Hi guys,
I've read all the information about developing UDFs which I could find. I know
that in earlier versions of Firebird it was not possible to pass NULL
parameters. However I am using Firebird 2.5 and I want to return a NULL value
instead of an empty BLOB. I do not want to pass NULLs. Is this possible?
Please take a look at this function:
BLOBCALLBACK blob_load(char *s, BLOBCALLBACK b)
{
if (b->blob_handle) {
unsigned char *buffer;
int buffsize = 4096;
FILE *file;
file = fopen(s, "rb");
if (file) {
buffer = (unsigned char *) malloc(buffsize);
if (buffer) {
int readSize;
for (;;) {
readSize = fread(buffer, 1, buffsize, file);
b->blob_put_segment(b->blob_handle, buffer, readSize);
if (readSize != buffsize) {
break;
}
}
free(buffer);
}
fclose(file);
}
}
return b;
}
It loads data from the disk and returns it as a blob. The problem is that
sometimes on the disk there might be an empty file. There is a difference
between an empty file and a file which does not exist and I would like to
reflect that by retuning a NULL if the file does not exist and returning an
empty blob in a case where file exists but it is empty.
I've tried to setup blob strucutre like this:
b->blob_get_segment = NULL;
b->blob_number_segments = NULL;
b->blob_max_segment = NULL;
b->blob_total_length = NULL;
b->blob_put_segment = NULL;
but without success.
So..is it possible to return NULL instead of an empty blob?
Thank you.
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