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Some error handling in get serial port names #171

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103 changes: 69 additions & 34 deletions src/main/cpp/windows/jssc.cpp
Original file line number Diff line number Diff line change
Expand Up @@ -24,6 +24,7 @@
*/
#include <jni.h>
#include <stdlib.h>
#include <stdio.h>
#include <windows.h>
#include <jssc_SerialNativeInterface.h>
#include "version.h"
Expand Down Expand Up @@ -643,47 +644,81 @@ JNIEXPORT jobjectArray JNICALL Java_jssc_SerialNativeInterface_waitEvents
*/
JNIEXPORT jobjectArray JNICALL Java_jssc_SerialNativeInterface_getSerialPortNames
(JNIEnv *env, jobject){
HKEY phkResult;
HKEY phkResult = NULL;
LPCSTR lpSubKey = "HARDWARE\\DEVICEMAP\\SERIALCOMM\\";
jobjectArray returnArray = NULL;
if(RegOpenKeyExA(HKEY_LOCAL_MACHINE, lpSubKey, 0, KEY_READ, &phkResult) == ERROR_SUCCESS){
boolean hasMoreElements = true;
DWORD keysCount = 0;
char valueName[256];
DWORD valueNameSize;
DWORD enumResult;
while(hasMoreElements){
valueNameSize = 256;
enumResult = RegEnumValueA(phkResult, keysCount, valueName, &valueNameSize, NULL, NULL, NULL, NULL);
if(enumResult == ERROR_SUCCESS){
keysCount++;
}
else if(enumResult == ERROR_NO_MORE_ITEMS){
hasMoreElements = false;
}
else {
hasMoreElements = false;
}
byte lpDataOnStack[256];
byte *lpData = lpDataOnStack;
DWORD lpData_capacity = 256;
char valueName[256];
DWORD valueNameSize;
DWORD enumResult;
boolean hasMoreElements = true;
DWORD keysCount = 0;
if(RegOpenKeyExA(HKEY_LOCAL_MACHINE, lpSubKey, 0, KEY_READ, &phkResult) != ERROR_SUCCESS){
returnArray = NULL;
goto Finally;
}
/* Iterate a 1st time to see how long our resulting array has to be. */
while(hasMoreElements){
valueNameSize = 256;
enumResult = RegEnumValueA(phkResult, keysCount, valueName, &valueNameSize, NULL, NULL, NULL, NULL);
if(enumResult == ERROR_SUCCESS){
keysCount++;
}
if(keysCount > 0){
jclass stringClass = env->FindClass("java/lang/String");
returnArray = env->NewObjectArray((jsize)keysCount, stringClass, NULL);
char lpValueName[256];
DWORD lpcchValueName;
byte lpData[256];
DWORD lpcbData;
DWORD result;
for(DWORD i = 0; i < keysCount; i++){
lpcchValueName = 256;
lpcbData = 256;
result = RegEnumValueA(phkResult, i, lpValueName, &lpcchValueName, NULL, NULL, lpData, &lpcbData);
if(result == ERROR_SUCCESS){
env->SetObjectArrayElement(returnArray, i, env->NewStringUTF((char*)lpData));
else if(enumResult == ERROR_NO_MORE_ITEMS){
hasMoreElements = false;
}
else {
hasMoreElements = false;
}
}
if(keysCount > 0){
jclass stringClass = env->FindClass("java/lang/String");
returnArray = env->NewObjectArray((jsize)keysCount, stringClass, NULL);
DWORD lpcbData;
DWORD result;
/* iterate 2nd time but this time our array is ready to catch results. */
for(DWORD i = 0; i < keysCount; i++){
valueNameSize = 256;
lpcbData = lpData_capacity;
result = RegEnumValueA(phkResult, i, valueName, &valueNameSize, NULL, NULL, lpData, &lpcbData);
if(result == ERROR_SUCCESS){
env->SetObjectArrayElement(returnArray, i, env->NewStringUTF((char*)lpData));
}else if(result == ERROR_MORE_DATA && lpData_capacity < UINT_MAX){
/* whoops our supplied buffer was not large enough. Fallback to a heap
* allocd one. RegEnumValueA was kind enough to set 'lpcbData' to the
* required length before return. */
lpData = (lpData == lpDataOnStack) ? NULL : lpData;
/* MS doc is unclear to me if returned size includes the required
* zero-term. So to stay safe, we provide one byte more. */
if(lpcbData < UINT_MAX) lpcbData += 1;
byte *tmp = (byte*)realloc(lpData, lpcbData*sizeof*tmp);
if(tmp == NULL){
jclass exClz = env->FindClass("java/lang/OutOfMemoryError");
if(exClz != NULL) env->ThrowNew(exClz, NULL);
returnArray = NULL;
goto Finally;
}
/* install new buffer and reset 'i' so we try the same element again. */
lpData_capacity = lpcbData;
lpData = tmp;
i -= 1;
}else{
char exMsg[128];
snprintf(exMsg, sizeof exMsg, "RegEnumValueA(): Code %ld: "
"https://learn.microsoft.com/en-us/windows/win32/debug/system-error-codes#system-error-codes",
result);
jclass exClz = env->FindClass("java/lang/RuntimeException");
if(exClz != NULL) env->ThrowNew(exClz, exMsg);
returnArray = NULL;
goto Finally;
}
}
CloseHandle(phkResult);
}
Finally:
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if(lpData != NULL && lpData != lpDataOnStack) free(lpData);
if(phkResult != NULL) CloseHandle(phkResult);
return returnArray;
}

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