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In writeBytes return actual numBytesWritten #195

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a7ec5da
Make writeBytes() return how many bytes actually got written
hiddenalpha Jul 27, 2025
64c3610
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hiddenalpha Jul 30, 2025
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51 changes: 28 additions & 23 deletions src/main/cpp/_nix_based/jssc.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -29,7 +29,6 @@
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <string.h>
#include <sys/ioctl.h>
#include <termios.h>
#include <time.h>
Expand All @@ -40,7 +39,6 @@
#endif
#ifdef __sun
#include <sys/filio.h>//Needed for FIONREAD in Solaris
#include <string.h>//Needed for select() function
#endif
#ifdef __APPLE__
#include <serial/ioss.h>//Needed for IOSSIOSPEED in Mac OS X (Non standard baudrate)
Expand All @@ -62,7 +60,16 @@
#include <jssc_SerialNativeInterface.h>
#include "version.h"

//#include <iostream> //-lCstd use for Solaris linker
#if defined(_MSC_VER) && _MSC_VER < 1800
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# define PRIsz "Iu"
# define PRIssz "Id"
#elif defined(__MINGW32__) && !defined(__MINGW64__)
# define PRIsz "u"
# define PRIssz "d"
#else
# define PRIsz "zu"
# define PRIssz "zd"
#endif

/*
* Get native library version
Expand Down Expand Up @@ -529,33 +536,31 @@ JNIEXPORT jboolean JNICALL Java_jssc_SerialNativeInterface_setDTR
/*
* Writing data to the port
*/
JNIEXPORT jboolean JNICALL Java_jssc_SerialNativeInterface_writeBytes
JNIEXPORT jint JNICALL Java_jssc_SerialNativeInterface_writeBytes
(JNIEnv *env, jobject, jlong portHandle, jbyteArray buffer){
if( buffer == NULL ){
ssize_t ret = 0;
jbyte *jBuffer = NULL;
if( !buffer ){
jclass exClz = env->FindClass("java/lang/NullPointerException");
if( exClz != NULL ) env->ThrowNew(exClz, "buffer");
return 0;
if( exClz ) env->ThrowNew(exClz, "buffer");
goto Finally;
}
jboolean ret = JNI_FALSE;
jbyte* jBuffer = env->GetByteArrayElements(buffer, JNI_FALSE);
if( jBuffer == NULL ){
jclass exClz = env->FindClass("java/lang/RuntimeException");
if( exClz != NULL ) env->ThrowNew(exClz, "jni->GetByteArrayElements() failed");
return 0;
jBuffer = env->GetByteArrayElements(buffer, NULL);
if( !jBuffer ){
jclass exClz = env->ExceptionCheck() ? NULL : env->FindClass("java/lang/RuntimeException");
if( exClz ) env->ThrowNew(exClz, "jni->GetByteArrayElements() failed");
goto Finally;
}
jint bufferSize = env->GetArrayLength(buffer);
jint result = write(portHandle, jBuffer, (size_t)bufferSize);
if( result == -1 ){
int err = errno; /*bakup errno*/
ret = write(portHandle, jBuffer, env->GetArrayLength(buffer));
if( ret == -1 ){
int err = errno;
jclass exClz = env->FindClass("java/io/IOException");
assert(exClz != NULL);
env->ThrowNew(exClz, strerror(err));
if( exClz ) env->ThrowNew(exClz, strerror(err));
goto Finally;
}
ret = (result == bufferSize) ? JNI_TRUE : JNI_FALSE;
Finally:
env->ReleaseByteArrayElements(buffer, jBuffer, 0);
return ret;
if( jBuffer ) env->ReleaseByteArrayElements(buffer, jBuffer, 0);
return (jint)ret;
}

/**
Expand Down Expand Up @@ -676,7 +681,7 @@ JNIEXPORT jbyteArray JNICALL Java_jssc_SerialNativeInterface_readBytes
lpBuffer = (jbyte*)malloc(byteCount*sizeof*lpBuffer);
if( !lpBuffer ){
char emsg[32]; emsg[0] = '\0';
snprintf(emsg, sizeof emsg, "malloc(%d) failed", byteCount*sizeof*lpBuffer);
snprintf(emsg, sizeof emsg, "malloc(%" PRIsz ") failed", byteCount*sizeof*lpBuffer);
jclass exClz = env->FindClass("java/lang/RuntimeException");
if( exClz ) env->ThrowNew(exClz, emsg);
returnArray = NULL; goto Finally;
Expand Down
173 changes: 0 additions & 173 deletions src/main/cpp/jssc_SerialNativeInterface.h
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70 changes: 51 additions & 19 deletions src/main/cpp/windows/jssc.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -29,7 +29,16 @@
#include <jssc_SerialNativeInterface.h>
#include "version.h"

//#include <iostream>
#if defined(_MSC_VER) && _MSC_VER < 1800
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# define PRIsz "Iu"
# define PRIssz "Id"
#elif defined(__MINGW32__) && !defined(__MINGW64__)
# define PRIsz "u"
# define PRIssz "d"
#else
# define PRIsz "zu"
# define PRIssz "zd"
#endif

#define MAX_PORT_NAME_STR_LEN 32

Expand Down Expand Up @@ -232,38 +241,61 @@ JNIEXPORT jboolean JNICALL Java_jssc_SerialNativeInterface_setDTR
* portHandle - port handle
* buffer - byte array for sending
*/
JNIEXPORT jboolean JNICALL Java_jssc_SerialNativeInterface_writeBytes
JNIEXPORT jint JNICALL Java_jssc_SerialNativeInterface_writeBytes
(JNIEnv *env, jobject, jlong portHandle, jbyteArray buffer){
HANDLE hComm = (HANDLE)portHandle;
DWORD lpNumberOfBytesTransferred;
DWORD lpNumberOfBytesWritten;
jboolean returnValue = JNI_FALSE;
if( buffer == NULL ){
jint returnValue = -1;
if( !buffer ){
jclass exClz = env->FindClass("java/lang/NullPointerException");
if( exClz != NULL ) env->ThrowNew(exClz, "buffer");
if( exClz ) env->ThrowNew(exClz, "buffer");
return 0;
}
jbyte* jBuffer = env->GetByteArrayElements(buffer, JNI_FALSE);
if( jBuffer == NULL ){
jclass exClz = env->FindClass("java/lang/RuntimeException");
if( exClz != NULL ) env->ThrowNew(exClz, "jni->GetByteArrayElements() failed");
jbyte *jBuffer = env->GetByteArrayElements(buffer, NULL);
if( !jBuffer ){
jclass exClz = env->ExceptionCheck() ? NULL : env->FindClass("java/lang/RuntimeException");
if( exClz ) env->ThrowNew(exClz, "jni->GetByteArrayElements() failed");
return 0;
}
OVERLAPPED *overlapped = new OVERLAPPED();
overlapped->hEvent = CreateEventA(NULL, true, false, NULL);
if(WriteFile(hComm, jBuffer, (DWORD)env->GetArrayLength(buffer), &lpNumberOfBytesWritten, overlapped)){
returnValue = JNI_TRUE;
}
else if(GetLastError() == ERROR_IO_PENDING){
if(WaitForSingleObject(overlapped->hEvent, INFINITE) == WAIT_OBJECT_0){
if(GetOverlappedResult(hComm, overlapped, &lpNumberOfBytesTransferred, false)){
returnValue = JNI_TRUE;
}
DWORD err = 0;
do{
err = !WriteFile(hComm, jBuffer, (DWORD)env->GetArrayLength(buffer), &lpNumberOfBytesWritten, overlapped);
if( !err ){ /* successfully written. we're already done. */
returnValue = lpNumberOfBytesWritten;
break;
}
}
err = GetLastError();
if( err != ERROR_IO_PENDING ){
break; /* some unknown error occurred. Go reporting it. */
}
/* our write above was async (IO_PENDING). So it was only fired off, but
* we do not know the result yet. Therefore we've to wait for the result. */
if( WaitForSingleObject(overlapped->hEvent, INFINITE) != WAIT_OBJECT_0 ){
/* too bad :( wait failed. */
err = GetLastError();
break;
}
/* waited successfully. Time to get the result. */
if( GetOverlappedResult(hComm, overlapped, &lpNumberOfBytesTransferred, false) ){
/* we know the result now */
returnValue = lpNumberOfBytesTransferred;
err = 0;
}else{ /* GetOverlappedResult has failed :( */
err = GetLastError();
}
}while(0);
env->ReleaseByteArrayElements(buffer, jBuffer, 0);
CloseHandle(overlapped->hEvent);
delete overlapped;
if( err ){
char emsg[128];
snprintf(emsg, sizeof emsg, "Error %lu: https://learn.microsoft.com/en-us/windows/win32/debug/system-error-codes#system-error-codes", (long unsigned)err);
jclass exClz = env->FindClass("java/io/IOException");
if( exClz ) env->ThrowNew(exClz, emsg);
}
return returnValue;
}

Expand Down Expand Up @@ -298,7 +330,7 @@ JNIEXPORT jbyteArray JNICALL Java_jssc_SerialNativeInterface_readBytes
lpBuffer = (jbyte*)malloc(byteCount*sizeof*lpBuffer);
if( !lpBuffer ){
char emsg[32]; emsg[0] = '\0';
snprintf(emsg, sizeof emsg, "malloc(%d) failed", byteCount*sizeof*lpBuffer);
snprintf(emsg, sizeof emsg, "malloc(%" PRIsz ") failed", byteCount*sizeof*lpBuffer);
jclass exClz = env->FindClass("java/lang/RuntimeException");
if( exClz ) env->ThrowNew(exClz, emsg);
returnArray = NULL; goto Finally;
Expand Down
2 changes: 1 addition & 1 deletion src/main/java/jssc/SerialNativeInterface.java
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Original file line number Diff line number Diff line change
Expand Up @@ -277,7 +277,7 @@ public static String getLibraryVersion() {
*
* @return If the operation is successfully completed, the method returns true, otherwise false
*/
public native boolean writeBytes(long handle, byte[] buffer) throws IOException;
public native int writeBytes(long handle, byte[] buffer) throws IOException;

/**
* Get bytes count in buffers of port
Expand Down
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