On Digital Unix V4.0B, it is:
/usr/include/sys/mman.h:#define MAP_FAILED (-1L) /*
unsuccessful return from mmap() */
On Aug 30, 2007, at 6:10 PM, Timo Sirainen wrote:
On 30.8.2007, at 15.49, Bérczi Gábor (Gabucino) wrote:
For example in src/lib/file-cache.c:
if (cache->mmap_base == MAP_FAILED) {
Should be fixed, probably like this:
if ((int)cache->mmap_base == MAP_FAILED) {
No. MAP_FAILED is supposed to be a pointer. For example in Linux:
/usr/include/sys/mman.h:#define MAP_FAILED ((void *) -1)
And in any case you really don't want to cast it to int, rather
ssize_t so that it won't break with 64bit systems.
And indeed, unsigned integers and -1 are rarely equal.
Not really, Dovecot does such comparisons a lot. :)
Casting an unsigned integer to signed where the original value
doesn't fit to the destination is undefined by ANSI C. Casting a
signed integer to unsigned integer however is valid. (unsigned
int)-1 means the largest value that the unsigned int can hold. So
comparing unsigned int to -1 means comparing it to the largest value.
