"Igor Pechtchanski" <[EMAIL PROTECTED]> wrote in message news:[EMAIL PROTECTED]
[snip]
>
> Umm, Elfyn, the semantics of "assert()" is that you assert some predicate
> to be true. If the predicate is indeed true, the program continues
> normally. If the predicate is false, the program fails.
> The predicate in this case is "ptr != MAP_FAILED". Thus, the predicate
> was false when the assertion failed, and ptr == MAP_FAILED.
>
> To the OP: this means that mmap() did fail for some reason. It should
> have set errno to indicate why. You should check that instead of
> asserting -- mmap does fail occasionally. Also FYI, once you assert, the
> following test for "ptr != MAP_FAILED" is redundant -- the program will
> not get there otherwise.
> Igor
[snip]
Here is updated function.
--------------------------------------
void read_file (char* filename_i)
{
int fd = open(filename_i, O_RDONLY);
assert (fd > 2);
off_t sz = lseek(fd, 0, SEEK_END);
char* ptr = (char*)mmap(0, sz, PROT_READ, 0, fd, 0);
errno = 0;
if (ptr != MAP_FAILED)
{
string str(ptr, ptr+sz);
munmap(ptr, sz);
}
else
{
assert (ptr == MAP_FAILED);
printf ("=== Error : %u %s ===\n", errno, strerror (errno));
}
assert (ptr != MAP_FAILED); // Here assertion failed
close(fd);
}
--------------------------------------
The program prints:
=== Error : 0 No error ===
Regards,
=====================================
Alex Vinokur
mailto:[EMAIL PROTECTED]
http://mathforum.org/library/view/10978.html
=====================================
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