Add rent exemption check (#155)

Author: tompntn

program/src/oracle/oracle.c

@@ -5,6 +5,30 @@
 #include "oracle.h"
 #include "upd_aggregate.h"
 
+// Returns the minimum number of lamports required to make an account
+// with dlen bytes of data rent exempt. These values were calculated 
+// using the getMinimumBalanceForRentExemption RPC call, and are
+// guaranteed never to increase.
+static uint64_t rent_exempt_amount( uint64_t dlen )
+{
+  switch ( dlen )
+  {
+  case sizeof( pc_map_table_t ):
+    return 143821440;
+  case PC_PROD_ACC_SIZE:
+    return 4454400;
+  case sizeof( pc_price_t ):
+    return 23942400;
+  default:
+    return UINT64_MAX;
+  }
+}
+
+static bool is_rent_exempt( uint64_t lamports, uint64_t dlen )
+{
+  return lamports >= rent_exempt_amount( dlen );
+}
+
 static bool valid_funding_account( SolAccountInfo *ka )
 {
   return ka->is_signer &&
@@ -18,7 +42,8 @@ static bool valid_signable_account( SolParameters *prm,
   return ka->is_signer &&
          ka->is_writable &&
          SolPubkey_same( ka->owner, prm->program_id ) &&
-         ka->data_len >= dlen;
+         ka->data_len >= dlen &&
+         is_rent_exempt( *ka->lamports, dlen );
 }
 
 static bool valid_writable_account( SolParameters *prm,
@@ -27,7 +52,8 @@ static bool valid_writable_account( SolParameters *prm,
 {
   return ka->is_writable &&
          SolPubkey_same( ka->owner, prm->program_id ) &&
-         ka->data_len >= dlen;
+         ka->data_len >= dlen &&
+         is_rent_exempt( *ka->lamports, dlen );
 }
 
 static uint64_t init_mapping( SolParameters *prm, SolAccountInfo *ka )

program/src/oracle/test_oracle.c

@@ -4,6 +4,10 @@ char heap_start[8192];
 #include "sort.c"
 #include <criterion/criterion.h>
 
+uint64_t MAPPING_ACCOUNT_LAMPORTS = 143821440;
+uint64_t PRODUCT_ACCOUNT_LAMPORTS = 4454400;
+uint64_t PRICE_ACCOUNT_LAMPORTS = 23942400;
+
 Test(oracle, init_mapping) {
 
   // start with perfect inputs
@@ -30,7 +34,7 @@ Test(oracle, init_mapping) {
       .executable  = false
   },{
       .key         = &mkey,
-      .lamports    = &pqty,
+      .lamports    = &MAPPING_ACCOUNT_LAMPORTS,
       .data_len    = sizeof( pc_map_table_t ),
       .data        = (uint8_t*)mptr,
       .owner       = &p_id,
@@ -96,7 +100,7 @@ Test(oracle, add_mapping ) {
   SolPubkey pkey = {.x = { 1, }};
   SolPubkey tkey = {.x = { 2, }};
   SolPubkey mkey = {.x = { 3, }};
-  uint64_t pqty = 100, tqty = 100;
+  uint64_t pqty = 100;
   pc_map_table_t mptr[1];
   sol_memset( mptr, 0, sizeof( pc_map_table_t ) );
   SolAccountInfo acc[] = {{
@@ -111,7 +115,7 @@ Test(oracle, add_mapping ) {
       .executable  = false
   },{
       .key         = &tkey,
-      .lamports    = &pqty,
+      .lamports    = &MAPPING_ACCOUNT_LAMPORTS,
       .data_len    = sizeof( pc_map_table_t ),
       .data        = (uint8_t*)tptr,
       .owner       = &p_id,
@@ -121,7 +125,7 @@ Test(oracle, add_mapping ) {
       .executable  = false
   },{
       .key         = &mkey,
-      .lamports    = &tqty,
+      .lamports    = &MAPPING_ACCOUNT_LAMPORTS,
       .data_len    = sizeof( pc_map_table_t ),
       .data        = (uint8_t*)mptr,
       .owner       = &p_id,
@@ -186,7 +190,7 @@ Test(oracle, add_product) {
       .executable  = false
   },{
       .key         = &mkey,
-      .lamports    = &pqty,
+      .lamports    = &MAPPING_ACCOUNT_LAMPORTS,
       .data_len    = sizeof( pc_map_table_t ),
       .data        = (uint8_t*)mptr,
       .owner       = &p_id,
@@ -196,7 +200,7 @@ Test(oracle, add_product) {
       .executable  = false
   },{
       .key         = &skey,
-      .lamports    = &pqty,
+      .lamports    = &PRODUCT_ACCOUNT_LAMPORTS,
       .data_len    = PC_PROD_ACC_SIZE,
       .data        = (uint8_t*)sptr,
       .owner       = &p_id,
@@ -259,7 +263,7 @@ Test( oracle, add_publisher ) {
   SolPubkey p_id  = {.x = { 0xff, }};
   SolPubkey pkey = {.x = { 1, }};
   SolPubkey skey = {.x = { 3, }};
-  uint64_t pqty = 100, sqty = 200;
+  uint64_t pqty = 100;
   pc_price_t sptr[1];
   sol_memset( sptr, 0, sizeof( pc_price_t ) );
   sptr->magic_ = PC_MAGIC;
@@ -278,7 +282,7 @@ Test( oracle, add_publisher ) {
       .executable  = false
   },{
       .key         = &skey,
-      .lamports    = &sqty,
+      .lamports    = &pqty,
       .data_len    = sizeof( pc_price_t ),
       .data        = (uint8_t*)sptr,
       .owner       = &p_id,
@@ -294,6 +298,13 @@ Test( oracle, add_publisher ) {
     .data_len   = sizeof( idata ),
     .program_id = &p_id
   };
+
+  // Expect the instruction to fail, because the price account isn't rent exempt
+  cr_assert( ERROR_INVALID_ARGUMENT == dispatch( &prm, acc ) );
+
+  // Now give the price account enough lamports to be rent exempt
+  acc[1].lamports = &PRICE_ACCOUNT_LAMPORTS;
+  
   cr_assert( SUCCESS == dispatch( &prm, acc ) );
   cr_assert( sptr->num_ == 1 );
   cr_assert( pc_pub_key_equal( &idata.pub_, &sptr->comp_[0].pub_ ) );
@@ -358,7 +369,7 @@ Test( oracle, upd_test ) {
       .executable  = false
   },{
       .key         = &mkey,
-      .lamports    = &pqty,
+      .lamports    = &PRICE_ACCOUNT_LAMPORTS,
       .data_len    = sizeof( pc_price_t ),
       .data        = (uint8_t*)mptr,
       .owner       = &p_id,
@@ -436,7 +447,7 @@ Test( oracle, upd_price ) {
       .executable  = false
   },{
       .key         = &skey,
-      .lamports    = &sqty,
+      .lamports    = &PRICE_ACCOUNT_LAMPORTS,
       .data_len    = sizeof( pc_price_t ),
       .data        = (uint8_t*)sptr,
       .owner       = &p_id,
@@ -547,7 +558,7 @@ Test( oracle, upd_price_no_fail_on_error ) {
       .executable  = false
   },{
       .key         = &skey,
-      .lamports    = &sqty,
+      .lamports    = &PRICE_ACCOUNT_LAMPORTS,
       .data_len    = sizeof( pc_price_t ),
       .data        = (uint8_t*)sptr,
       .owner       = &p_id,
@@ -745,7 +756,7 @@ Test( oracle, del_publisher ) {
   };
   SolPubkey pkey = {.x = { 1, }};
   SolPubkey skey = {.x = { 3, }};
-  uint64_t pqty = 100, sqty = 200;
+  uint64_t pqty = 100;
   pc_price_t sptr[1];
   sol_memset( sptr, 0, sizeof( pc_price_t ) );
   sptr->magic_ = PC_MAGIC;
@@ -768,7 +779,7 @@ Test( oracle, del_publisher ) {
       .executable  = false
   },{
       .key         = &skey,
-      .lamports    = &sqty,
+      .lamports    = &PRICE_ACCOUNT_LAMPORTS,
       .data_len    = sizeof( pc_price_t ),
       .data        = (uint8_t*)sptr,
       .owner       = (SolPubkey*)&p_id,