index/pop3c/pop3c-sync.c

	pop3c-sync.c revision d546cddd14aa72823a1104e371527ae0a8a99e00
e59faf65ce864fe95dc00f5d52b8323cdbd0608aTimo Sirainen/* Copyright (c) 2011-2016 Dovecot authors, see the included COPYING file */
0cb2e8eb55e70f8ebe1e8349bdf49e4cbe5d8834Timo Sirainen
0cb2e8eb55e70f8ebe1e8349bdf49e4cbe5d8834Timo Sirainen#include "lib.h"
e05a4c4136fec723f019bee8383103080203f127Timo Sirainen#include "ioloop.h"
0cb2e8eb55e70f8ebe1e8349bdf49e4cbe5d8834Timo Sirainen#include "istream.h"
fdc557286bc9f92c5f3bb49096ff6e2bcec0ea79Timo Sirainen#include "bsearch-insert-pos.h"
0cb2e8eb55e70f8ebe1e8349bdf49e4cbe5d8834Timo Sirainen#include "str.h"
0cb2e8eb55e70f8ebe1e8349bdf49e4cbe5d8834Timo Sirainen#include "strnum.h"
0cb2e8eb55e70f8ebe1e8349bdf49e4cbe5d8834Timo Sirainen#include "index-mail.h"
24fc71a693331ffe77e2b6d81c70aca6fa055e47Timo Sirainen#include "pop3c-client.h"
d5cebe7f98e63d4e2822863ef2faa4971e8b3a5dTimo Sirainen#include "pop3c-storage.h"
e05a4c4136fec723f019bee8383103080203f127Timo Sirainen#include "pop3c-sync.h"
0cb2e8eb55e70f8ebe1e8349bdf49e4cbe5d8834Timo Sirainen
0cb2e8eb55e70f8ebe1e8349bdf49e4cbe5d8834Timo Sirainenstruct pop3c_sync_msg {
0cb2e8eb55e70f8ebe1e8349bdf49e4cbe5d8834Timo Sirainen    uint32_t seq;
eb0816090cf5a549280ad783b9aa6fec199d36baTimo Sirainen    const char *uidl;
eb0816090cf5a549280ad783b9aa6fec199d36baTimo Sirainen};
9f19a50d5966643c4d1c5ca06868ac2ad31bc4d5Timo SirainenARRAY_DEFINE_TYPE(pop3c_sync_msg, struct pop3c_sync_msg);
0cb2e8eb55e70f8ebe1e8349bdf49e4cbe5d8834Timo Sirainen
eb0816090cf5a549280ad783b9aa6fec199d36baTimo Sirainenint pop3c_sync_get_uidls(struct pop3c_mailbox *mbox)
eb0816090cf5a549280ad783b9aa6fec199d36baTimo Sirainen{
eb0816090cf5a549280ad783b9aa6fec199d36baTimo Sirainen    ARRAY_TYPE(const_string) uidls;
d22301419109ed4a38351715e6760011421dadecTimo Sirainen    struct istream *input;
eb0816090cf5a549280ad783b9aa6fec199d36baTimo Sirainen    const char *error, *cline;
eb0816090cf5a549280ad783b9aa6fec199d36baTimo Sirainen    char *line, *p;
eb0816090cf5a549280ad783b9aa6fec199d36baTimo Sirainen    unsigned int seq, line_seq;
eb0816090cf5a549280ad783b9aa6fec199d36baTimo Sirainen
eb0816090cf5a549280ad783b9aa6fec199d36baTimo Sirainen    if (mbox->msg_uidls != NULL)
eb0816090cf5a549280ad783b9aa6fec199d36baTimo Sirainen        return 0;
eb0816090cf5a549280ad783b9aa6fec199d36baTimo Sirainen    if ((pop3c_client_get_capabilities(mbox->client) &
eb0816090cf5a549280ad783b9aa6fec199d36baTimo Sirainen         POP3C_CAPABILITY_UIDL) == 0) {
01937f71b3ae0d5b30b813372f44a3e7e86c89dcTimo Sirainen        mail_storage_set_error(mbox->box.storage,
eb0816090cf5a549280ad783b9aa6fec199d36baTimo Sirainen                       MAIL_ERROR_NOTPOSSIBLE,
0cb2e8eb55e70f8ebe1e8349bdf49e4cbe5d8834Timo Sirainen                       "UIDLs not supported by server");
eb0816090cf5a549280ad783b9aa6fec199d36baTimo Sirainen        return -1;
eb0816090cf5a549280ad783b9aa6fec199d36baTimo Sirainen    }
9f19a50d5966643c4d1c5ca06868ac2ad31bc4d5Timo Sirainen
ca98d6a1bbe73499da758a36bfab2963375c8d06Timo Sirainen    if (pop3c_client_cmd_stream(mbox->client, "UIDL\r\n",
eb0816090cf5a549280ad783b9aa6fec199d36baTimo Sirainen                    &input, &error) < 0) {
eb0816090cf5a549280ad783b9aa6fec199d36baTimo Sirainen        mail_storage_set_critical(mbox->box.storage,
eb0816090cf5a549280ad783b9aa6fec199d36baTimo Sirainen                      "UIDL failed: %s", error);
0cb2e8eb55e70f8ebe1e8349bdf49e4cbe5d8834Timo Sirainen        return -1;
eb0816090cf5a549280ad783b9aa6fec199d36baTimo Sirainen    }
9f19a50d5966643c4d1c5ca06868ac2ad31bc4d5Timo Sirainen
eb0816090cf5a549280ad783b9aa6fec199d36baTimo Sirainen    mbox->uidl_pool = pool_alloconly_create("POP3 UIDLs", 1024*32);
eb0816090cf5a549280ad783b9aa6fec199d36baTimo Sirainen    p_array_init(&uidls, mbox->uidl_pool, 64); seq = 0;
0cb2e8eb55e70f8ebe1e8349bdf49e4cbe5d8834Timo Sirainen    while ((line = i_stream_read_next_line(input)) != NULL) {
0cb2e8eb55e70f8ebe1e8349bdf49e4cbe5d8834Timo Sirainen        seq++;
0cb2e8eb55e70f8ebe1e8349bdf49e4cbe5d8834Timo Sirainen        p = strchr(line, ' ');
eb0816090cf5a549280ad783b9aa6fec199d36baTimo Sirainen        if (p == NULL) {
d6badc27cd6e8d3398877b6766cb0aaeef3a7800Timo Sirainen            mail_storage_set_critical(mbox->box.storage,
eb0816090cf5a549280ad783b9aa6fec199d36baTimo Sirainen                "Invalid UIDL line: %s", line);
d22301419109ed4a38351715e6760011421dadecTimo Sirainen            break;
d22301419109ed4a38351715e6760011421dadecTimo Sirainen        }
eb0816090cf5a549280ad783b9aa6fec199d36baTimo Sirainen        *p++ = '\0';
eb0816090cf5a549280ad783b9aa6fec199d36baTimo Sirainen        if (str_to_uint(line, &line_seq) < 0 || line_seq != seq) {
eb0816090cf5a549280ad783b9aa6fec199d36baTimo Sirainen            mail_storage_set_critical(mbox->box.storage,
01937f71b3ae0d5b30b813372f44a3e7e86c89dcTimo Sirainen                "Unexpected UIDL seq: %s != %u", line, seq);
eb0816090cf5a549280ad783b9aa6fec199d36baTimo Sirainen            break;
eb0816090cf5a549280ad783b9aa6fec199d36baTimo Sirainen        }
d6badc27cd6e8d3398877b6766cb0aaeef3a7800Timo Sirainen
d6badc27cd6e8d3398877b6766cb0aaeef3a7800Timo Sirainen        cline = p_strdup(mbox->uidl_pool, p);
eb0816090cf5a549280ad783b9aa6fec199d36baTimo Sirainen        array_append(&uidls, &cline, 1);
eb0816090cf5a549280ad783b9aa6fec199d36baTimo Sirainen    }
eb0816090cf5a549280ad783b9aa6fec199d36baTimo Sirainen    i_stream_destroy(&input);
d6badc27cd6e8d3398877b6766cb0aaeef3a7800Timo Sirainen    if (line != NULL) {
a2f250a332dfc1e6cd4ffd196c621eb9dbf7b8a1Timo Sirainen        pool_unref(&mbox->uidl_pool);
d6badc27cd6e8d3398877b6766cb0aaeef3a7800Timo Sirainen        return -1;
a341c4cdbd4b93ba479f465ad3f569dc82f57312Timo Sirainen    }
013e3b3942e9550fde619a0b3ce6bdd04edc4268Timo Sirainen    if (seq == 0) {
a2f250a332dfc1e6cd4ffd196c621eb9dbf7b8a1Timo Sirainen        /* make msg_uidls non-NULL */
db87d16551d1081ada01f787ea21aa3ed1402c31Timo Sirainen        array_append_zero(&uidls);
db87d16551d1081ada01f787ea21aa3ed1402c31Timo Sirainen    }
db87d16551d1081ada01f787ea21aa3ed1402c31Timo Sirainen    mbox->msg_uidls = array_idx(&uidls, 0);
db87d16551d1081ada01f787ea21aa3ed1402c31Timo Sirainen    mbox->msg_count = seq;
9293bf90039454f47e94e4ba3722a775cfa7d25cTimo Sirainen    return 0;
ca98d6a1bbe73499da758a36bfab2963375c8d06Timo Sirainen}
d6badc27cd6e8d3398877b6766cb0aaeef3a7800Timo Sirainen
ca98d6a1bbe73499da758a36bfab2963375c8d06Timo Sirainenint pop3c_sync_get_sizes(struct pop3c_mailbox *mbox)
ca98d6a1bbe73499da758a36bfab2963375c8d06Timo Sirainen{
eb0816090cf5a549280ad783b9aa6fec199d36baTimo Sirainen    struct istream *input;
eb0816090cf5a549280ad783b9aa6fec199d36baTimo Sirainen    const char *error;
eb0816090cf5a549280ad783b9aa6fec199d36baTimo Sirainen    char *line, *p;
eb0816090cf5a549280ad783b9aa6fec199d36baTimo Sirainen    unsigned int seq, line_seq;
eb0816090cf5a549280ad783b9aa6fec199d36baTimo Sirainen
ca98d6a1bbe73499da758a36bfab2963375c8d06Timo Sirainen    i_assert(mbox->msg_sizes == NULL);
eb0816090cf5a549280ad783b9aa6fec199d36baTimo Sirainen
eb0816090cf5a549280ad783b9aa6fec199d36baTimo Sirainen    if (mbox->msg_uidls == NULL) {
eb0816090cf5a549280ad783b9aa6fec199d36baTimo Sirainen        if (pop3c_sync_get_uidls(mbox) < 0)
eb0816090cf5a549280ad783b9aa6fec199d36baTimo Sirainen            return -1;
eb0816090cf5a549280ad783b9aa6fec199d36baTimo Sirainen    }
eb0816090cf5a549280ad783b9aa6fec199d36baTimo Sirainen    if (mbox->msg_count == 0) {
eb0816090cf5a549280ad783b9aa6fec199d36baTimo Sirainen        mbox->msg_sizes = i_new(uoff_t, 1);
eb0816090cf5a549280ad783b9aa6fec199d36baTimo Sirainen        return 0;
eb0816090cf5a549280ad783b9aa6fec199d36baTimo Sirainen    }
eb0816090cf5a549280ad783b9aa6fec199d36baTimo Sirainen
eb0816090cf5a549280ad783b9aa6fec199d36baTimo Sirainen    if (pop3c_client_cmd_stream(mbox->client, "LIST\r\n",
eb0816090cf5a549280ad783b9aa6fec199d36baTimo Sirainen                    &input, &error) < 0) {
eb0816090cf5a549280ad783b9aa6fec199d36baTimo Sirainen        mail_storage_set_critical(mbox->box.storage,
eb0816090cf5a549280ad783b9aa6fec199d36baTimo Sirainen                      "LIST failed: %s", error);
eb0816090cf5a549280ad783b9aa6fec199d36baTimo Sirainen        return -1;
eb0816090cf5a549280ad783b9aa6fec199d36baTimo Sirainen    }
eb0816090cf5a549280ad783b9aa6fec199d36baTimo Sirainen
eb0816090cf5a549280ad783b9aa6fec199d36baTimo Sirainen    mbox->msg_sizes = i_new(uoff_t, mbox->msg_count); seq = 0;
d6badc27cd6e8d3398877b6766cb0aaeef3a7800Timo Sirainen    while ((line = i_stream_read_next_line(input)) != NULL) {
d6badc27cd6e8d3398877b6766cb0aaeef3a7800Timo Sirainen        if (++seq > mbox->msg_count) {
4d2211dac61c615c5bdfd501ea54d46c89d41b0fTimo Sirainen            mail_storage_set_critical(mbox->box.storage,
d6badc27cd6e8d3398877b6766cb0aaeef3a7800Timo Sirainen                "Too much data in LIST: %s", line);
96308127e006bb3b1108093bcf4cc1fd9481cb7aTimo Sirainen            break;
d6badc27cd6e8d3398877b6766cb0aaeef3a7800Timo Sirainen        }
d6badc27cd6e8d3398877b6766cb0aaeef3a7800Timo Sirainen        p = strchr(line, ' ');
d6badc27cd6e8d3398877b6766cb0aaeef3a7800Timo Sirainen        if (p == NULL) {
ca98d6a1bbe73499da758a36bfab2963375c8d06Timo Sirainen            mail_storage_set_critical(mbox->box.storage,
d6badc27cd6e8d3398877b6766cb0aaeef3a7800Timo Sirainen                "Invalid LIST line: %s", line);
9f19a50d5966643c4d1c5ca06868ac2ad31bc4d5Timo Sirainen            break;
741d705983e10046f07ef372b760bcdd169b068aTimo Sirainen        }
d6badc27cd6e8d3398877b6766cb0aaeef3a7800Timo Sirainen        *p++ = '\0';
96308127e006bb3b1108093bcf4cc1fd9481cb7aTimo Sirainen        if (str_to_uint(line, &line_seq) < 0 || line_seq != seq) {
96308127e006bb3b1108093bcf4cc1fd9481cb7aTimo Sirainen            mail_storage_set_critical(mbox->box.storage,
96308127e006bb3b1108093bcf4cc1fd9481cb7aTimo Sirainen                "Unexpected LIST seq: %s != %u", line, seq);
96308127e006bb3b1108093bcf4cc1fd9481cb7aTimo Sirainen            break;
4d2211dac61c615c5bdfd501ea54d46c89d41b0fTimo Sirainen        }
9f19a50d5966643c4d1c5ca06868ac2ad31bc4d5Timo Sirainen        if (str_to_uoff(p, &mbox->msg_sizes[seq-1]) < 0) {
61b0637759146621cbb7edcbd0b03a71cfd66dfeTimo Sirainen            mail_storage_set_critical(mbox->box.storage,
61b0637759146621cbb7edcbd0b03a71cfd66dfeTimo Sirainen                "Invalid LIST size: %s", p);
61b0637759146621cbb7edcbd0b03a71cfd66dfeTimo Sirainen            break;
61b0637759146621cbb7edcbd0b03a71cfd66dfeTimo Sirainen        }
9f19a50d5966643c4d1c5ca06868ac2ad31bc4d5Timo Sirainen    }
9f19a50d5966643c4d1c5ca06868ac2ad31bc4d5Timo Sirainen    i_stream_destroy(&input);
9f19a50d5966643c4d1c5ca06868ac2ad31bc4d5Timo Sirainen    if (line != NULL) {
9f19a50d5966643c4d1c5ca06868ac2ad31bc4d5Timo Sirainen        i_free_and_null(mbox->msg_sizes);
ca98d6a1bbe73499da758a36bfab2963375c8d06Timo Sirainen        return -1;
ca98d6a1bbe73499da758a36bfab2963375c8d06Timo Sirainen    }
741d705983e10046f07ef372b760bcdd169b068aTimo Sirainen    return 0;
d6badc27cd6e8d3398877b6766cb0aaeef3a7800Timo Sirainen}
d6badc27cd6e8d3398877b6766cb0aaeef3a7800Timo Sirainen
0cb2e8eb55e70f8ebe1e8349bdf49e4cbe5d8834Timo Sirainenstatic void
0cb2e8eb55e70f8ebe1e8349bdf49e4cbe5d8834Timo Sirainenpop3c_get_local_msgs(pool_t pool, ARRAY_TYPE(pop3c_sync_msg) *local_msgs,
0cb2e8eb55e70f8ebe1e8349bdf49e4cbe5d8834Timo Sirainen             uint32_t messages_count,
0cb2e8eb55e70f8ebe1e8349bdf49e4cbe5d8834Timo Sirainen             struct mail_cache_view *cache_view,
ca98d6a1bbe73499da758a36bfab2963375c8d06Timo Sirainen             unsigned int cache_idx)
d6badc27cd6e8d3398877b6766cb0aaeef3a7800Timo Sirainen{
0cb2e8eb55e70f8ebe1e8349bdf49e4cbe5d8834Timo Sirainen    string_t *str = t_str_new(128);
d6badc27cd6e8d3398877b6766cb0aaeef3a7800Timo Sirainen    struct pop3c_sync_msg msg;
741d705983e10046f07ef372b760bcdd169b068aTimo Sirainen    uint32_t seq;
ca98d6a1bbe73499da758a36bfab2963375c8d06Timo Sirainen
ca98d6a1bbe73499da758a36bfab2963375c8d06Timo Sirainen    memset(&msg, 0, sizeof(msg));
0cb2e8eb55e70f8ebe1e8349bdf49e4cbe5d8834Timo Sirainen    for (seq = 1; seq <= messages_count; seq++) {
48270badadd82279bfe50ae3d187aea8b0b2b30eTimo Sirainen        str_truncate(str, 0);
48270badadd82279bfe50ae3d187aea8b0b2b30eTimo Sirainen        if (mail_cache_lookup_field(cache_view, str, seq,
48270badadd82279bfe50ae3d187aea8b0b2b30eTimo Sirainen                        cache_idx) > 0)
48270badadd82279bfe50ae3d187aea8b0b2b30eTimo Sirainen            msg.uidl = p_strdup(pool, str_c(str));
48270badadd82279bfe50ae3d187aea8b0b2b30eTimo Sirainen        msg.seq = seq;
48270badadd82279bfe50ae3d187aea8b0b2b30eTimo Sirainen        array_idx_set(local_msgs, seq-1, &msg);
48270badadd82279bfe50ae3d187aea8b0b2b30eTimo Sirainen    }
48270badadd82279bfe50ae3d187aea8b0b2b30eTimo Sirainen}
48270badadd82279bfe50ae3d187aea8b0b2b30eTimo Sirainen
48270badadd82279bfe50ae3d187aea8b0b2b30eTimo Sirainenstatic void
pop3c_get_remote_msgs(ARRAY_TYPE(pop3c_sync_msg) *remote_msgs,
              struct pop3c_mailbox *mbox)
{
    struct pop3c_sync_msg *msg;
    uint32_t seq;

    for (seq = 1; seq <= mbox->msg_count; seq++) {
        msg = array_append_space(remote_msgs);
        msg->seq = seq;
        msg->uidl = mbox->msg_uidls[seq-1];
    }
}

static int pop3c_sync_msg_uidl_cmp(const struct pop3c_sync_msg *msg1,
                   const struct pop3c_sync_msg *msg2)
{
    return null_strcmp(msg1->uidl, msg2->uidl);
}

static void
pop3c_sync_messages(struct pop3c_mailbox *mbox,
            struct mail_index_view *sync_view,
            struct mail_index_transaction *sync_trans,
            struct mail_cache_view *cache_view)
{
    struct index_mailbox_context *ibox =
        INDEX_STORAGE_CONTEXT(&mbox->box);
    const struct mail_index_header *hdr;
    struct mail_cache_transaction_ctx *cache_trans;
    ARRAY_TYPE(pop3c_sync_msg) local_msgs, remote_msgs;
    const struct pop3c_sync_msg *lmsg, *rmsg;
    uint32_t seq1, seq2, next_uid;
    unsigned int lidx, ridx, lcount, rcount;
    unsigned int cache_idx = ibox->cache_fields[MAIL_CACHE_POP3_UIDL].idx;
    pool_t pool;

    i_assert(mbox->msg_uids == NULL);

    /* set our uidvalidity */
    hdr = mail_index_get_header(sync_view);
    if (hdr->uid_validity == 0) {
        uint32_t uid_validity = ioloop_time;
        mail_index_update_header(sync_trans,
            offsetof(struct mail_index_header, uid_validity),
            &uid_validity, sizeof(uid_validity), TRUE);
    }

    pool = pool_alloconly_create(MEMPOOL_GROWING"pop3c sync", 10240);
    p_array_init(&local_msgs, pool, hdr->messages_count);
    pop3c_get_local_msgs(pool, &local_msgs, hdr->messages_count,
                 cache_view, cache_idx);
    p_array_init(&remote_msgs, pool, mbox->msg_count);
    pop3c_get_remote_msgs(&remote_msgs, mbox);

    /* sort the messages by UIDLs, because some servers reorder messages */
    array_sort(&local_msgs, pop3c_sync_msg_uidl_cmp);
    array_sort(&remote_msgs, pop3c_sync_msg_uidl_cmp);

    /* skip over existing messages with matching UIDLs and expunge the ones
       that no longer exist in remote. (+1 to avoid malloc(0) assert) */
    mbox->msg_uids = i_new(uint32_t, mbox->msg_count + 1);
    cache_trans = mail_cache_get_transaction(cache_view, sync_trans);

    lmsg = array_get(&local_msgs, &lcount);
    rmsg = array_get(&remote_msgs, &rcount);
    next_uid = hdr->next_uid;
    lidx = ridx = 0;
    while (lidx < lcount || ridx < rcount) {
        uint32_t lseq = lidx < lcount ? lmsg[lidx].seq : 0;
        uint32_t rseq = ridx < rcount ? rmsg[ridx].seq : 0;
        int ret;

        if (lidx >= lcount)
            ret = 1;
        else if (ridx >= rcount || lmsg[lidx].uidl == NULL)
            ret = -1;
        else
            ret = strcmp(lmsg[lidx].uidl, rmsg[ridx].uidl);
        if (ret < 0) {
            /* message expunged in remote, or we didn't have a
               local message's UIDL in cache. */
            mail_index_expunge(sync_trans, lseq);
            lidx++;
        } else if (ret > 0) {
            /* new message in remote */
            i_assert(mbox->msg_uids[rseq-1] == 0);
            mbox->msg_uids[rseq-1] = next_uid;
            mail_index_append(sync_trans, next_uid++, &lseq);
            mail_cache_add(cache_trans, lseq, cache_idx,
                       rmsg[ridx].uidl,
                       strlen(rmsg[ridx].uidl)+1);
            ridx++;
        } else {
            /* UIDL matched */
            i_assert(mbox->msg_uids[rseq-1] == 0);
            mail_index_lookup_uid(sync_view, lseq,
                          &mbox->msg_uids[rseq-1]);
            lidx++;
            ridx++;
        }
    }

    /* mark the newly seen messages as recent */
    if (mail_index_lookup_seq_range(sync_view, hdr->first_recent_uid,
                    hdr->next_uid, &seq1, &seq2))
        mailbox_recent_flags_set_seqs(&mbox->box, sync_view, seq1, seq2);
    pool_unref(&pool);
}

int pop3c_sync(struct pop3c_mailbox *mbox)
{
        struct mail_index_sync_ctx *index_sync_ctx;
    struct mail_index_view *sync_view, *trans_view;
    struct mail_index_transaction *sync_trans;
    struct mail_index_sync_rec sync_rec;
    struct mail_cache_view *cache_view = NULL;
    enum mail_index_sync_flags sync_flags;
    unsigned int idx;
    string_t *str;
    const char *reply;
    int ret;
    bool deletions = FALSE;

    if (pop3c_sync_get_uidls(mbox) < 0)
        return -1;

    sync_flags = index_storage_get_sync_flags(&mbox->box) |
        MAIL_INDEX_SYNC_FLAG_FLUSH_DIRTY;

    ret = mail_index_sync_begin(mbox->box.index, &index_sync_ctx,
                    &sync_view, &sync_trans, sync_flags);
    if (ret <= 0) {
        if (ret < 0)
            mailbox_set_index_error(&mbox->box);
        return ret;
    }

    if (mbox->msg_uids == NULL) {
        trans_view = mail_index_transaction_open_updated_view(sync_trans);
        cache_view = mail_cache_view_open(mbox->box.cache, trans_view);
        pop3c_sync_messages(mbox, sync_view, sync_trans, cache_view);
    }

    /* mark expunges messages as deleted in this pop3 session,
       if those exist */
    str = t_str_new(32);
    while (mail_index_sync_next(index_sync_ctx, &sync_rec)) {
        if (sync_rec.type != MAIL_INDEX_SYNC_TYPE_EXPUNGE)
            continue;

        if (!bsearch_insert_pos(&sync_rec.uid1, mbox->msg_uids,
                    mbox->msg_count, sizeof(uint32_t),
                    uint32_cmp, &idx)) {
            /* no such messages in this session */
            continue;
        }
        for (; idx < mbox->msg_count; idx++) {
            i_assert(mbox->msg_uids[idx] >= sync_rec.uid1);
            if (mbox->msg_uids[idx] > sync_rec.uid2)
                break;

            str_truncate(str, 0);
            str_printfa(str, "DELE %u\r\n", idx+1);
            pop3c_client_cmd_line_async_nocb(mbox->client, str_c(str));
            deletions = TRUE;
        }
    }

    if (mail_index_sync_commit(&index_sync_ctx) < 0) {
        mailbox_set_index_error(&mbox->box);
        return -1;
    }
    if (cache_view != NULL) {
        mail_cache_view_close(&cache_view);
        mail_index_view_close(&trans_view);
    }
    if (deletions) {
        if (pop3c_client_cmd_line(mbox->client, "QUIT\r\n",
                      &reply) < 0) {
            mail_storage_set_error(mbox->box.storage,
                           MAIL_ERROR_TEMP, reply);
            return -1;
        }
    }
    return 0;
}

struct mailbox_sync_context *
pop3c_storage_sync_init(struct mailbox *box, enum mailbox_sync_flags flags)
{
    struct pop3c_mailbox *mbox = (struct pop3c_mailbox *)box;
    int ret = 0;

    if (!box->opened) {
        if (mailbox_open(box) < 0)
            ret = -1;
    } else {
        if ((flags & MAILBOX_SYNC_FLAG_FULL_READ) != 0 &&
            mbox->msg_uidls == NULL) {
            /* FIXME: reconnect */
        }
    }

    if (ret == 0)
        ret = pop3c_sync(mbox);

    return index_mailbox_sync_init(box, flags, ret < 0);
}