/* Packet queues Copyright (C) 1995, 1996, 1998, 1999, 2002, 2006 Free Software Foundation, Inc. Written by Miles Bader This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */ #include #include #include #include #include "pq.h" /* ---------------------------------------------------------------- */ /* Create a new packet queue, returning it in PQ. The only possible error is ENOMEM. */ error_t pq_create (struct pq **pq) { *pq = malloc (sizeof (struct pq)); if (! *pq) return ENOMEM; (*pq)->head = (*pq)->tail = 0; (*pq)->free = 0; return 0; } /* Free every packet (and its contents) in the linked list rooted at HEAD. */ static void free_packets (struct packet *head) { if (head) { struct packet *next = head->next; if (head->ports) free (head->ports); if (head->buf_len > 0) { if (head->buf_vm_alloced) munmap (head->buf, head->buf_len); else free (head->buf); } free (head); free_packets (next); } } /* Frees PQ and any resources it holds, including deallocating any ports in packets left in the queue. */ void pq_free (struct pq *pq) { pq_drain (pq); free_packets (pq->free); free (pq); } /* ---------------------------------------------------------------- */ /* Remove the first packet (if any) in PQ, deallocating any resources it holds. True is returned if a packet was found, false otherwise. */ int pq_dequeue (struct pq *pq) { extern void pipe_dealloc_addr (void *addr); struct packet *packet = pq->head; if (! packet) return 0; /* Deallocate any resource in PACKET. */ if (packet->num_ports) packet_dealloc_ports (packet); if (packet->source) pipe_dealloc_addr (packet->source); pq->head = packet->next; packet->next = pq->free; pq->free = packet; if (pq->head) pq->head->prev = 0; else pq->tail = 0; return 1; } /* Empties out PQ. This *will* deallocate any ports in any of the packets. */ void pq_drain (struct pq *pq) { while (pq_dequeue (pq)) ; } /* Pushes a new packet of type TYPE and source SOURCE onto the tail of the queue, and returns it, or 0 if there was an allocation error. */ struct packet * pq_queue (struct pq *pq, unsigned type, void *source) { struct packet *packet = pq->free; if (!packet) { packet = malloc (sizeof (struct packet)); if (!packet) return 0; packet->buf = 0; packet->buf_len = 0; packet->ports = 0; packet->ports_alloced = 0; packet->buf_vm_alloced = 0; } else pq->free = packet->next; packet->num_ports = 0; packet->buf_start = packet->buf_end = packet->buf; packet->type = type; packet->source = source; packet->next = 0; packet->prev = pq->tail; if (pq->tail) pq->tail->next = packet; pq->tail = packet; if (!pq->head) pq->head = packet; return packet; } /* ---------------------------------------------------------------- */ /* Returns a legal size to which PACKET can be set allowing enough room for EXTRA bytes more than what's already in it, and perhaps more. */ size_t packet_new_size (struct packet *packet, size_t extra) { size_t new_len = (packet->buf_end - packet->buf) + extra; if (packet->buf_vm_alloced || new_len >= PACKET_SIZE_LARGE) /* Round NEW_LEN up to a page boundary (OLD_LEN should already be). */ return round_page (new_len); else /* Otherwise, just round up to a multiple of 512 bytes. */ return (new_len + 511) & ~511; } /* Try to extend PACKET to be NEW_LEN bytes long, which should be greater than the current packet size. This should be a valid length -- i.e., if it's greater than PACKET_SIZE_LARGE, it should be a mulitple of VM_PAGE_SIZE. If PACKET cannot be extended for some reason, false is returned, otherwise true. */ int packet_extend (struct packet *packet, size_t new_len) { size_t old_len = packet->buf_len; if (old_len == 0) /* No existing buffer to extend. */ return 0; if (packet->buf_vm_alloced) /* A vm_alloc'd packet. */ { char *extension = packet->buf + old_len; /* Try to allocate memory at the end of our current buffer. */ if (vm_allocate (mach_task_self (), (vm_address_t *)&extension, new_len - old_len, 0) != 0) return 0; } else /* A malloc'd packet. */ { char *new_buf; char *old_buf = packet->buf; if (new_len >= PACKET_SIZE_LARGE) /* The old packet length is malloc'd, but we want to vm_allocate the new length, so we'd have to copy the old contents. */ return 0; new_buf = realloc (old_buf, new_len); if (! new_buf) return 0; packet->buf = new_buf; packet->buf_start = new_buf + (packet->buf_start - old_buf); packet->buf_end = new_buf + (packet->buf_end - old_buf); } packet->buf_len = new_len; return 1; } /* Reallocate PACKET to have NEW_LEN bytes of buffer space, which should be greater than the current packet size. This should be a valid length -- i.e., if it's greater than PACKET_SIZE_LARGE, it should be a multiple of VM_PAGE_SIZE. If an error occurs, PACKET is not modified and the error is returned. */ error_t packet_realloc (struct packet *packet, size_t new_len) { error_t err; char *new_buf; char *old_buf = packet->buf; int vm_alloc = (new_len >= PACKET_SIZE_LARGE); /* Make a new buffer. */ if (vm_alloc) { new_buf = mmap (0, new_len, PROT_READ|PROT_WRITE, MAP_ANON, 0, 0); err = (new_buf == (char *) -1) ? errno : 0; } else { new_buf = malloc (new_len); err = (new_buf ? 0 : ENOMEM); } if (! err) { size_t old_len = packet->buf_len; char *start = packet->buf_start, *end = packet->buf_end; /* Copy what we must. */ if (end != start) /* If there was an operation like vm_move, we could use that in the case where both the old and the new buffers were vm_alloced (on the assumption that creating COW pages is somewhat more costly). But there's not, and bcopy will do vm_copy where it can. Will we still takes faults on the new copy, even though we've deallocated the old one??? XXX */ bcopy (start, new_buf, end - start); /* And get rid of the old buffer. */ if (old_len > 0) { if (packet->buf_vm_alloced) vm_deallocate (mach_task_self (), (vm_address_t)old_buf, old_len); else free (old_buf); } packet->buf = new_buf; packet->buf_len = new_len; packet->buf_vm_alloced = vm_alloc; packet->buf_start = new_buf; packet->buf_end = new_buf + (end - start); } return err; } /* ---------------------------------------------------------------- */ /* If PACKET has any ports, deallocates them. */ void packet_dealloc_ports (struct packet *packet) { unsigned i; for (i = 0; i < packet->num_ports; i++) { mach_port_t port = packet->ports[i]; if (port != MACH_PORT_NULL) mach_port_deallocate (mach_task_self (), port); } } /* Sets PACKET's ports to be PORTS, of length NUM_PORTS. ENOMEM is returned if a memory allocation error occurred, otherwise, 0. */ error_t packet_set_ports (struct packet *packet, mach_port_t *ports, size_t num_ports) { if (packet->num_ports > 0) packet_dealloc_ports (packet); if (num_ports > packet->ports_alloced) { mach_port_t *new_ports = malloc (sizeof (mach_port_t) * num_ports); if (! new_ports) return ENOMEM; free (packet->ports); packet->ports = new_ports; packet->ports_alloced = num_ports; } bcopy (ports, packet->ports, sizeof (mach_port_t) * num_ports); packet->num_ports = num_ports; return 0; } /* Returns any ports in PACKET in PORTS and NUM_PORTS, and removes them from PACKET. */ error_t packet_read_ports (struct packet *packet, mach_port_t **ports, size_t *num_ports) { int length = packet->num_ports * sizeof (mach_port_t); if (*num_ports < packet->num_ports) { *ports = mmap (0, length, PROT_READ|PROT_WRITE, MAP_ANON, 0, 0); if (*ports == (mach_port_t *) -1) return errno; } *num_ports = packet->num_ports; bcopy (packet->ports, *ports, length); packet->num_ports = 0; return 0; } /* Append the bytes in DATA, of length DATA_LEN, to what's already in PACKET, and return the amount appended in AMOUNT if that's not the null pointer. */ error_t packet_write (struct packet *packet, char *data, size_t data_len, size_t *amount) { error_t err = packet_ensure (packet, data_len); if (err) return err; /* Add the new data. */ bcopy (data, packet->buf_end, data_len); packet->buf_end += data_len; if (amount != NULL) *amount = data_len; return 0; } /* Remove or peek up to AMOUNT bytes from the beginning of the data in PACKET, and puts it into *DATA, and the amount read into DATA_LEN. If more than the original *DATA_LEN bytes are available, new memory is vm_allocated, and the address and length of this array put into DATA and DATA_LEN. */ static error_t packet_fetch (struct packet *packet, char **data, size_t *data_len, size_t amount, int remove) { char *start = packet->buf_start; char *end = packet->buf_end; if (amount > end - start) amount = end - start; if (amount > 0) { char *buf = packet->buf; if (remove && packet->buf_vm_alloced && amount >= vm_page_size) /* We can return memory from BUF directly without copying. */ { if (buf + vm_page_size <= start) /* BUF_START has been advanced past the start of the buffer (perhaps by a series of small reads); as we're going to assume everything before START is gone, make sure we deallocate any memory on pages before those we return to the user. */ vm_deallocate (mach_task_self (), (vm_address_t)buf, trunc_page (start) - (vm_address_t)buf); *data = start; /* Return the buffer directly. */ start += amount; /* Advance the read point. */ if (start < end) /* Since returning a partial page actually means returning the whole page, we have to be careful not to grab past the page boundary before the end of the data we want. */ { char *non_aligned_start = start; start = (char *)trunc_page (start); amount -= non_aligned_start - start; } else /* This read will be up to the end of the buffer, so we can just consume any space on the page following BUF_END (vm_alloced buffers are always allocated in whole pages). */ { start = (char *)round_page (start); packet->buf_end = start; /* Ensure BUF_START <= BUF_END. */ } /* We've actually consumed the memory at the start of BUF. */ packet->buf = start; packet->buf_start = start; packet->buf_len -= start - buf; } else /* Just copy the data the old fashioned way.... */ { if (*data_len < amount) *data = mmap (0, amount, PROT_READ|PROT_WRITE, MAP_ANON, 0, 0); bcopy (start, *data, amount); start += amount; if (remove && start - buf > 2 * PACKET_SIZE_LARGE) /* Get rid of unused space at the beginning of the buffer -- we know it's vm_alloced because of the size, and this will allow the buffer to just slide through memory. Because we wait for a relatively large amount of free space before doing this, and packet_write() would have gotten rid the free space if it didn't require copying much data, it's unlikely that this will happen if it would have been cheaper to just move the packet contents around to make space for the next write. */ { vm_size_t dealloc = trunc_page (start) - (vm_address_t)buf; vm_deallocate (mach_task_self (), (vm_address_t)buf, dealloc); packet->buf = buf + dealloc; packet->buf_len -= dealloc; } if (remove) packet->buf_start = start; } } *data_len = amount; return 0; } /* Removes up to AMOUNT bytes from the beginning of the data in PACKET, and puts it into *DATA, and the amount read into DATA_LEN. If more than the original *DATA_LEN bytes are available, new memory is vm_allocated, and the address and length of this array put into DATA and DATA_LEN. */ error_t packet_read (struct packet *packet, char **data, size_t *data_len, size_t amount) { return packet_fetch (packet, data, data_len, amount, 1); } /* Peek up to AMOUNT bytes from the beginning of the data in PACKET, and puts it into *DATA, and the amount read into DATA_LEN. If more than the original *DATA_LEN bytes are available, new memory is vm_allocated, and the address and length of this array put into DATA and DATA_LEN. */ error_t packet_peek (struct packet *packet, char **data, size_t *data_len, size_t amount) { return packet_fetch (packet, data, data_len, amount, 0); }