plugins/trash/trash-plugin.c

	trash-plugin.c revision 77c0730f0ef7c5de3ab1490874fdcc336b942de7
/* Copyright (c) 2005-2008 Dovecot authors, see the included COPYING file */

#include "lib.h"
#include "array.h"
#include "istream.h"
#include "mail-namespace.h"
#include "mail-search-build.h"
#include "quota-private.h"
#include "quota-plugin.h"
#include "trash-plugin.h"

#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>

#define INIT_TRASH_MAILBOX_COUNT 4
#define MAX_RETRY_COUNT 3

#define TRASH_USER_CONTEXT(obj) \
    MODULE_CONTEXT(obj, trash_user_module)

struct trash_mailbox {
    const char *name;
    int priority; /* lower number = higher priority */

    struct mail_storage *storage;

    /* temporarily set while cleaning: */
    struct mailbox *box;
    struct mailbox_transaction_context *trans;
    struct mail_search_context *search_ctx;
    struct mail *mail;

    unsigned int mail_set:1;
};

struct trash_user {
    union mail_user_module_context module_ctx;

    /* ordered by priority, highest first */
    ARRAY_DEFINE(trash_boxes, struct trash_mailbox);
};

const char *trash_plugin_version = PACKAGE_VERSION;

static MODULE_CONTEXT_DEFINE_INIT(trash_user_module,
                  &mail_user_module_register);
static void (*trash_next_hook_mail_namespaces_created)
    (struct mail_namespace *namespaces);
static int (*trash_next_quota_test_alloc)(struct quota_transaction_context *,
                      uoff_t, bool *);

static int trash_clean_mailbox_open(struct trash_mailbox *trash)
{
    struct mail_search_args *search_args;

    trash->box = mailbox_open(trash->storage, trash->name, NULL,
                  MAILBOX_OPEN_KEEP_RECENT);
    if (trash->box == NULL)
        return 0;

    if (mailbox_sync(trash->box, MAILBOX_SYNC_FLAG_FULL_READ, 0, NULL) < 0)
        return -1;

    trash->trans = mailbox_transaction_begin(trash->box, 0);
    trash->mail = mail_alloc(trash->trans, MAIL_FETCH_PHYSICAL_SIZE |
                 MAIL_FETCH_RECEIVED_DATE, NULL);

    search_args = mail_search_build_init();
    mail_search_build_add_all(search_args);
    trash->search_ctx = mailbox_search_init(trash->trans,
                        search_args, NULL);
    mail_search_args_unref(&search_args);

    return mailbox_search_next(trash->search_ctx, trash->mail);
}

static int trash_clean_mailbox_get_next(struct trash_mailbox *trash,
                    time_t *received_time_r)
{
    int ret;

    if (!trash->mail_set) {
        if (trash->box == NULL)
            ret = trash_clean_mailbox_open(trash);
        else
            ret = mailbox_search_next(trash->search_ctx,
                          trash->mail);
        if (ret <= 0) {
            *received_time_r = 0;
            return ret;
        }
        trash->mail_set = TRUE;
    }

    if (mail_get_received_date(trash->mail, received_time_r) < 0)
        return -1;
    return 1;
}

static int trash_try_clean_mails(struct quota_transaction_context *ctx,
                 uint64_t size_needed)
{
    struct trash_user *tuser = TRASH_USER_CONTEXT(ctx->quota->user);
    struct trash_mailbox *trashes;
    unsigned int i, j, count, oldest_idx;
    time_t oldest, received = 0;
    uint64_t size, size_expunged = 0, expunged_count = 0;
    int ret = 0;

    trashes = array_get_modifiable(&tuser->trash_boxes, &count);
    for (i = 0; i < count; ) {
        /* expunge oldest mails first in all trash boxes with
           same priority */
        oldest_idx = count;
        oldest = (time_t)-1;
        for (j = i; j < count; j++) {
            if (trashes[j].priority != trashes[i].priority)
                break;

            ret = trash_clean_mailbox_get_next(&trashes[j],
                               &received);
            if (ret < 0)
                goto err;
            if (ret > 0) {
                if (oldest == (time_t)-1 || received < oldest) {
                    oldest = received;
                    oldest_idx = j;
                }
            }
        }

        if (oldest_idx < count) {
            if (mail_get_physical_size(trashes[oldest_idx].mail,
                           &size) < 0) {
                /* maybe expunged already? */
                trashes[oldest_idx].mail_set = FALSE;
                continue;
            }

            mail_expunge(trashes[oldest_idx].mail);
            expunged_count++;
            size_expunged += size;
            if (size_expunged >= size_needed)
                break;
            trashes[oldest_idx].mail_set = FALSE;
        } else {
            /* find more mails from next priority's mailbox */
            i = j;
        }
    }

err:
    for (i = 0; i < count; i++) {
        struct trash_mailbox *trash = &trashes[i];

        if (trash->box == NULL)
            continue;

        trash->mail_set = FALSE;
        mail_free(&trash->mail);
        (void)mailbox_search_deinit(&trash->search_ctx);

        if (size_expunged >= size_needed)
            (void)mailbox_transaction_commit(&trash->trans);
        else {
            /* couldn't get enough space, don't expunge anything */
                        mailbox_transaction_rollback(&trash->trans);
        }

        mailbox_close(&trash->box);
    }

    if (size_expunged < size_needed) {
        if (getenv("DEBUG") != NULL) {
            i_info("trash plugin: Failed to remove enough messages "
                   "(needed %llu bytes, expunged only %llu bytes)",
                   (unsigned long long)size_needed,
                   (unsigned long long)size_expunged);
        }
        return FALSE;
    }

    ctx->bytes_used = ctx->bytes_used > (int64_t)size_expunged ?
        ctx->bytes_used - size_expunged : 0;
    ctx->count_used = ctx->count_used > (int64_t)expunged_count ?
        ctx->count_used - expunged_count : 0;
    return TRUE;
}

static int
trash_quota_test_alloc(struct quota_transaction_context *ctx,
               uoff_t size, bool *too_large_r)
{
    int ret, i;

    for (i = 0; ; i++) {
        ret = trash_next_quota_test_alloc(ctx, size, too_large_r);
        if (ret != 0 || *too_large_r) {
            if (getenv("DEBUG") != NULL && *too_large_r) {
                i_info("trash plugin: Mail is larger than "
                       "quota, won't even try to handle");
            }
            return ret;
        }

        if (i == MAX_RETRY_COUNT) {
            /* trash_try_clean_mails() should have returned 0 if
               it couldn't get enough space, but allow retrying
               it a couple of times if there was some extra space
               that was needed.. */
            break;
        }

        /* not enough space. try deleting some from mailbox. */
        ret = trash_try_clean_mails(ctx, size);
        if (ret <= 0)
            return 0;
    }

    return 0;
}

static bool trash_find_storage(struct mail_user *user,
                   struct trash_mailbox *trash)
{
    struct mail_namespace *ns;
    const char *name;

    for (ns = user->namespaces; ns != NULL; ns = ns->next) {
        name = trash->name;
        if (mail_namespace_update_name(ns, &name)) {
            if (name != trash->name)
                trash->name = p_strdup(user->pool, name);
            trash->storage = ns->storage;
            return TRUE;
        }
    }
    return FALSE;
}

static int trash_mailbox_priority_cmp(const void *p1, const void *p2)
{
    const struct trash_mailbox *t1 = p1, *t2 = p2;

    return t1->priority - t2->priority;
}

static int read_configuration(struct mail_user *user, const char *path)
{
    struct trash_user *tuser = TRASH_USER_CONTEXT(user);
    struct istream *input;
    const char *line, *name;
    struct trash_mailbox *trash;
    unsigned int count;
    int fd, ret = 0;

    fd = open(path, O_RDONLY);
    if (fd == -1) {
        i_error("trash plugin: open(%s) failed: %m", path);
        return -1;
    }

    p_array_init(&tuser->trash_boxes, user->pool, INIT_TRASH_MAILBOX_COUNT);

    input = i_stream_create_fd(fd, (size_t)-1, FALSE);
    while ((line = i_stream_read_next_line(input)) != NULL) {
        /* <priority> <mailbox name> */
        name = strchr(line, ' ');
        if (name == NULL || name[1] == '\0' || *line == '#')
            continue;

        trash = array_append_space(&tuser->trash_boxes);
        trash->name = p_strdup(user->pool, name+1);
        trash->priority = atoi(t_strdup_until(line, name));

        if (!trash_find_storage(user, trash)) {
            i_error("trash: Namespace not found for mailbox '%s'",
                trash->name);
            ret = -1;
        }

        if (getenv("DEBUG") != NULL) {
            i_info("trash plugin: Added '%s' with priority %d",
                   trash->name, trash->priority);
        }
    }
    i_stream_destroy(&input);
    (void)close(fd);

    trash = array_get_modifiable(&tuser->trash_boxes, &count);
    qsort(trash, count, sizeof(*trash), trash_mailbox_priority_cmp);
    return ret;
}

static void
trash_hook_mail_namespaces_created(struct mail_namespace *namespaces)
{
    struct mail_user *user = namespaces->user;
    struct trash_user *tuser;
    const char *env;

    if (trash_next_hook_mail_namespaces_created != NULL)
        trash_next_hook_mail_namespaces_created(namespaces);

    env = getenv("TRASH");
    if (env == NULL) {
        if (getenv("DEBUG") != NULL)
            i_info("trash: No trash setting - plugin disabled");
        return;
    }

    if (quota_set == NULL) {
        i_error("trash plugin: quota plugin not initialized");
        return;
    }

    tuser = p_new(user->pool, struct trash_user, 1);
    tuser->module_ctx.super = user->v;
    MODULE_CONTEXT_SET(user, trash_user_module, tuser);

    if (read_configuration(user, env) == 0) {
        trash_next_quota_test_alloc = quota_set->test_alloc;
        quota_set->test_alloc = trash_quota_test_alloc;
    }
}

void trash_plugin_init(void)
{
    trash_next_hook_mail_namespaces_created = hook_mail_namespaces_created;
    hook_mail_namespaces_created = trash_hook_mail_namespaces_created;
}

void trash_plugin_deinit(void)
{
    hook_mail_namespaces_created = trash_hook_mail_namespaces_created;
    quota_set->test_alloc = trash_next_quota_test_alloc;
}