On Thu, 13 Jul 2006, Brian Ford wrote:
> On Thu, 13 Jul 2006, Corinna Vinschen wrote:
> > I added an (hopefully) appropriate patch, which commits a page within a
> > MAP_NORESERVE area when memory in this page is accessed by the
> > application. If commiting the memory fails, SIGBUS is generated. Please
> > test CVS HEAD or the next developer snapshot from
> > http://cygwin.com/snapshots/
>
> Wow! Thanks. Given my limited Windows API knowledge, that sounded
> difficult to accomplish properly. I'll test it for you shortly.
One problem found. If the memory is not touched before using it as a
buffer to a read call, the read returns -1 with errno set to ISDIR. STC
attached.
Thanks again for looking at this.
--
Brian Ford
Lead Realtime Software Engineer
VITAL - Visual Simulation Systems
FlightSafety International
the best safety device in any aircraft is a well-trained crew...
.
#include <sys/mman.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdio.h>
#include <unistd.h>
#include <string.h>
int
main(int argc, char * argv[])
{
int virt_size, fd;
void *addr;
addr = NULL;
virt_size = 0x18000000;
addr = mmap(addr, virt_size, (PROT_READ|PROT_WRITE),
(MAP_NORESERVE|MAP_PRIVATE|MAP_ANON), -1, 0);
if (addr == MAP_FAILED)
{
perror("mapping VM scratch space");
return -1;
}
fd = open("/proc/self/exe", O_RDONLY);
if (fd < 0)
{
perror("open self");
return -1;
}
#ifdef PRE_TOUCH
memset(addr, -1, sysconf(_SC_PAGESIZE));
#endif
if (read(fd, addr, sysconf(_SC_PAGESIZE)) < 0)
{
perror("read");
close(fd);
return -1;
}
close(fd);
return 0;
}
--
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