str_mid.c

Go to the documentation of this file.

/* mid$ function */

#include "fb.h"

FBCALL FBSTRING *fb_StrMid( FBSTRING *src, ssize_t start, ssize_t len )
{
    FBSTRING    *dst;
        ssize_t src_len;

        FB_STRLOCK();

    if( (src != NULL) && (src->data != NULL) && (FB_STRSIZE( src ) > 0) )
        {
        src_len = FB_STRSIZE( src );

        if( (start > 0) && (start <= src_len) && (len != 0) )
        {
                --start;

                if( len < 0 )
                        len = src_len;

                if( start + len > src_len )
                        len = src_len - start;

                        /* alloc temp string */
            dst = fb_hStrAllocTemp_NoLock( NULL, len );
                        if( dst != NULL )
            {
                                FB_MEMCPY( dst->data, src->data + start, len );
                                /* null term */
                                dst->data[len] = '\0';
            }
                else
                        dst = &__fb_ctx.null_desc;
        }
        else
                dst = &__fb_ctx.null_desc;
        }
        else
                dst = &__fb_ctx.null_desc;

        /* del if temp */
        fb_hStrDelTemp_NoLock( src );

        FB_STRUNLOCK();

        return dst;
}