Use a std::string_view for JSON data

CHANGELOG.md

@@ -5,6 +5,7 @@ All notable changes to this project will be documented in this file.
 ## [Unreleased]
 
 - Hold direction buttons to change IP.
+- Fix a hang that occurs after 30 minutes.
 
 ## [1.3.0] - 2024-03-18
 

source/main.cpp

@@ -175,12 +175,9 @@ static int sendPadData() {
             }
         }
 
-        // The buffer sent to the computer
-        char msg_data[2048];
-        pad_to_json(pad_data, msg_data, sizeof(msg_data));
-
-        // Send the message
-        udp_print(msg_data);
+        // Convert the data to JSON and send it
+        std::string_view msg = pad_to_json(pad_data);
+        udp_print(msg);
 
         // Make a small delay to prevent filling up the computer receive buffer
         std::this_thread::sleep_for(std::chrono::milliseconds(10));

source/udp.cpp

@@ -19,7 +19,7 @@ static volatile bool udp_lock = false;
  * @param ipString The IP address to connect to.
  * @param ipport The port to connect to.
  */
-void udp_init(const char * ipString, uint16_t ipport)
+void udp_init(std::string_view ipString, uint16_t ipport)
 {
     udp_socket = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);
     if(udp_socket < 0) {
@@ -30,10 +30,9 @@ void udp_init(const char * ipString, uint16_t ipport)
     memset(&connect_addr, 0, sizeof(connect_addr));
     connect_addr.sin_family = AF_INET;
     connect_addr.sin_port = ipport;
-    inet_aton(ipString, &connect_addr.sin_addr);
+    inet_aton(ipString.data(), &connect_addr.sin_addr);
 
-    if(connect(udp_socket, (struct sockaddr*)&connect_addr, sizeof(connect_addr)) < 0)
-    {
+    if(connect(udp_socket, (struct sockaddr*)&connect_addr, sizeof(connect_addr)) < 0) {
         close(udp_socket);
         udp_socket = -1;
     }
@@ -44,8 +43,7 @@ void udp_init(const char * ipString, uint16_t ipport)
  */
 void udp_deinit(void)
 {
-    if(udp_socket >= 0)
-    {
+    if(udp_socket >= 0) {
         close(udp_socket);
         udp_socket = -1;
     }
@@ -56,7 +54,7 @@ void udp_deinit(void)
  * @param str The string to send.
  * @return Returns true on success, false otherwise.
  */
-bool udp_print(const char *str)
+bool udp_print(std::string_view str)
 {
     // socket is always 0 initially as it is in the BSS
     if(udp_socket < 0) {
@@ -70,17 +68,15 @@ bool udp_print(const char *str)
 
     bool result = true;
 
-    int len = strlen(str);
-    while (len > 0) {
-        const int block = len < 1400 ? len : 1400; // take max 1400 bytes per UDP packet
-        const int ret = send(udp_socket, str, block, 0);
+    while (str.empty() == false) {
+        const size_t block = std::min(str.size(), static_cast<size_t>(1400)); // take max 1400 bytes per UDP packet
+        const ssize_t ret = send(udp_socket, str.data(), block, 0);
         if(ret < 0) {
             result = false;
             break;
         }
 
-        len -= ret;
-        str += ret;
+        str.remove_prefix(ret);
     }
 
     udp_lock = false;

source/udp.h

@@ -1,15 +1,15 @@
 #pragma once
 
-#include <stdbool.h>
-#include <stdint.h>
+#include <cstdint>
+#include <string_view>
 
 #ifdef __cplusplus
 extern "C" {
 #endif
 
-void udp_init(const char * ipString, uint16_t ipport);
+void udp_init(std::string_view ipString, uint16_t ipport);
 void udp_deinit(void);
-bool udp_print(const char *str);
+bool udp_print(std::string_view str);
 
 #ifdef __cplusplus
 }

source/vpad_to_json.cpp

@@ -39,10 +39,9 @@ static const std::map gcmask = {
 /**
  * Convert GamePad data to JSON string used by UsendMii.
  * @param[in] pad_data Controllers data.
- * @param[out] out Buffer where to copy the formatted data.
- * @param[in] out_size Size of the out buffer.
+ * @return Returns the JSON string.
  */
-void pad_to_json(PADData pad_data, char* out, uint32_t out_size)
+std::string_view pad_to_json(PADData pad_data)
 {
     VPADTouchData TPCalibrated;
     VPADGetTPCalibratedPointEx(VPAD_CHAN_0, VPAD_TP_854X480, &TPCalibrated, &pad_data.vpad->tpNormal);
@@ -266,6 +265,6 @@ void pad_to_json(PADData pad_data, char* out, uint32_t out_size)
 
     writer.EndObject(); // End root object
 
-    // Convert to string
-    strncpy(out, sb.GetString(), out_size);
+    // Convert to string_view
+    return std::string_view(sb.GetString(), sb.GetSize());
 }

source/vpad_to_json.h

@@ -5,6 +5,7 @@
 #include <padscore/kpad.h>
 #include <vpad/input.h>
 #include <nn/hpad/hpad.h>
+#include <string_view>
 
 #ifdef __cplusplus
 extern "C" {
@@ -19,7 +20,7 @@ typedef struct {
     HPADStatus* hpad[4];  /**< USB Gamecube Controller Adapter. */
 } PADData;
 
-void pad_to_json(PADData pad_data, char* out, uint32_t out_size);
+std::string_view pad_to_json(PADData pad_data);
 
 #ifdef __cplusplus
 }