields and for mail_*cache_fields settings? */
    initial_registering = cache->file_fields_count == 0;

    orig = &cache->fields[newfield->idx];
    if ((newfield->decision & MAIL_CACHE_DECISION_FORCED) != 0 ||
        ((orig->field.decision & MAIL_CACHE_DECISION_FORCED) == 0 &&
         newfield->decision > orig->field.decision)) {
        orig->field.decision = newfield->decision;
        if (!initial_registering)
            orig->decision_dirty = TRUE;
    }
    if (orig->field.last_used < newfield->last_used) {
        orig->field.last_used = newfield->last_used;
        if (!initial_registering)
            orig->decision_dirty = TRUE;
    }
    if (orig->decision_dirty)
        cache->field_header_write_pending = TRUE;

    (void)field_type_verify(cache, newfield->idx,
                newfield->type, newfield->field_size);
}

void mail_cache_register_fields(struct mail_cache *cache,
                struct mail_cache_field *fields,
                unsigned int fields_count)
{
    char *name;
    void *value;
    unsigned int new_idx;
    unsigned int i, j, registered_count;

    new_idx = cache->fields_count;
    for (i = 0; i < fields_count; i++) {
        if (hash_table_lookup_full(cache->field_name_hash,
                       fields[i].name, &name, &value)) {
            fields[i].idx = POINTER_CAST_TO(value, unsigned int);
            mail_cache_field_update(cache, &fields[i]);
            continue;
        }

        /* check if the same header is being registered in the
           same field array */
        for (j = 0; j < i; j++) {
            if (strcasecmp(fields[i].name, fields[j].name) == 0) {
                fields[i].idx = fields[j].idx;
                break;
            }
        }

        if (j == i)
            fields[i].idx = new_idx++;
    }

    if (new_idx == cache->fields_count)
        return;

    /* @UNSAFE */
    cache->fields = i_realloc_type(cache->fields,
                       struct mail_cache_field_private,
                       cache->fields_count, new_idx);
    cache->field_file_map =
        i_realloc_type(cache->field_file_map, uint32_t,
                   cache->fields_count, new_idx);

    registered_count = cache->fields_count;
    for (i = 0; i < fields_count; i++) {
        unsigned int idx = fields[i].idx;

        if (idx < registered_count)
            continue;

        /* new index - save it */
        name = p_strdup(cache->field_pool, fields[i].name);
        cache->fields[idx].field = fields[i];
        cache->fields[idx].field.name = name;
        cache->fields[idx].field.last_used = fields[i].last_used;
        cache->field_file_map[idx] = (uint32_t)-1;

        if (!field_has_fixed_size(cache->fields[idx].field.type))
            cache->fields[idx].field.field_size = UINT_MAX;

        hash_table_insert(cache->field_name_hash, name,
                  POINTER_CAST(idx));
        registered_count++;
    }
    i_assert(registered_count == new_idx);
    cache->fields_count = new_idx;
}

unsigned int
mail_cache_register_lookup(struct mail_cache *cache, const char *name)
{
    char *key;
    void *value;

    if (hash_table_lookup_full(cache->field_name_hash, name, &key, &value))
        return POINTER_CAST_TO(value, unsigned int);
    else
        return UINT_MAX;
}

const struct mail_cache_field *
mail_cache_register_get_field(struct mail_cache *cache, unsigned int field_idx)
{
    i_assert(field_idx < cache->fields_count);

    return &cache->fields[field_idx].field;
}

struct mail_cache_field *
mail_cache_register_get_list(struct mail_cache *cache, pool_t pool,
                 unsigned int *count_r)
{
        struct mail_cache_field *list;
    unsigned int i;

    if (!cache->opened)
        (void)mail_cache_open_and_verify(cache);

    list = cache->fields_count == 0 ? NULL :
        p_new(pool, struct mail_cache_field, cache->fields_count);
    for (i = 0; i < cache->fields_count; i++) {
        list[i] = cache->fields[i].field;
        list[i].name = p_strdup(pool, list[i].name);
    }

    *count_r = cache->fields_count;
    return list;
}

static int
mail_cache_header_fields_get_offset(struct mail_cache *cache,
                    uint32_t *offset_r,
                    const struct mail_cache_header_fields **field_hdr_r)
{
    const struct mail_cache_header_fields *field_hdr;
    struct mail_cache_header_fields tmp_field_hdr;
    const void *data;
    uint32_t offset = 0, next_offset, field_hdr_size;
    unsigned int next_count = 0;
    int ret;

    if (MAIL_CACHE_IS_UNUSABLE(cache)) {
        *offset_r = 0;
        if (field_hdr_r != NULL)
            *field_hdr_r = NULL;
        return 0;
    }

    /* find the latest header */
    offset = 0;
    next_offset = cache->last_field_header_offset != 0 ?
        cache->last_field_header_offset :
        mail_index_offset_to_uint32(cache->hdr->field_header_offset);
    while (next_offset != 0) {
        if (next_offset == offset) {
            mail_cache_set_corrupted(cache,
                "next_offset in field header loops");
            return -1;
        }
        /* In Dovecot v2.2+ we don't try to use any holes,
           so next_offset must always be larger than current offset.
           also makes it easier to guarantee there aren't any loops
           (which we don't bother doing for old files) */
        if (next_offset < offset && cache->hdr->minor_version != 0) {
            mail_cache_set_corrupted(cache,
                "next_offset in field header decreases");
            return -1;
        }
        offset = next_offset;

        if (cache->mmap_base != NULL || cache->map_with_read) {
            ret = mail_cache_map(cache, offset, sizeof(*field_hdr),
                         &data);
            if (ret <= 0) {
                if (ret < 0)
                    return -1;
                mail_cache_set_corrupted(cache,
                    "header field next_offset points outside file");
                return -1;
            }
            field_hdr = data;
        } else {
            /* if we need to follow multiple offsets to get to
               the last one, it's faster to just pread() the file
               instead of going through cache */
            ret = pread_full(cache->fd, &tmp_field_hdr,
                     sizeof(tmp_field_hdr), offset);
            if (ret < 0) {
                mail_cache_set_syscall_error(cache, "pread()");
                return -1;
            }
            if (ret == 0) {
                mail_cache_set_corrupted(cache,
                    "header field next_offset points outside file");
                return -1;
            }
            field_hdr = &tmp_field_hdr;
        }

        next_offset =
            mail_index_offset_to_uint32(field_hdr->next_offset);
        next_count++;
    }

    if (offset == 0) {
        mail_cache_set_corrupted(cache, "missing header fields");
        return -1;
    }
    cache->last_field_header_offset = offset;

    if (next_count > cache->index->optimization_set.cache.compress_header_continue_count)
        cache->need_compress_file_seq = cache->hdr->file_seq;

    if (field_hdr_r != NULL) {
        /* detect corrupted size later */
        field_hdr_size = I_MAX(field_hdr->size, sizeof(*field_hdr));
        if (cache->file_cache != NULL) {
            /* invalidate the cache fields area to make sure we
               get the latest cache decisions/last_used fields */
            file_cache_invalidate(cache->file_cache, offset,
                          field_hdr_size);
        }
        if (cache->read_buf != NULL)
            buffer_set_used_size(cache->read_buf, 0);
        ret = mail_cache_map(cache, offset, field_hdr_size, &data);
        if (ret < 0)
            return -1;
        if (ret == 0) {
            mail_cache_set_corrupted(cache,
                "header field size outside file");
            return -1;
        }
        *field_hdr_r = data;
    }
    *offset_r = offset;
    return 0;
}

int mail_cache_header_fields_read(struct mail_cache *cache)
{
    const struct mail_cache_header_fields *field_hdr;
    struct mail_cache_field field;
    const uint32_t *last_used, *sizes;
    const uint8_t *types, *decisions;
    const char *p, *names, *end;
    char *orig_key;
    void *orig_value;
    unsigned int fidx, new_fields_count;
    enum mail_cache_decision_type dec;
    time_t max_drop_time;
    uint32_t offset, i;

    if (mail_cache_header_fields_get_offset(cache, &offset, &field_hdr) < 0)
        return -1;

    if (offset == 0) {
        /* no fields - the file is empty */
        return 0;
    }

    /* check the fixed size of the header. name[] has to be checked
       separately */
    if (field_hdr->fields_count > INT_MAX / MAIL_CACHE_FIELD_NAMES(1) ||
        field_hdr->size < MAIL_CACHE_FIELD_NAMES(field_hdr->fields_count)) {
        mail_cache_set_corrupted(cache, "invalid field header size");
        return -1;
    }

    new_fields_count = field_hdr->fields_count;
    if (new_fields_count != 0) {
        cache->file_field_map =
            i_realloc_type(cache->file_field_map, unsigned int,
                       cache->file_fields_count, new_fields_count);
    } else {
        i_free_and_null(cache->file_field_map);
    }
    cache->file_fields_count = new_fields_count;

    last_used = CONST_PTR_OFFSET(field_hdr, MAIL_CACHE_FIELD_LAST_USED());
    sizes = CONST_PTR_OFFSET(field_hdr,
        MAIL_CACHE_FIELD_SIZE(field_hdr->fields_count));
    types = CONST_PTR_OFFSET(field_hdr,
        MAIL_CACHE_FIELD_TYPE(field_hdr->fields_count));
    decisions = CONST_PTR_OFFSET(field_hdr,
        MAIL_CACHE_FIELD_DECISION(field_hdr->fields_count));
    names = CONST_PTR_OFFSET(field_hdr,
        MAIL_CACHE_FIELD_NAMES(field_hdr->fields_count));
    end = CONST_PTR_OFFSET(field_hdr, field_hdr->size);
    i_assert(names <= end);

    /* clear the old mapping */
    for (i = 0; i < cache->fields_count; i++)
        cache->field_file_map[i] = (uint32_t)-1;

    max_drop_time = cache->index->map->hdr.day_stamp == 0 ? 0 :
        cache->index->map->hdr.day_stamp -
        cache->index->optimization_set.cache.unaccessed_field_drop_secs;

    i_zero(&field);
    for (i = 0; i < field_hdr->fields_count; i++) {
        for (p = names; p != end && *p != '\0'; p++) ;
        if (p == end || *names == '\0') {
            mail_cache_set_corrupted(cache,
                "field header names corrupted");
            return -1;
        }

        if (types[i] > MAIL_CACHE_FIELD_COUNT) {
            mail_cache_set_corrupted(cache, "field type corrupted");
            return -1;
        }
        if (!field_decision_is_valid(decisions[i])) {
            mail_cache_set_corrupted(cache,
                "field decision type corrupted");
            return -1;
        }

        /* ignore any forced-flags in the file */
        enum mail_cache_decision_type file_dec =
            decisions[i] & ~MAIL_CACHE_DECISION_FORCED;

        if (hash_table_lookup_full(cache->field_name_hash, names,
                       &orig_key, &orig_value)) {
            /* already exists, see if decision can be updated */
            fidx = POINTER_CAST_TO(orig_value, unsigned int);
            enum mail_cache_decision_type cur_dec =
                cache->fields[fidx].field.decision;
            if ((cur_dec & MAIL_CACHE_DECISION_FORCED) != 0) {
                /* Forced decision. If the decision has
                   changed, update the fields in the file. */
                if ((cur_dec & ~MAIL_CACHE_DECISION_FORCED) != file_dec)
                    cache->field_header_write_pending = TRUE;
            } else if (cache->fields[fidx].decision_dirty) {
                /* Decisions have recently been updated
                   internally. Don't change them. */
            } else {
                /* Use the decision from the cache file. */
                cache->fields[fidx].field.decision = file_dec;
            }
            if (field_type_verify(cache, fidx,
                          types[i], sizes[i]) < 0)
                return -1;
        } else {
            /* field is currently unknown, so just use whatever
               exists in the file. */
            field.name = names;
            field.type = types[i];
            field.field_size = sizes[i];
            field.decision = file_dec;
            mail_cache_register_fields(cache, &field, 1);
            fidx = field.idx;
        }
        if (cache->field_file_map[fidx] != (uint32_t)-1) {
            mail_cache_set_corrupted(cache,
                "Duplicated field in header: %s", names);
            return -1;
        }
        cache->fields[fidx].used = TRUE;

        cache->field_file_map[fidx] = i;
        cache->file_field_map[i] = fidx;

        /* update last_used if it's newer than ours */
        if ((time_t)last_used[i] > cache->fields[fidx].field.last_used)
            cache->fields[fidx].field.last_used = last_used[i];

        dec = cache->fields[fidx].field.decision;
        if (cache->fields[fidx].field.last_used < max_drop_time &&
            cache->fields[fidx].field.last_used != 0 &&
            (dec & MAIL_CACHE_DECISION_FORCED) == 0 &&
            dec != MAIL_CACHE_DECISION_NO) {
            /* time to drop this field. don't bother dropping
               fields that have never been used. */
            cache->need_compress_file_seq = cache->hdr->file_seq;
        }

                names = p + 1;
    }
    return 0;
}

static void copy_to_buf(struct mail_cache *cache, buffer_t *dest, bool add_new,
            size_t offset, size_t size)
{
    const void *data;
    unsigned int i, field;

    /* copy the existing fields */
    for (i = 0; i < cache->file_fields_count; i++) {
        field = cache->file_field_map[i];
                data = CONST_PTR_OFFSET(&cache->fields[field], offset);
        buffer_append(dest, data, size);
    }
    if (!add_new)
        return;

    /* copy newly wanted fields */
    for (i = 0; i < cache->fields_count; i++) {
        if (CACHE_FIELD_IS_NEWLY_WANTED(cache, i)) {
            data = CONST_PTR_OFFSET(&cache->fields[i], offset);
            buffer_append(dest, data, size);
        }
    }
}

static void copy_to_buf_byte(struct mail_cache *cache, buffer_t *dest,
                 bool add_new, size_t offset)
{
    const int *data;
    unsigned int i, field;
    uint8_t byte;

    /* copy the existing fields */
    for (i = 0; i < cache->file_fields_count; i++) {
        field = cache->file_field_map[i];
                data = CONST_PTR_OFFSET(&cache->fields[field], offset);
        byte = (uint8_t)*data;
        buffer_append(dest, &byte, 1);
    }
    if (!add_new)
        return;

    /* copy newly wanted fields */
    for (i = 0; i < cache->fields_count; i++) {
        if (CACHE_FIELD_IS_NEWLY_WANTED(cache, i)) {
            data = CONST_PTR_OFFSET(&cache->fields[i], offset);
            byte = (uint8_t)*data;
            buffer_append(dest, &byte, 1);
        }
    }
}

static int mail_cache_header_fields_update_locked(struct mail_cache *cache)
{
    buffer_t *buffer;
    uint32_t i, offset, dec_offset;
    int ret = 0;

    if (mail_cache_header_fields_read(cache) < 0 ||
        mail_cache_header_fields_get_offset(cache, &offset, NULL) < 0)
        return -1;

    buffer = t_buffer_create(256);

    copy_to_buf(cache, buffer, FALSE,
            offsetof(struct mail_cache_field, last_used),
            sizeof(uint32_t));
    ret = mail_cache_write(cache, buffer->data, buffer->used,
                   offset + MAIL_CACHE_FIELD_LAST_USED());
    if (ret == 0) {
        buffer_set_used_size(buffer, 0);
        copy_to_buf_byte(cache, buffer, FALSE,
                 offsetof(struct mail_cache_field, decision));

        dec_offset = offset +
            MAIL_CACHE_FIELD_DECISION(cache->file_fields_count);
        ret = mail_cache_write(cache, buffer->data, buffer->used,
                       dec_offset);
        if (ret == 0) {
            for (i = 0; i < cache->file_fields_count; i++)
                cache->fields[i].decision_dirty = FALSE;
        }
    }

    if (ret == 0)
        cache->field_header_write_pending = FALSE;
    return ret;
}

int mail_cache_header_fields_update(struct mail_cache *cache)
{
    int ret;

    if (cache->locked) {
        T_BEGIN {
            ret = mail_cache_header_fields_update_locked(cache);
        } T_END;
        return ret;
    }

    if (mail_cache_lock(cache) <= 0)
        return -1;

    T_BEGIN {
        ret = mail_cache_header_fields_update_locked(cache);
    } T_END;
    if (mail_cache_unlock(cache) < 0)
        ret = -1;
    return ret;
}

void mail_cache_header_fields_get(struct mail_cache *cache, buffer_t *dest)
{
    struct mail_cache_header_fields hdr;
    unsigned int field;
    const char *name;
    uint32_t i;

    i_zero(&hdr);
    hdr.fields_count = cache->file_fields_count;
    for (i = 0; i < cache->fields_count; i++) {
        if (CACHE_FIELD_IS_NEWLY_WANTED(cache, i))
            hdr.fields_count++;
    }
    buffer_append(dest, &hdr, sizeof(hdr));

    /* we have to keep the field order for the existing fields. */
    copy_to_buf(cache, dest, TRUE,
            offsetof(struct mail_cache_field, last_used),
            sizeof(uint32_t));
    copy_to_buf(cache, dest, TRUE,
            offsetof(struct mail_cache_field, field_size),
            sizeof(uint32_t));
    copy_to_buf_byte(cache, dest, TRUE,
             offsetof(struct mail_cache_field, type));
    copy_to_buf_byte(cache, dest, TRUE,
             offsetof(struct mail_cache_field, decision));

    i_assert(dest->used == sizeof(hdr) +
         (sizeof(uint32_t)*2 + 2) * hdr.fields_count);

    /* add existing fields' names */
    for (i = 0; i < cache->file_fields_count; i++) {
        field = cache->file_field_map[i];
        name = cache->fields[field].field.name;
        buffer_append(dest, name, strlen(name)+1);
    }
    /* add newly wanted fields' names */
    for (i = 0; i < cache->fields_count; i++) {
        if (CACHE_FIELD_IS_NEWLY_WANTED(cache, i)) {
            name = cache->fields[i].field.name;
            buffer_append(dest, name, strlen(name)+1);
        }
    }

    hdr.size = dest->used;
    buffer_write(dest, 0, &hdr, sizeof(hdr));

    if ((hdr.size & 3) != 0)
        buffer_append_zero(dest, 4 - (hdr.size & 3));
}

int mail_cache_header_fields_get_next_offset(struct mail_cache *cache,
                         uint32_t *offset_r)
{
    if (mail_cache_header_fields_get_offset(cache, offset_r, NULL) < 0)
        return -1;

    if (*offset_r == 0) {
        *offset_r = offsetof(struct mail_cache_header,
                     field_header_offset);
    } else {
        *offset_r += offsetof(struct mail_cache_header_fields,
                      next_offset);
    }
    return 0;
}