Voy a llamar a una función DLL C y la necesidad de proporcionar la siguiente estructura C:Marshalling matriz de cadenas a char ** en C#
typedef struct
{
char *mTableId;
char **mFieldNames;
int mNumFields;
char *mFilter;
char *mSort;
int mOffset;
int mMaxRecords;
char *mTargetRecordFilter;
int mSurroundingRecordsCount;
int *mOwnerIds;
int mNumOwnerIds;
gsi_bool mCacheFlag;
} SAKESearchForRecordsInput;
El problema es con char ** mFieldNames; He tratado de cálculo de referencias de forma automática la siguiente manera:
[MarshalAs (UnmanagedType.LPArray, ArraySubType = UnmanagedType.LPTStr, SizeConst = 9)] [] mFieldNames public String;
De esta manera me sale un error en Marshal.SizeOf() - no se puede calcular el tamaño correcto. Entonces decidí tratar con punteros manualmente. De hecho, es solo un puntero a la matriz de cadenas C. Este es mi código que conduce a
System.AccessViolationException: Intenté leer o escribir en la memoria protegida. Esto a menudo es una indicación de que otra memoria está corrupta.
Así que he metido los punteros en alguna parte. El código me parece bien, ¿dónde está el error?
C#:
[StructLayout(LayoutKind.Sequential)]
unsafe public class SAKESearchForRecordsInput {
[MarshalAs(UnmanagedType.LPTStr)]
public String mTableId;
//[MarshalAs(UnmanagedType.LPArray, ArraySubType = UnmanagedType.LPTStr, SizeConst = 9)] // HARDCODED!?!
//public String[] mFieldNames; // char **mFieldNames;
public IntPtr mFieldNames;
public int mNumFields;
[MarshalAs(UnmanagedType.LPTStr)]
public String mFilter;
[MarshalAs(UnmanagedType.LPTStr)]
public String mSort;
public int mOffset;
public int mMaxRecords;
//[MarshalAs(UnmanagedType.LPTStr)]
public IntPtr mTargetRecordFilter;
public int mSurroundingRecordsCount;
public IntPtr mOwnerIds;
public int mNumOwnerIds;
public gsi_bool mCacheFlag;
}
[DllImport("saketestd.dll")]
unsafe static extern void* sakeSearchForRecords(
IntPtr sake,
IntPtr input, //SAKESearchForRecordsInput *
SAKERequestCallback callback, //SAKERequestCallback
IntPtr userData);
unsafe public bool sakeSearchForRecordsE() {
bool ret = false;
try {
searchInput.mTableId = "bbdx_score";
//searchInput.mFieldNames = mFieldNames.to;
searchInput.mFilter = "num_ratings = 0 AND filestore > 0";
searchInput.mSort = "";
searchInput.mOffset = 0;
searchInput.mMaxRecords = 1;
//searchInput.mTargetRecordFilter = "";
searchInput.mSurroundingRecordsCount = 0;
searchInput.mOwnerIds = IntPtr.Zero;
searchInput.mNumOwnerIds = 0;
searchInput.mCacheFlag = true;
int sakeSize = Marshal.SizeOf(sake);
debug.AddLine(this.getMethodName() + ": sizeof(sake): " + sakeSize);
IntPtr pSake = Marshal.AllocHGlobal(sakeSize);
Marshal.StructureToPtr(sake, pSake, true);
int inputSize = Marshal.SizeOf(searchInput);
debug.AddLine(this.getMethodName() + ": sizeof(input): " + inputSize);
IntPtr pInput = Marshal.AllocHGlobal(inputSize);
Marshal.StructureToPtr(searchInput, pInput, true);
IntPtr[] mFieldNamesPtr;
int i;
if (true) { // IntPtr[]
mFieldNamesPtr = new IntPtr[mFieldNames.Length];
i = 0;
foreach (string str in mFieldNames) {
mFieldNamesPtr[i++] = Marshal.StringToHGlobalAnsi(str);
}
//searchInput.mFieldNames = mFieldNamesPtr;
} else {
//searchInput.mFieldNames = mFieldNames;
}
searchInput.mNumFields = mFieldNames.Length;
void* pRequestInternal = null;
void* p = mFieldNamesPtr[0].ToPointer();
searchInput.mFieldNames = (IntPtr)p;
pRequestInternal = sakeSearchForRecords(
pSake,
pInput,
new SAKERequestCallback(this.sakeSearchForRecordsCB),
IntPtr.Zero
);
sake = (SAKEInternal)Marshal.PtrToStructure(pSake, typeof(SAKEInternal));
if (searchRequest == null) {
debug.AddLine(this.getMethodName() + ": mStartRequestResult: " + sake.mStartRequestResult);
} else {
ret = true;
this.searchRequest = (SAKERequestInternal)Marshal.PtrToStructure(
new IntPtr(pRequestInternal),
typeof(SAKERequestInternal)
);
searchInput = (SAKESearchForRecordsInput)Marshal.PtrToStructure(
pInput,
typeof(SAKESearchForRecordsInput)
);
if (true) {
i = 0;
foreach (string str in mFieldNames) {
Marshal.FreeHGlobal(mFieldNamesPtr[i++]);
}
}
PrintStruct ps = new PrintStruct(sake);
debug.AddLine(this.getMethodName() + ": sake: " + ps);
ps = new PrintStruct(searchRequest);
debug.AddLine(this.getMethodName() + ": searchRequest: " + ps.print_r());
ps = new PrintStruct(searchInput);
debug.AddLine(this.getMethodName() + ": searchInput: " + ps.print_r());
}
Marshal.FreeHGlobal(pSake);
Marshal.FreeHGlobal(pInput);
} catch (Exception ex) {
debug.Text += ex.ToString();
}
return ret;
}
Actualización: se rompe en sakeSearchForRecords(); – Slawa