Return to Exchange after a swap transaction

src/main.c

@@ -252,18 +252,7 @@ void coin_main() {
     app_exit();
 }
 
-struct libargs_s {
-    unsigned int id;
-    unsigned int command;
-    unsigned int unused;
-    union {
-        check_address_parameters_t *check_address;
-        create_transaction_parameters_t *create_transaction;
-        get_printable_amount_parameters_t *get_printable_amount;
-    };
-};
-
-static void library_main_helper(struct libargs_s *args) {
+static void library_main_helper(libargs_t *args) {
     check_api_level(CX_COMPAT_APILEVEL);
     PRINTF("Inside a library \n");
     switch (args->command) {
@@ -290,7 +279,7 @@ static void library_main_helper(struct libargs_s *args) {
     }
 }
 
-void library_main(struct libargs_s *args) {
+void library_main(libargs_t *args) {
     bool end = false;
     /* This loop ensures that library_main_helper and os_lib_end are called
      * within a try context, even if an exception is thrown */
@@ -322,7 +311,7 @@ __attribute__((section(".boot"))) int main(int arg0) {
         coin_main();
     } else {
         // Called as library from another app
-        struct libargs_s *args = (struct libargs_s *) arg0;
+        libargs_t *args = (libargs_t *) arg0;
         if (args->id == 0x100) {
             library_main(args);
         } else {

src/swap/handle_get_printable_amount.c

@@ -1,6 +1,7 @@
 #include <stdint.h>
 
 #include "handle_get_printable_amount.h"
+#include "swap_utils.h"
 #include "../xrp/xrp_helpers.h"
 
 /* return 0 on error, 1 otherwise */

src/swap/handle_swap_sign_transaction.c

@@ -4,6 +4,10 @@
 #include "os_io_seproxyhal.h"
 #include "../apdu/global.h"
 #include "swap_lib_calls.h"
+#include "swap_utils.h"
+
+// Save the BSS address where we will write the return value when finished
+static uint8_t* G_swap_sign_return_value_address;
 
 bool copy_transaction_parameters(create_transaction_parameters_t* params) {
     // first copy parameters to stack, and then to global data.
@@ -27,12 +31,21 @@ bool copy_transaction_parameters(create_transaction_parameters_t* params) {
         return false;
     }
 
+    // Full reset the global variables
     os_explicit_zero_BSS_segment();
+    // Keep the address at wich we'll reply the signing status
+    G_swap_sign_return_value_address = &params->result;
+    // Commit the values read from exchange to the clean global space
     memcpy(&approval_strings.swap, &stack_data, sizeof(stack_data));
 
     return true;
 }
 
+void __attribute__((noreturn)) finalize_exchange_sign_transaction(bool is_success) {
+    *G_swap_sign_return_value_address = is_success;
+    os_lib_end();
+}
+
 void handle_swap_sign_transaction(void) {
     called_from_swap = true;
     reset_transaction_context();

src/swap/handle_swap_sign_transaction.h

@@ -4,6 +4,7 @@
 #include "swap_lib_calls.h"
 
 bool copy_transaction_parameters(create_transaction_parameters_t* sign_transaction_params);
+void __attribute__((noreturn)) finalize_exchange_sign_transaction(bool is_success);
 void handle_swap_sign_transaction(void);
 
 #endif  // _HANDLE_SWAP_SIGN_TRANSACTION_H_

src/swap/swap_lib_calls.h

@@ -1,52 +1,80 @@
 #pragma once
 
-#include <stddef.h>
-#include <stdbool.h>
-#include <stdint.h>
+/* This file is the shared API between Exchange and the apps started in Library mode for Exchange
+ *
+ * DO NOT MODIFY THIS FILE IN APPLICATIONS OTHER THAN EXCHANGE
+ * On modification in Exchange, forward the changes to all applications supporting Exchange
+ */
+
+#include "stdbool.h"
+#include "stdint.h"
+
+#define RUN_APPLICATION 1
 
 #define SIGN_TRANSACTION 2
 
 #define CHECK_ADDRESS 3
 
 #define GET_PRINTABLE_AMOUNT 4
 
+/*
+ * Amounts are stored as bytes, with a max size of 16 (see protobuf
+ * specifications). Max 16B integer is 340282366920938463463374607431768211455
+ * in decimal, which is a 32-long char string.
+ * The printable amount also contains spaces, the ticker symbol (with variable
+ * size, up to 12 in Ethereum for instance) and a terminating null byte, so 50
+ * bytes total should be a fair maximum.
+ */
+#define MAX_PRINTABLE_AMOUNT_SIZE 50
+
 // structure that should be send to specific coin application to get address
 typedef struct check_address_parameters_s {
     // IN
-    unsigned char* coin_configuration;
-    unsigned char coin_configuration_length;
+    uint8_t *coin_configuration;
+    uint8_t coin_configuration_length;
     // serialized path, segwit, version prefix, hash used, dictionary etc.
     // fields and serialization format depends on spesific coin app
-    unsigned char* address_parameters;
-    unsigned char address_parameters_length;
-    char* address_to_check;
-    char* extra_id_to_check;
+    uint8_t *address_parameters;
+    uint8_t address_parameters_length;
+    char *address_to_check;
+    char *extra_id_to_check;
     // OUT
     int result;
 } check_address_parameters_t;
 
 // structure that should be send to specific coin application to get printable amount
 typedef struct get_printable_amount_parameters_s {
     // IN
-    unsigned char* coin_configuration;
-    unsigned char coin_configuration_length;
-    unsigned char* amount;
-    unsigned char amount_length;
+    uint8_t *coin_configuration;
+    uint8_t coin_configuration_length;
+    uint8_t *amount;
+    uint8_t amount_length;
     bool is_fee;
     // OUT
-    char printable_amount[30];
-    // int result;
+    char printable_amount[MAX_PRINTABLE_AMOUNT_SIZE];
 } get_printable_amount_parameters_t;
 
 typedef struct create_transaction_parameters_s {
-    unsigned char* coin_configuration;
-    unsigned char coin_configuration_length;
-    unsigned char* amount;
-    unsigned char amount_length;
-    unsigned char* fee_amount;
-    unsigned char fee_amount_length;
-    char* destination_address;
-    char* destination_address_extra_id;
+    // IN
+    uint8_t *coin_configuration;
+    uint8_t coin_configuration_length;
+    uint8_t *amount;
+    uint8_t amount_length;
+    uint8_t *fee_amount;
+    uint8_t fee_amount_length;
+    char *destination_address;
+    char *destination_address_extra_id;
+    // OUT
+    uint8_t result;
 } create_transaction_parameters_t;
 
-bool swap_str_to_u64(const uint8_t* src, size_t length, uint64_t* result);
+typedef struct libargs_s {
+    unsigned int id;
+    unsigned int command;
+    unsigned int unused;
+    union {
+        check_address_parameters_t *check_address;
+        create_transaction_parameters_t *create_transaction;
+        get_printable_amount_parameters_t *get_printable_amount;
+    };
+} libargs_t;

src/swap/swap_lib_calls.c → src/swap/swap_utils.c

@@ -1,6 +1,6 @@
 #include <string.h>
 
-#include "swap_lib_calls.h"
+#include "swap_utils.h"
 
 bool swap_str_to_u64(const uint8_t* src, size_t length, uint64_t* result) {
     const size_t num_bytes = 8;

src/swap/swap_utils.h

@@ -0,0 +1,7 @@
+#pragma once
+
+#include <stddef.h>
+#include <stdbool.h>
+#include <stdint.h>
+
+bool swap_str_to_u64(const uint8_t* src, size_t length, uint64_t* result);

src/transaction/transaction.c

@@ -25,6 +25,7 @@
 #include "../xrp/format.h"
 #include "../xrp/readers.h"
 #include "../xrp/xrp_helpers.h"
+#include "handle_swap_sign_transaction.h"
 #include <string.h>
 
 static action_t approval_action;
@@ -172,11 +173,11 @@ void review_transaction(parseResult_t *transaction, action_t on_approve, action_
     if (called_from_swap) {
         if (check_swap_conditions_and_sign(transaction)) {
             approval_action();
+            finalize_exchange_sign_transaction(true);
         } else {
             rejection_action();
+            finalize_exchange_sign_transaction(false);
         }
-        called_from_swap = false;
-        os_sched_exit(0);
     } else {
         display_review_menu(transaction, on_approval_menu_result);
     }

tests/src/test_swap.c

@@ -7,6 +7,7 @@
 
 #include "cx.h"
 #include "../src/swap/handle_check_address.h"
+#include "../src/swap/swap_utils.h"
 #include "../src/xrp/xrp_helpers.h"
 
 void test_check_address(void **state) {