/* Copyright (C) 2001-2023 Artifex Software, Inc.
   All Rights Reserved.

   This software is provided AS-IS with no warranty, either express or
   implied.

   This software is distributed under license and may not be copied,
   modified or distributed except as expressly authorized under the terms
   of the license contained in the file LICENSE in this distribution.

   Refer to licensing information at http://www.artifex.com or contact
   Artifex Software, Inc.,  39 Mesa Street, Suite 108A, San Francisco,
   CA 94129, USA, for further information.
*/


/* DataSource procedures */

#include "memory_.h"
#include "gx.h"
#include "gsdsrc.h"
#include "gserrors.h"
#include "stream.h"

/* GC descriptor */
public_st_data_source();
static
ENUM_PTRS_WITH(data_source_enum_ptrs, gs_data_source_t *psrc)
{
    if (psrc->type == data_source_type_string)
        ENUM_RETURN_CONST_STRING_PTR(gs_data_source_t, data.str);
    else if (psrc->type == data_source_type_stream)
        ENUM_RETURN_PTR(gs_data_source_t, data.strm);
    else			/* bytes or floats */
        ENUM_RETURN_PTR(gs_data_source_t, data.str.data);
}
ENUM_PTRS_END
static RELOC_PTRS_WITH(data_source_reloc_ptrs, gs_data_source_t *psrc)
{
    if (psrc->type == data_source_type_string)
        RELOC_CONST_STRING_PTR(gs_data_source_t, data.str);
    else if (psrc->type == data_source_type_stream)
        RELOC_PTR(gs_data_source_t, data.strm);
    else			/* bytes or floats */
        RELOC_PTR(gs_data_source_t, data.str.data);
}
RELOC_PTRS_END

/* Access data from a string or a byte object. */
/* Does check bounds, and returns 0 data oob. Spec calls for rangecheck,
   but CPSI implementation silently gives (bogus) data. */
int
data_source_access_string(const gs_data_source_t * psrc, ulong start,
                          uint length, byte * buf, const byte ** ptr)
{
    const byte *p = psrc->data.str.data + start;

    if (start + length <= psrc->data.str.size) {
        if (ptr)
            *ptr = p;
        else
            memcpy(buf, p, length);
    } else {
        if (start < psrc->data.str.size) {
            uint oklen = psrc->data.str.size - start;
            memcpy(buf, p, oklen);
            memset(buf + oklen, 0, length - oklen);
        } else {
            memset(buf, 0, length);
        }
        *ptr = buf;
    }
    return 0;
}
/* access_bytes is identical to access_string, but has a different */
/* GC procedure. */
int
data_source_access_bytes(const gs_data_source_t * psrc, ulong start,
                         uint length, byte * buf, const byte ** ptr)
{
    const byte *p = psrc->data.str.data + start;

    if (ptr)
        *ptr = p;
    else
        memcpy(buf, p, length);
    return 0;
}

/* Access data from a stream. */
/* Returns gs_error_rangecheck if out of bounds. */
int
data_source_access_stream(const gs_data_source_t * psrc, ulong start,
                          uint length, byte * buf, const byte ** ptr)
{
    stream *s = psrc->data.strm;
    const byte *p;

    if (start >= s->position &&
        (p = start - s->position + s->cbuf) + length <=
        s->cursor.r.limit + 1
        ) {
        if (ptr)
            *ptr = p;
        else
            memcpy(buf, p, length);
    } else {
        uint nread;
        int code = sseek(s, start);

        if (code < 0)
            return_error(gs_error_rangecheck);
        code = sgets(s, buf, length, &nread);
        if (code < 0)
            return_error(gs_error_rangecheck);
        if (nread != length)
            return_error(gs_error_rangecheck);
        if (ptr)
            *ptr = buf;
    }
    return 0;
}