lib-storage/list/subscription-file.c

	subscription-file.c revision bcb4e51a409d94ae670de96afb8483a4f7855294
/* Copyright (c) 2002-2018 Dovecot authors, see the included COPYING file */

#include "lib.h"
#include "str.h"
#include "strescape.h"
#include "istream.h"
#include "ostream.h"
#include "nfs-workarounds.h"
#include "mkdir-parents.h"
#include "file-dotlock.h"
#include "mailbox-list-private.h"
#include "subscription-file.h"

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

#define SUBSCRIPTION_FILE_ESTALE_RETRY_COUNT NFS_ESTALE_RETRY_COUNT
#define SUBSCRIPTION_FILE_LOCK_TIMEOUT 120
#define SUBSCRIPTION_FILE_CHANGE_TIMEOUT 30

struct subsfile_list_context {
    struct mailbox_list *list;
    struct istream *input;
    char *path;
    string_t *name;

    unsigned int version;
    bool failed;
};

static const char version2_header[] = "V\t2\n\n";

static void subsread_set_syscall_error(struct mailbox_list *list,
                       const char *function, const char *path)
{
    if (errno == EACCES && !list->mail_set->mail_debug) {
        mailbox_list_set_error(list, MAIL_ERROR_PERM,
                       "No permission to read subscriptions");
    } else {
        mailbox_list_set_critical(list,
            "%s failed with subscription file %s: %m",
            function, path);
    }
}

static void subswrite_set_syscall_error(struct mailbox_list *list,
                    const char *function, const char *path)
{
    if (errno == EACCES && !list->mail_set->mail_debug) {
        mailbox_list_set_error(list, MAIL_ERROR_PERM,
                       "No permission to modify subscriptions");
    } else {
        mailbox_list_set_critical(list,
            "%s failed with subscription file %s: %m",
            function, path);
    }
}

static void
subsfile_list_read_header(struct mailbox_list *list, struct istream *input,
              unsigned int *version_r)
{
    const unsigned char version2_header_len = strlen(version2_header);
    const unsigned char *data;
    size_t size;
    int ret;

    *version_r = 0;

    ret = i_stream_read_bytes(input, &data, &size, version2_header_len);
    if (ret < 0) {
        i_assert(ret == -1);
        if (input->stream_errno != 0)
            subswrite_set_syscall_error(list, "read()", i_stream_get_name(input));
        return;
    }
    if (ret > 0 &&
        memcmp(data, version2_header, version2_header_len) == 0) {
        *version_r = 2;
        i_stream_skip(input, version2_header_len);
    }
}

static const char *next_line(struct mailbox_list *list, const char *path,
                 struct istream *input, bool *failed_r,
                 bool ignore_estale)
{
    const char *line;

    *failed_r = FALSE;

    while ((line = i_stream_next_line(input)) == NULL) {
                switch (i_stream_read(input)) {
        case -1:
                        if (input->stream_errno != 0 &&
                            (input->stream_errno != ESTALE || !ignore_estale)) {
                                subswrite_set_syscall_error(list,
                                "read()", path);
                                *failed_r = TRUE;
                        }
            return NULL;
        case -2:
            /* mailbox name too large */
            mailbox_list_set_critical(list,
                "Subscription file %s contains lines longer "
                "than %u characters", path,
                (unsigned int)list->mailbox_name_max_length);
            *failed_r = TRUE;
            return NULL;
        }
    }

    return line;
}

int subsfile_set_subscribed(struct mailbox_list *list, const char *path,
                const char *temp_prefix, const char *name,
                bool set)
{
    const struct mail_storage_settings *mail_set = list->mail_set;
    struct dotlock_settings dotlock_set;
    struct dotlock *dotlock;
    struct mailbox_permissions perm;
    const char *line, *dir, *fname, *escaped_name;
    struct istream *input = NULL;
    struct ostream *output;
    int fd_in, fd_out;
    enum mailbox_list_path_type type;
    bool found, changed = FALSE, failed = FALSE;
    unsigned int version = 2;

    if (strcasecmp(name, "INBOX") == 0)
        name = "INBOX";

    i_zero(&dotlock_set);
    dotlock_set.use_excl_lock = mail_set->dotlock_use_excl;
    dotlock_set.nfs_flush = mail_set->mail_nfs_storage;
    dotlock_set.temp_prefix = temp_prefix;
    dotlock_set.timeout = SUBSCRIPTION_FILE_LOCK_TIMEOUT;
    dotlock_set.stale_timeout = SUBSCRIPTION_FILE_CHANGE_TIMEOUT;

    mailbox_list_get_root_permissions(list, &perm);
    fd_out = file_dotlock_open_group(&dotlock_set, path, 0,
                     perm.file_create_mode,
                     perm.file_create_gid,
                     perm.file_create_gid_origin, &dotlock);
    if (fd_out == -1 && errno == ENOENT) {
        /* directory hasn't been created yet. */
        type = list->set.control_dir != NULL ?
            MAILBOX_LIST_PATH_TYPE_CONTROL :
            MAILBOX_LIST_PATH_TYPE_DIR;
        fname = strrchr(path, '/');
        if (fname != NULL) {
            dir = t_strdup_until(path, fname);
            if (mailbox_list_mkdir_root(list, dir, type) < 0)
                return -1;
        }
        fd_out = file_dotlock_open_group(&dotlock_set, path, 0,
                         perm.file_create_mode,
                         perm.file_create_gid,
                         perm.file_create_gid_origin,
                         &dotlock);
    }
    if (fd_out == -1) {
        if (errno == EAGAIN) {
            mailbox_list_set_error(list, MAIL_ERROR_TEMP,
                "Timeout waiting for subscription file lock");
        } else {
            subswrite_set_syscall_error(list, "file_dotlock_open()",
                            path);
        }
        return -1;
    }

    fd_in = nfs_safe_open(path, O_RDONLY);
    if (fd_in == -1 && errno != ENOENT) {
        subswrite_set_syscall_error(list, "open()", path);
        file_dotlock_delete(&dotlock);
        return -1;
    }
    if (fd_in != -1) {
        input = i_stream_create_fd_autoclose(&fd_in, list->mailbox_name_max_length+1);
        i_stream_set_return_partial_line(input, TRUE);
        subsfile_list_read_header(list, input, &version);
    }

    found = FALSE;
    output = o_stream_create_fd_file(fd_out, 0, FALSE);
    o_stream_cork(output);
    if (version >= 2)
        o_stream_send_str(output, version2_header);
    if (version < 2 || name[0] == '\0')
        escaped_name = name;
    else {
        const char *const *tmp;
        char separators[2];
        string_t *str = t_str_new(64);

        separators[0] = mailbox_list_get_hierarchy_sep(list);
        separators[1] = '\0';
        tmp = t_strsplit(name, separators);
        str_append_tabescaped(str, *tmp);
        for (tmp++; *tmp != NULL; tmp++) {
            str_append_c(str, '\t');
            str_append_tabescaped(str, *tmp);
        }
        escaped_name = str_c(str);
    }
    if (input != NULL) {
        while ((line = next_line(list, path, input,
                     &failed, FALSE)) != NULL) {
            if (strcmp(line, escaped_name) == 0) {
                found = TRUE;
                if (!set) {
                    changed = TRUE;
                    continue;
                }
            }

            o_stream_nsend_str(output, line);
            o_stream_nsend(output, "\n", 1);
        }
        i_stream_destroy(&input);
    }

    if (!failed && set && !found) {
        /* append subscription */
        line = t_strconcat(escaped_name, "\n", NULL);
        o_stream_nsend_str(output, line);
        changed = TRUE;
    }

    if (changed && !failed) {
        if (o_stream_finish(output) < 0) {
            subswrite_set_syscall_error(list, "write()", path);
            failed = TRUE;
        } else if (mail_set->parsed_fsync_mode != FSYNC_MODE_NEVER) {
            if (fsync(fd_out) < 0) {
                subswrite_set_syscall_error(list, "fsync()",
                                path);
                failed = TRUE;
            }
        }
    } else {
        o_stream_abort(output);
    }
    o_stream_destroy(&output);

    if (failed || !changed) {
        if (file_dotlock_delete(&dotlock) < 0) {
            subswrite_set_syscall_error(list,
                "file_dotlock_delete()", path);
            failed = TRUE;
        }
    } else {
        enum dotlock_replace_flags flags =
            DOTLOCK_REPLACE_FLAG_VERIFY_OWNER;
        if (file_dotlock_replace(&dotlock, flags) < 0) {
            subswrite_set_syscall_error(list,
                "file_dotlock_replace()", path);
            failed = TRUE;
        }
    }
    return failed ? -1 : (changed ? 1 : 0);
}

struct subsfile_list_context *
subsfile_list_init(struct mailbox_list *list, const char *path)
{
    struct subsfile_list_context *ctx;
    int fd;

    ctx = i_new(struct subsfile_list_context, 1);
    ctx->list = list;

    fd = nfs_safe_open(path, O_RDONLY);
    if (fd == -1) {
        if (errno != ENOENT) {
            subsread_set_syscall_error(list, "open()", path);
            ctx->failed = TRUE;
        }
    } else {
        ctx->input = i_stream_create_fd_autoclose(&fd,
                    list->mailbox_name_max_length+1);
        i_stream_set_return_partial_line(ctx->input, TRUE);
        subsfile_list_read_header(ctx->list, ctx->input, &ctx->version);
    }
    ctx->path = i_strdup(path);
    ctx->name = str_new(default_pool, 128);
    return ctx;
}

int subsfile_list_deinit(struct subsfile_list_context **_ctx)
{
    struct subsfile_list_context *ctx = *_ctx;
    int ret = ctx->failed ? -1 : 0;

    *_ctx = NULL;

    i_stream_destroy(&ctx->input);
    str_free(&ctx->name);
    i_free(ctx->path);
    i_free(ctx);
    return ret;
}

int subsfile_list_fstat(struct subsfile_list_context *ctx, struct stat *st_r)
{
    const struct stat *st;

    if (ctx->failed)
        return -1;

    if (i_stream_stat(ctx->input, FALSE, &st) < 0) {
        ctx->failed = TRUE;
        return -1;
    }
    *st_r = *st;
    return 0;
}

static const char *
subsfile_list_unescaped(struct subsfile_list_context *ctx, const char *line)
{
    const char *p;

    str_truncate(ctx->name, 0);
    while ((p = strchr(line, '\t')) != NULL) {
        str_append_tabunescaped(ctx->name, line, p-line);
        str_append_c(ctx->name, mailbox_list_get_hierarchy_sep(ctx->list));
        line = p+1;
    }
    str_append_tabunescaped(ctx->name, line, strlen(line));
    return str_c(ctx->name);
}

const char *subsfile_list_next(struct subsfile_list_context *ctx)
{
        const char *line;
        unsigned int i;
        int fd;

        if (ctx->failed || ctx->input == NULL)
        return NULL;

        for (i = 0;; i++) {
                line = next_line(ctx->list, ctx->path, ctx->input, &ctx->failed,
                 i < SUBSCRIPTION_FILE_ESTALE_RETRY_COUNT);
        if (ctx->input->stream_errno != ESTALE ||
                    i == SUBSCRIPTION_FILE_ESTALE_RETRY_COUNT)
                        break;

                /* Reopen the subscription file and re-send everything.
                   this isn't the optimal behavior, but it's allowed by
                   IMAP and this way we don't have to read everything into
                   memory or try to play any guessing games. */
                i_stream_destroy(&ctx->input);

                fd = nfs_safe_open(ctx->path, O_RDONLY);
                if (fd == -1) {
                        /* In case of ENOENT all the subscriptions got lost.
                           Just return end of subscriptions list in that
                           case. */
                        if (errno != ENOENT) {
                                subsread_set_syscall_error(ctx->list, "open()",
                               ctx->path);
                                ctx->failed = TRUE;
                        }
                        return NULL;
                }

        ctx->input = i_stream_create_fd_autoclose(&fd,
                    ctx->list->mailbox_name_max_length+1);
        i_stream_set_return_partial_line(ctx->input, TRUE);
    }

    if (ctx->version > 1 && line != NULL)
        line = subsfile_list_unescaped(ctx, line);
        return line;
}