merchant

commit 60e2a7848465684a35041df7f56cd57d54941d16
parent 9458a7ddacc7b3939777fa9a5b802484451849a5
Author: Christian Grothoff <christian@grothoff.org>
Date:   Thu,  6 Aug 2026 00:14:37 +0200

fix stock update to include monotonicity constraint on fractional stock

Diffstat:
M
src/backenddb/test_merchantdb.c
 | 
33
+++++++++++++++++++++++++++++++++
M
src/backenddb/update_product.sql
 | 
7
++++++-

2 files changed, 39 insertions(+), 1 deletion(-)
diff --git a/src/backenddb/test_merchantdb.c b/src/backenddb/test_merchantdb.c
@@ -2070,6 +2070,39 @@ run_test_products (struct TestProducts_Closure *cls)
                       false,
                       -1));
 
+  /* Stock is the pair (total_stock, total_stock_frac): raise the
+     fractional part, then check that lowering only the fractional part
+     is refused just like lowering the integer part. */
+  cls->products[0].product.total_stock_frac = 500000;
+  TEST_RET_ON_FAIL (test_update_product (
+                      &cls->instance,
+                      &cls->products[0],
+                      0,
+                      NULL,
+                      GNUNET_DB_STATUS_SUCCESS_ONE_RESULT,
+                      false,
+                      false,
+                      false,
+                      false,
+                      false,
+                      -1));
+  {
+    struct ProductData frac_dec = cls->products[0];
+
+    frac_dec.product.total_stock_frac = 400000;
+    TEST_RET_ON_FAIL (test_update_product (
+                        &cls->instance,
+                        &frac_dec,
+                        0,
+                        NULL,
+                        GNUNET_DB_STATUS_SUCCESS_ONE_RESULT,
+                        false,
+                        false,
+                        false,
+                        false,
+                        true,
+                        -1));
+  }
   {
     struct ProductData stock_dec = cls->products[0];
 
diff --git a/src/backenddb/update_product.sql b/src/backenddb/update_product.sql
@@ -103,7 +103,12 @@ END IF;
 
 my_product_serial = rec.product_serial;
 
-IF rec.total_stock > in_total_stock
+-- Stock is the pair (total_stock, total_stock_frac); comparing only the
+-- integer part would let a PATCH that keeps total_stock but lowers
+-- total_stock_frac slip past this guard.
+IF (rec.total_stock > in_total_stock)
+   OR (    (rec.total_stock = in_total_stock)
+       AND (rec.total_stock_frac > in_total_stock_frac) )
 THEN
   out_stocked_reduced=TRUE;
   RETURN;