src/lib-dict/dict-file.c

/* Copyright (c) 2008-2018 Dovecot authors, see the included COPYING file */

#include "lib.h"
#include "array.h"
#include "hash.h"
#include "str.h"
#include "strescape.h"
#include "home-expand.h"
#include "mkdir-parents.h"
#include "eacces-error.h"
#include "file-lock.h"
#include "file-dotlock.h"
#include "nfs-workarounds.h"
#include "istream.h"
#include "ostream.h"
#include "dict-transaction-memory.h"
#include "dict-private.h"

#include <stdio.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/stat.h>

struct file_dict {
    struct dict dict;
    pool_t hash_pool;
    enum file_lock_method lock_method;

    char *path;
    HASH_TABLE(char *, char *) hash;
    int fd;

    bool refreshed;
};

struct file_dict_iterate_path {
    const char *path;
    size_t len;
};

struct file_dict_iterate_context {
    struct dict_iterate_context ctx;
    pool_t pool;

    struct hash_iterate_context *iter;
    struct file_dict_iterate_path *paths;

    enum dict_iterate_flags flags;
    const char *error;
};

static struct dotlock_settings file_dict_dotlock_settings = {
    .timeout = 60*2,
    .stale_timeout = 60,
    .use_io_notify = TRUE
};

static int
file_dict_init(struct dict *driver, const char *uri,
           const struct dict_settings *set,
           struct dict **dict_r, const char **error_r)
{
    struct file_dict *dict;
    const char *p, *path;

    dict = i_new(struct file_dict, 1);
    dict->lock_method = FILE_LOCK_METHOD_DOTLOCK;

    p = strchr(uri, ':');
    if (p == NULL) {
        /* no parameters */
        path = uri;
    } else {
        path = t_strdup_until(uri, p++);
        if (strcmp(p, "lock=fcntl") == 0)
            dict->lock_method = FILE_LOCK_METHOD_FCNTL;
        else if (strcmp(p, "lock=flock") == 0)
            dict->lock_method = FILE_LOCK_METHOD_FLOCK;
        else {
            *error_r = t_strdup_printf("Invalid parameter: %s", p+1);
            i_free(dict);
            return -1;
        }
    }
    dict->path = set->home_dir == NULL ? i_strdup(path) :
        i_strdup(home_expand_tilde(path, set->home_dir));
    dict->dict = *driver;
    dict->hash_pool = pool_alloconly_create("file dict", 1024);
    hash_table_create(&dict->hash, dict->hash_pool, 0, str_hash, strcmp);
    dict->fd = -1;
    *dict_r = &dict->dict;
    return 0;
}

static void file_dict_deinit(struct dict *_dict)
{
    struct file_dict *dict = (struct file_dict *)_dict;

    i_close_fd_path(&dict->fd, dict->path);
    hash_table_destroy(&dict->hash);
    pool_unref(&dict->hash_pool);
    i_free(dict->path);
    i_free(dict);
}

static bool file_dict_need_refresh(struct file_dict *dict)
{
    struct stat st1, st2;

    if (dict->dict.iter_count > 0) {
        /* Change nothing while there are iterators or they can crash
           because the hash table content recreated. */
        return FALSE;
    }

    if (dict->fd == -1)
        return TRUE;

    /* Disable NFS flushing for now since it can cause unnecessary
       problems and there's no easy way for us to know here if
       mail_nfs_storage=yes. In any case it's pretty much an unsupported
       setting nowadays. */
    /*nfs_flush_file_handle_cache(dict->path);*/
    if (nfs_safe_stat(dict->path, &st1) < 0) {
        i_error("stat(%s) failed: %m", dict->path);
        return FALSE;
    }

    if (fstat(dict->fd, &st2) < 0) {
        if (errno != ESTALE)
            i_error("fstat(%s) failed: %m", dict->path);
        return TRUE;
    }
    if (st1.st_ino != st2.st_ino ||
        !CMP_DEV_T(st1.st_dev, st2.st_dev)) {
        /* file changed */
        return TRUE;
    }
    return FALSE;
}

static int file_dict_open_latest(struct file_dict *dict, const char **error_r)
{
    int open_type;

    if (!file_dict_need_refresh(dict))
        return 0;

    i_close_fd_path(&dict->fd, dict->path);

    open_type = dict->lock_method == FILE_LOCK_METHOD_DOTLOCK ?
        O_RDONLY : O_RDWR;
    dict->fd = open(dict->path, open_type);
    if (dict->fd == -1) {
        if (errno == ENOENT)
            return 0;
        if (errno == EACCES)
            *error_r = eacces_error_get("open", dict->path);
        else
            *error_r = t_strdup_printf("open(%s) failed: %m", dict->path);
        return -1;
    }
    dict->refreshed = FALSE;
    return 1;
}

static int file_dict_refresh(struct file_dict *dict, const char **error_r)
{
    struct istream *input;
    char *key, *value;

    if (file_dict_open_latest(dict, error_r) < 0)
        return -1;
    if (dict->refreshed || dict->dict.iter_count > 0)
        return 0;

    hash_table_clear(dict->hash, TRUE);
    p_clear(dict->hash_pool);

    if (dict->fd != -1) {
        input = i_stream_create_fd(dict->fd, (size_t)-1);

        while ((key = i_stream_read_next_line(input)) != NULL) {
            /* strdup() before the second read */
            key = str_tabunescape(p_strdup(dict->hash_pool, key));

            if ((value = i_stream_read_next_line(input)) == NULL)
                break;

            value = str_tabunescape(p_strdup(dict->hash_pool, value));
            hash_table_update(dict->hash, key, value);
        }
        i_stream_destroy(&input);
    }
    dict->refreshed = TRUE;
    return 0;
}

static int file_dict_lookup(struct dict *_dict, pool_t pool, const char *key,
                const char **value_r, const char **error_r)
{
    struct file_dict *dict = (struct file_dict *)_dict;

    if (file_dict_refresh(dict, error_r) < 0)
        return -1;

    *value_r = p_strdup(pool, hash_table_lookup(dict->hash, key));
    return *value_r == NULL ? 0 : 1;
}

static struct dict_iterate_context *
file_dict_iterate_init(struct dict *_dict, const char *const *paths,
               enum dict_iterate_flags flags)
{
        struct file_dict_iterate_context *ctx;
    struct file_dict *dict = (struct file_dict *)_dict;
    unsigned int i, path_count;
    const char *error;
    pool_t pool;

    pool = pool_alloconly_create("file dict iterate", 256);
    ctx = p_new(pool, struct file_dict_iterate_context, 1);
    ctx->ctx.dict = _dict;
    ctx->pool = pool;

    for (path_count = 0; paths[path_count] != NULL; path_count++) ;
    ctx->paths = p_new(pool, struct file_dict_iterate_path, path_count + 1);
    for (i = 0; i < path_count; i++) {
        ctx->paths[i].path = p_strdup(pool, paths[i]);
        ctx->paths[i].len = strlen(paths[i]);
    }
    ctx->flags = flags;

    if (file_dict_refresh(dict, &error) < 0)
        ctx->error = p_strdup(pool, error);

    ctx->iter = hash_table_iterate_init(dict->hash);
    return &ctx->ctx;
}

static const struct file_dict_iterate_path *
file_dict_iterate_find_path(struct file_dict_iterate_context *ctx,
                const char *key)
{
    unsigned int i;

    for (i = 0; ctx->paths[i].path != NULL; i++) {
        if (strncmp(ctx->paths[i].path, key, ctx->paths[i].len) == 0)
            return &ctx->paths[i];
    }
    return NULL;
}

static bool file_dict_iterate(struct dict_iterate_context *_ctx,
                  const char **key_r, const char **value_r)
{
    struct file_dict_iterate_context *ctx =
        (struct file_dict_iterate_context *)_ctx;
    const struct file_dict_iterate_path *path;
    char *key, *value;

    while (hash_table_iterate(ctx->iter,
                  ((struct file_dict *)_ctx->dict)->hash,
                  &key, &value)) {
        path = file_dict_iterate_find_path(ctx, key);
        if (path == NULL)
            continue;

        if ((ctx->flags & DICT_ITERATE_FLAG_RECURSE) != 0) {
            /* match everything */
        } else if ((ctx->flags & DICT_ITERATE_FLAG_EXACT_KEY) != 0) {
            if (key[path->len] != '\0')
                continue;
        } else {
            if (strchr(key + path->len, '/') != NULL)
                continue;
        }

        *key_r = key;
        *value_r = value;
        return TRUE;
    }
    return FALSE;
}

static int file_dict_iterate_deinit(struct dict_iterate_context *_ctx,
                    const char **error_r)
{
    struct file_dict_iterate_context *ctx =
        (struct file_dict_iterate_context *)_ctx;
    int ret = ctx->error != NULL ? -1 : 0;

    *error_r = t_strdup(ctx->error);
    hash_table_iterate_deinit(&ctx->iter);
    pool_unref(&ctx->pool);
    return ret;
}

static struct dict_transaction_context *
file_dict_transaction_init(struct dict *_dict)
{
    struct dict_transaction_memory_context *ctx;
    pool_t pool;

    pool = pool_alloconly_create("file dict transaction", 2048);
    ctx = p_new(pool, struct dict_transaction_memory_context, 1);
    dict_transaction_memory_init(ctx, _dict, pool);
    return &ctx->ctx;
}

static void file_dict_apply_changes(struct dict_transaction_memory_context *ctx,
                    bool *atomic_inc_not_found_r)
{
    struct file_dict *dict = (struct file_dict *)ctx->ctx.dict;
    const char *tmp;
    char *key, *value, *old_value;
    char *orig_key, *orig_value;
    const struct dict_transaction_memory_change *change;
    size_t new_len;
    long long diff;

    array_foreach(&ctx->changes, change) {
        if (hash_table_lookup_full(dict->hash, change->key,
                       &orig_key, &orig_value)) {
            key = orig_key;
            old_value = orig_value;
        } else {
            key = NULL;
            old_value = NULL;
        }
        value = NULL;

        switch (change->type) {
        case DICT_CHANGE_TYPE_INC:
            if (old_value == NULL) {
                *atomic_inc_not_found_r = TRUE;
                break;
            }
            if (str_to_llong(old_value, &diff) < 0)
                i_unreached();
            diff += change->value.diff;
            tmp = t_strdup_printf("%lld", diff);
            new_len = strlen(tmp);
            if (old_value == NULL || new_len > strlen(old_value))
                value = p_strdup(dict->hash_pool, tmp);
            else {
                memcpy(old_value, tmp, new_len + 1);
                value = old_value;
            }
            /* fall through */
        case DICT_CHANGE_TYPE_SET:
            if (key == NULL)
                key = p_strdup(dict->hash_pool, change->key);
            if (value == NULL) {
                value = p_strdup(dict->hash_pool,
                         change->value.str);
            }
            hash_table_update(dict->hash, key, value);
            break;
        case DICT_CHANGE_TYPE_UNSET:
            if (old_value != NULL)
                hash_table_remove(dict->hash, key);
            break;
        }
    }
}

static int
fd_copy_stat_permissions(const struct stat *src_st,
             int dest_fd, const char *dest_path)
{
    struct stat dest_st;

    if (fstat(dest_fd, &dest_st) < 0) {
        i_error("fstat(%s) failed: %m", dest_path);
        return -1;
    }

    if (src_st->st_gid != dest_st.st_gid &&
        ((src_st->st_mode & 0070) >> 3 != (src_st->st_mode & 0007))) {
        /* group has different permissions from world.
           preserve the group. */
        if (fchown(dest_fd, (uid_t)-1, src_st->st_gid) < 0) {
            i_error("fchown(%s, -1, %s) failed: %m",
                dest_path, dec2str(src_st->st_gid));
            return -1;
        }
    }

    if ((src_st->st_mode & 07777) != (dest_st.st_mode & 07777)) {
        if (fchmod(dest_fd, src_st->st_mode & 07777) < 0) {
            i_error("fchmod(%s, %o) failed: %m",
                dest_path, (int)(src_st->st_mode & 0777));
            return -1;
        }
    }
    return 0;
}

static int fd_copy_permissions(int src_fd, const char *src_path,
                   int dest_fd, const char *dest_path)
{
    struct stat src_st;

    if (fstat(src_fd, &src_st) < 0) {
        i_error("fstat(%s) failed: %m", src_path);
        return -1;
    }
    return fd_copy_stat_permissions(&src_st, dest_fd, dest_path);
}

static int
fd_copy_parent_dir_permissions(const char *src_path, int dest_fd,
                   const char *dest_path)
{
    struct stat src_st;
    const char *src_dir, *p;

    p = strrchr(src_path, '/');
    if (p == NULL)
        src_dir = ".";
    else
        src_dir = t_strdup_until(src_path, p);
    if (stat(src_dir, &src_st) < 0) {
        i_error("stat(%s) failed: %m", src_dir);
        return -1;
    }
    src_st.st_mode &= 0666;
    return fd_copy_stat_permissions(&src_st, dest_fd, dest_path);
}

static int file_dict_mkdir(struct file_dict *dict, const char **error_r)
{
    const char *path, *p, *root;
    struct stat st;
    mode_t mode = 0700;

    p = strrchr(dict->path, '/');
    if (p == NULL)
        return 0;
    path = t_strdup_until(dict->path, p);

    if (stat_first_parent(path, &root, &st) < 0) {
        if (errno == EACCES)
            *error_r = eacces_error_get("stat", root);
        else
            *error_r = t_strdup_printf("stat(%s) failed: %m", root);
        return -1;
    }
    if ((st.st_mode & S_ISGID) != 0) {
        /* preserve parent's permissions when it has setgid bit */
        mode = st.st_mode;
    }

    if (mkdir_parents(path, mode) < 0 && errno != EEXIST) {
        if (errno == EACCES)
            *error_r = eacces_error_get("mkdir_parents", path);
        else
            *error_r = t_strdup_printf("mkdir_parents(%s) failed: %m", path);
        return -1;
    }
    return 0;
}

static int
file_dict_lock(struct file_dict *dict, struct file_lock **lock_r,
           const char **error_r)
{
    int ret;

    if (file_dict_open_latest(dict, error_r) < 0)
        return -1;

    if (dict->fd == -1) {
        /* quota file doesn't exist yet, we need to create it */
        dict->fd = open(dict->path, O_CREAT | O_RDWR, 0600);
        if (dict->fd == -1 && errno == ENOENT) {
            if (file_dict_mkdir(dict, error_r) < 0)
                return -1;
            dict->fd = open(dict->path, O_CREAT | O_RDWR, 0600);
        }
        if (dict->fd == -1) {
            if (errno == EACCES)
                *error_r = eacces_error_get("creat", dict->path);
            else {
                *error_r = t_strdup_printf(
                    "creat(%s) failed: %m", dict->path);
            }
            return -1;
        }
        (void)fd_copy_parent_dir_permissions(dict->path, dict->fd,
                             dict->path);
    }

    do {
        if (file_wait_lock(dict->fd, dict->path, F_WRLCK,
                   dict->lock_method,
                   file_dict_dotlock_settings.timeout,
                   lock_r) <= 0) {
            *error_r = t_strdup_printf(
                "file_wait_lock(%s) failed: %m", dict->path);
            return -1;
        }
        /* check again if we need to reopen the file because it was
           just replaced */
    } while ((ret = file_dict_open_latest(dict, error_r)) > 0);

    return ret < 0 ? -1 : 0;
}

static int
file_dict_write_changes(struct dict_transaction_memory_context *ctx,
            bool *atomic_inc_not_found_r, const char **error_r)
{
    struct file_dict *dict = (struct file_dict *)ctx->ctx.dict;
    struct dotlock *dotlock = NULL;
    struct file_lock *lock = NULL;
    const char *temp_path = NULL;
    struct hash_iterate_context *iter;
    struct ostream *output;
    char *key, *value;
    string_t *str;
    int fd = -1;

    *atomic_inc_not_found_r = FALSE;

    switch (dict->lock_method) {
    case FILE_LOCK_METHOD_FCNTL:
    case FILE_LOCK_METHOD_FLOCK:
        if (file_dict_lock(dict, &lock, error_r) < 0)
            return -1;
        temp_path = t_strdup_printf("%s.tmp", dict->path);
        fd = creat(temp_path, 0600);
        if (fd == -1) {
            *error_r = t_strdup_printf(
                "dict-file: creat(%s) failed: %m", temp_path);
            file_unlock(&lock);
            return -1;
        }
        break;
    case FILE_LOCK_METHOD_DOTLOCK:
        fd = file_dotlock_open(&file_dict_dotlock_settings, dict->path, 0,
                       &dotlock);
        if (fd == -1 && errno == ENOENT) {
            if (file_dict_mkdir(dict, error_r) < 0)
                return -1;
            fd = file_dotlock_open(&file_dict_dotlock_settings,
                           dict->path, 0, &dotlock);
        }
        if (fd == -1) {
            *error_r = t_strdup_printf(
                "dict-file: file_dotlock_open(%s) failed: %m",
                dict->path);
            return -1;
        }
        temp_path = file_dotlock_get_lock_path(dotlock);
        break;
    }

    /* refresh once more now that we're locked */
    if (file_dict_refresh(dict, error_r) < 0) {
        if (dotlock != NULL)
            file_dotlock_delete(&dotlock);
        else {
            i_close_fd(&fd);
            file_unlock(&lock);
        }
        return -1;
    }
    if (dict->fd != -1) {
        /* preserve the permissions */
        (void)fd_copy_permissions(dict->fd, dict->path, fd, temp_path);
    } else {
        /* get initial permissions from parent directory */
        (void)fd_copy_parent_dir_permissions(dict->path, fd, temp_path);
    }
    file_dict_apply_changes(ctx, atomic_inc_not_found_r);

    output = o_stream_create_fd(fd, 0);
    o_stream_cork(output);
    iter = hash_table_iterate_init(dict->hash);
    str = t_str_new(256);
    while (hash_table_iterate(iter, dict->hash, &key, &value)) {
        str_truncate(str, 0);
        str_append_tabescaped(str, key);
        str_append_c(str, '\n');
        str_append_tabescaped(str, value);
        str_append_c(str, '\n');
        o_stream_nsend(output, str_data(str), str_len(str));
    }
    hash_table_iterate_deinit(&iter);

    if (o_stream_finish(output) <= 0) {
        *error_r = t_strdup_printf("write(%s) failed: %s", temp_path,
                       o_stream_get_error(output));
        o_stream_destroy(&output);
        i_close_fd(&fd);
        return -1;
    }
    o_stream_destroy(&output);

    if (dotlock != NULL) {
        if (file_dotlock_replace(&dotlock,
                DOTLOCK_REPLACE_FLAG_DONT_CLOSE_FD) < 0) {
            *error_r = t_strdup_printf("file_dotlock_replace() failed: %m");
            i_close_fd(&fd);
            return -1;
        }
    } else {
        if (rename(temp_path, dict->path) < 0) {
            *error_r = t_strdup_printf("rename(%s, %s) failed: %m",
                           temp_path, dict->path);
            file_unlock(&lock);
            i_close_fd(&fd);
            return -1;
        }
        file_lock_free(&lock);
    }

    i_close_fd(&dict->fd);
    dict->fd = fd;
    return 0;
}

static void
file_dict_transaction_commit(struct dict_transaction_context *_ctx,
                 bool async ATTR_UNUSED,
                 dict_transaction_commit_callback_t *callback,
                 void *context)
{
    struct dict_transaction_memory_context *ctx =
        (struct dict_transaction_memory_context *)_ctx;
    struct dict_commit_result result;
    bool atomic_inc_not_found;

    i_zero(&result);
    if (file_dict_write_changes(ctx, &atomic_inc_not_found, &result.error) < 0)
        result.ret = DICT_COMMIT_RET_FAILED;
    else if (atomic_inc_not_found)
        result.ret = DICT_COMMIT_RET_NOTFOUND;
    else
        result.ret = DICT_COMMIT_RET_OK;
    pool_unref(&ctx->pool);

    callback(&result, context);
}

struct dict dict_driver_file = {
    .name = "file",
    {
        .init = file_dict_init,
        .deinit = file_dict_deinit,
        .lookup = file_dict_lookup,
        .iterate_init = file_dict_iterate_init,
        .iterate = file_dict_iterate,
        .iterate_deinit = file_dict_iterate_deinit,
        .transaction_init = file_dict_transaction_init,
        .transaction_commit = file_dict_transaction_commit,
        .transaction_rollback = dict_transaction_memory_rollback,
        .set = dict_transaction_memory_set,
        .unset = dict_transaction_memory_unset,
        .atomic_inc = dict_transaction_memory_atomic_inc,
    }
};