/amanda/tags/3_2_0/device-src/s3-device.c

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/*
 * Copyright (c) 2008, 2009, 2010 Zmanda, Inc.  All Rights Reserved.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 as published
 * by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
 * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * for more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, write to the Free Software Foundation, Inc.,
 * 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
 *
 * Contact information: Zmanda Inc., 465 S. Mathilda Ave., Suite 300
 * Sunnyvale, CA 94085, USA, or: http://www.zmanda.com
 */

/* An S3 device uses Amazon's S3 service (http://www.amazon.com/s3) to store
 * data.  It stores data in keys named with a user-specified prefix, inside a
 * user-specified bucket.  Data is stored in the form of numbered (large)
 * blocks.
 */

#include "amanda.h"
#include <string.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include <dirent.h>
#include <regex.h>
#include <time.h>
#include "util.h"
#include "conffile.h"
#include "device.h"
#include "s3.h"
#include <curl/curl.h>
#ifdef HAVE_OPENSSL_HMAC_H
# include <openssl/hmac.h>
#else
# ifdef HAVE_CRYPTO_HMAC_H
#  include <crypto/hmac.h>
# else
#  ifdef HAVE_HMAC_H
#   include <hmac.h>
#  endif
# endif
#endif

/*
 * Type checking and casting macros
 */
#define TYPE_S3_DEVICE	(s3_device_get_type())
#define S3_DEVICE(obj)	G_TYPE_CHECK_INSTANCE_CAST((obj), s3_device_get_type(), S3Device)
#define S3_DEVICE_CONST(obj)	G_TYPE_CHECK_INSTANCE_CAST((obj), s3_device_get_type(), S3Device const)
#define S3_DEVICE_CLASS(klass)	G_TYPE_CHECK_CLASS_CAST((klass), s3_device_get_type(), S3DeviceClass)
#define IS_S3_DEVICE(obj)	G_TYPE_CHECK_INSTANCE_TYPE((obj), s3_device_get_type ())

#define S3_DEVICE_GET_CLASS(obj)	G_TYPE_INSTANCE_GET_CLASS((obj), s3_device_get_type(), S3DeviceClass)
static GType	s3_device_get_type	(void);

/*
 * Main object structure
 */
typedef struct _S3MetadataFile S3MetadataFile;

typedef struct _S3Device S3Device;
struct _S3Device {
    Device __parent__;

    /* The "easy" curl handle we use to access Amazon S3 */
    S3Handle *s3;

    /* S3 access information */
    char *bucket;
    char *prefix;

    /* The S3 access information. */
    char *secret_key;
    char *access_key;
    char *user_token;

    char *bucket_location;
    char *storage_class;

    char *ca_info;

    /* a cache for unsuccessful reads (where we get the file but the caller
     * doesn't have space for it or doesn't want it), where we expect the
     * next call will request the same file.
     */
    char *cached_buf;
    char *cached_key;
    int cached_size;

    /* Produce verbose output? */
    gboolean verbose;

    /* Use SSL? */
    gboolean use_ssl;

    /* Throttling */
    guint64 max_send_speed;
    guint64 max_recv_speed;
};

/*
 * Class definition
 */
typedef struct _S3DeviceClass S3DeviceClass;
struct _S3DeviceClass {
    DeviceClass __parent__;
};


/*
 * Constants and static data
 */

#define S3_DEVICE_NAME "s3"

/* Maximum key length as specified in the S3 documentation
 * (*excluding* null terminator) */
#define S3_MAX_KEY_LENGTH 1024

/* Note: for compatability, min can only be decreased and max increased */
#define S3_DEVICE_MIN_BLOCK_SIZE 1024
#define S3_DEVICE_MAX_BLOCK_SIZE (100*1024*1024)
#define S3_DEVICE_DEFAULT_BLOCK_SIZE (10*1024*1024)

/* This goes in lieu of file number for metadata. */
#define SPECIAL_INFIX "special-"

/* pointer to the class of our parent */
static DeviceClass *parent_class = NULL;

/*
 * device-specific properties
 */

/* Authentication information for Amazon S3. Both of these are strings. */
static DevicePropertyBase device_property_s3_access_key;
static DevicePropertyBase device_property_s3_secret_key;
#define PROPERTY_S3_SECRET_KEY (device_property_s3_secret_key.ID)
#define PROPERTY_S3_ACCESS_KEY (device_property_s3_access_key.ID)

/* Same, but for S3 with DevPay. */
static DevicePropertyBase device_property_s3_user_token;
#define PROPERTY_S3_USER_TOKEN (device_property_s3_user_token.ID)

/* Location constraint for new buckets created on Amazon S3. */
static DevicePropertyBase device_property_s3_bucket_location;
#define PROPERTY_S3_BUCKET_LOCATION (device_property_s3_bucket_location.ID)

/* Storage class */
static DevicePropertyBase device_property_s3_storage_class;
#define PROPERTY_S3_STORAGE_CLASS (device_property_s3_storage_class.ID)

/* Path to certificate authority certificate */
static DevicePropertyBase device_property_ssl_ca_info;
#define PROPERTY_SSL_CA_INFO (device_property_ssl_ca_info.ID)

/* Whether to use SSL with Amazon S3. */
static DevicePropertyBase device_property_s3_ssl;
#define PROPERTY_S3_SSL (device_property_s3_ssl.ID)

/* Speed limits for sending and receiving */
static DevicePropertyBase device_property_max_send_speed;
static DevicePropertyBase device_property_max_recv_speed;
#define PROPERTY_MAX_SEND_SPEED (device_property_max_send_speed.ID)
#define PROPERTY_MAX_RECV_SPEED (device_property_max_recv_speed.ID)


/*
 * prototypes
 */

void s3_device_register(void);

/*
 * utility functions */

/* Given file and block numbers, return an S3 key.
 *
 * @param self: the S3Device object
 * @param file: the file number
 * @param block: the block within that file
 * @returns: a newly allocated string containing an S3 key.
 */
static char *
file_and_block_to_key(S3Device *self,
                      int file,
                      guint64 block);

/* Given the name of a special file (such as 'tapestart'), generate
 * the S3 key to use for that file.
 *
 * @param self: the S3Device object
 * @param special_name: name of the special file
 * @param file: a file number to include; omitted if -1
 * @returns: a newly alocated string containing an S3 key.
 */
static char *
special_file_to_key(S3Device *self,
                    char *special_name,
                    int file);
/* Write an amanda header file to S3.
 *
 * @param self: the S3Device object
 * @param label: the volume label
 * @param timestamp: the volume timestamp
 */
static gboolean
write_amanda_header(S3Device *self,
                    char *label,
                    char * timestamp);

/* "Fast forward" this device to the end by looking up the largest file number
 * present and setting the current file number one greater.
 *
 * @param self: the S3Device object
 */
static gboolean
seek_to_end(S3Device *self);

/* Find the number of the last file that contains any data (even just a header).
 *
 * @param self: the S3Device object
 * @returns: the last file, or -1 in event of an error
 */
static int
find_last_file(S3Device *self);

/* Delete all blocks in the given file, including the filestart block
 *
 * @param self: the S3Device object
 * @param file: the file to delete
 */
static gboolean
delete_file(S3Device *self,
            int file);


/* Delete all files in the given device
 *
 * @param self: the S3Device object
 */
static gboolean
delete_all_files(S3Device *self);

/* Set up self->s3 as best as possible.
 *
 * The return value is TRUE iff self->s3 is useable.
 *
 * @param self: the S3Device object
 * @returns: TRUE if the handle is set up
 */
static gboolean
setup_handle(S3Device * self);

/*
 * class mechanics */

static void
s3_device_init(S3Device * o);

static void
s3_device_class_init(S3DeviceClass * c);

static void
s3_device_finalize(GObject * o);

static Device*
s3_device_factory(char * device_name, char * device_type, char * device_node);

/*
 * Property{Get,Set}Fns */

static gboolean s3_device_set_access_key_fn(Device *self,
    DevicePropertyBase *base, GValue *val,
    PropertySurety surety, PropertySource source);

static gboolean s3_device_set_secret_key_fn(Device *self,
    DevicePropertyBase *base, GValue *val,
    PropertySurety surety, PropertySource source);

static gboolean s3_device_set_user_token_fn(Device *self,
    DevicePropertyBase *base, GValue *val,
    PropertySurety surety, PropertySource source);

static gboolean s3_device_set_bucket_location_fn(Device *self,
    DevicePropertyBase *base, GValue *val,
    PropertySurety surety, PropertySource source);

static gboolean s3_device_set_storage_class_fn(Device *self,
    DevicePropertyBase *base, GValue *val,
    PropertySurety surety, PropertySource source);

static gboolean s3_device_set_ca_info_fn(Device *self,
    DevicePropertyBase *base, GValue *val,
    PropertySurety surety, PropertySource source);

static gboolean s3_device_set_verbose_fn(Device *self,
    DevicePropertyBase *base, GValue *val,
    PropertySurety surety, PropertySource source);

static gboolean s3_device_set_ssl_fn(Device *self,
    DevicePropertyBase *base, GValue *val,
    PropertySurety surety, PropertySource source);

static gboolean s3_device_set_max_send_speed_fn(Device *self,
    DevicePropertyBase *base, GValue *val,
    PropertySurety surety, PropertySource source);

static gboolean s3_device_set_max_recv_speed_fn(Device *self,
    DevicePropertyBase *base, GValue *val,
    PropertySurety surety, PropertySource source);

/*
 * virtual functions */

static void
s3_device_open_device(Device *pself, char *device_name,
		  char * device_type, char * device_node);

static DeviceStatusFlags s3_device_read_label(Device * self);

static gboolean
s3_device_start(Device * self,
                DeviceAccessMode mode,
                char * label,
                char * timestamp);

static gboolean
s3_device_finish(Device * self);

static gboolean
s3_device_start_file(Device * self,
                     dumpfile_t * jobInfo);

static gboolean
s3_device_write_block(Device * self,
                      guint size,
                      gpointer data);

static gboolean
s3_device_finish_file(Device * self);

static dumpfile_t*
s3_device_seek_file(Device *pself,
                    guint file);

static gboolean
s3_device_seek_block(Device *pself,
                     guint64 block);

static int
s3_device_read_block(Device * pself,
                     gpointer data,
                     int *size_req);

static gboolean
s3_device_recycle_file(Device *pself,
                       guint file);

static gboolean
s3_device_erase(Device *pself);

/*
 * Private functions
 */

static char *
file_and_block_to_key(S3Device *self,
                      int file,
                      guint64 block)
{
    char *s3_key = g_strdup_printf("%sf%08x-b%016llx.data",
                                   self->prefix, file, (long long unsigned int)block);
    g_assert(strlen(s3_key) <= S3_MAX_KEY_LENGTH);
    return s3_key;
}

static char *
special_file_to_key(S3Device *self,
                    char *special_name,
                    int file)
{
    if (file == -1)
        return g_strdup_printf("%s" SPECIAL_INFIX "%s", self->prefix, special_name);
    else
        return g_strdup_printf("%sf%08x-%s", self->prefix, file, special_name);
}

static gboolean
write_amanda_header(S3Device *self,
                    char *label,
                    char * timestamp)
{
    CurlBuffer amanda_header = {NULL, 0, 0, 0};
    char * key = NULL;
    gboolean result;
    dumpfile_t * dumpinfo = NULL;
    Device *d_self = DEVICE(self);
    size_t header_size;

    /* build the header */
    header_size = 0; /* no minimum size */
    dumpinfo = make_tapestart_header(DEVICE(self), label, timestamp);
    amanda_header.buffer = device_build_amanda_header(DEVICE(self), dumpinfo,
        &header_size);
    if (amanda_header.buffer == NULL) {
	device_set_error(d_self,
	    stralloc(_("Amanda tapestart header won't fit in a single block!")),
	    DEVICE_STATUS_DEVICE_ERROR);
	dumpfile_free(dumpinfo);
	g_free(amanda_header.buffer);
	return FALSE;
    }

    /* write out the header and flush the uploads. */
    key = special_file_to_key(self, "tapestart", -1);
    g_assert(header_size < G_MAXUINT); /* for cast to guint */
    amanda_header.buffer_len = (guint)header_size;
    result = s3_upload(self->s3, self->bucket, key, S3_BUFFER_READ_FUNCS,
                       &amanda_header, NULL, NULL);
    g_free(amanda_header.buffer);
    g_free(key);

    if (!result) {
	device_set_error(d_self,
	    vstrallocf(_("While writing amanda header: %s"), s3_strerror(self->s3)),
	    DEVICE_STATUS_DEVICE_ERROR | DEVICE_STATUS_VOLUME_ERROR);
	dumpfile_free(dumpinfo);
    } else {
	dumpfile_free(d_self->volume_header);
	d_self->volume_header = dumpinfo;
    }

    return result;
}

static gboolean
seek_to_end(S3Device *self) {
    int last_file;

    Device *pself = DEVICE(self);

    last_file = find_last_file(self);
    if (last_file < 0)
        return FALSE;

    pself->file = last_file;

    return TRUE;
}

/* Convert an object name into a file number, assuming the given prefix
 * length. Returns -1 if the object name is invalid, or 0 if the object name
 * is a "special" key. */
static int key_to_file(guint prefix_len, const char * key) {
    int file;
    int i;

    /* skip the prefix */
    if (strlen(key) <= prefix_len)
	return -1;

    key += prefix_len;

    if (strncmp(key, SPECIAL_INFIX, strlen(SPECIAL_INFIX)) == 0) {
        return 0;
    }

    /* check that key starts with 'f' */
    if (key[0] != 'f')
	return -1;
    key++;

    /* check that key is of the form "%08x-" */
    for (i = 0; i < 8; i++) {
        if (!(key[i] >= '0' && key[i] <= '9') &&
            !(key[i] >= 'a' && key[i] <= 'f') &&
            !(key[i] >= 'A' && key[i] <= 'F')) break;
    }
    if (key[i] != '-') return -1;
    if (i < 8) return -1;

    /* convert the file number */
    errno = 0;
    file = strtoul(key, NULL, 16);
    if (errno != 0) {
        g_warning(_("unparseable file number '%s'"), key);
        return -1;
    }

    return file;
}

/* Find the number of the last file that contains any data (even just a header).
 * Returns -1 in event of an error
 */
static int
find_last_file(S3Device *self) {
    gboolean result;
    GSList *keys;
    unsigned int prefix_len = strlen(self->prefix);
    int last_file = 0;
    Device *d_self = DEVICE(self);

    /* list all keys matching C{PREFIX*-*}, stripping the C{-*} */
    result = s3_list_keys(self->s3, self->bucket, self->prefix, "-", &keys);
    if (!result) {
	device_set_error(d_self,
	    vstrallocf(_("While listing S3 keys: %s"), s3_strerror(self->s3)),
	    DEVICE_STATUS_DEVICE_ERROR | DEVICE_STATUS_VOLUME_ERROR);
        return -1;
    }

    for (; keys; keys = g_slist_remove(keys, keys->data)) {
        int file = key_to_file(prefix_len, keys->data);

        /* and if it's the last, keep it */
        if (file > last_file)
            last_file = file;
    }

    return last_file;
}

/* Find the number of the file following the requested one, if any.
 * Returns 0 if there is no such file or -1 in event of an error
 */
static int
find_next_file(S3Device *self, int last_file) {
    gboolean result;
    GSList *keys;
    unsigned int prefix_len = strlen(self->prefix);
    int next_file = 0;
    Device *d_self = DEVICE(self);

    /* list all keys matching C{PREFIX*-*}, stripping the C{-*} */
    result = s3_list_keys(self->s3, self->bucket, self->prefix, "-", &keys);
    if (!result) {
	device_set_error(d_self,
	    vstrallocf(_("While listing S3 keys: %s"), s3_strerror(self->s3)),
	    DEVICE_STATUS_DEVICE_ERROR | DEVICE_STATUS_VOLUME_ERROR);
        return -1;
    }

    for (; keys; keys = g_slist_remove(keys, keys->data)) {
        int file;

        file = key_to_file(prefix_len, (char*)keys->data);

        if (file < 0) {
            /* Set this in case we don't find a next file; this is not a
             * hard error, so if we can find a next file we'll return that
             * instead. */
            next_file = -1;
        }

        if (file < next_file && file > last_file) {
            next_file = file;
        }
    }

    return next_file;
}

static gboolean
delete_file(S3Device *self,
            int file)
{
    gboolean result;
    GSList *keys;
    char *my_prefix = g_strdup_printf("%sf%08x-", self->prefix, file);
    Device *d_self = DEVICE(self);

    result = s3_list_keys(self->s3, self->bucket, my_prefix, NULL, &keys);
    if (!result) {
	device_set_error(d_self,
	    vstrallocf(_("While listing S3 keys: %s"), s3_strerror(self->s3)),
	    DEVICE_STATUS_DEVICE_ERROR | DEVICE_STATUS_VOLUME_ERROR);
        return FALSE;
    }

    /* this will likely be a *lot* of keys */
    for (; keys; keys = g_slist_remove(keys, keys->data)) {
        if (self->verbose) g_debug(_("Deleting %s"), (char*)keys->data);
        if (!s3_delete(self->s3, self->bucket, keys->data)) {
	    device_set_error(d_self,
		vstrallocf(_("While deleting key '%s': %s"),
			    (char*)keys->data, s3_strerror(self->s3)),
		DEVICE_STATUS_DEVICE_ERROR);
            g_slist_free(keys);
            return FALSE;
        }
    }

    return TRUE;
}

static gboolean
delete_all_files(S3Device *self)
{
    int file, last_file;

    /*
     * Note: this has to be allowed to retry for a while because the bucket
     * may have been created and not yet appeared
     */
    last_file = find_last_file(self);
    if (last_file < 0) {
        guint response_code;
        s3_error_code_t s3_error_code;
        s3_error(self->s3, NULL, &response_code, &s3_error_code, NULL, NULL, NULL);

        /*
         * if the bucket doesn't exist, it doesn't conatin any files,
         * so the operation is a success
         */
        if ((response_code == 404 && s3_error_code == S3_ERROR_NoSuchBucket)) {
            /* find_last_file set an error; clear it */
            device_set_error(DEVICE(self), NULL, DEVICE_STATUS_SUCCESS);
            return TRUE;
        } else {
            /* find_last_file already set the error */
            return FALSE;
        }
    }

    for (file = 1; file <= last_file; file++) {
        if (!delete_file(self, file))
            /* delete_file already set our error message */
            return FALSE;
    }

    return TRUE;
}

/*
 * Class mechanics
 */

void
s3_device_register(void)
{
    static const char * device_prefix_list[] = { S3_DEVICE_NAME, NULL };
    g_assert(s3_init());

    /* set up our properties */
    device_property_fill_and_register(&device_property_s3_secret_key,
                                      G_TYPE_STRING, "s3_secret_key",
       "Secret access key to authenticate with Amazon S3");
    device_property_fill_and_register(&device_property_s3_access_key,
                                      G_TYPE_STRING, "s3_access_key",
       "Access key ID to authenticate with Amazon S3");
    device_property_fill_and_register(&device_property_s3_user_token,
                                      G_TYPE_STRING, "s3_user_token",
       "User token for authentication Amazon devpay requests");
    device_property_fill_and_register(&device_property_s3_bucket_location,
                                      G_TYPE_STRING, "s3_bucket_location",
       "Location constraint for buckets on Amazon S3");
    device_property_fill_and_register(&device_property_s3_storage_class,
                                      G_TYPE_STRING, "s3_storage_class",
       "Storage class as specified by Amazon (STANDARD or REDUCED_REDUNDANCY)");
    device_property_fill_and_register(&device_property_ssl_ca_info,
                                      G_TYPE_STRING, "ssl_ca_info",
       "Path to certificate authority certificate");
    device_property_fill_and_register(&device_property_s3_ssl,
                                      G_TYPE_BOOLEAN, "s3_ssl",
       "Whether to use SSL with Amazon S3");
    device_property_fill_and_register(&device_property_max_send_speed,
                                      G_TYPE_UINT64, "max_send_speed",
       "Maximum average upload speed (bytes/sec)");
    device_property_fill_and_register(&device_property_max_recv_speed,
                                      G_TYPE_UINT64, "max_recv_speed",
       "Maximum average download speed (bytes/sec)");

    /* register the device itself */
    register_device(s3_device_factory, device_prefix_list);
}

static GType
s3_device_get_type(void)
{
    static GType type = 0;

    if G_UNLIKELY(type == 0) {
        static const GTypeInfo info = {
            sizeof (S3DeviceClass),
            (GBaseInitFunc) NULL,
            (GBaseFinalizeFunc) NULL,
            (GClassInitFunc) s3_device_class_init,
            (GClassFinalizeFunc) NULL,
            NULL /* class_data */,
            sizeof (S3Device),
            0 /* n_preallocs */,
            (GInstanceInitFunc) s3_device_init,
            NULL
        };

        type = g_type_register_static (TYPE_DEVICE, "S3Device", &info,
                                       (GTypeFlags)0);
    }

    return type;
}

static void
s3_device_init(S3Device * self)
{
    Device * dself = DEVICE(self);
    GValue response;

    /* Register property values
     * Note: Some aren't added until s3_device_open_device()
     */
    bzero(&response, sizeof(response));

    g_value_init(&response, CONCURRENCY_PARADIGM_TYPE);
    g_value_set_enum(&response, CONCURRENCY_PARADIGM_SHARED_READ);
    device_set_simple_property(dself, PROPERTY_CONCURRENCY,
	    &response, PROPERTY_SURETY_GOOD, PROPERTY_SOURCE_DETECTED);
    g_value_unset(&response);

    g_value_init(&response, STREAMING_REQUIREMENT_TYPE);
    g_value_set_enum(&response, STREAMING_REQUIREMENT_NONE);
    device_set_simple_property(dself, PROPERTY_STREAMING,
	    &response, PROPERTY_SURETY_GOOD, PROPERTY_SOURCE_DETECTED);
    g_value_unset(&response);

    g_value_init(&response, G_TYPE_BOOLEAN);
    g_value_set_boolean(&response, TRUE);
    device_set_simple_property(dself, PROPERTY_APPENDABLE,
	    &response, PROPERTY_SURETY_GOOD, PROPERTY_SOURCE_DETECTED);
    g_value_unset(&response);

    g_value_init(&response, G_TYPE_BOOLEAN);
    g_value_set_boolean(&response, TRUE);
    device_set_simple_property(dself, PROPERTY_PARTIAL_DELETION,
	    &response, PROPERTY_SURETY_GOOD, PROPERTY_SOURCE_DETECTED);
    g_value_unset(&response);

    g_value_init(&response, G_TYPE_BOOLEAN);
    g_value_set_boolean(&response, TRUE);
    device_set_simple_property(dself, PROPERTY_FULL_DELETION,
	    &response, PROPERTY_SURETY_GOOD, PROPERTY_SOURCE_DETECTED);
    g_value_unset(&response);

    g_value_init(&response, G_TYPE_BOOLEAN);
    g_value_set_boolean(&response, TRUE); /* well, there *is* no EOM on S3 .. */
    device_set_simple_property(dself, PROPERTY_LEOM,
	    &response, PROPERTY_SURETY_GOOD, PROPERTY_SOURCE_DETECTED);
    g_value_unset(&response);

    g_value_init(&response, G_TYPE_BOOLEAN);
    g_value_set_boolean(&response, FALSE);
    device_set_simple_property(dself, PROPERTY_COMPRESSION,
	    &response, PROPERTY_SURETY_GOOD, PROPERTY_SOURCE_DETECTED);
    g_value_unset(&response);

    g_value_init(&response, MEDIA_ACCESS_MODE_TYPE);
    g_value_set_enum(&response, MEDIA_ACCESS_MODE_READ_WRITE);
    device_set_simple_property(dself, PROPERTY_MEDIUM_ACCESS_TYPE,
	    &response, PROPERTY_SURETY_GOOD, PROPERTY_SOURCE_DETECTED);
    g_value_unset(&response);

}

static void
s3_device_class_init(S3DeviceClass * c G_GNUC_UNUSED)
{
    GObjectClass *g_object_class = (GObjectClass*) c;
    DeviceClass *device_class = (DeviceClass *)c;

    parent_class = g_type_class_ref (TYPE_DEVICE);

    device_class->open_device = s3_device_open_device;
    device_class->read_label = s3_device_read_label;
    device_class->start = s3_device_start;
    device_class->finish = s3_device_finish;

    device_class->start_file = s3_device_start_file;
    device_class->write_block = s3_device_write_block;
    device_class->finish_file = s3_device_finish_file;

    device_class->seek_file = s3_device_seek_file;
    device_class->seek_block = s3_device_seek_block;
    device_class->read_block = s3_device_read_block;
    device_class->recycle_file = s3_device_recycle_file;

    device_class->erase = s3_device_erase;

    g_object_class->finalize = s3_device_finalize;

    device_class_register_property(device_class, PROPERTY_S3_ACCESS_KEY,
	    PROPERTY_ACCESS_GET_MASK | PROPERTY_ACCESS_SET_BEFORE_START,
	    device_simple_property_get_fn,
	    s3_device_set_access_key_fn);

    device_class_register_property(device_class, PROPERTY_S3_SECRET_KEY,
	    PROPERTY_ACCESS_GET_MASK | PROPERTY_ACCESS_SET_BEFORE_START,
	    device_simple_property_get_fn,
	    s3_device_set_secret_key_fn);

    device_class_register_property(device_class, PROPERTY_S3_USER_TOKEN,
	    PROPERTY_ACCESS_GET_MASK | PROPERTY_ACCESS_SET_BEFORE_START,
	    device_simple_property_get_fn,
	    s3_device_set_user_token_fn);

    device_class_register_property(device_class, PROPERTY_S3_BUCKET_LOCATION,
	    PROPERTY_ACCESS_GET_MASK | PROPERTY_ACCESS_SET_BEFORE_START,
	    device_simple_property_get_fn,
	    s3_device_set_bucket_location_fn);

    device_class_register_property(device_class, PROPERTY_S3_STORAGE_CLASS,
	    PROPERTY_ACCESS_GET_MASK | PROPERTY_ACCESS_SET_BEFORE_START,
	    device_simple_property_get_fn,
	    s3_device_set_storage_class_fn);

    device_class_register_property(device_class, PROPERTY_SSL_CA_INFO,
	    PROPERTY_ACCESS_GET_MASK | PROPERTY_ACCESS_SET_BEFORE_START,
	    device_simple_property_get_fn,
	    s3_device_set_ca_info_fn);

    device_class_register_property(device_class, PROPERTY_VERBOSE,
	    PROPERTY_ACCESS_GET_MASK | PROPERTY_ACCESS_SET_BEFORE_START,
	    device_simple_property_get_fn,
	    s3_device_set_verbose_fn);

    device_class_register_property(device_class, PROPERTY_S3_SSL,
	    PROPERTY_ACCESS_GET_MASK | PROPERTY_ACCESS_SET_BEFORE_START,
	    device_simple_property_get_fn,
	    s3_device_set_ssl_fn);

    device_class_register_property(device_class, PROPERTY_MAX_SEND_SPEED,
	    PROPERTY_ACCESS_GET_MASK | PROPERTY_ACCESS_SET_BEFORE_START,
	    device_simple_property_get_fn,
	    s3_device_set_max_send_speed_fn);

    device_class_register_property(device_class, PROPERTY_MAX_RECV_SPEED,
	    PROPERTY_ACCESS_GET_MASK | PROPERTY_ACCESS_SET_BEFORE_START,
	    device_simple_property_get_fn,
	    s3_device_set_max_recv_speed_fn);

    device_class_register_property(device_class, PROPERTY_COMPRESSION,
	    PROPERTY_ACCESS_GET_MASK,
	    device_simple_property_get_fn,
	    NULL);
}

static gboolean
s3_device_set_access_key_fn(Device *p_self, DevicePropertyBase *base,
    GValue *val, PropertySurety surety, PropertySource source)
{
    S3Device *self = S3_DEVICE(p_self);

    amfree(self->access_key);
    self->access_key = g_value_dup_string(val);
    device_clear_volume_details(p_self);

    return device_simple_property_set_fn(p_self, base, val, surety, source);
}

static gboolean
s3_device_set_secret_key_fn(Device *p_self, DevicePropertyBase *base,
    GValue *val, PropertySurety surety, PropertySource source)
{
    S3Device *self = S3_DEVICE(p_self);

    amfree(self->secret_key);
    self->secret_key = g_value_dup_string(val);
    device_clear_volume_details(p_self);

    return device_simple_property_set_fn(p_self, base, val, surety, source);
}

static gboolean
s3_device_set_user_token_fn(Device *p_self, DevicePropertyBase *base,
    GValue *val, PropertySurety surety, PropertySource source)
{
    S3Device *self = S3_DEVICE(p_self);

    amfree(self->user_token);
    self->user_token = g_value_dup_string(val);
    device_clear_volume_details(p_self);

    return device_simple_property_set_fn(p_self, base, val, surety, source);
}

static gboolean
s3_device_set_bucket_location_fn(Device *p_self, DevicePropertyBase *base,
    GValue *val, PropertySurety surety, PropertySource source)
{
    S3Device *self = S3_DEVICE(p_self);
    char *str_val = g_value_dup_string(val);

    if (str_val[0] && self->use_ssl && !s3_curl_location_compat()) {
	device_set_error(p_self, stralloc(_(
		"Location constraint given for Amazon S3 bucket, "
		"but libcurl is too old support wildcard certificates.")),
	    DEVICE_STATUS_DEVICE_ERROR);
        goto fail;
    }

    if (str_val[0] && !s3_bucket_location_compat(self->bucket)) {
	device_set_error(p_self, g_strdup_printf(_(
		"Location constraint given for Amazon S3 bucket, "
		"but the bucket name (%s) is not usable as a subdomain."),
		self->bucket),
	    DEVICE_STATUS_DEVICE_ERROR);
        goto fail;
    }

    amfree(self->bucket_location);
    self->bucket_location = str_val;
    device_clear_volume_details(p_self);

    return device_simple_property_set_fn(p_self, base, val, surety, source);
fail:
    g_free(str_val);
    return FALSE;
}

static gboolean
s3_device_set_storage_class_fn(Device *p_self, DevicePropertyBase *base,
    GValue *val, PropertySurety surety, PropertySource source)
{
    S3Device *self = S3_DEVICE(p_self);
    char *str_val = g_value_dup_string(val);

    amfree(self->storage_class);
    self->storage_class = str_val;
    device_clear_volume_details(p_self);

    return device_simple_property_set_fn(p_self, base, val, surety, source);
}

static gboolean
s3_device_set_ca_info_fn(Device *p_self, DevicePropertyBase *base,
    GValue *val, PropertySurety surety, PropertySource source)
{
    S3Device *self = S3_DEVICE(p_self);

    amfree(self->ca_info);
    self->ca_info = g_value_dup_string(val);
    device_clear_volume_details(p_self);

    return device_simple_property_set_fn(p_self, base, val, surety, source);
}

static gboolean
s3_device_set_verbose_fn(Device *p_self, DevicePropertyBase *base,
    GValue *val, PropertySurety surety, PropertySource source)
{
    S3Device *self = S3_DEVICE(p_self);

    self->verbose = g_value_get_boolean(val);
    /* Our S3 handle may not yet have been instantiated; if so, it will
     * get the proper verbose setting when it is created */
    if (self->s3)
	s3_verbose(self->s3, self->verbose);

    return device_simple_property_set_fn(p_self, base, val, surety, source);
}

static gboolean
s3_device_set_ssl_fn(Device *p_self, DevicePropertyBase *base,
    GValue *val, PropertySurety surety, PropertySource source)
{
    S3Device *self = S3_DEVICE(p_self);
    gboolean new_val;

    new_val = g_value_get_boolean(val);
    /* Our S3 handle may not yet have been instantiated; if so, it will
     * get the proper use_ssl setting when it is created */
    if (self->s3 && !s3_use_ssl(self->s3, new_val)) {
	device_set_error(p_self, g_strdup_printf(_(
                "Error setting S3 SSL/TLS use "
                "(tried to enable SSL/TLS for S3, but curl doesn't support it?)")),
	    DEVICE_STATUS_DEVICE_ERROR);
        return FALSE;
    }
    self->use_ssl = new_val;

    return device_simple_property_set_fn(p_self, base, val, surety, source);
}

static gboolean
s3_device_set_max_send_speed_fn(Device *p_self,
    DevicePropertyBase *base, GValue *val,
    PropertySurety surety, PropertySource source)
{
    S3Device *self = S3_DEVICE(p_self);
    guint64 new_val;

    new_val = g_value_get_uint64(val);
    if (self->s3 && !s3_set_max_send_speed(self->s3, new_val)) {
	device_set_error(p_self,
		g_strdup("Could not set S3 maximum send speed"),
		DEVICE_STATUS_DEVICE_ERROR);
        return FALSE;
    }
    self->max_send_speed = new_val;

    return device_simple_property_set_fn(p_self, base, val, surety, source);
}

static gboolean
s3_device_set_max_recv_speed_fn(Device *p_self,
    DevicePropertyBase *base, GValue *val,
    PropertySurety surety, PropertySource source)
{
    S3Device *self = S3_DEVICE(p_self);
    guint64 new_val;

    new_val = g_value_get_uint64(val);
    if (self->s3 && !s3_set_max_recv_speed(self->s3, new_val)) {
	device_set_error(p_self,
		g_strdup("Could not set S3 maximum recv speed"),
		DEVICE_STATUS_DEVICE_ERROR);
        return FALSE;
    }
    self->max_recv_speed = new_val;

    return device_simple_property_set_fn(p_self, base, val, surety, source);
}

static Device*
s3_device_factory(char * device_name, char * device_type, char * device_node)
{
    Device *rval;
    S3Device * s3_rval;
    g_assert(0 == strcmp(device_type, S3_DEVICE_NAME));
    rval = DEVICE(g_object_new(TYPE_S3_DEVICE, NULL));
    s3_rval = (S3Device*)rval;

    device_open_device(rval, device_name, device_type, device_node);
    return rval;
}

/*
 * Virtual function overrides
 */

static void
s3_device_open_device(Device *pself, char *device_name,
			char * device_type, char * device_node)
{
    S3Device *self = S3_DEVICE(pself);
    char * name_colon;
    GValue tmp_value;

    pself->min_block_size = S3_DEVICE_MIN_BLOCK_SIZE;
    pself->max_block_size = S3_DEVICE_MAX_BLOCK_SIZE;
    pself->block_size = S3_DEVICE_DEFAULT_BLOCK_SIZE;

    /* Device name may be bucket/prefix, to support multiple volumes in a
     * single bucket. */
    name_colon = strchr(device_node, '/');
    if (name_colon == NULL) {
        self->bucket = g_strdup(device_node);
        self->prefix = g_strdup("");
    } else {
        self->bucket = g_strndup(device_node, name_colon - device_node);
        self->prefix = g_strdup(name_colon + 1);
    }

    if (self->bucket == NULL || self->bucket[0] == '\0') {
	device_set_error(pself,
	    vstrallocf(_("Empty bucket name in device %s"), device_name),
	    DEVICE_STATUS_DEVICE_ERROR);
        amfree(self->bucket);
        amfree(self->prefix);
        return;
    }

    g_debug(_("S3 driver using bucket '%s', prefix '%s'"), self->bucket, self->prefix);

    /* default values */
    self->verbose = FALSE;

    /* use SSL if available */
    self->use_ssl = s3_curl_supports_ssl();
    bzero(&tmp_value, sizeof(GValue));
    g_value_init(&tmp_value, G_TYPE_BOOLEAN);
    g_value_set_boolean(&tmp_value, self->use_ssl);
    device_set_simple_property(pself, device_property_s3_ssl.ID,
	&tmp_value, PROPERTY_SURETY_GOOD, PROPERTY_SOURCE_DEFAULT);

    if (parent_class->open_device) {
        parent_class->open_device(pself, device_name, device_type, device_node);
    }
}

static void s3_device_finalize(GObject * obj_self) {
    S3Device *self = S3_DEVICE (obj_self);

    if(G_OBJECT_CLASS(parent_class)->finalize)
        (* G_OBJECT_CLASS(parent_class)->finalize)(obj_self);

    if(self->s3) s3_free(self->s3);
    if(self->bucket) g_free(self->bucket);
    if(self->prefix) g_free(self->prefix);
    if(self->access_key) g_free(self->access_key);
    if(self->secret_key) g_free(self->secret_key);
    if(self->user_token) g_free(self->user_token);
    if(self->bucket_location) g_free(self->bucket_location);
    if(self->storage_class) g_free(self->storage_class);
    if(self->ca_info) g_free(self->ca_info);
}

static gboolean setup_handle(S3Device * self) {
    Device *d_self = DEVICE(self);
    if (self->s3 == NULL) {

        if (self->access_key == NULL || self->access_key[0] == '\0') {
	    device_set_error(d_self,
		stralloc(_("No Amazon access key specified")),
		DEVICE_STATUS_DEVICE_ERROR);
            return FALSE;
	}

	if (self->secret_key == NULL || self->secret_key[0] == '\0') {
	    device_set_error(d_self,
		stralloc(_("No Amazon secret key specified")),
		DEVICE_STATUS_DEVICE_ERROR);
            return FALSE;
	}

	if (!self->use_ssl && self->ca_info) {
	    amfree(self->ca_info);
	}

        self->s3 = s3_open(self->access_key, self->secret_key, self->user_token,
            self->bucket_location, self->storage_class, self->ca_info);
        if (self->s3 == NULL) {
	    device_set_error(d_self,
		stralloc(_("Internal error creating S3 handle")),
		DEVICE_STATUS_DEVICE_ERROR);
            return FALSE;
        }
    }

    s3_verbose(self->s3, self->verbose);

    if (!s3_use_ssl(self->s3, self->use_ssl)) {
	device_set_error(d_self, g_strdup_printf(_(
                "Error setting S3 SSL/TLS use "
                "(tried to enable SSL/TLS for S3, but curl doesn't support it?)")),
	    DEVICE_STATUS_DEVICE_ERROR);
        return FALSE;
    }

    if (self->max_send_speed &&
	    !s3_set_max_send_speed(self->s3, self->max_send_speed)) {
	device_set_error(d_self,
		g_strdup("Could not set S3 maximum send speed"),
		DEVICE_STATUS_DEVICE_ERROR);
        return FALSE;
    }

    if (self->max_recv_speed &&
	    !s3_set_max_recv_speed(self->s3, self->max_recv_speed)) {
	device_set_error(d_self,
		g_strdup("Could not set S3 maximum recv speed"),
		DEVICE_STATUS_DEVICE_ERROR);
        return FALSE;
    }

    return TRUE;
}

static DeviceStatusFlags
s3_device_read_label(Device *pself) {
    S3Device *self = S3_DEVICE(pself);
    char *key;
    CurlBuffer buf = {NULL, 0, 0, S3_DEVICE_MAX_BLOCK_SIZE};
    dumpfile_t *amanda_header;

    /* note that this may be called from s3_device_start, when
     * self->access_mode is not ACCESS_NULL */

    amfree(pself->volume_label);
    amfree(pself->volume_time);
    dumpfile_free(pself->volume_header);
    pself->volume_header = NULL;

    if (device_in_error(self)) return pself->status;

    if (!setup_handle(self)) {
        /* setup_handle already set our error message */
	return pself->status;
    }

    key = special_file_to_key(self, "tapestart", -1);
    if (!s3_read(self->s3, self->bucket, key, S3_BUFFER_WRITE_FUNCS, &buf, NULL, NULL)) {
        guint response_code;
        s3_error_code_t s3_error_code;
        s3_error(self->s3, NULL, &response_code, &s3_error_code, NULL, NULL, NULL);

        /* if it's an expected error (not found), just return FALSE */
        if (response_code == 404 &&
             (s3_error_code == S3_ERROR_NoSuchKey || s3_error_code == S3_ERROR_NoSuchBucket)) {
            g_debug(_("Amanda header not found while reading tapestart header (this is expected for empty tapes)"));
	    device_set_error(pself,
		stralloc(_("Amanda header not found -- unlabeled volume?")),
		  DEVICE_STATUS_DEVICE_ERROR
		| DEVICE_STATUS_VOLUME_ERROR
		| DEVICE_STATUS_VOLUME_UNLABELED);
            return pself->status;
        }

        /* otherwise, log it and return */
	device_set_error(pself,
	    vstrallocf(_("While trying to read tapestart header: %s"), s3_strerror(self->s3)),
	    DEVICE_STATUS_DEVICE_ERROR | DEVICE_STATUS_VOLUME_ERROR);
        return pself->status;
    }

    /* handle an empty file gracefully */
    if (buf.buffer_len == 0) {
	device_set_error(pself, stralloc(_("Empty header file")), DEVICE_STATUS_VOLUME_ERROR);
        return pself->status;
    }

    g_assert(buf.buffer != NULL);
    amanda_header = g_new(dumpfile_t, 1);
    parse_file_header(buf.buffer, amanda_header, buf.buffer_pos);
    pself->volume_header = amanda_header;
    g_free(buf.buffer);

    if (amanda_header->type != F_TAPESTART) {
	device_set_error(pself, stralloc(_("Invalid amanda header")), DEVICE_STATUS_VOLUME_ERROR);
        return pself->status;
    }

    pself->volume_label = g_strdup(amanda_header->name);
    pself->volume_time = g_strdup(amanda_header->datestamp);
    /* pself->volume_header is already set */

    device_set_error(pself, NULL, DEVICE_STATUS_SUCCESS);

    return pself->status;
}

static gboolean
s3_device_start (Device * pself, DeviceAccessMode mode,
                 char * label, char * timestamp) {
    S3Device * self;

    self = S3_DEVICE(pself);

    if (device_in_error(self)) return FALSE;

    if (!setup_handle(self)) {
        /* setup_handle already set our error message */
	return FALSE;
    }

    pself->access_mode = mode;
    pself->in_file = FALSE;

    /* try creating the bucket, in case it doesn't exist */
    if (mode != ACCESS_READ && !s3_make_bucket(self->s3, self->bucket)) {
        guint response_code;
        s3_error_code_t s3_error_code;
        s3_error(self->s3, NULL, &response_code, &s3_error_code, NULL, NULL, NULL);

        /* if it isn't an expected error (bucket already exists),
         * return FALSE */
        if (response_code != 409 ||
            s3_error_code != S3_ERROR_BucketAlreadyExists) {
	    device_set_error(pself,
		vstrallocf(_("While creating new S3 bucket: %s"), s3_strerror(self->s3)),
		DEVICE_STATUS_DEVICE_ERROR);
            return FALSE;
        }
    }

    /* take care of any dirty work for this mode */
    switch (mode) {
        case ACCESS_READ:
	    if (pself->volume_label == NULL && s3_device_read_label(pself) != DEVICE_STATUS_SUCCESS) {
		/* s3_device_read_label already set our error message */
		return FALSE;
	    }
            break;

        case ACCESS_WRITE:
            delete_all_files(self);

            /* write a new amanda header */
            if (!write_amanda_header(self, label, timestamp)) {
                return FALSE;
            }

	    pself->volume_label = newstralloc(pself->volume_label, label);
	    pself->volume_time = newstralloc(pself->volume_time, timestamp);

	    /* unset the VOLUME_UNLABELED flag, if it was set */
	    device_set_error(pself, NULL, DEVICE_STATUS_SUCCESS);
            break;

        case ACCESS_APPEND:
	    if (pself->volume_label == NULL && s3_device_read_label(pself) != DEVICE_STATUS_SUCCESS) {
		/* s3_device_read_label already set our error message */
		return FALSE;
	    }
            return seek_to_end(self);
            break;

        case ACCESS_NULL:
            g_assert_not_reached();
    }

    return TRUE;
}

static gboolean
s3_device_finish (Device * pself) {
    /* we're not in a file anymore */
    pself->access_mode = ACCESS_NULL;

    if (device_in_error(pself)) return FALSE;

    return TRUE;
}

/* functions for writing */


static gboolean
s3_device_start_file (Device *pself, dumpfile_t *jobInfo) {
    S3Device *self = S3_DEVICE(pself);
    CurlBuffer amanda_header = {NULL, 0, 0, 0};
    gboolean result;
    size_t header_size;
    char *key;

    if (device_in_error(self)) return FALSE;

    pself->is_eom = FALSE;

    /* Set the blocksize to zero, since there's no header to skip (it's stored
     * in a distinct file, rather than block zero) */
    jobInfo->blocksize = 0;

    /* Build the amanda header. */
    header_size = 0; /* no minimum size */
    amanda_header.buffer = device_build_amanda_header(pself, jobInfo,
        &header_size);
    if (amanda_header.buffer == NULL) {
	device_set_error(pself,
	    stralloc(_("Amanda file header won't fit in a single block!")),
	    DEVICE_STATUS_DEVICE_ERROR);
	return FALSE;
    }
    amanda_header.buffer_len = header_size;

    /* set the file and block numbers correctly */
    pself->file = (pself->file > 0)? pself->file+1 : 1;
    pself->block = 0;
    pself->in_file = TRUE;

    /* write it out as a special block (not the 0th) */
    key = special_file_to_key(self, "filestart", pself->file);
    result = s3_upload(self->s3, self->bucket, key, S3_BUFFER_READ_FUNCS,
                       &amanda_header, NULL, NULL);
    g_free(amanda_header.buffer);
    g_free(key);
    if (!result) {
	device_set_error(pself,
	    vstrallocf(_("While writing filestart header: %s"), s3_strerror(self->s3)),
	    DEVICE_STATUS_DEVICE_ERROR | DEVICE_STATUS_VOLUME_ERROR);
        return FALSE;
    }

    return TRUE;
}

static gboolean
s3_device_write_block (Device * pself, guint size, gpointer data) {
    gboolean result;
    char *filename;
    S3Device * self = S3_DEVICE(pself);
    CurlBuffer to_write = {data, size, 0, 0};

    g_assert (self != NULL);
    g_assert (data != NULL);
    if (device_in_error(self)) return FALSE;

    filename = file_and_block_to_key(self, pself->file, pself->block);

    result = s3_upload(self->s3, self->bucket, filename, S3_BUFFER_READ_FUNCS,
        &to_write, NULL, NULL);
    g_free(filename);
    if (!result) {
	device_set_error(pself,
	    vstrallocf(_("While writing data block to S3: %s"), s3_strerror(self->s3)),
	    DEVICE_STATUS_DEVICE_ERROR | DEVICE_STATUS_VOLUME_ERROR);
        return FALSE;
    }

    pself->block++;

    return TRUE;
}

static gboolean
s3_device_finish_file (Device * pself) {
    if (device_in_error(pself)) return FALSE;

    /* we're not in a file anymore */
    pself->in_file = FALSE;

    return TRUE;
}

static gboolean
s3_device_recycle_file(Device *pself, guint file) {
    S3Device *self = S3_DEVICE(pself);
    if (device_in_error(self)) return FALSE;

    return delete_file(self, file);
    /* delete_file already set our error message if necessary */
}

static gboolean
s3_device_erase(Device *pself) {
    S3Device *self = S3_DEVICE(pself);
    char *key = NULL;
    const char *errmsg = NULL;
    guint response_code;
    s3_error_code_t s3_error_code;

    if (!setup_handle(self)) {
        /* error set by setup_handle */
        return FALSE;
    }

    key = special_file_to_key(self, "tapestart", -1);
    if (!s3_delete(self->s3, self->bucket, key)) {
        s3_error(self->s3, &errmsg, NULL, NULL, NULL, NULL, NULL);
	device_set_error(pself,
	    stralloc(errmsg),
	    DEVICE_STATUS_DEVICE_ERROR);
        return FALSE;
    }
    g_free(key);

    if (!delete_all_files(self))
        return FALSE;

    if (!s3_delete_bucket(self->s3, self->bucket)) {
        s3_error(self->s3, NULL, &response_code, &s3_error_code, NULL, NULL, NULL);

        /*
         * ignore the error if the bucket isn't empty (there may be data from elsewhere)
         * or the bucket not existing (already deleted perhaps?)
         */
        if (!(
                (response_code == 409 && s3_error_code == S3_ERROR_BucketNotEmpty) ||
                (response_code == 404 && s3_error_code == S3_ERROR_NoSuchBucket))) {

            device_set_error(pself,
	        stralloc(errmsg),
	        DEVICE_STATUS_DEVICE_ERROR);
            return FALSE;
        }
    }
    return TRUE;
}

/* functions for reading */

static dumpfile_t*
s3_device_seek_file(Device *pself, guint file) {
    S3Device *self = S3_DEVICE(pself);
    gboolean result;
    char *key;
    CurlBuffer buf = {NULL, 0, 0, S3_DEVICE_MAX_BLOCK_SIZE};
    dumpfile_t *amanda_header;
    const char *errmsg = NULL;

    if (device_in_error(self)) return NULL;

    pself->file = file;
    pself->is_eof = FALSE;
    pself->in_file = FALSE;
    pself->block = 0;

    /* read it in */
    key = special_file_to_key(self, "filestart", pself->file);
    result = s3_read(self->s3, self->bucket, key, S3_BUFFER_WRITE_FUNCS,
        &buf, NULL, NULL);
    g_free(key);

    if (!result) {
        guint response_code;
        s3_error_code_t s3_error_code;
        s3_error(self->s3, &errmsg, &response_code, &s3_error_code, NULL, NULL, NULL);

        /* if it's an expected error (not found), check what to do. */
        if (response_code == 404 && s3_error_code == S3_ERROR_NoSuchKey) {
            int next_file;
            next_file = find_next_file(self, pself->file);
            if (next_file > 0) {
                /* Note short-circut of dispatcher. */
                return s3_device_seek_file(pself, next_file);
            } else if (next_file == 0) {
                /* No next file. Check if we are one past the end. */
                key = special_file_to_key(self, "filestart", pself->file - 1);
                result = s3_read(self->s3, self->bucket, key,
                    S3_BUFFER_WRITE_FUNCS, &buf, NULL, NULL);
                g_free(key);
                if (result) {
		    /* pself->file, etc. are already correct */
                    return make_tapeend_header();
                } else {
		    device_set_error(pself,
			stralloc(_("Attempt to read past tape-end file")),
			DEVICE_STATUS_SUCCESS);
                    return NULL;
                }
            }
        } else {
            /* An unexpected error occured finding out if we are the last file. */
	    device_set_error(pself,
		stralloc(errmsg),
		DEVICE_STATUS_DEVICE_ERROR);
            return NULL;
        }
    }

    /* and make a dumpfile_t out of it */
    g_assert(buf.buffer != NULL);
    amanda_header = g_new(dumpfile_t, 1);
    fh_init(amanda_header);
    parse_file_header(buf.buffer, amanda_header, buf.buffer_pos);
    g_free(buf.buffer);

    switch (amanda_header->type) {
        case F_DUMPFILE:
        case F_CONT_DUMPFILE:
        case F_SPLIT_DUMPFILE:
            break;

        default:
	    device_set_error(pself,
		stralloc(_("Invalid amanda header while reading file header")),
		DEVICE_STATUS_VOLUME_ERROR);
            g_free(amanda_header);
            return NULL;
    }

    pself->in_file = TRUE;
    return amanda_header;
}

static gboolean
s3_device_seek_block(Device *pself, guint64 block) {
    if (device_in_error(pself)) return FALSE;

    pself->block = block;
    return TRUE;
}

typedef struct s3_read_block_data {
    gpointer data;
    int size_req;
    int size_written;

    CurlBuffer curl;
} s3_read_block_data;

/* wrapper around s3_buffer_write_func to write as much data as possible to
 * the user's buffer, and switch to a dynamically allocated buffer if that
 * isn't large enough */
static size_t
s3_read_block_write_func(void *ptr, size_t size, size_t nmemb, void *stream)
{
    s3_read_block_data *dat = stream;
    guint new_bytes, bytes_needed;

    /* if data is NULL, call through to s3_buffer_write_func */
    if (!dat->data) {
	return s3_buffer_write_func(ptr, size, nmemb, (void *)(&dat->curl));
    }

    new_bytes = (guint) size * nmemb;
    bytes_needed = dat->size_written + new_bytes;

    if (bytes_needed > (guint)dat->size_req) {
	/* this read will overflow the user's buffer, so malloc ourselves
	 * a new buffer and keep reading */
	dat->curl.buffer = g_malloc(bytes_needed);
	dat->curl.buffer_len = bytes_needed;
	dat->curl.buffer_pos = dat->size_written;
	memcpy(dat->curl.buffer, dat->data, dat->size_written);
	dat->data = NULL; /* signal that the user's buffer is too small */
	return s3_buffer_write_func(ptr, size, nmemb, (void *)(&dat->curl));
    }

    /* copy it into the dat->data buffer, and increment the size */
    memcpy(dat->data + dat->size_written, ptr, new_bytes);
    dat->size_written += new_bytes;

    return new_bytes;
}

static int
s3_device_read_block (Device * pself, gpointer data, int *size_req) {
    S3Device * self = S3_DEVICE(pself);
    char *key;
    s3_read_block_data dat = {NULL, 0, 0, { NULL, 0, 0, S3_DEVICE_MAX_BLOCK_SIZE} };
    gboolean result;

    g_assert (self != NULL);
    if (device…