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authorMiles Bader <miles@gnu.org>1996-01-14 04:47:48 +0000
committerMiles Bader <miles@gnu.org>1996-01-14 04:47:48 +0000
commit25e8145300ec1ad38f82fce22258955e5fedafd4 (patch)
treeda3f7efe469752d9d4f0e3012396ada6b7934a8a /libpipe/pq.c
parenta22738e903562f8df335cca68c3d76770cd8b94a (diff)
(packet_size_adjust): Function removed.
(packet_new_size): New function. (packet_read): Re-arrange to be slightly less confusing. Reverse start-past-buf-beginning test that may have leaked memory.
Diffstat (limited to 'libpipe/pq.c')
-rw-r--r--libpipe/pq.c72
1 files changed, 33 insertions, 39 deletions
diff --git a/libpipe/pq.c b/libpipe/pq.c
index 8177dfe2..504182e9 100644
--- a/libpipe/pq.c
+++ b/libpipe/pq.c
@@ -19,9 +19,8 @@
Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */
#include <malloc.h>
-#include <string.h> /* for bcopy */
+#include <string.h>
#include <stddef.h>
-#include <assert.h>
#include "pq.h"
@@ -147,17 +146,18 @@ pq_queue (struct pq *pq, unsigned type, void *source)
/* ---------------------------------------------------------------- */
-/* Returns a size to which a packet can be set, which will be at least GOAL,
- but perhaps more. */
+/* 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_size_adjust (size_t goal)
+packet_new_size (struct packet *packet, size_t extra)
{
- if (goal > PACKET_SIZE_LARGE)
- /* Round GOAL up to a page boundary (OLD_LEN should already be). */
- return round_page (goal);
+ 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 (goal + 511) & ~511;
+ return (new_len + 511) & ~511;
}
/* Try to extend PACKET to be NEW_LEN bytes long, which should be greater
@@ -178,7 +178,6 @@ packet_extend (struct packet *packet, size_t new_len)
/* 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)
@@ -348,57 +347,52 @@ packet_read (struct packet *packet,
char **data, size_t *data_len, size_t amount)
{
char *start = packet->buf_start;
+ char *end = packet->buf_end;
- if (amount > packet->buf_end - start)
- amount = packet->buf_end - start;
+ if (amount > end - start)
+ amount = end - start;
if (amount > 0)
{
- if (packet->buf_vm_alloced && amount > vm_page_size)
+ if (packet->buf_vm_alloced && amount >= vm_page_size)
/* We can return memory from BUF directly without copying. */
{
char *buf = packet->buf;
- char *end = packet->buf_end;
-
- /* Return the buffer directly. */
- *data = start;
- if (buf > start)
+ 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. */
- {
- char *first_page = (char *)trunc_page (start);
- if (first_page > buf)
- vm_deallocate (mach_task_self (),
- (vm_address_t)buf, first_page - buf);
- }
+ 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 + amount < end)
+ 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, unless the rest
- of the page is unimportant. */
- amount = (char *)trunc_page (start + amount) - start;
-
- /* Advance the read point. */
- start = (char *)round_page (start + amount);
-
- if (start > end)
- /* Make sure BUF_START is never beyond BUF_END (page-aligning the
- new BUF_START may have move it past). */
+ boundary before the end of the data we want. */
{
- packet->buf_end = start;
- packet->buf_len = 0; /* Pin at 0, despite moving past the end. */
+ char *non_aligned_start = start;
+ start = (char *)trunc_page (start);
+ amount -= non_aligned_start - start;
}
else
- /* Adjust BUF_LEN to reflect what the read has consumed. */
- packet->buf_len -= start - buf;
+ /* 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.... */