src/lib-storage/mail-namespace.c

	mail-namespace.c revision 5b560a354d9ce6d38134717af6554dae269d860f
965ed6ea3fc8f7637bd0d159d2fdb283a191ce34Timo Sirainen/* Copyright (c) 2005-2012 Dovecot authors, see the included COPYING file */
965ed6ea3fc8f7637bd0d159d2fdb283a191ce34Timo Sirainen
965ed6ea3fc8f7637bd0d159d2fdb283a191ce34Timo Sirainen#include "lib.h"
965ed6ea3fc8f7637bd0d159d2fdb283a191ce34Timo Sirainen#include "array.h"
965ed6ea3fc8f7637bd0d159d2fdb283a191ce34Timo Sirainen#include "str.h"
965ed6ea3fc8f7637bd0d159d2fdb283a191ce34Timo Sirainen#include "file-lock.h"
965ed6ea3fc8f7637bd0d159d2fdb283a191ce34Timo Sirainen#include "settings-parser.h"
965ed6ea3fc8f7637bd0d159d2fdb283a191ce34Timo Sirainen#include "mailbox-list-private.h"
965ed6ea3fc8f7637bd0d159d2fdb283a191ce34Timo Sirainen#include "mail-storage-private.h"
965ed6ea3fc8f7637bd0d159d2fdb283a191ce34Timo Sirainen#include "mail-storage-settings.h"
965ed6ea3fc8f7637bd0d159d2fdb283a191ce34Timo Sirainen#include "mail-namespace.h"
965ed6ea3fc8f7637bd0d159d2fdb283a191ce34Timo Sirainen
965ed6ea3fc8f7637bd0d159d2fdb283a191ce34Timo Sirainen#include <stdlib.h>
965ed6ea3fc8f7637bd0d159d2fdb283a191ce34Timo Sirainen
e65cc79f80577e83c706f0678c78e2c0bd91434fTimo Sirainenvoid mail_namespace_add_storage(struct mail_namespace *ns,
7d6389e4053c2dac1fb37180b5756b00785983dcTimo Sirainen                struct mail_storage *storage)
7d6389e4053c2dac1fb37180b5756b00785983dcTimo Sirainen{
25ee72451d16374ed27fdbf829f4ec756c778352Timo Sirainen    /* currently we support only a single storage */
f1ddb98e6b639394ae205b305be1ddcfab102578Timo Sirainen    i_assert(ns->storage == NULL);
965ed6ea3fc8f7637bd0d159d2fdb283a191ce34Timo Sirainen    ns->storage = storage;
e82af44fe25ca9b88210f313548dc08538e4a677Timo Sirainen
965ed6ea3fc8f7637bd0d159d2fdb283a191ce34Timo Sirainen    if (storage->v.add_list != NULL)
b567e0172c73dcf7642462e86962060358dd5f28Timo Sirainen        storage->v.add_list(storage, ns->list);
b567e0172c73dcf7642462e86962060358dd5f28Timo Sirainen    hook_mail_namespace_storage_added(ns);
10c5fd417af4ee30b68c967f5e7d5a49f4f149b5Timo Sirainen}
10c5fd417af4ee30b68c967f5e7d5a49f4f149b5Timo Sirainen
10c5fd417af4ee30b68c967f5e7d5a49f4f149b5Timo Sirainenvoid mail_namespace_finish_list_init(struct mail_namespace *ns,
10c5fd417af4ee30b68c967f5e7d5a49f4f149b5Timo Sirainen                     struct mailbox_list *list)
965ed6ea3fc8f7637bd0d159d2fdb283a191ce34Timo Sirainen{
473080c7c0d25ddfdf77e7dfa0ba8f73c6c669d5Timo Sirainen    ns->list = list;
e714eed72515794c46c6712a611e5ab924d903daTimo Sirainen    ns->prefix_len = strlen(ns->prefix);
e714eed72515794c46c6712a611e5ab924d903daTimo Sirainen}
1f18053d463f0294387b5e4dd11f9010bda9a24eTimo Sirainen
e82af44fe25ca9b88210f313548dc08538e4a677Timo Sirainenstatic void mail_namespace_free(struct mail_namespace *ns)
e714eed72515794c46c6712a611e5ab924d903daTimo Sirainen{
e714eed72515794c46c6712a611e5ab924d903daTimo Sirainen    if (ns->storage != NULL)
965ed6ea3fc8f7637bd0d159d2fdb283a191ce34Timo Sirainen        mail_storage_unref(&ns->storage);
965ed6ea3fc8f7637bd0d159d2fdb283a191ce34Timo Sirainen    if (ns->list != NULL)
965ed6ea3fc8f7637bd0d159d2fdb283a191ce34Timo Sirainen        mailbox_list_destroy(&ns->list);
c4457e497e01b57565d24da624968699b166e02aTimo Sirainen
c4457e497e01b57565d24da624968699b166e02aTimo Sirainen    if (ns->owner != ns->user && ns->owner != NULL)
965ed6ea3fc8f7637bd0d159d2fdb283a191ce34Timo Sirainen        mail_user_unref(&ns->owner);
965ed6ea3fc8f7637bd0d159d2fdb283a191ce34Timo Sirainen    i_free(ns->prefix);
965ed6ea3fc8f7637bd0d159d2fdb283a191ce34Timo Sirainen    i_free(ns);
965ed6ea3fc8f7637bd0d159d2fdb283a191ce34Timo Sirainen}
965ed6ea3fc8f7637bd0d159d2fdb283a191ce34Timo Sirainen
965ed6ea3fc8f7637bd0d159d2fdb283a191ce34Timo Sirainenstatic int
965ed6ea3fc8f7637bd0d159d2fdb283a191ce34Timo Sirainennamespace_add(struct mail_user *user,
965ed6ea3fc8f7637bd0d159d2fdb283a191ce34Timo Sirainen          struct mail_namespace_settings *ns_set,
965ed6ea3fc8f7637bd0d159d2fdb283a191ce34Timo Sirainen          struct mail_namespace_settings *unexpanded_ns_set,
965ed6ea3fc8f7637bd0d159d2fdb283a191ce34Timo Sirainen          const struct mail_storage_settings *mail_set,
0d7d27765267594a5870892268ab345148306d49Timo Sirainen          struct mail_namespace **ns_p, const char **error_r)
0d7d27765267594a5870892268ab345148306d49Timo Sirainen{
9f431ccfb6932746db56245c8a3d3415717ef545Timo Sirainen        struct mail_namespace *ns;
965ed6ea3fc8f7637bd0d159d2fdb283a191ce34Timo Sirainen    const char *driver, *error;
965ed6ea3fc8f7637bd0d159d2fdb283a191ce34Timo Sirainen
965ed6ea3fc8f7637bd0d159d2fdb283a191ce34Timo Sirainen    ns = i_new(struct mail_namespace, 1);
965ed6ea3fc8f7637bd0d159d2fdb283a191ce34Timo Sirainen    ns->refcount = 1;
965ed6ea3fc8f7637bd0d159d2fdb283a191ce34Timo Sirainen    ns->user = user;
965ed6ea3fc8f7637bd0d159d2fdb283a191ce34Timo Sirainen    if (strncmp(ns_set->type, "private", 7) == 0) {
ed5e91e58dfc372c2135c55427bf6f25a7725042Timo Sirainen        ns->owner = user;
ed5e91e58dfc372c2135c55427bf6f25a7725042Timo Sirainen        ns->type = NAMESPACE_PRIVATE;
ed5e91e58dfc372c2135c55427bf6f25a7725042Timo Sirainen    } else if (strncmp(ns_set->type, "shared", 6) == 0)
ed5e91e58dfc372c2135c55427bf6f25a7725042Timo Sirainen        ns->type = NAMESPACE_SHARED;
965ed6ea3fc8f7637bd0d159d2fdb283a191ce34Timo Sirainen    else if (strncmp(ns_set->type, "public", 6) == 0)
965ed6ea3fc8f7637bd0d159d2fdb283a191ce34Timo Sirainen        ns->type = NAMESPACE_PUBLIC;
25ee72451d16374ed27fdbf829f4ec756c778352Timo Sirainen    else {
25ee72451d16374ed27fdbf829f4ec756c778352Timo Sirainen        *error_r = t_strdup_printf("Unknown namespace type: %s",
965ed6ea3fc8f7637bd0d159d2fdb283a191ce34Timo Sirainen                       ns_set->type);
9f431ccfb6932746db56245c8a3d3415717ef545Timo Sirainen        mail_namespace_free(ns);
0d7d27765267594a5870892268ab345148306d49Timo Sirainen        return -1;
9f431ccfb6932746db56245c8a3d3415717ef545Timo Sirainen    }
965ed6ea3fc8f7637bd0d159d2fdb283a191ce34Timo Sirainen
965ed6ea3fc8f7637bd0d159d2fdb283a191ce34Timo Sirainen    if (strcmp(ns_set->list, "children") == 0)
965ed6ea3fc8f7637bd0d159d2fdb283a191ce34Timo Sirainen        ns->flags |= NAMESPACE_FLAG_LIST_CHILDREN;
965ed6ea3fc8f7637bd0d159d2fdb283a191ce34Timo Sirainen    else if (strcmp(ns_set->list, "yes") == 0)
08aea01ef9a9d20703e0fcf8618e6195c0037a44Timo Sirainen        ns->flags |= NAMESPACE_FLAG_LIST_PREFIX;
08aea01ef9a9d20703e0fcf8618e6195c0037a44Timo Sirainen    else if (strcmp(ns_set->list, "no") != 0) {
d1f0acc7fc722e13e8296228703adfe8a884d59eTimo Sirainen        *error_r = t_strdup_printf("Invalid list setting value: %s",
ebfcfd258acc89633c47d9c3b0b40a1a3f75cdcbTimo Sirainen                       ns_set->list);
d1f0acc7fc722e13e8296228703adfe8a884d59eTimo Sirainen        mail_namespace_free(ns);
965ed6ea3fc8f7637bd0d159d2fdb283a191ce34Timo Sirainen        return -1;
    }

    if (ns_set->inbox) {
        ns->flags |= NAMESPACE_FLAG_INBOX_USER |
            NAMESPACE_FLAG_INBOX_ANY;
    }
    if (ns_set->hidden)
        ns->flags |= NAMESPACE_FLAG_HIDDEN;
    if (ns_set->subscriptions)
        ns->flags |= NAMESPACE_FLAG_SUBSCRIPTIONS;

    if (*ns_set->location == '\0')
        ns_set->location = mail_set->mail_location;

    if (mail_set->mail_debug) {
        i_debug("Namespace %s: type=%s, prefix=%s, sep=%s, "
            "inbox=%s, hidden=%s, list=%s, subscriptions=%s "
            "location=%s",
            ns_set->name, ns_set->type, ns_set->prefix,
            ns_set->separator == NULL ? "" : ns_set->separator,
            ns_set->inbox ? "yes" : "no",
            ns_set->hidden ? "yes" : "no",
            ns_set->list,
            ns_set->subscriptions ? "yes" : "no", ns_set->location);
    }

    ns->set = ns_set;
    ns->unexpanded_set = unexpanded_ns_set;
    ns->mail_set = mail_set;
    ns->prefix = i_strdup(ns_set->prefix);

    if (ns->type == NAMESPACE_SHARED &&
        (strchr(ns->prefix, '%') != NULL ||
         strchr(ns->set->location, '%') != NULL)) {
        /* dynamic shared namespace. the above check catches wrong
           mixed %% usage, but still allows for specifying a shared
           namespace to an explicit location without any %% */
        ns->flags |= NAMESPACE_FLAG_NOQUOTA | NAMESPACE_FLAG_NOACL;
        driver = "shared";
    } else {
        driver = NULL;
    }

    if (mail_storage_create(ns, driver, 0, &error) < 0) {
        *error_r = t_strdup_printf("Namespace '%s': %s",
                       ns->prefix, error);
        mail_namespace_free(ns);
        return -1;
    }

    *ns_p = ns;
    return 0;
}

static bool namespace_is_valid_alias_storage(struct mail_namespace *ns,
                         const char **error_r)
{
    if (strcmp(ns->storage->name, ns->alias_for->storage->name) != 0) {
        *error_r = t_strdup_printf(
            "Namespace %s can't have alias_for=%s "
            "to a different storage type (%s vs %s)",
            ns->prefix, ns->alias_for->prefix,
            ns->storage->name, ns->alias_for->storage->name);
        return FALSE;
    }

    if ((ns->storage->class_flags & MAIL_STORAGE_CLASS_FLAG_UNIQUE_ROOT) != 0 &&
        ns->storage != ns->alias_for->storage) {
        *error_r = t_strdup_printf(
            "Namespace %s can't have alias_for=%s "
            "to a different storage (different root dirs)",
            ns->prefix, ns->alias_for->prefix);
        return FALSE;
    }
    return TRUE;
}

static int
namespace_set_alias_for(struct mail_namespace *ns,
            struct mail_namespace *all_namespaces,
            const char **error_r)
{
    if (ns->set->alias_for != NULL) {
        ns->alias_for = mail_namespace_find_prefix(all_namespaces,
                               ns->set->alias_for);
        if (ns->alias_for == NULL) {
            *error_r = t_strdup_printf("Invalid namespace alias_for: %s",
                           ns->set->alias_for);
            return -1;
        }
        if (ns->alias_for->alias_for != NULL) {
            *error_r = t_strdup_printf("Chained namespace alias_for: %s",
                           ns->set->alias_for);
            return -1;
        }
        if (!namespace_is_valid_alias_storage(ns, error_r))
            return -1;

        ns->alias_chain_next = ns->alias_for->alias_chain_next;
        ns->alias_for->alias_chain_next = ns;
    }
    return 0;
}

static bool
namespaces_check(struct mail_namespace *namespaces, const char **error_r)
{
    struct mail_namespace *ns, *inbox_ns = NULL;
    unsigned int subscriptions_count = 0;
    bool visible_namespaces = FALSE;
    char ns_sep, list_sep = '\0';

    for (ns = namespaces; ns != NULL; ns = ns->next) {
        ns_sep = mail_namespace_get_sep(ns);
        if (mail_namespace_find_prefix(ns->next, ns->prefix) != NULL) {
            *error_r = t_strdup_printf(
                "Duplicate namespace prefix: \"%s\"",
                ns->prefix);
            return FALSE;
        }
        if (namespace_set_alias_for(ns, namespaces, error_r) < 0)
            return FALSE;
        if ((ns->flags & NAMESPACE_FLAG_HIDDEN) == 0)
            visible_namespaces = TRUE;
        if ((ns->flags & NAMESPACE_FLAG_INBOX_USER) != 0) {
            if (inbox_ns != NULL) {
                *error_r = "There can be only one namespace with "
                    "inbox=yes";
                return FALSE;
            }
            inbox_ns = ns;
        }
        if (*ns->prefix != '\0' &&
            (ns->flags & (NAMESPACE_FLAG_LIST_PREFIX |
                  NAMESPACE_FLAG_LIST_CHILDREN)) != 0 &&
            ns->prefix[strlen(ns->prefix)-1] != ns_sep) {
            *error_r = t_strdup_printf(
                "list=yes requires prefix=%s "
                "to end with separator", ns->prefix);
            return FALSE;
        }
        if (*ns->prefix != '\0' &&
            (ns->flags & (NAMESPACE_FLAG_LIST_PREFIX |
                  NAMESPACE_FLAG_LIST_CHILDREN)) != 0 &&
            ns->prefix[0] == ns_sep) {
            *error_r = t_strdup_printf(
                "list=yes requires prefix=%s "
                "not to start with separator", ns->prefix);
            return FALSE;
        }
        if ((ns->flags & (NAMESPACE_FLAG_LIST_PREFIX |
                  NAMESPACE_FLAG_LIST_CHILDREN)) != 0) {
            if (list_sep == '\0')
                list_sep = ns_sep;
            else if (list_sep != ns_sep) {
                *error_r = "All list=yes namespaces must use "
                    "the same separator";
                return FALSE;
            }
        }
        if ((ns->flags & NAMESPACE_FLAG_SUBSCRIPTIONS) != 0)
            subscriptions_count++;
    }

    if (inbox_ns == NULL) {
        *error_r = "inbox=yes namespace missing";
        return FALSE;
    }
    if (list_sep == '\0') {
        *error_r = "no list=yes namespaces";
        return FALSE;
    }
    if (!visible_namespaces) {
        *error_r = "no hidden=no namespaces";
        return FALSE;
    }
    if (subscriptions_count == 0) {
        *error_r = "no subscriptions=yes namespaces";
        return FALSE;
    }
    return TRUE;
}

int mail_namespaces_init(struct mail_user *user, const char **error_r)
{
    const struct mail_storage_settings *mail_set;
    struct mail_namespace_settings *const *ns_set;
    struct mail_namespace_settings *const *unexpanded_ns_set;
    struct mail_namespace *namespaces, *ns, **ns_p;
    unsigned int i, count, count2;

    i_assert(user->initialized);

        namespaces = NULL; ns_p = &namespaces;

    mail_set = mail_user_set_get_storage_set(user);
    if (array_is_created(&user->set->namespaces)) {
        ns_set = array_get(&user->set->namespaces, &count);
        unexpanded_ns_set =
            array_get(&user->unexpanded_set->namespaces, &count2);
        i_assert(count == count2);
    } else {
        ns_set = unexpanded_ns_set = NULL;
        count = 0;
    }
    for (i = 0; i < count; i++) {
        if (namespace_add(user, ns_set[i], unexpanded_ns_set[i],
                  mail_set, ns_p, error_r) < 0) {
            if (!ns_set[i]->ignore_on_failure)
                return -1;
            if (mail_set->mail_debug) {
                i_debug("Skipping namespace %s: %s",
                    ns_set[i]->prefix, *error_r);
            }
        } else {
            ns_p = &(*ns_p)->next;
        }
    }

    if (namespaces != NULL) {
        if (!namespaces_check(namespaces, error_r)) {
            *error_r = t_strconcat("namespace configuration error: ",
                           *error_r, NULL);
            while (namespaces != NULL) {
                ns = namespaces;
                namespaces = ns->next;
                mail_namespace_free(ns);
            }
            return -1;
        }
        mail_user_add_namespace(user, &namespaces);

        T_BEGIN {
            hook_mail_namespaces_created(namespaces);
        } T_END;
        return 0;
    }

    /* no namespaces defined, create a default one */
    return mail_namespaces_init_location(user, NULL, error_r);
}

int mail_namespaces_init_location(struct mail_user *user, const char *location,
                  const char **error_r)
{
    struct mail_namespace_settings *inbox_set, *unexpanded_inbox_set;
    struct mail_namespace *ns;
    const struct mail_storage_settings *mail_set;
    const char *error, *driver, *location_source;
    bool default_location = FALSE;

    i_assert(location == NULL || *location != '\0');

    ns = i_new(struct mail_namespace, 1);
    ns->refcount = 1;
    ns->type = NAMESPACE_PRIVATE;
    ns->flags = NAMESPACE_FLAG_INBOX_USER | NAMESPACE_FLAG_INBOX_ANY |
        NAMESPACE_FLAG_LIST_PREFIX | NAMESPACE_FLAG_SUBSCRIPTIONS;
    ns->owner = user;

    inbox_set = p_new(user->pool, struct mail_namespace_settings, 1);
    *inbox_set = mail_namespace_default_settings;
    inbox_set->inbox = TRUE;

    unexpanded_inbox_set = p_new(user->pool, struct mail_namespace_settings, 1);
    *unexpanded_inbox_set = *inbox_set;

    driver = NULL;
    mail_set = mail_user_set_get_storage_set(user);
    if (location != NULL) {
        inbox_set->location = p_strdup(user->pool, location);
        location_source = "mail_location parameter";
    } else if (*mail_set->mail_location != '\0') {
        location_source = "mail_location setting";
        inbox_set->location = mail_set->mail_location;
        default_location = TRUE;
    } else {
        location_source = "environment MAIL";
        inbox_set->location = getenv("MAIL");
    }
    if (inbox_set->location == NULL) {
        /* support also maildir-specific environment */
        inbox_set->location = getenv("MAILDIR");
        if (inbox_set->location == NULL)
            inbox_set->location = "";
        else {
            driver = "maildir";
            location_source = "environment MAILDIR";
        }
    }
    if (default_location) {
        /* treat this the same as if a namespace was created with
           default settings. dsync relies on finding a namespace
           without explicit location setting. */
        unexpanded_inbox_set->location = SETTING_STRVAR_UNEXPANDED;
    } else {
        unexpanded_inbox_set->location =
            p_strconcat(user->pool, SETTING_STRVAR_EXPANDED,
                    inbox_set->location, NULL);
    }

    ns->set = inbox_set;
    ns->unexpanded_set = unexpanded_inbox_set;
    ns->mail_set = mail_set;
    ns->prefix = i_strdup(ns->set->prefix);
    ns->user = user;

    if (mail_storage_create(ns, driver, 0, &error) < 0) {
        if (*inbox_set->location != '\0') {
            *error_r = t_strdup_printf(
                "Initializing mail storage from %s "
                "failed: %s", location_source, error);
        } else {
            *error_r = t_strdup_printf("mail_location not set and "
                    "autodetection failed: %s", error);
        }
        mail_namespace_free(ns);
        return -1;
    }
    user->namespaces = ns;

    T_BEGIN {
        hook_mail_namespaces_created(ns);
    } T_END;
    return 0;
}

struct mail_namespace *mail_namespaces_init_empty(struct mail_user *user)
{
    struct mail_namespace *ns;

    ns = i_new(struct mail_namespace, 1);
    ns->refcount = 1;
    ns->user = user;
    ns->owner = user;
    ns->prefix = i_strdup("");
    ns->flags = NAMESPACE_FLAG_INBOX_USER | NAMESPACE_FLAG_INBOX_ANY |
        NAMESPACE_FLAG_LIST_PREFIX | NAMESPACE_FLAG_SUBSCRIPTIONS;
    ns->mail_set = mail_user_set_get_storage_set(user);
    user->namespaces = ns;
    return ns;
}

void mail_namespaces_deinit(struct mail_namespace **_namespaces)
{
    struct mail_namespace *ns, *next;

    /* update *_namespaces as needed, instead of immediately setting it
       to NULL. for example mdbox_storage.destroy() wants to go through
       user's namespaces. */
    while (*_namespaces != NULL) {
        ns = *_namespaces;
        next = ns->next;

        mail_namespace_free(ns);
        *_namespaces = next;
    }
}

void mail_namespaces_set_storage_callbacks(struct mail_namespace *namespaces,
                       struct mail_storage_callbacks *callbacks,
                       void *context)
{
    struct mail_namespace *ns;

    for (ns = namespaces; ns != NULL; ns = ns->next)
        mail_storage_set_callbacks(ns->storage, callbacks, context);
}

void mail_namespace_ref(struct mail_namespace *ns)
{
    i_assert(ns->refcount > 0);

    ns->refcount++;
}

void mail_namespace_unref(struct mail_namespace **_ns)
{
    struct mail_namespace *ns = *_ns;

    i_assert(ns->refcount > 0);

    *_ns = NULL;

    if (--ns->refcount > 0)
        return;

    i_assert(ns->destroyed);
    mail_namespace_free(ns);
}

void mail_namespace_destroy(struct mail_namespace *ns)
{
    struct mail_namespace **nsp;

    i_assert(!ns->destroyed);

    /* remove from user's namespaces list */
    for (nsp = &ns->user->namespaces; *nsp != NULL; nsp = &(*nsp)->next) {
        if (*nsp == ns) {
            *nsp = ns->next;
            break;
        }
    }
    ns->destroyed = TRUE;

    mail_namespace_unref(&ns);
}

struct mail_storage *
mail_namespace_get_default_storage(struct mail_namespace *ns)
{
    /* currently we don't support more than one storage per namespace */
    return ns->storage;
}

char mail_namespace_get_sep(struct mail_namespace *ns)
{
    return *ns->set->separator != '\0' ? *ns->set->separator :
        mailbox_list_get_hierarchy_sep(ns->list);
}

char mail_namespaces_get_root_sep(struct mail_namespace *namespaces)
{
    while ((namespaces->flags & NAMESPACE_FLAG_LIST_PREFIX) == 0)
        namespaces = namespaces->next;
    return mail_namespace_get_sep(namespaces);
}

static bool mail_namespace_is_usable_prefix(struct mail_namespace *ns,
                        const char *mailbox, bool inbox)
{
    if (strncmp(ns->prefix, mailbox, ns->prefix_len) == 0) {
        /* true exact prefix match */
        return TRUE;
    }

    if (inbox && strncmp(ns->prefix, "INBOX", 5) == 0 &&
        strncmp(ns->prefix+5, mailbox+5, ns->prefix_len-5) == 0) {
        /* we already checked that mailbox begins with case-insensitive
           INBOX. this namespace also begins with INBOX and the rest
           of the prefix matches too. */
        return TRUE;
    }

    if (strncmp(ns->prefix, mailbox, ns->prefix_len-1) == 0 &&
        mailbox[ns->prefix_len-1] == '\0' &&
        ns->prefix[ns->prefix_len-1] == mail_namespace_get_sep(ns)) {
        /* we're trying to access the namespace prefix itself */
        return TRUE;
    }
    return FALSE;
}

static struct mail_namespace *
mail_namespace_find_mask(struct mail_namespace *namespaces, const char *box,
             enum namespace_flags flags,
             enum namespace_flags mask)
{
        struct mail_namespace *ns = namespaces;
    struct mail_namespace *best = NULL;
    unsigned int best_len = 0;
    bool inbox;

    inbox = strncasecmp(box, "INBOX", 5) == 0;
    if (inbox && box[5] == '\0') {
        /* find the INBOX namespace */
        while (ns != NULL) {
            if ((ns->flags & NAMESPACE_FLAG_INBOX_USER) != 0 &&
                (ns->flags & mask) == flags)
                return ns;
            if (*ns->prefix == '\0')
                best = ns;
            ns = ns->next;
        }
        return best;
    }

    for (; ns != NULL; ns = ns->next) {
        if (ns->prefix_len >= best_len && (ns->flags & mask) == flags &&
            mail_namespace_is_usable_prefix(ns, box, inbox)) {
            best = ns;
            best_len = ns->prefix_len;
        }
    }
    return best;
}

static struct mail_namespace *
mail_namespace_find_shared(struct mail_namespace *ns, const char *mailbox)
{
    struct mailbox_list *list = ns->list;
    struct mail_storage *storage;

    if (mailbox_list_get_storage(&list, mailbox, &storage) < 0)
        return ns;

    return mailbox_list_get_namespace(list);
}

struct mail_namespace *
mail_namespace_find(struct mail_namespace *namespaces, const char *mailbox)
{
    struct mail_namespace *ns;

    ns = mail_namespace_find_mask(namespaces, mailbox, 0, 0);
    if (ns != NULL && ns->type == NAMESPACE_SHARED &&
        (ns->flags & NAMESPACE_FLAG_AUTOCREATED) == 0) {
        /* see if we need to autocreate a namespace for shared user */
        if (strchr(mailbox, mail_namespace_get_sep(ns)) != NULL)
            return mail_namespace_find_shared(ns, mailbox);
    }
    return ns;
}

struct mail_namespace *
mail_namespace_find_unalias(struct mail_namespace *namespaces,
                const char **mailbox)
{
    struct mail_namespace *ns;
    const char *storage_name;

    ns = mail_namespace_find(namespaces, *mailbox);
    if (ns != NULL && ns->alias_for != NULL) {
        storage_name =
            mailbox_list_get_storage_name(ns->list, *mailbox);
        ns = ns->alias_for;
        *mailbox = mailbox_list_get_vname(ns->list, storage_name);
    }
    return ns;
}

struct mail_namespace *
mail_namespace_find_visible(struct mail_namespace *namespaces,
                const char *mailbox)
{
    return mail_namespace_find_mask(namespaces, mailbox, 0,
                    NAMESPACE_FLAG_HIDDEN);
}

struct mail_namespace *
mail_namespace_find_subscribable(struct mail_namespace *namespaces,
                 const char *mailbox)
{
    return mail_namespace_find_mask(namespaces, mailbox,
                    NAMESPACE_FLAG_SUBSCRIPTIONS,
                    NAMESPACE_FLAG_SUBSCRIPTIONS);
}

struct mail_namespace *
mail_namespace_find_unsubscribable(struct mail_namespace *namespaces,
                   const char *mailbox)
{
    return mail_namespace_find_mask(namespaces, mailbox,
                    0, NAMESPACE_FLAG_SUBSCRIPTIONS);
}

struct mail_namespace *
mail_namespace_find_inbox(struct mail_namespace *namespaces)
{
    while ((namespaces->flags & NAMESPACE_FLAG_INBOX_USER) == 0)
        namespaces = namespaces->next;
    return namespaces;
}

struct mail_namespace *
mail_namespace_find_prefix(struct mail_namespace *namespaces,
               const char *prefix)
{
        struct mail_namespace *ns;
    unsigned int len = strlen(prefix);

    for (ns = namespaces; ns != NULL; ns = ns->next) {
        if (ns->prefix_len == len &&
            strcmp(ns->prefix, prefix) == 0)
            return ns;
    }
    return NULL;
}

struct mail_namespace *
mail_namespace_find_prefix_nosep(struct mail_namespace *namespaces,
                 const char *prefix)
{
        struct mail_namespace *ns;
    unsigned int len = strlen(prefix);

    for (ns = namespaces; ns != NULL; ns = ns->next) {
        if (ns->prefix_len == len + 1 &&
            strncmp(ns->prefix, prefix, len) == 0 &&
            ns->prefix[len] == mail_namespace_get_sep(ns))
            return ns;
    }
    return NULL;
}