file_putback.c

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/* some kind of ungetc function */

#include "fb.h"

int fb_FilePutBackEx( FB_FILE *handle, const void *src, size_t chars )
{
        int res;
        size_t bytes;

    if( !FB_HANDLE_USED(handle) )
                return fb_ErrorSetNum( FB_RTERROR_ILLEGALFUNCTIONCALL );

    FB_LOCK();

    res = fb_ErrorSetNum( FB_RTERROR_OK );

    /* UTF? */
    if( handle->encod != FB_FILE_ENCOD_ASCII )
        bytes = chars * sizeof( FB_WCHAR );
    else
        bytes = chars;

    if( handle->putback_size + bytes > sizeof(handle->putback_buffer) )
    {
        res = fb_ErrorSetNum( FB_RTERROR_FILEIO );
    }
    else
    {
        /* note: if encoding != ASCII, putback buffer will be in
           wchar format, not in UTF */
        if( handle->putback_size )
        {
            memmove( handle->putback_buffer + bytes,
                     handle->putback_buffer,
                     handle->putback_size );
        }

        if( handle->encod == FB_FILE_ENCOD_ASCII )
                memcpy( handle->putback_buffer, src, bytes );
        else
        {
                /* char to wchar */
                FB_WCHAR *dst = (FB_WCHAR *)handle->putback_buffer;
                const char *patch = (const char *)src;
                while( chars-- > 0 )
                        *dst++ = *patch++;
        }

        handle->putback_size += bytes;
    }

        FB_UNLOCK();

        return res;
}

FBCALL int fb_FilePutBack( int fnum, const void *data, size_t length )
{
    return fb_FilePutBackEx( FB_FILE_TO_HANDLE(fnum), data, length );
}