Re: [xml] about xmlReadMemory()

[Nick Wellnhofer <wellnhofer aevum de>]

On 03/03/2021 09:30, nicolas bats wrote:
> Hi Nick,
> I've experimented with xmlReadIO and it's cool.
> this message just to check I'm doing right:
> -I register an xmlInputReadCallback of type: size_t myCallback(void* context, 
> char* buffer, int length)
> -I do my stuff in the callback and if data I use exceed the length of the 
> buffer, I realloc it.
> Is this schema good?
> Do I need to set size_t as the return type of myCallback?

No, the read callback is supposed to fill the buffer with up to 'length' 
bytes. Try something like:

typedef struct {
    const char *ptr;
    size_t remaining;
} myContext;

static int
myReadCallback(void *vcontext, char *buffer, int len) {
    myContext *context = vcontext;

    if (context->remaining < len)
        len = context->remaining;
    memcpy(buffer, context->ptr, len);
    context->ptr += len;
    context->remaining -= len;

    return len;
}

xmlDocPtr
myReadMemory(const char *buffer, size_t size, const char *URL,
             const char *encoding, int options) {
    myContext context;

    context.ptr = buffer;
    context.remaining = size;

    return xmlReadIO(myReadCallback, NULL, &context, URL, encoding, options);
}