src/lib-fs/fs-api.c

	fs-api.c revision 251457b81928bab1ad25193e8a09bda829abe9ee
/* Copyright (c) 2010-2012 Dovecot authors, see the included COPYING file */

#include "lib.h"
#include "array.h"
#include "module-dir.h"
#include "str.h"
#include "istream.h"
#include "ostream.h"
#include "fs-api-private.h"

static struct module *fs_modules = NULL;
static ARRAY(const struct fs *) fs_classes;

static int
fs_alloc(const struct fs *fs_class, const char *args,
     const struct fs_settings *set, struct fs **fs_r, const char **error_r)
{
    struct fs *fs;
    int ret;

    fs = fs_class->v.alloc();
    fs->last_error = str_new(default_pool, 64);

    T_BEGIN {
        ret = fs_class->v.init(fs, args, set);
    } T_END;
    if (ret < 0) {
        /* a bit kludgy way to allow data stack frame usage in normal
           conditions but still be able to return error message from
           data stack. */
        *error_r = t_strdup_printf("%s: %s", fs_class->name,
                       fs_last_error(fs));
        fs_deinit(&fs);
        return -1;
    }
    *fs_r = fs;
    return 0;
}

static void fs_class_register(const struct fs *fs_class)
{
    array_append(&fs_classes, &fs_class, 1);
}

static void fs_classes_init(void)
{
    i_array_init(&fs_classes, 8);
    fs_class_register(&fs_class_posix);
    fs_class_register(&fs_class_sis);
    fs_class_register(&fs_class_sis_queue);
}

static const struct fs *fs_class_find(const char *driver)
{
    const struct fs *const *classp;

    if (!array_is_created(&fs_classes))
        fs_classes_init();

    array_foreach(&fs_classes, classp) {
        if (strcmp((*classp)->name, driver) == 0)
            return *classp;
    }
    return NULL;
}

static void fs_class_deinit_modules(void)
{
    module_dir_unload(&fs_modules);
}

static void fs_class_try_load_plugin(const char *driver)
{
    const char *module_name = t_strdup_printf("fs_%s", driver);
    struct module *module;
    struct module_dir_load_settings mod_set;
    const struct fs *fs_class;

    memset(&mod_set, 0, sizeof(mod_set));
    mod_set.abi_version = DOVECOT_ABI_VERSION;
    mod_set.ignore_missing = TRUE;

    fs_modules = module_dir_load_missing(fs_modules, MODULE_DIR,
                         module_name, &mod_set);
    module_dir_init(fs_modules);

    module = module_dir_find(fs_modules, module_name);
    fs_class = module == NULL ? NULL :
        module_get_symbol(module, t_strdup_printf("fs_class_%s", driver));
    if (fs_class != NULL)
        fs_class_register(fs_class);

    lib_atexit(fs_class_deinit_modules);
}

int fs_init(const char *driver, const char *args,
        const struct fs_settings *set,
        struct fs **fs_r, const char **error_r)
{
    const struct fs *fs_class;

    fs_class = fs_class_find(driver);
    if (fs_class == NULL) {
        T_BEGIN {
            fs_class_try_load_plugin(driver);
        } T_END;
        fs_class = fs_class_find(driver);
    }
    if (fs_class == NULL) {
        *error_r = t_strdup_printf("Unknown fs driver: %s", driver);
        return -1;
    }
    return fs_alloc(fs_class, args, set, fs_r, error_r);
}

void fs_deinit(struct fs **_fs)
{
    struct fs *fs = *_fs;
    string_t *last_error = fs->last_error;

    *_fs = NULL;

    if (fs->files_open_count > 0) {
        i_panic("fs-%s: %u files still open",
            fs->name, fs->files_open_count);
    }

    fs->v.deinit(fs);
    str_free(&last_error);
}

struct fs_file *fs_file_init(struct fs *fs, const char *path, int mode_flags)
{
    struct fs_file *file;

    i_assert(path != NULL);

    T_BEGIN {
        file = fs->v.file_init(fs, path, mode_flags & FS_OPEN_MODE_MASK,
                       mode_flags & ~FS_OPEN_MODE_MASK);
    } T_END;
    fs->files_open_count++;
    return file;
}

void fs_file_deinit(struct fs_file **_file)
{
    struct fs_file *file = *_file;

    i_assert(file->fs->files_open_count > 0);

    *_file = NULL;

    file->fs->files_open_count--;
    file->fs->v.file_deinit(file);
}

enum fs_properties fs_get_properties(struct fs *fs)
{
    return fs->v.get_properties(fs);
}

void fs_set_metadata(struct fs_file *file, const char *key, const char *value)
{
    if (file->fs->v.set_metadata != NULL)
        file->fs->v.set_metadata(file, key, value);
}

int fs_get_metadata(struct fs_file *file,
            const ARRAY_TYPE(fs_metadata) **metadata_r)
{
    if (file->fs->v.get_metadata == NULL) {
        fs_set_error(file->fs, "Metadata not supported by backend");
        return -1;
    }
    return file->fs->v.get_metadata(file, metadata_r);
}

const char *fs_file_path(struct fs_file *file)
{
    return file->path;
}

const char *fs_last_error(struct fs *fs)
{
    if (str_len(fs->last_error) == 0)
        return "BUG: Unknown fs error";
    return str_c(fs->last_error);
}

const char *fs_file_last_error(struct fs_file *file)
{
    return fs_last_error(file->fs);
}

bool fs_prefetch(struct fs_file *file, uoff_t length)
{
    return file->fs->v.prefetch(file, length);
}

ssize_t fs_read(struct fs_file *file, void *buf, size_t size)
{
    const unsigned char *data;
    size_t data_size;
    ssize_t ret;

    if (file->fs->v.read != NULL)
        return file->fs->v.read(file, buf, size);

    /* backend didn't bother to implement read(), but we can do it with
       streams. */
    if (file->pending_read_input == NULL)
        file->pending_read_input = fs_read_stream(file, size+1);
    ret = i_stream_read_data(file->pending_read_input,
                 &data, &data_size, size-1);
    if (ret == 0) {
        fs_set_error_async(file->fs);
        return -1;
    }
    if (ret < 0 && file->pending_read_input->stream_errno != 0) {
        fs_set_error(file->fs, "read(%s) failed: %m",
                 i_stream_get_name(file->pending_read_input));
    } else {
        ret = I_MIN(size, data_size);
        memcpy(buf, data, ret);
    }
    i_stream_unref(&file->pending_read_input);
    return ret;
}

struct istream *fs_read_stream(struct fs_file *file, size_t max_buffer_size)
{
    return file->fs->v.read_stream(file, max_buffer_size);
}

int fs_write(struct fs_file *file, const void *data, size_t size)
{
    struct ostream *output;
    ssize_t ret;
    int err;

    if (file->fs->v.write != NULL)
        return file->fs->v.write(file, data, size);

    /* backend didn't bother to implement write(), but we can do it with
       streams. */
    if (!file->write_pending) {
        output = fs_write_stream(file);
        if ((ret = o_stream_send(output, data, size)) < 0) {
            err = errno;
            fs_set_error(file->fs, "fs_write(%s) failed: %m",
                     o_stream_get_name(output));
            fs_write_stream_abort(file, &output);
            errno = err;
            return -1;
        }
        i_assert((size_t)ret == size);
        ret = fs_write_stream_finish(file, &output);
    } else {
        ret = fs_write_stream_finish_async(file);
    }
    if (ret == 0) {
        fs_set_error_async(file->fs);
        file->write_pending = TRUE;
        return -1;
    }
    file->write_pending = FALSE;
    return ret < 0 ? -1 : 0;
}

struct ostream *fs_write_stream(struct fs_file *file)
{
    file->fs->v.write_stream(file);
    i_assert(file->output != NULL);
    return file->output;
}

int fs_write_stream_finish(struct fs_file *file, struct ostream **output)
{
    i_assert(*output == file->output);

    *output = NULL;
    return file->fs->v.write_stream_finish(file, TRUE);
}

int fs_write_stream_finish_async(struct fs_file *file)
{
    return file->fs->v.write_stream_finish(file, TRUE);
}

void fs_write_stream_abort(struct fs_file *file, struct ostream **output)
{
    i_assert(*output == file->output);

    *output = NULL;
    (void)file->fs->v.write_stream_finish(file, FALSE);
}

void fs_file_set_async_callback(struct fs_file *file,
                fs_file_async_callback_t *callback,
                void *context)
{
    if (file->fs->v.set_async_callback != NULL)
        file->fs->v.set_async_callback(file, callback, context);
    else
        callback(context);
}

int fs_wait_async(struct fs *fs)
{
    if (fs->v.wait_async == NULL)
        return 0;
    else
        return fs->v.wait_async(fs);
}

int fs_lock(struct fs_file *file, unsigned int secs, struct fs_lock **lock_r)
{
    return file->fs->v.lock(file, secs, lock_r);
}

void fs_unlock(struct fs_lock **_lock)
{
    struct fs_lock *lock = *_lock;

    *_lock = NULL;
    lock->file->fs->v.unlock(lock);
}

int fs_exists(struct fs_file *file)
{
    return file->fs->v.exists(file);
}

int fs_stat(struct fs_file *file, struct stat *st_r)
{
    return file->fs->v.stat(file, st_r);
}

int fs_copy(struct fs_file *src, struct fs_file *dest)
{
    i_assert(src->fs == dest->fs);
    return src->fs->v.copy(src, dest);
}

int fs_copy_finish_async(struct fs_file *dest)
{
    return dest->fs->v.copy(NULL, dest);
}

int fs_rename(struct fs_file *src, struct fs_file *dest)
{
    i_assert(src->fs == dest->fs);
    return src->fs->v.rename(src, dest);
}

int fs_delete(struct fs_file *file)
{
    return file->fs->v.delete_file(file);
}

struct fs_iter *fs_iter_init(struct fs *fs, const char *path)
{
    return fs->v.iter_init(fs, path);
}

int fs_iter_deinit(struct fs_iter **_iter)
{
    struct fs_iter *iter = *_iter;

    *_iter = NULL;
    return iter->fs->v.iter_deinit(iter);
}

const char *fs_iter_next(struct fs_iter *iter)
{
    return iter->fs->v.iter_next(iter);
}

void fs_set_error(struct fs *fs, const char *fmt, ...)
{
    va_list args;

    va_start(args, fmt);
    str_truncate(fs->last_error, 0);
    str_vprintfa(fs->last_error, fmt, args);
    va_end(args);
}

void fs_set_critical(struct fs *fs, const char *fmt, ...)
{
    va_list args;

    va_start(args, fmt);
    str_truncate(fs->last_error, 0);
    str_vprintfa(fs->last_error, fmt, args);
    i_error("fs-%s: %s", fs->name, str_c(fs->last_error));
    va_end(args);
}

void fs_set_error_async(struct fs *fs)
{
    fs_set_error(fs, "Asynchronous operation in progress");
    errno = EAGAIN;
}