gnunet-android

gnunet_pq_lib.h (57784B)

---

 /*
    This file is part of GNUnet
    Copyright (C) 2016, 2017, 2020-2022 GNUnet e.V.
 
    GNUnet is free software: you can redistribute it and/or modify it
    under the terms of the GNU Affero General Public License as published
    by the Free Software Foundation, either version 3 of the License,
    or (at your option) any later version.
 
    GNUnet 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
    Affero General Public License for more details.
 
    You should have received a copy of the GNU Affero General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
      SPDX-License-Identifier: AGPL3.0-or-later
  */
 /**
  * @file include/gnunet_pq_lib.h
  * @brief helper functions for Postgres DB interactions
  * @author Christian Grothoff
  */
 #ifndef GNUNET_PQ_LIB_H
 #define GNUNET_PQ_LIB_H
 
 
 #include <libpq-fe.h>
 #include <stdint.h>
 #include "gnunet_common.h"
 #include "gnunet_time_lib.h"
 #include "gnunet_util_lib.h"
 #include "gnunet_db_lib.h"
 #include "postgres_ext.h"
 
 /**
  * Postgres context.
  */
 struct GNUNET_PQ_Context;
 
 /* ************************* pq_query_helper.c functions ************************ */
 
 
 /**
  * Function called to convert input argument into SQL parameters.
  *
  * @param cls closure
  * @param data pointer to input argument
  * @param data_len number of bytes in @a data (if applicable)
  * @param[out] param_values SQL data to set
  * @param[out] param_lengths SQL length data to set
  * @param[out] param_formats SQL format data to set
  * @param param_length number of entries available in the @a param_values, @a param_lengths and @a param_formats arrays
  * @param[out] scratch buffer for dynamic allocations (to be done via #GNUNET_malloc()
  * @param scratch_length number of entries left in @a scratch
  * @return -1 on error, number of offsets used in @a scratch otherwise
  */
 typedef int
 (*GNUNET_PQ_QueryConverter) (void *cls,
                              const void *data,
                              size_t data_len,
                              void *param_values[],
                              int param_lengths[],
                              int param_formats[],
                              unsigned int param_length,
                              void *scratch[],
                              unsigned int scratch_length);
 
 /**
  * Function called to cleanup the closure of SQL parameters converter. Will be
  * called with GNUNET_PQ_query_params_cleanup
  *
  * @param cls closure
  */
 typedef void
 (*GNUNET_PQ_QueryConverter_Cleanup)(void *cls);
 
 /**
  * @brief Description of a DB query parameter.
  */
 struct GNUNET_PQ_QueryParam
 {
   /**
    * Function for how to handle this type of entry.
    */
   GNUNET_PQ_QueryConverter conv;
 
   /**
    * Closure for @e conv.
    * The function @conv_cls_cleanup can be set to cleanup the closure.
    * The cleanup of the closure MUST be triggered manually by a call to
    * GNUNET_PQ_query_params_cleanup.
    */
   void *conv_cls;
 
   /**
    * Function to cleanup the closure @a conv_cls, may be NULL.
    * The cleanup of the closure MUST be triggered manually by a call to
    * GNUNET_PQ_query_params_cleanup.
    */
   GNUNET_PQ_QueryConverter_Cleanup conv_cls_cleanup;
 
   /**
    * Data or NULL.
    */
   const void *data;
 
   /**
    * Size of @e data
    */
   size_t size;
 
   /**
    * Number of parameters eaten by this operation.
    */
   unsigned int num_params;
 
 };
 
 /**
  * Must be called to cleanup memory from closures after the query parameters
  * have been used as much as needed.
  *
  * @param params Array of GNUNET_PQ_QueryParam which must terminate with a GNUNET_PQ_query_param_end
  */
 void
 GNUNET_PQ_cleanup_query_params_closures (
   const struct GNUNET_PQ_QueryParam *params);
 
 /**
  * End of query parameter specification.
  */
 #define GNUNET_PQ_query_param_end \
         {                               \
           .conv = NULL,                 \
           .conv_cls = NULL,             \
           .data = NULL,                 \
           .size = 0,                    \
           .num_params = 0               \
         }
 
 
 /**
  * Generate query parameter to create a NULL value.
  *
  * @return query parameter to use to insert NULL into DB
  */
 struct GNUNET_PQ_QueryParam
 GNUNET_PQ_query_param_null (void);
 
 
 /**
  * Generate query parameter for a buffer @a ptr of
  * @a ptr_size bytes.
  *
  * @param ptr pointer to the query parameter to pass
  * @param ptr_size number of bytes in @a ptr
  * @return query parameter to use
  */
 struct GNUNET_PQ_QueryParam
 GNUNET_PQ_query_param_fixed_size (const void *ptr,
                                   size_t ptr_size);
 
 
 /**
  * Generate query parameter for a string.
  *
  * @param ptr pointer to the string query parameter to pass
  * @return query parameter to use
  */
 struct GNUNET_PQ_QueryParam
 GNUNET_PQ_query_param_string (const char *ptr);
 
 
 /**
  * Pass a boolean into a query.
  *
  * @param b boolean bit to pass
  * @return query parameter to use
  */
 struct GNUNET_PQ_QueryParam
 GNUNET_PQ_query_param_bool (bool b);
 
 /**
  * Returns the oid for a given datatype by name.
  *
  * @param db The db-connection
  * @param name The name of the datatype
  * @param[out] oid The OID of the datatype.
  * @return GNUNET_OK when the datatype was found, GNUNET_SYSERR otherwise
  */
 enum GNUNET_GenericReturnValue
 GNUNET_PQ_get_oid_by_name (
   struct GNUNET_PQ_Context *db,
   const char *name,
   Oid *oid);
 
 
 /**
  * The header for a postgresql array in binary format. note that this a
  * simplified special case of the general structure (which contains pointers),
  * as we only support one-dimensional arrays.
  *
  * Note that all values must be in network-byte-order.
  */
 struct GNUNET_PQ_ArrayHeader_P
 {
   uint32_t ndim;     /* number of dimensions. we only support ndim = 1 */
   uint32_t has_null;
   uint32_t oid;      /* oid of the elements */
   uint32_t dim;      /* size of the array */
   uint32_t lbound;   /* index value of first element in the db (default: 1). */
 } __attribute__((packed));
 
 
 /**
  * Generate query parameter for an array of bool in host byte order.
  *
  * @param num Number of elements in @a elements
  * @param elements Continuous array of @a num boolean elements
  * @param db Database context, needed for database-depending encoding of @a elements
  * @return query parameter to use
  */
 struct GNUNET_PQ_QueryParam
 GNUNET_PQ_query_param_array_bool (
   unsigned int num,
   const bool *elements,
   struct GNUNET_PQ_Context *db);
 
 /**
  * Generate query parameter for an array of uint16_t in host byte order.
  * Note that the (unsigned) elements are not checked to wrap over INT2_MAX
  *
  * @param num Number of elements in @a elements
  * @param elements Continuous array of @a num uint16 elements
  * @param db Database context, needed for database-depending encoding of @a elements
  * @return query parameter to use
  */
 struct GNUNET_PQ_QueryParam
 GNUNET_PQ_query_param_array_uint16 (
   unsigned int num,
   const uint16_t *elements,
   struct GNUNET_PQ_Context *db);
 
 /**
  * Generate query parameter for an array of uint32_t in host byte order.
  * Note that the (unsigned) elements are not checked to wrap over INT4_MAX
  *
  * @param num Number of elements in @a elements
  * @param elements Continuous Array of @a num uint32_t elements
  * @param db Database context, needed for database-depending encoding of @a elements
  * @return query parameter to use
  */
 struct GNUNET_PQ_QueryParam
 GNUNET_PQ_query_param_array_uint32 (
   unsigned int num,
   const uint32_t *elements,
   struct GNUNET_PQ_Context *db);
 
 /**
  * Generate query parameter for an array of uint64 in host byte order.
  * Note that the (unsigned) elements are not checked to wrap over INT8_MAX
  *
  * @param num Number of elements in @a elements
  * @param elements Continuous array of @a num uint64_t elements
  * @param db Database context, needed for database-depending encoding of @a elements
  * @return query parameter to use
  */
 struct GNUNET_PQ_QueryParam
 GNUNET_PQ_query_param_array_uint64 (
   unsigned int num,
   const uint64_t *elements,
   struct GNUNET_PQ_Context *db);
 
 /**
  * Generate query parameter for an array of buffers @a elements, each of
  * corresponding size given in @a sizes.
  *
  * @param num Number of elements in @a elements
  * @param elements Continuous array of @a num buffers, each of corresponding size given in @a sizes.
  * @param sizes Pointer to sizes in bytes of each element in @a elements
  * @param db Database context, needed for database-depending encoding of @a elements
  * @return query parameter to use
  */
 struct GNUNET_PQ_QueryParam
 GNUNET_PQ_query_param_array_bytes (
   unsigned int num,
   const void *elements,
   const size_t *sizes,
   struct GNUNET_PQ_Context *db);
 
 /**
  * Generate query parameter for an array of buffers @a elements,
  * with sizes @a sizes.
  *
  * @param num Number of elements in @a elements
  * @param elements Continuous array of @a num buffers, each with the same size
  * @a same_size
  * @param sizes Sizes in bytes of each element in @a elements
  * @param db Database context, needed for database-depending encoding of @a
  * elements
  * @return query parameter to use
  */
 struct GNUNET_PQ_QueryParam GNUNET_PQ_query_param_array_ptrs_bytes (
   unsigned int num,
   const void *elements[static num],
   const size_t *sizes,
   struct GNUNET_PQ_Context *db);
 
 /**
  * Generate query parameter for an array of buffers @a elements,
  * each of the same size @a size.
  *
  * @param num Number of elements in @a elements
  * @param elements Continuous array of @a num buffers, each with the same size @a same_size
  * @param same_size Size in bytes of each element in @a elements
  * @param db Database context, needed for database-depending encoding of @a elements
  * @return query parameter to use
  */
 struct GNUNET_PQ_QueryParam
 GNUNET_PQ_query_param_array_bytes_same_size (
   unsigned int num,
   const void *elements,
   size_t same_size,
   struct GNUNET_PQ_Context *db);
 
 /**
  * Generate array of equal-sized query parameter with size determined
  * by variable type from a pointer to an continuous array.
  *
  * @param num Number of elements in @a elements
  * @param elements Continuous array of the query parameter to pass.
  * @param db Database context, needed for database-depending encoding of @a elements
  * @return query parameter to use
  */
 #define GNUNET_PQ_query_param_array_auto_from_type(num, elements, db) \
         GNUNET_PQ_query_param_array_bytes_same_size ((num), \
                                                      (elements), \
                                                      sizeof(*(elements)), \
                                                      (db))
 
 /**
  * Generate query parameter for an array of pointers to buffers @a elements,
  * each of the same size @a size.
  *
  * @param num Number of elements in @a elements
  * @param elements Array of @a num pointers to buffers, each with the same size @a same_size
  * @param same_size Size in bytes of each element in @a elements
  * @param db Database context, needed for database-depending encoding of @a elements
  * @return query parameter to use
  */
 struct GNUNET_PQ_QueryParam
 GNUNET_PQ_query_param_array_ptrs_bytes_same_size (
   unsigned int num,
   const void *elements[static num],
   size_t same_size,
   struct GNUNET_PQ_Context *db);
 
 
 /**
  * Generate array of equal-sized query parameter with size determined by
  * variable type from a pointer to an array of pointers to objects of the same
  * type.
  *
  * @param num Number of elements in @a elements
  * @param elements Continuous array of the query parameter to pass.
  * @param db Database context, needed for database-depending encoding of @a elements
  * @return query parameter to use
  */
 #define GNUNET_PQ_query_param_array_ptrs_auto_from_type(num, elements, db) \
         GNUNET_PQ_query_param_array_ptrs_bytes_same_size ((num), \
                                                           (const void **) ( \
                                                             elements), \
                                                           sizeof(*(elements[0])) \
                                                           , \
                                                           (db))
 
 
 /**
  * Generate query parameter for an array of strings (continuous)
  *
  * @param num Number of elements in @a elements
  * @param elements Array of @a num continuous strings (zero-terminated each)
  * @param db Database context, needed for database-depending encoding of @a elements
  * @return query parameter to use
  */
 struct GNUNET_PQ_QueryParam
 GNUNET_PQ_query_param_array_string (
   unsigned int num,
   const char *elements,
   struct GNUNET_PQ_Context *db);
 
 
 /**
  * Generate query parameter for an array of strings (pointers)
  *
  * @param num Number of elements in @a elements
  * @param elements Array of @a num pointer to strings
  * @param db Database context, needed for database-depending encoding of @a elements
  * @return query parameter to use
  */
 struct GNUNET_PQ_QueryParam
 GNUNET_PQ_query_param_array_ptrs_string (
   unsigned int num,
   const char *elements[static num],
   struct GNUNET_PQ_Context *db);
 
 
 /**
  * Generate fixed-size query parameter with size determined
  * by variable type.
  *
  * @param x pointer to the query parameter to pass.
  * @return query parameter to use
  */
 #define GNUNET_PQ_query_param_auto_from_type(x) \
         GNUNET_PQ_query_param_fixed_size ((x), sizeof(*(x)))
 
 /**
  * Generate query parameter for an array of absolute time stamps (continuous)
  *
  * @param num Number of elements in @a elements
  * @param elements Array of @a num absolute timestamps
  * @return query parameter to use
  */
 struct GNUNET_PQ_QueryParam
 GNUNET_PQ_query_param_array_abs_time (
   unsigned int num,
   const struct GNUNET_TIME_Absolute *elements,
   struct GNUNET_PQ_Context *db);
 
 /**
  * Generate query parameter for an array of absolute time stamps (pointers)
  *
  * @param num Number of elements in @a elements
  * @param elements Array of @a num pointers to absolute timestamps
  * @return query parameter to use
  */
 struct GNUNET_PQ_QueryParam
 GNUNET_PQ_query_param_array_ptrs_abs_time (
   unsigned int num,
   const struct GNUNET_TIME_Absolute *elements[],
   struct GNUNET_PQ_Context *db);
 
 /**
  * Generate query parameter for an array of relative time stamps (continuous)
  *
  * @param num Number of elements in @a elements
  * @param elements Array of @a num relative timestamps
  * @return query parameter to use
  */
 struct GNUNET_PQ_QueryParam
 GNUNET_PQ_query_param_array_rel_time (
   unsigned int num,
   const struct GNUNET_TIME_Relative *elements,
   struct GNUNET_PQ_Context *db);
 
 /**
  * Generate query parameter for an array of relative time stamps (pointers)
  *
  * @param num Number of elements in @a elements
  * @param elements Array of @a num pointers to relative timestamps
  * @return query parameter to use
  */
 struct GNUNET_PQ_QueryParam
 GNUNET_PQ_query_param_array_ptrs_rel_time (
   unsigned int num,
   const struct GNUNET_TIME_Relative *elements[],
   struct GNUNET_PQ_Context *db);
 
 /**
  * Generate query parameter for an array of time stamps (continuous)
  *
  * @param num Number of elements in @a elements
  * @param elements Array of @a num timestamps
  * @return query parameter to use
  */
 struct GNUNET_PQ_QueryParam
 GNUNET_PQ_query_param_array_timestamp (
   unsigned int num,
   const struct GNUNET_TIME_Timestamp *elements,
   struct GNUNET_PQ_Context *db);
 
 /**
  * Generate query parameter for an array of time stamps (pointers)
  *
  * @param num Number of elements in @a elements
  * @param elements Array of @a num pointers to relative timestamps
  * @return query parameter to use
  */
 struct GNUNET_PQ_QueryParam
 GNUNET_PQ_query_param_array_ptrs_timestamp (
   unsigned int num,
   const struct GNUNET_TIME_Timestamp *elements[],
   struct GNUNET_PQ_Context *db);
 
 /**
  * Generate query parameter for an RSA public key.  The
  * database must contain a BLOB type in the respective position.
  *
  * @param x the query parameter to pass.
  * @return query parameter to use
  */
 struct GNUNET_PQ_QueryParam
 GNUNET_PQ_query_param_rsa_public_key (
   const struct GNUNET_CRYPTO_RsaPublicKey *x);
 
 
 /**
  * Generate query parameter for an RSA signature.  The
  * database must contain a BLOB type in the respective position.
  *
  * @param x the query parameter to pass
  * @return query parameter to use
  */
 struct GNUNET_PQ_QueryParam
 GNUNET_PQ_query_param_rsa_signature (
   const struct GNUNET_CRYPTO_RsaSignature *x);
 
 
 /**
  * Generate query parameter for a relative time value.
  * The database must store a 64-bit integer.
  *
  * @param x pointer to the query parameter to pass
  * @return query parameter to use
  */
 struct GNUNET_PQ_QueryParam
 GNUNET_PQ_query_param_relative_time (const struct GNUNET_TIME_Relative *x);
 
 
 /**
  * Generate query parameter for an absolute time value.
  * The database must store a 64-bit integer.
  *
  * @param x pointer to the query parameter to pass
  * @return query parameter to use
  */
 struct GNUNET_PQ_QueryParam
 GNUNET_PQ_query_param_absolute_time (const struct GNUNET_TIME_Absolute *x);
 
 
 /**
  * Generate query parameter for a timestamp.
  * The database must store a 64-bit integer.
  *
  * @param x pointer to the query parameter to pass
  * @return query parameter to use
  */
 struct GNUNET_PQ_QueryParam
 GNUNET_PQ_query_param_timestamp (const struct GNUNET_TIME_Timestamp *x);
 
 
 /**
  * Generate query parameter for an absolute time value.
  * The database must store a 64-bit integer.
  *
  * @param x pointer to the query parameter to pass
  * @return query parameter to use
  */
 struct GNUNET_PQ_QueryParam
 GNUNET_PQ_query_param_absolute_time_nbo (
   const struct GNUNET_TIME_AbsoluteNBO *x);
 
 
 /**
  * Generate query parameter for a timestamp in NBO.
  * The database must store a 64-bit integer.
  *
  * @param x pointer to the query parameter to pass
  * @return query parameter to use
  */
 struct GNUNET_PQ_QueryParam
 GNUNET_PQ_query_param_timestamp_nbo (
   const struct GNUNET_TIME_TimestampNBO *x);
 
 
 /**
  * Generate query parameter for an uint16_t in host byte order.
  *
  * @param x pointer to the query parameter to pass
  * @return query parameter to use
  */
 struct GNUNET_PQ_QueryParam
 GNUNET_PQ_query_param_uint16 (const uint16_t *x);
 
 
 /**
  * Generate query parameter for an uint32_t in host byte order.
  *
  * @param x pointer to the query parameter to pass
  * @return query parameter to use
  */
 struct GNUNET_PQ_QueryParam
 GNUNET_PQ_query_param_uint32 (const uint32_t *x);
 
 
 /**
  * Generate query parameter for an uint64_t in host byte order.
  *
  * @param x pointer to the query parameter to pass
  * @return query parameter to use
  */
 struct GNUNET_PQ_QueryParam
 GNUNET_PQ_query_param_uint64 (const uint64_t *x);
 
 
 /**
  * Generate query parameter for an int16_t in host byte order.
  *
  * @param x pointer to the query parameter to pass
  * @return query parameter to use
  */
 struct GNUNET_PQ_QueryParam
 GNUNET_PQ_query_param_int16 (const int16_t *x);
 
 /**
  * Generate query parameter for an int64_t in host byte order.
  *
  * @param x pointer to the query parameter to pass
  * @return query parameter to use
  */
 struct GNUNET_PQ_QueryParam
 GNUNET_PQ_query_param_int64 (const int64_t *x);
 
 /**
  * Generate query parameter for a blind sign public key.
  * Internally, the various attributes of the public key
  * will be serialized into on variable-size BLOB.
  *
  * @param pub pointer to the query parameter to pass
  *
  */
 struct GNUNET_PQ_QueryParam
 GNUNET_PQ_query_param_blind_sign_pub (
   const struct GNUNET_CRYPTO_BlindSignPublicKey *pub);
 
 /**
  * Generate query parameter for a blind sign private key of variable size.
  *
  * @param priv pointer to the query parameter to pass
  *
  */
 struct GNUNET_PQ_QueryParam
 GNUNET_PQ_query_param_blind_sign_priv (
   const struct GNUNET_CRYPTO_BlindSignPrivateKey *priv);
 
 /**
  * Generate query parameter for an unblinded signature of variable size.
  *
  * @param sig pointer to the query parameter to pass
  *
  */
 struct GNUNET_PQ_QueryParam
 GNUNET_PQ_query_param_unblinded_sig (
   const struct GNUNET_CRYPTO_UnblindedSignature *sig);
 
 /**
  * Generate query parameter for a blinded signature of variable size.
  *
  * @param b_sig pointer to the query parameter to pass
  *
  */
 struct GNUNET_PQ_QueryParam
 GNUNET_PQ_query_param_blinded_sig (
   const struct GNUNET_CRYPTO_BlindedSignature *b_sig);
 
 /* ************************* pq_result_helper.c functions ************************ */
 
 
 /**
  * Extract data from a Postgres database @a result at row @a row.
  *
  * @param cls closure
  * @param result where to extract data from
  * @param int row to extract data from
  * @param fname name (or prefix) of the fields to extract from
  * @param[in,out] dst_size where to store size of result, may be NULL
  * @param[out] dst where to store the result
  * @return
  *   #GNUNET_YES if all results could be extracted
  *   #GNUNET_NO if the field was NULL
  *   #GNUNET_SYSERR if a result was invalid (non-existing field)
  */
 typedef enum GNUNET_GenericReturnValue
 (*GNUNET_PQ_ResultConverter)(void *cls,
                              PGresult *result,
                              int row,
                              const char *fname,
                              size_t *dst_size,
                              void *dst);
 
 
 /**
  * Function called to clean up memory allocated
  * by a #GNUNET_PQ_ResultConverter.
  *
  * @param cls closure
  * @param rd result data to clean up
  */
 typedef void
 (*GNUNET_PQ_ResultCleanup) (void *cls,
                             void *rd);
 
 
 /**
  * @brief Description of a DB result cell.
  */
 struct GNUNET_PQ_ResultSpec
 {
   /**
    * What is the format of the result?
    */
   GNUNET_PQ_ResultConverter conv;
 
   /**
    * Function to clean up result data, NULL if cleanup is not necessary.
    */
   GNUNET_PQ_ResultCleanup cleaner;
 
   /**
    * Closure for @e conv and @e cleaner.
    */
   void *cls;
 
   /**
    * Destination for the data.
    */
   void *dst;
 
   /**
    * Allowed size for the data, 0 for variable-size (in this case, the type of
    * @e dst is a `void **` and we need to allocate a buffer of the right
    * size).
    */
   size_t dst_size;
 
   /**
    * Field name of the desired result.
    */
   const char *fname;
 
   /**
    * Where to store actual size of the result.
    */
   size_t *result_size;
 
   /**
    * True if NULL is allowed for a value in the database.
    */
   bool is_nullable;
 
   /**
    * Points to a location where we should store "true" if the result found is
    * NULL, and otherwise "false". Only used if @e is_nullable is true.
    */
   bool *is_null;
 
 };
 
 
 /**
  * End of result parameter specification.
  *
  * @return array last entry for the result specification to use
  */
 #define GNUNET_PQ_result_spec_end         \
         {                                       \
           .conv = NULL,                         \
           .cleaner = NULL,                      \
           .cls = NULL,                          \
           .dst = NULL,                          \
           .dst_size = 0,                        \
           .fname = NULL,                        \
           .result_size = NULL,                  \
           .is_nullable = false,                 \
           .is_null = NULL                       \
         }
 
 
 /**
  * Allow NULL value to be found in the database for the given value.
  *
  * @param rs result spec entry to modify
  * @param[out] is_null location set to 'true' if the
  *     value was indeed NULL, set to 'false' if the
  *     value was non-NULL
  * @return array entry for the result specification to use
  */
 struct GNUNET_PQ_ResultSpec
 GNUNET_PQ_result_spec_allow_null (struct GNUNET_PQ_ResultSpec rs,
                                   bool *is_null);
 
 
 /**
  * Variable-size result expected.
  *
  * @param name name of the field in the table
  * @param[out] dst where to store the result, allocated
  * @param[out] sptr where to store the size of @a dst
  * @return array entry for the result specification to use
  */
 struct GNUNET_PQ_ResultSpec
 GNUNET_PQ_result_spec_variable_size (const char *name,
                                      void **dst,
                                      size_t *sptr);
 
 
 /**
  * Fixed-size result expected.
  *
  * @param name name of the field in the table
  * @param[out] dst where to store the result
  * @param dst_size number of bytes in @a dst
  * @return array entry for the result specification to use
  */
 struct GNUNET_PQ_ResultSpec
 GNUNET_PQ_result_spec_fixed_size (const char *name,
                                   void *dst,
                                   size_t dst_size);
 
 
 /**
  * We expect a fixed-size result, with size determined by the type of `* dst`
  *
  * @param name name of the field in the table
  * @param dst point to where to store the result, type fits expected result size
  * @return array entry for the result specification to use
  */
 #define GNUNET_PQ_result_spec_auto_from_type(name, dst) \
         GNUNET_PQ_result_spec_fixed_size (name, (dst), sizeof(*(dst)))
 
 
 /**
  * 0-terminated string expected.
  *
  * @param name name of the field in the table
  * @param[out] dst where to store the result, allocated
  * @return array entry for the result specification to use
  */
 struct GNUNET_PQ_ResultSpec
 GNUNET_PQ_result_spec_string (const char *name,
                               char **dst);
 
 
 /**
  * boolean expected.
  *
  * @param name name of the field in the table
  * @param[out] dst where to store the result
  * @return array entry for the result specification to use
  */
 struct GNUNET_PQ_ResultSpec
 GNUNET_PQ_result_spec_bool (const char *name,
                             bool *dst);
 
 
 /**
  * RSA public key expected.
  *
  * @param name name of the field in the table
  * @param[out] rsa where to store the result
  * @return array entry for the result specification to use
  */
 struct GNUNET_PQ_ResultSpec
 GNUNET_PQ_result_spec_rsa_public_key (const char *name,
                                       struct GNUNET_CRYPTO_RsaPublicKey **rsa);
 
 
 /**
  * RSA signature expected.
  *
  * @param name name of the field in the table
  * @param[out] sig where to store the result;
  * @return array entry for the result specification to use
  */
 struct GNUNET_PQ_ResultSpec
 GNUNET_PQ_result_spec_rsa_signature (const char *name,
                                      struct GNUNET_CRYPTO_RsaSignature **sig);
 
 
 /**
  * Absolute time expected.
  *
  * @param name name of the field in the table
  * @param[out] at where to store the result
  * @return array entry for the result specification to use
  */
 struct GNUNET_PQ_ResultSpec
 GNUNET_PQ_result_spec_absolute_time (const char *name,
                                      struct GNUNET_TIME_Absolute *at);
 
 
 /**
  * Timestamp expected.
  *
  * @param name name of the field in the table
  * @param[out] t where to store the result
  * @return array entry for the result specification to use
  */
 struct GNUNET_PQ_ResultSpec
 GNUNET_PQ_result_spec_timestamp (const char *name,
                                  struct GNUNET_TIME_Timestamp *t);
 
 
 /**
  * Relative time expected.
  *
  * @param name name of the field in the table
  * @param[out] rt where to store the result
  * @return array entry for the result specification to use
  */
 struct GNUNET_PQ_ResultSpec
 GNUNET_PQ_result_spec_relative_time (const char *name,
                                      struct GNUNET_TIME_Relative *rt);
 
 
 /**
  * Absolute time expected.
  *
  * @param name name of the field in the table
  * @param[out] at where to store the result
  * @return array entry for the result specification to use
  */
 struct GNUNET_PQ_ResultSpec
 GNUNET_PQ_result_spec_absolute_time_nbo (const char *name,
                                          struct GNUNET_TIME_AbsoluteNBO *at);
 
 
 /**
  * Timestamp expected.
  *
  * @param name name of the field in the table
  * @param[out] tn where to store the result
  * @return array entry for the result specification to use
  */
 struct GNUNET_PQ_ResultSpec
 GNUNET_PQ_result_spec_timestamp_nbo (const char *name,
                                      struct GNUNET_TIME_TimestampNBO *tn);
 
 
 /**
  * uint16_t expected.
  *
  * @param name name of the field in the table
  * @param[out] u16 where to store the result
  * @return array entry for the result specification to use
  */
 struct GNUNET_PQ_ResultSpec
 GNUNET_PQ_result_spec_uint16 (const char *name,
                               uint16_t *u16);
 
 
 /**
  * uint32_t expected.
  *
  * @param name name of the field in the table
  * @param[out] u32 where to store the result
  * @return array entry for the result specification to use
  */
 struct GNUNET_PQ_ResultSpec
 GNUNET_PQ_result_spec_uint32 (const char *name,
                               uint32_t *u32);
 
 
 /**
  * uint64_t expected.
  *
  * @param name name of the field in the table
  * @param[out] u64 where to store the result
  * @return array entry for the result specification to use
  */
 struct GNUNET_PQ_ResultSpec
 GNUNET_PQ_result_spec_uint64 (const char *name,
                               uint64_t *u64);
 
 
 /**
  * int16_t expected.
  *
  * @param name name of the field in the table
  * @param[out] i16 where to store the result
  * @return array entry for the result specification to use
  */
 struct GNUNET_PQ_ResultSpec
 GNUNET_PQ_result_spec_int16 (const char *name,
                              int16_t *i16);
 
 
 /**
  * int64_t expected.
  *
  * @param name name of the field in the table
  * @param[out] i64 where to store the result
  * @return array entry for the result specification to use
  */
 struct GNUNET_PQ_ResultSpec
 GNUNET_PQ_result_spec_int64 (const char *name,
                              int64_t *i64);
 
 /**
  * Allow NULL values in an array to be found in the database for the given value.
  *
  * @param rs result spec entry to modify, MUST be one for the _array_ types
  * @param[out] is_nulls location where to put the array of bools,
  *     whose elements will be set to 'true' if the value was indeed NULL,
  *     or to 'false' if the value was non-NULL.
  *     This parameter MUST NOT be NULL itself.
  *     The length of the allocated array will be equal to the length of
  *     the result for the values in @a rs.
  * @return array entry for the result specification to use
  */
 struct GNUNET_PQ_ResultSpec
 GNUNET_PQ_result_spec_array_allow_nulls (
   struct GNUNET_PQ_ResultSpec rs,
   bool **is_nulls);
 
 /**
  * array of bool expected.
  *
  * @param db Database context, needed for OID lookup for the correct type
  * @param name name of the field in the table
  * @param[out] num where to store the number of elements in the array @a bools.
  * @param[out] bools pointer to where to store the result, an array of @a num bool's. Allocated by the function, MUST be freed with GNUNET_free.
  * @return array entry for the result specification to use
  */
 struct GNUNET_PQ_ResultSpec
 GNUNET_PQ_result_spec_array_bool (
   struct GNUNET_PQ_Context *db,
   const char *name,
   size_t *num,
   bool **bools);
 
 /**
  * array of uint16_t expected.
  *
  * @param db Database context, needed for OID lookup for the correct type
  * @param name name of the field in the table
  * @param[out] num where to store the number of elements in the array @a u16s.
  * @param[out] dst pointer to where to store the an array of @a num uint16_t's. Allocated by the function, MUST be freed with GNUNET_free.
  * @return array entry for the result specification to use
  */
 struct GNUNET_PQ_ResultSpec
 GNUNET_PQ_result_spec_array_uint16 (
   struct GNUNET_PQ_Context *db,
   const char *name,
   size_t *num,
   uint16_t **dst);
 
 /**
  * array of uint32_t expected.
  *
  * @param db Database context, needed for OID lookup for the correct type
  * @param name name of the field in the table
  * @param[out] num where to store the number of elements in the array @a u32s.
  * @param[out] dst pointer to where to store the array of @a num uint32_t's. Allocated by the function, MUST be freed with GNUNET_free.
  * @return array entry for the result specification to use
  */
 struct GNUNET_PQ_ResultSpec
 GNUNET_PQ_result_spec_array_uint32 (
   struct GNUNET_PQ_Context *db,
   const char *name,
   size_t *num,
   uint32_t **dst);
 
 /**
  * array of uint64_t expected.
  *
  * @param db Database context, needed for OID lookup for the correct type
  * @param name name of the field in the table
  * @param[out] num where to store the number of elements in the array @a u64s.
  * @param[out] dst pointer to where to store the array of @a num uint64_t's. Allocated by the function, MUST be freed with GNUNET_free.
  * @return array entry for the result specification to use
  */
 struct GNUNET_PQ_ResultSpec
 GNUNET_PQ_result_spec_array_uint64 (
   struct GNUNET_PQ_Context *db,
   const char *name,
   size_t *num,
   uint64_t **dst);
 
 
 /**
  * array of absolute time expected.
  *
  * @param db Database context, needed for OID lookup for the correct type
  * @param name name of the field in the table
  * @param[out] num where to store the number of elements in the array @a u64s.
  * @param[out] dst pointer to where to store the array of @a num absolute time. Allocated by the function, MUST be freed with GNUNET_free.
  * @return array entry for the result specification to use
  */
 struct GNUNET_PQ_ResultSpec
 GNUNET_PQ_result_spec_array_abs_time (
   struct GNUNET_PQ_Context *db,
   const char *name,
   size_t *num,
   struct GNUNET_TIME_Absolute **dst);
 
 /**
  * array of relative time expected.
  *
  * @param db Database context, needed for OID lookup for the correct type
  * @param name name of the field in the table
  * @param[out] num where to store the number of elements in the array @a u64s.
  * @param[out] dst pointer to where to store the array of @a num relate time. Allocated by the function, MUST be freed with GNUNET_free.
  * @return array entry for the result specification to use
  */
 struct GNUNET_PQ_ResultSpec
 GNUNET_PQ_result_spec_array_rel_time (
   struct GNUNET_PQ_Context *db,
   const char *name,
   size_t *num,
   struct GNUNET_TIME_Relative **dst);
 
 /**
  * array of relative time expected.
  *
  * @param db Database context, needed for OID lookup for the correct type
  * @param name name of the field in the table
  * @param[out] num where to store the number of elements in the array @a u64s.
  * @param[out] dst pointer to where to store the array of @a num timestamps. Allocated by the function, MUST be freed with GNUNET_free.
  * @return array entry for the result specification to use
  */
 
 struct GNUNET_PQ_ResultSpec
 GNUNET_PQ_result_spec_array_timestamp (
   struct GNUNET_PQ_Context *db,
   const char *name,
   size_t *num,
   struct GNUNET_TIME_Timestamp **dst);
 
 /**
  * Array of variable-size result expected.
  *
  * @param db Database context, needed for OID lookup for the correct type
  * @param name name of the field in the table
  * @param[out] num where to store the number of elements
  * @param[out] sizes where to store the @a num size's of byte-buffers in @a dst
  * @param[out] dst where to store the continuous array of @a num byte-buffers of sizes given in @a size, allocated
  * @return array entry for the result specification to use
  */
 struct GNUNET_PQ_ResultSpec
 GNUNET_PQ_result_spec_array_variable_size (
   struct GNUNET_PQ_Context *db,
   const char *name,
   size_t *num,
   size_t **sizes,
   void **dst);
 
 
 /**
  * Array of fixed-size result expected.
  *
  * @param db Database context, needed for OID lookup for the correct type
  * @param name name of the field in the table
  * @param size number of bytes expected in each element of @a dst
  * @param[out] num where to store the number of elements
  * @param[out] dst where to store the results, an continuous array of @num fixed-size elements
  * @return array entry for the result specification to use
  */
 struct GNUNET_PQ_ResultSpec
 GNUNET_PQ_result_spec_array_fixed_size (
   struct GNUNET_PQ_Context *db,
   const char *name,
   size_t size,
   size_t *num,
   void **dst);
 
 
 /**
  * We expect a fixed-size result, with size determined by the type of `* dst`
  *
  * @param db Database context, needed for OID lookup for the correct type
  * @param name name of the field in the table
  * @param num pointer to where to store the number of elements
  * @param dst pointer to where to store the results, type fits expected result size
  * @return array entry for the result specification to use
  */
 #define GNUNET_PQ_result_spec_auto_array_from_type(db, name, num, dst) \
         GNUNET_PQ_result_spec_array_fixed_size ( \
           (db), \
           (name), \
           sizeof(*(dst)), \
           (num), \
           (void *) &(dst))
 
 
 /**
  * Array of 0-terminated strings expected.
  *
  * @param db Database context, needed for OID lookup for the correct type
  * @param name name of the field in the table
  * @param[out] num where to store the number of elements
  * @param[out] dst where to store the allocated continuous array of @a num 0-terminated strings
  * @return array entry for the result specification to use
  */
 struct GNUNET_PQ_ResultSpec
 GNUNET_PQ_result_spec_array_string (
   struct GNUNET_PQ_Context *db,
   const char *name,
   size_t *num,
   char **dst);
 
 
 /**
  * Blind sign public key expected.
  *
  * @param name name of the field in the table
  * @param[out] public_key where to store the denomination signature
  * @return array entry for the result specification to use
  */
 struct GNUNET_PQ_ResultSpec
 GNUNET_PQ_result_spec_blind_sign_pub (
   const char *name,
   struct GNUNET_CRYPTO_BlindSignPublicKey **public_key);
 
 
 /**
  * Blinded signature expected.
  *
  * @param name name of the field in the table
  * @param[out] b_sig where to store the blinded signature
  * @return array entry for the result specification to use
  */
 struct GNUNET_PQ_ResultSpec
 GNUNET_PQ_result_spec_blinded_sig (
   const char *name,
   struct GNUNET_CRYPTO_BlindedSignature **b_sig);
 
 
 /**
  * Unblinded signature expected.
  *
  * @param name name of the field in the table
  * @param[out] ub_sig where to store the unblinded signature
  * @return array entry for the result specification to use
  */
 struct GNUNET_PQ_ResultSpec
 GNUNET_PQ_result_spec_unblinded_sig (
   const char *name,
   struct GNUNET_CRYPTO_UnblindedSignature **ub_sig);
 
 
 /**
  * Blind sign private key expected.
  *
  * @param name name of the field in the table
  * @param[out] private_key where to store the denomination signature
  * @return array entry for the result specification to use
  */
 struct GNUNET_PQ_ResultSpec
 GNUNET_PQ_result_spec_blind_sign_priv (
   const char *name,
   struct GNUNET_CRYPTO_BlindSignPrivateKey **private_key);
 
 /* ************************* pq.c functions ************************ */
 
 /**
  * Execute a prepared statement.
  *
  * @param db database context
  * @param name name of the prepared statement
  * @param params parameters to the statement
  * @return postgres result
  * @deprecated (should become an internal API)
  */
 PGresult *
 GNUNET_PQ_exec_prepared (struct GNUNET_PQ_Context *db,
                          const char *name,
                          const struct GNUNET_PQ_QueryParam *params);
 
 
 /**
  * Extract results from a query result according to the given specification.
  *
  * @param result result to process
  * @param[in,out] rs result specification to extract for
  * @param row row from the result to extract
  * @return
  *   #GNUNET_YES if all results could be extracted
  *   #GNUNET_SYSERR if a result was invalid (non-existing field)
  */
 enum GNUNET_GenericReturnValue
 GNUNET_PQ_extract_result (PGresult *result,
                           struct GNUNET_PQ_ResultSpec *rs,
                           int row);
 
 
 /**
  * Free all memory that was allocated in @a rs during
  * #GNUNET_PQ_extract_result().
  *
  * @param rs result specification to clean up
  */
 void
 GNUNET_PQ_cleanup_result (struct GNUNET_PQ_ResultSpec *rs);
 
 
 /* ******************** pq_eval.c functions ************** */
 
 
 /**
  * Check the @a result's error code to see what happened.
  * Also logs errors.
  *
  * @param db database to execute the statement in
  * @param statement_name name of the statement that created @a result
  * @param result result to check
  * @return status code from the result, mapping PQ status
  *         codes to `enum GNUNET_DB_QueryStatus`.  Never
  *         returns positive values as this function does
  *         not look at the result set.
  * @deprecated (low level, let's see if we can do with just the high-level functions)
  */
 enum GNUNET_DB_QueryStatus
 GNUNET_PQ_eval_result (struct GNUNET_PQ_Context *db,
                        const char *statement_name,
                        PGresult *result);
 
 
 /**
  * Execute a named prepared @a statement that is NOT a SELECT
  * statement in @a connection using the given @a params.  Returns the
  * resulting session state.
  *
  * @param db database to execute the statement with
  * @param statement_name name of the statement
  * @param params parameters to give to the statement (#GNUNET_PQ_query_param_end-terminated)
  * @return status code from the result, mapping PQ status
  *         codes to `enum GNUNET_DB_QueryStatus`.   If the
  *         statement was a DELETE or UPDATE statement, the
  *         number of affected rows is returned; if the
  *         statement was an INSERT statement, and no row
  *         was added due to a UNIQUE violation, we return
  *         zero; if INSERT was successful, we return one.
  */
 enum GNUNET_DB_QueryStatus
 GNUNET_PQ_eval_prepared_non_select (struct GNUNET_PQ_Context *db,
                                     const char *statement_name,
                                     const struct GNUNET_PQ_QueryParam *params);
 
 
 /**
  * Function to be called with the results of a SELECT statement
  * that has returned @a num_results results.
  *
  * @param cls closure
  * @param result the postgres result
  * @param num_result the number of results in @a result
  */
 typedef void
 (*GNUNET_PQ_PostgresResultHandler) (void *cls,
                                     PGresult *result,
                                     unsigned int num_results);
 
 
 /**
  * Execute a named prepared @a statement that is a SELECT statement
  * which may return multiple results in @a connection using the given
  * @a params.  Call @a rh with the results.  Returns the query
  * status including the number of results given to @a rh (possibly zero).
  * @a rh will not have been called if the return value is negative.
  *
  * @param db database to execute the statement with
  * @param statement_name name of the statement
  * @param params parameters to give to the statement (#GNUNET_PQ_query_param_end-terminated)
  * @param rh function to call with the result set, NULL to ignore
  * @param rh_cls closure to pass to @a rh
  * @return status code from the result, mapping PQ status
  *         codes to `enum GNUNET_DB_QueryStatus`.
  */
 enum GNUNET_DB_QueryStatus
 GNUNET_PQ_eval_prepared_multi_select (struct GNUNET_PQ_Context *db,
                                       const char *statement_name,
                                       const struct GNUNET_PQ_QueryParam *params,
                                       GNUNET_PQ_PostgresResultHandler rh,
                                       void *rh_cls);
 
 
 /**
  * Execute a named prepared @a statement that is a SELECT statement
  * which must return a single result in @a connection using the given
  * @a params.  Stores the result (if any) in @a rs, which the caller
  * must then clean up using #GNUNET_PQ_cleanup_result() if the return
  * value was #GNUNET_DB_STATUS_SUCCESS_ONE_RESULT.  Returns the
  * resulting session status.
  *
  * @param db database to execute the statement with
  * @param statement_name name of the statement
  * @param params parameters to give to the statement (#GNUNET_PQ_query_param_end-terminated)
  * @param[in,out] rs result specification to use for storing the result of the query
  * @return status code from the result, mapping PQ status
  *         codes to `enum GNUNET_DB_QueryStatus`.
  */
 enum GNUNET_DB_QueryStatus
 GNUNET_PQ_eval_prepared_singleton_select (
   struct GNUNET_PQ_Context *db,
   const char *statement_name,
   const struct GNUNET_PQ_QueryParam *params,
   struct GNUNET_PQ_ResultSpec *rs);
 
 
 /* ******************** pq_prepare.c functions ************** */
 
 
 /**
  * Information needed to prepare a list of SQL statements using
  * #GNUNET_PQ_prepare_statements().
  */
 struct GNUNET_PQ_PreparedStatement
 {
   /**
    * Name of the statement.
    */
   const char *name;
 
   /**
    * Actual SQL statement.
    */
   const char *sql;
 
 };
 
 
 /**
  * Terminator for prepared statement list.
  */
 #define GNUNET_PQ_PREPARED_STATEMENT_END \
         {                                      \
           NULL, NULL                           \
         }
 
 
 /**
  * Create a `struct GNUNET_PQ_PreparedStatement`.
  *
  * @param name name of the statement
  * @param sql actual SQL statement
  * @return initialized struct
  */
 struct GNUNET_PQ_PreparedStatement
 GNUNET_PQ_make_prepare (const char *name,
                         const char *sql);
 
 
 /**
  * Request creation of prepared statements @a ps from Postgres.
  *
  * @param db database to prepare the statements for
  * @param ps #GNUNET_PQ_PREPARED_STATEMENT_END-terminated array of prepared
  *            statements.
  * @return #GNUNET_OK on success,
  *         #GNUNET_SYSERR on error
  */
 enum GNUNET_GenericReturnValue
 GNUNET_PQ_prepare_statements (struct GNUNET_PQ_Context *db,
                               const struct GNUNET_PQ_PreparedStatement *ps);
 
 
 /**
  * Request creation of prepared statements @a ps from Postgres, but do not
  * automatically re-prepare the statement if we are disconnected from the
  * database.
  *
  * @param db database to prepare the statements for
  * @param ps #GNUNET_PQ_PREPARED_STATEMENT_END-terminated array of prepared
  *            statements.
  * @return #GNUNET_OK on success,
  *         #GNUNET_SYSERR on error
  */
 enum GNUNET_GenericReturnValue
 GNUNET_PQ_prepare_once (struct GNUNET_PQ_Context *db,
                         const struct GNUNET_PQ_PreparedStatement *ps);
 
 
 /* ******************** pq_exec.c functions ************** */
 
 
 /**
  * Information needed to run a list of SQL statements using
  * #GNUNET_PQ_exec_statements().
  */
 struct GNUNET_PQ_ExecuteStatement
 {
   /**
    * Actual SQL statement.
    */
   const char *sql;
 
   /**
    * Should we ignore errors?
    */
   int ignore_errors;
 };
 
 
 /**
  * Terminator for executable statement list.
  */
 #define GNUNET_PQ_EXECUTE_STATEMENT_END \
         {                                     \
           NULL, GNUNET_SYSERR                 \
         }
 
 
 /**
  * Create a `struct GNUNET_PQ_ExecuteStatement` where errors are fatal.
  *
  * @param sql actual SQL statement
  * @return initialized struct
  */
 struct GNUNET_PQ_ExecuteStatement
 GNUNET_PQ_make_execute (const char *sql);
 
 
 /**
  * Create a `struct GNUNET_PQ_ExecuteStatement` where errors should
  * be tolerated.
  *
  * @param sql actual SQL statement
  * @return initialized struct
  */
 struct GNUNET_PQ_ExecuteStatement
 GNUNET_PQ_make_try_execute (const char *sql);
 
 
 /**
  * Request execution of an array of statements @a es from Postgres.
  *
  * @param db database to execute the statements in
  * @param es #GNUNET_PQ_PREPARED_STATEMENT_END-terminated array of prepared
  *            statements.
  * @return #GNUNET_OK on success (modulo statements where errors can be ignored)
  *         #GNUNET_SYSERR on error
  */
 enum GNUNET_GenericReturnValue
 GNUNET_PQ_exec_statements (struct GNUNET_PQ_Context *db,
                            const struct GNUNET_PQ_ExecuteStatement *es);
 
 
 /* ******************** pq_connect.c functions ************** */
 
 
 /**
  * Flags to control PQ operation.
  */
 enum GNUNET_PQ_Options
 {
   /**
    * Traditional default. Do nothing special.
    */
   GNUNET_PQ_FLAG_NONE = 0,
 
   /**
    * Dropping database. Do not attempt to initialize
    * versioning schema if not present.
    */
   GNUNET_PQ_FLAG_DROP = 1,
 
   /**
    * Check database version is current.  Fail to connect if it is not.
    */
   GNUNET_PQ_FLAG_CHECK_CURRENT = 2
 };
 
 
 /**
  * Create a connection to the Postgres database using @a config_str for the
  * configuration.  Initialize logging via GNUnet's log routines and disable
  * Postgres's logger.  Also ensures that the statements in @a load_path and @a
  * es are executed whenever we (re)connect to the database, and that the
  * prepared statements in @a ps are "ready".  If statements in @a es fail that
  * were created with #GNUNET_PQ_make_execute(), then the entire operation
  * fails.
  *
  * In @a load_path, a list of "$XXXX.sql" files is expected where $XXXX
  * must be a sequence of contiguous integer values starting at 0000.
  * These files are then loaded in sequence using "psql $config_str" before
  * running statements from @a es.  The directory is inspected again on
  * reconnect.
  *
  * @param config_str configuration to use
  * @param load_path path to directory with SQL transactions to run, can be NULL
  * @param es #GNUNET_PQ_PREPARED_STATEMENT_END-terminated
  *            array of statements to execute upon EACH connection, can be NULL
  * @param ps array of prepared statements to prepare, can be NULL
  * @return NULL on error
  */
 struct GNUNET_PQ_Context *
 GNUNET_PQ_connect (const char *config_str,
                    const char *load_path,
                    const struct GNUNET_PQ_ExecuteStatement *es,
                    const struct GNUNET_PQ_PreparedStatement *ps);
 
 
 /**
  * Execute SQL statements from @a buf against @a db.
  * The given filename infix in @a buf is prefixed with
  * the "load_path" and ".sql" is appended to construct
  * the full filename.
  *
  * @param db database context to use
  * @param buf filename infix (!) with the SQL code to run
  * @return #GNUNET_OK on success, #GNUNET_NO if patch @a buf does not exist, #GNUNET_SYSERR on error
  */
 enum GNUNET_GenericReturnValue
 GNUNET_PQ_exec_sql (struct GNUNET_PQ_Context *db,
                     const char *buf);
 
 
 /**
  * Create a connection to the Postgres database using @a config_str for the
  * configuration.  Initialize logging via GNUnet's log routines and disable
  * Postgres's logger.  Also ensures that the statements in @a load_path and @a
  * es are executed whenever we (re)connect to the database, and that the
  * prepared statements in @a ps are "ready".  If statements in @a es fail that
  * were created with #GNUNET_PQ_make_execute(), then the entire operation
  * fails.
  *
  * In @a load_path, a list of "$XXXX.sql" files is expected where $XXXX
  * must be a sequence of contiguous integer values starting at 0000.
  * These files are then loaded in sequence using "psql $config_str" before
  * running statements from @e es.  The directory is inspected again on
  * reconnect.
  *
  * @param config_str configuration to use
  * @param load_path path to directory with SQL transactions to run, can be NULL
  * @param auto_suffix infix of SQL series to run on every reconnect; runs multiple (!) files, of the form auto_suffix-XXXX where XXXX is from 0 to 9999 (consecutive).
  * @param es #GNUNET_PQ_PREPARED_STATEMENT_END-terminated
  *            array of statements to execute upon EACH connection, can be NULL
  * @param ps array of prepared statements to prepare, can be NULL
  * @param flags connection flags
  * @return NULL on error
  */
 struct GNUNET_PQ_Context *
 GNUNET_PQ_connect2 (const char *config_str,
                     const char *load_path,
                     const char *auto_suffix,
                     const struct GNUNET_PQ_ExecuteStatement *es,
                     const struct GNUNET_PQ_PreparedStatement *ps,
                     enum GNUNET_PQ_Options flags);
 
 
 /**
  * Connect to a postgres database using the configuration option "CONFIG" in
  * @a section.  Also ensures that the statements in @a es are executed
  * whenever we (re)connect to the database, and that the prepared statements
  * in @a ps are "ready".
  *
  * The caller does not have to ensure that @a es and @a ps remain allocated
  * and initialized in memory until #GNUNET_PQ_disconnect() is called, as a copy will be made.
  *
  * @param cfg configuration
  * @param section configuration section to use to get Postgres configuration options
  * @param load_path_suffix suffix to append to the SQL_DIR in the configuration
  * @param es #GNUNET_PQ_PREPARED_STATEMENT_END-terminated
  *            array of statements to execute upon EACH connection, can be NULL
  * @param ps array of prepared statements to prepare, can be NULL
  * @return the postgres handle, NULL on error
  */
 struct GNUNET_PQ_Context *
 GNUNET_PQ_connect_with_cfg (const struct GNUNET_CONFIGURATION_Handle *cfg,
                             const char *section,
                             const char *load_path_suffix,
                             const struct GNUNET_PQ_ExecuteStatement *es,
                             const struct GNUNET_PQ_PreparedStatement *ps);
 
 
 /**
  * Connect to a postgres database using the configuration
  * option "CONFIG" in @a section.  Also ensures that the
  * statements in @a es are executed whenever we (re)connect to the
  * database, and that the prepared statements in @a ps are "ready".
  *
  * The caller does not have to ensure that @a es and @a ps remain allocated
  * and initialized in memory until #GNUNET_PQ_disconnect() is called, as a
  * copy will be made.
  *
  * @param cfg configuration
  * @param section configuration section to use to get Postgres configuration options
  * @param load_path_suffix suffix to append to the SQL_DIR in the configuration
  * @param es #GNUNET_PQ_PREPARED_STATEMENT_END-terminated
  *            array of statements to execute upon EACH connection, can be NULL
  * @param ps array of prepared statements to prepare, can be NULL
  * @param flags connection flags
  * @return the postgres handle, NULL on error
  */
 struct GNUNET_PQ_Context *
 GNUNET_PQ_connect_with_cfg2 (const struct GNUNET_CONFIGURATION_Handle *cfg,
                              const char *section,
                              const char *load_path_suffix,
                              const struct GNUNET_PQ_ExecuteStatement *es,
                              const struct GNUNET_PQ_PreparedStatement *ps,
                              enum GNUNET_PQ_Options flags);
 
 
 /**
  * Reinitialize the database @a db if the connection is down.
  *
  * @param db database connection to reinitialize
  */
 void
 GNUNET_PQ_reconnect_if_down (struct GNUNET_PQ_Context *db);
 
 
 /**
  * Reinitialize the database @a db.
  *
  * @param db database connection to reinitialize
  */
 void
 GNUNET_PQ_reconnect (struct GNUNET_PQ_Context *db);
 
 
 /**
  * Register callback to be invoked on events of type @a es.
  *
  * Unlike many other calls, this function is thread-safe
  * and may be called from threads that are different
  * from the one that setup @a db. However, the @a cb
  * will always be called from the thread that runs
  * #GNUNET_PQ_event_do_poll() or the GNUnet scheduler.
  *
  * @param db database context to use
  * @param es specification of the event to listen for
  * @param timeout when to trigger @a cb based on timeout
  * @param cb function to call when the event happens, possibly
  *         multiple times (until #GNUNET_PQ_event_listen_cancel() is invoked), including on timeout
  * @param cb_cls closure for @a cb
  * @return handle useful to cancel the listener
  */
 struct GNUNET_DB_EventHandler *
 GNUNET_PQ_event_listen (struct GNUNET_PQ_Context *db,
                         const struct GNUNET_DB_EventHeaderP *es,
                         struct GNUNET_TIME_Relative timeout,
                         GNUNET_DB_EventCallback cb,
                         void *cb_cls);
 
 
 /**
  * Stop notifications.
  *
  * Unlike many other calls, this function is thread-safe
  * and may be called from threads that are different
  * from the one that setup @a db. However, the @a cb
  * will always be called from the thread that runs
  * #GNUNET_PQ_event_do_poll() or the GNUnet scheduler.
  *
  * @param eh handle to unregister.
  */
 void
 GNUNET_PQ_event_listen_cancel (struct GNUNET_DB_EventHandler *eh);
 
 
 /**
  * Poll for events right now. Useful if we may have
  * triggered an event for ourselves.  Not needed when
  * using GNUNET_PQ_event_notify(), but useful when
  * stored procedures may have triggered events.
  * Does nothing if there are no events.
  *
  * @param[in,out] db database to check for events
  */
 void
 GNUNET_PQ_event_do_poll (struct GNUNET_PQ_Context *db);
 
 
 /**
  * Notify all that listen on @a es of an event.
  *
  * Unlike many other calls, this function is thread-safe and may be called
  * from threads that are different from the one that setup @a db. However, the
  * @a cb will always be called from the thread that runs
  * #GNUNET_PQ_event_do_poll() or the GNUnet scheduler.
  *
  * @param db database context to use
  * @param es specification of the event to generate
  * @param extra additional event data provided
  * @param extra_size number of bytes in @a extra
  */
 void
 GNUNET_PQ_event_notify (struct GNUNET_PQ_Context *db,
                         const struct GNUNET_DB_EventHeaderP *es,
                         const void *extra,
                         size_t extra_size);
 
 
 /**
  * Compute the channel that one should notify upon for the given event
  * specification.
  *
  * @param es event specification
  * @return channel to notify upon
  */
 char *
 GNUNET_PQ_get_event_notify_channel (const struct GNUNET_DB_EventHeaderP *es);
 
 
 /**
  * Within the @a db context, run all the SQL files in the load path
  * where the name starts with the @a load_suffix and ends with
  * consecutive numbers from "[0000-9999].sql".
  *
  * @param db database context to use
  * @param load_suffix suffix to append to the load path
  *         to find the XXXX.sql files, usually "subsystem-".
  *
  * @return #GNUNET_OK on success
  */
 enum GNUNET_GenericReturnValue
 GNUNET_PQ_run_sql (struct GNUNET_PQ_Context *db,
                    const char *load_suffix);
 
 
 /**
  * Disconnect from the database, destroying the prepared statements
  * and releasing other associated resources.
  *
  * @param db database handle to disconnect (will be free'd)
  */
 void
 GNUNET_PQ_disconnect (struct GNUNET_PQ_Context *db);
 
 
 #endif /* GNUNET_PQ_LIB_H_ */
 
 /* end of include/gnunet_pq_lib.h */