[WiP] added TALER_AMOUNT type to Postgres - first in age_withdraw

- Added a type TALER_AMOUNT (val INT8, frac INT4) to Postgres.

- Added PLSQL functions/procedures
	- amount_normalize(a)
	- amount_add(a, b)
	- amount_left_minus_right(l, r, diff, ok bool)

- Added PQ-helper functions
	- TALER_PQ_query_param_amount_tuple()
	- TALER_PQ_result_spec_amount_tuple()

- In table 'age_withdraw', changed fields 'amount_with_fee_val' and '..._frac'
  into single field 'amount_with_fee' be of type TALER_AMOUNT

- Changed functions/stored procedures 'do_age_withdraw' and
  'get_age_withdraw' to use new APIs.

=> make check runs through without errors,
   age-withdraw and -reveal test passes.

2 files changed, 223 insertions, 5 deletions

diff --git a/src/pq/pq_query_helper.c b/src/pq/pq_query_helper.c
index 9a02cddab..9ada23575 100644
--- a/src/pq/pq_query_helper.c
+++ b/src/pq/pq_query_helper.c
@@ -21,6 +21,7 @@
  * @author Christian Grothoff
  */
 #include "platform.h"
+#include <gnunet/gnunet_common.h>
 #include <gnunet/gnunet_util_lib.h>
 #include <gnunet/gnunet_pq_lib.h>
 #include "taler_pq_lib.h"
@@ -150,6 +151,84 @@ TALER_PQ_query_param_amount (const struct TALER_Amount *x)
 
 
 /**
+ * Function called to convert input amount into SQL parameter as tuple.
+ *
+ * @param cls closure
+ * @param data pointer to input argument, here a `struct TALER_Amount`
+ * @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
+ */
+static int
+qconv_amount_tuple (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)
+{
+  const struct GNUNET_PQ_Context *db = cls;
+  const struct TALER_Amount *amount = data;
+  size_t sz;
+
+  GNUNET_assert (NULL != db);
+  GNUNET_assert (NULL != amount);
+  GNUNET_assert (1 == param_length);
+  GNUNET_assert (1 <= scratch_length);
+  GNUNET_assert (sizeof (struct TALER_Amount) == data_len);
+  GNUNET_static_assert (sizeof(uint32_t) == sizeof(Oid));
+
+  {
+    char *out;
+    struct TALER_PQ_Amount_P d = MAKE_TALER_PQ_AMOUNT_P (db, amount);
+
+    sz = sizeof(uint32_t); /* number of elements in tuple */
+    sz += sizeof(d);
+
+    out = GNUNET_malloc (sz);
+    scratch[0] = out;
+
+    *(uint32_t *) out = htonl (2);
+    out += sizeof(uint32_t);
+
+    *(struct TALER_PQ_Amount_P*) out = d;
+
+  }
+
+  param_values[0] = scratch[0];
+  param_lengths[0] = sz;
+  param_formats[0] = 1;
+
+  return 1;
+}
+
+
+struct GNUNET_PQ_QueryParam
+TALER_PQ_query_param_amount_tuple (
+  const struct GNUNET_PQ_Context *db,
+  const struct TALER_Amount *amount)
+{
+  struct GNUNET_PQ_QueryParam res = {
+    .conv_cls = (void *) db,
+    .conv = &qconv_amount_tuple,
+    .data = amount,
+    .size = sizeof (*amount),
+    .num_params = 1,
+  };
+
+  return res;
+}
+
+
+/**
  * Function called to convert input argument into SQL parameters.
  *
  * @param cls closure
@@ -793,7 +872,7 @@ qconv_array (
     RETURN_UNLESS ((0 == num) || (y / num == x));
 
     /* size of header */
-    total_size  = x = sizeof(struct TALER_PQ_ArrayHeader);
+    total_size  = x = sizeof(struct TALER_PQ_ArrayHeader_P);
     total_size += y;
     RETURN_UNLESS (total_size >= x);
 
@@ -862,7 +941,7 @@ qconv_array (
   /* Write data */
   {
     char *out = elements;
-    struct TALER_PQ_ArrayHeader h = {
+    struct TALER_PQ_ArrayHeader_P h = {
       .ndim = htonl (1),        /* We only support one-dimensional arrays */
       .has_null = htonl (0),    /* We do not support NULL entries in arrays */
       .lbound = htonl (1),      /* Default start index value */
diff --git a/src/pq/pq_result_helper.c b/src/pq/pq_result_helper.c
index 0a734bbc9..3ef2e71fb 100644
--- a/src/pq/pq_result_helper.c
+++ b/src/pq/pq_result_helper.c
@@ -265,6 +265,145 @@ TALER_PQ_result_spec_amount (const char *name,
 
 
 /**
+ * Extract an amount from a tuple from a Postgres database @a result at row @a row.
+ *
+ * @param cls closure, a `const char *` giving the currency
+ * @param result where to extract data from
+ * @param row 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 at least one result was NULL
+ *   #GNUNET_SYSERR if a result was invalid (non-existing field)
+ */
+static enum GNUNET_GenericReturnValue
+extract_amount_tuple (void *cls,
+                      PGresult *result,
+                      int row,
+                      const char *fname,
+                      size_t *dst_size,
+                      void *dst)
+{
+  struct TALER_Amount *r_amount = dst;
+  const char *currency = cls;
+  int col;
+  int len;
+
+  if (sizeof (struct TALER_Amount) != *dst_size)
+  {
+    GNUNET_break (0);
+    return GNUNET_SYSERR;
+  }
+
+  /* Set return value to invalid in case we don't finish */
+  memset (r_amount,
+          0,
+          sizeof (struct TALER_Amount));
+  col = PQfnumber (result,
+                   fname);
+  if (col < 0)
+  {
+    GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
+                "Field `%s' does not exist in result\n",
+                fname);
+    return GNUNET_SYSERR;
+  }
+  if (PQgetisnull (result,
+                   row,
+                   col))
+  {
+    return GNUNET_NO;
+  }
+
+  /* Parse the tuple */
+  {
+    char *in;
+    uint32_t num;
+    struct TALER_PQ_Amount_P ap;
+    int size;
+    const static int expected_size = sizeof(uint32_t) /* length */
+                                     + sizeof(struct TALER_PQ_Amount_P);
+
+    size = PQgetlength (result,
+                        row,
+                        col);
+
+    if (expected_size != size)
+    {
+      GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
+                  "Incorrect size of binary field `%s' (got %d, expected %d)\n",
+                  fname,
+                  size,
+                  expected_size);
+      return GNUNET_SYSERR;
+    }
+
+    in = PQgetvalue (result,
+                     row,
+                     col);
+
+    num = ntohl (*(uint32_t *) in);
+    if (2 != num)
+    {
+      GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
+                  "Incorrect number of elements in tuple-field `%s'\n",
+                  fname);
+      return GNUNET_SYSERR;
+    }
+    in += sizeof(uint32_t);
+    ap = *(struct TALER_PQ_Amount_P *) in;
+
+    /* TODO[oec]: OID-checks? */
+
+    r_amount->value = GNUNET_ntohll (ap.v);
+    r_amount->fraction = ntohl (ap.f);
+  }
+
+  if (r_amount->value >= TALER_AMOUNT_MAX_VALUE)
+  {
+    GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
+                "Value in field `%s' exceeds legal range\n",
+                fname);
+    return GNUNET_SYSERR;
+  }
+  if (r_amount->fraction >= TALER_AMOUNT_FRAC_BASE)
+  {
+    GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
+                "Fraction in field `%s' exceeds legal range\n",
+                fname);
+    return GNUNET_SYSERR;
+  }
+
+  len = GNUNET_MIN (TALER_CURRENCY_LEN - 1,
+                    strlen (currency));
+
+  GNUNET_memcpy (r_amount->currency,
+                 currency,
+                 len);
+  return GNUNET_OK;
+}
+
+
+struct GNUNET_PQ_ResultSpec
+TALER_PQ_result_spec_amount_tuple (const char *name,
+                                   const char *currency,
+                                   struct TALER_Amount *amount)
+{
+  struct GNUNET_PQ_ResultSpec res = {
+    .conv = &extract_amount_tuple,
+    .cls = (void *) currency,
+    .dst = (void *) amount,
+    .dst_size = sizeof (*amount),
+    .fname = name
+  };
+
+  return res;
+}
+
+
+/**
  * Extract data from a Postgres database @a result at row @a row.
  *
  * @param cls closure
@@ -1027,7 +1166,7 @@ extract_array_generic (
   int data_sz;
   char *data;
   void *out = NULL;
-  struct TALER_PQ_ArrayHeader header;
+  struct TALER_PQ_ArrayHeader_P header;
   int col_num;
 
   GNUNET_assert (NULL != dst);
@@ -1053,8 +1192,8 @@ extract_array_generic (
   FAIL_IF (NULL == data);
 
   {
-    struct TALER_PQ_ArrayHeader *h =
-      (struct TALER_PQ_ArrayHeader *) data;
+    struct TALER_PQ_ArrayHeader_P *h =
+      (struct TALER_PQ_ArrayHeader_P *) data;
 
     header.ndim = ntohl (h->ndim);
     header.has_null = ntohl (h->has_null);