/* Ensures that 'b' has room for at least 'size' bytes at its head,
* reallocating and copying its data if necessary. Its tailroom, if any, is
* preserved. */
void
dp_packet_prealloc_headroom(struct dp_packet *b, size_t size)
{
if (size > dp_packet_headroom(b)) {
dp_packet_resize__(b, MAX(size, 64), dp_packet_tailroom(b));
}
}
/* Returns a string that describes some of 'b''s metadata plus a hex dump of up
* to 'maxbytes' from the start of the buffer. */
char *
dp_packet_to_string(const struct dp_packet *b, size_t maxbytes)
{
struct ds s;
ds_init(&s);
ds_put_format(&s, "size=%"PRIu32", allocated=%"PRIu32", head=%"PRIuSIZE", tail=%"PRIuSIZE"\n",
dp_packet_size(b), b->allocated,
dp_packet_headroom(b), dp_packet_tailroom(b));
ds_put_hex_dump(&s, dp_packet_data(b), MIN(dp_packet_size(b), maxbytes), 0, false);
return ds_cstr(&s);
}
/* Shifts all of the data within the allocated space in 'b' by 'delta' bytes.
* For example, a 'delta' of 1 would cause each byte of data to move one byte
* forward (from address 'p' to 'p+1'), and a 'delta' of -1 would cause each
* byte to move one byte backward (from 'p' to 'p-1'). */
void
dp_packet_shift(struct dp_packet *b, int delta)
{
ovs_assert(delta > 0 ? delta <= dp_packet_tailroom(b)
: delta < 0 ? -delta <= dp_packet_headroom(b)
: true);
if (delta != 0) {
char *dst = (char *) dp_packet_data(b) + delta;
memmove(dst, dp_packet_data(b), dp_packet_size(b));
dp_packet_set_data(b, dst);
}
}
static void
dp_packet_copy__(struct dp_packet *b, uint8_t *new_base,
size_t new_headroom, size_t new_tailroom)
{
const uint8_t *old_base = dp_packet_base(b);
size_t old_headroom = dp_packet_headroom(b);
size_t old_tailroom = dp_packet_tailroom(b);
size_t copy_headroom = MIN(old_headroom, new_headroom);
size_t copy_tailroom = MIN(old_tailroom, new_tailroom);
memcpy(&new_base[new_headroom - copy_headroom],
&old_base[old_headroom - copy_headroom],
copy_headroom + dp_packet_size(b) + copy_tailroom);
}
