Originální popis anglicky:
msync - synchronize a file with a memory map
Návod, kniha: Linux Programmer's Manual
#include <sys/mman.h>
int msync(void *start, size_t length, int
flags);
msync flushes changes made to the in-core copy of a file that was mapped
into memory using
mmap(2) back to disk. Without use of this call there
is no guarantee that changes are written back before
munmap(2) is
called. To be more precise, the part of the file that corresponds to the
memory area starting at
start and having length
length is
updated. The
flags argument may have the bits MS_ASYNC, MS_SYNC and
MS_INVALIDATE set, but not both MS_ASYNC and MS_SYNC. MS_ASYNC specifies that
an update be scheduled, but the call returns immediately. MS_SYNC asks for an
update and waits for it to complete. MS_INVALIDATE asks to invalidate other
mappings of the same file (so that they can be updated with the fresh values
just written).
On success, zero is returned. On error, -1 is returned, and
errno is set
appropriately.
- EINVAL
- start is not a multiple of PAGESIZE, or any bit
other than MS_ASYNC | MS_INVALIDATE | MS_SYNC is set in flags.
- ENOMEM
- The indicated memory (or part of it) was not mapped.
On POSIX systems on which
msync is available, both
_POSIX_MAPPED_FILES and
_POSIX_SYNCHRONIZED_IO are defined in
<unistd.h> to a value greater than 0. (See also
sysconf(3).)
POSIX.1b (formerly POSIX.4)
This call was introduced in Linux 1.3.21, and then used EFAULT instead of
ENOMEM. In Linux 2.4.19 this was changed to the POSIX value ENOMEM.
mmap(2)
B.O. Gallmeister, POSIX.4, O'Reilly, pp. 128-129 and 389-391.
