Mail Archives: cygwin/2003/07/03/21:28:52
Corinna Vinschen wrote:
>> In other words, addr -= (off - gran_off). This address should
>> now be 64k aligned. Error if it isn't.
>>
>> Use this address when calling MapViewOfFileEx(). If the call fails
>> and MAP_FIXED is not set, then try again with addr = 0.
>
> Yes, that's what I mentioned in my first reply. I think it's worth
> a try. I've checked in a patch. I've tested it and it looks pretty
> good.
I've had a look at your patch and working with the code I've
discovered some minor issues. I've included a revised patch for you
to review.
o The if (addr) test is redundant (it will always succeed -- I think
you meant to write *addr, but I think it's better to simply do
away with the test since it doesn't buy anything).
o I think there is a problem with the address arithmetic in the match()
method used by munmap(). Compare the code in list::match (__off64_t
off, DWORD len) with list::match (caddr_t addr, DWORD len,
__off32_t start).
I believe the address relationships are:
get_offset() get_size()
<-------------> <----------------------------------->
+----------------------------------------------------+
| : |
+----------------------------------------------------+
^ ^ <----------------------------->
| | len
get_address() |
addr
Earl
--
--- mmap.cc.original 2003-07-03 13:24:58.000000000 -0700
+++ mmap.cc 2003-07-03 18:14:10.000000000 -0700
@@ -328,7 +328,7 @@
{
for (int i = start + 1; i < nrecs; ++i)
if (addr >= recs[i].get_address ()
- && addr + len <= recs[i].get_address ()
+ && addr + len <= recs[i].get_address () + recs[i].get_offset ()
+ (PAGE_CNT (recs[i].get_size ()) * getpagesize ()))
return i;
return -1;
@@ -439,7 +439,7 @@
if (off % getpagesize ()
|| (!(flags & MAP_SHARED) && !(flags & MAP_PRIVATE))
|| ((flags & MAP_SHARED) && (flags & MAP_PRIVATE))
- || ((flags & MAP_FIXED) && ((DWORD)addr % granularity))
+ || ((flags & MAP_FIXED) && ((DWORD)addr % getpagesize ()))
|| !len)
{
set_errno (EINVAL);
@@ -470,8 +470,6 @@
DWORD gran_len = howmany (off + len, granularity) * granularity -
gran_off;
fhandler_base *fh;
- caddr_t base = addr;
- HANDLE h;
if (fd != -1)
{
@@ -541,7 +539,13 @@
&& (wincap.has_working_copy_on_write () || fd != -1))
access = FILE_MAP_COPY;
- h = fh->mmap (&base, gran_len, access, flags, gran_off);
+ caddr_t base = addr;
+ /* This shifts the base address to the next lower 64K boundary.
+ The offset is re-added when evaluating the return value. */
+ if (base)
+ base -= off - gran_off;
+
+ HANDLE h = fh->mmap (&base, gran_len, access, flags, gran_off);
if (h == INVALID_HANDLE_VALUE)
{
@@ -814,9 +818,13 @@
}
DWORD high = off >> 32, low = off & 0xffffffff;
- void *base = MapViewOfFileEx (h, access, high, low, len,
- (flags & MAP_FIXED) ? *addr : NULL);
- debug_printf ("%x = MapViewOfFileEx (h:%x, access:%x, 0, off:%D,
len:%d, addr:%x)", base, h, access, off, len, (flags & MAP_FIXED) ?
*addr : NULL);
+ /* If a non-zero address is given, try mapping using the given
address first.
+ If it fails and flags is not MAP_FIXED, try again with NULL
address. */
+ void *base = MapViewOfFileEx (h, access, high, low, len, *addr);
+ if (!base && !(flags & MAP_FIXED))
+ base = MapViewOfFileEx (h, access, high, low, len, NULL);
+ debug_printf ("%x = MapViewOfFileEx (h:%x, access:%x, 0, off:%D, "
+ "len:%d, addr:%x)", base, h, access, off, len, *addr);
if (!base || ((flags & MAP_FIXED) && base != *addr))
{
if (!base)
--
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