mprotect(2) manual page
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mprotect - set protection of memory mapping
#include <sys/types.h>
#include <sys/mman.h>
int mprotect(caddr_t addr, size_t len, int prot);
The function
mprotect() changes the access protections on the mappings specified by
the range [addr, addr + len) to be that specified by prot. Legitimate values
for prot are the same as those permitted for mmap and are defined in <sys/mman.h>
as:
PROT_READ /* page can be read */
PROT_WRITE /* page can be written */
PROT_EXEC /* page can be executed */
PROT_NONE /* page can not be accessed */
Upon successful completion, the function mprotect() returns
a value of 0; otherwise, it returns a value of -1 and sets errno to indicate
an error.
Under the following conditions, the function mprotect()
fails and sets errno to:
- EACCES
- prot specifies a protection that violates
the access permission the process has to the underlying memory object.
- EAGAIN
- the address range [addr, addr + len) includes one or more pages that have
been locked in memory and that were mapped MAP_PRIVATE;
prot includes PROT_WRITE;
and the system has insufficient resources to reserve memory for the private
pages that may be created. These private pages may be created by store operations
into the now-writable address range.
- EINVAL
- addr is not a multiple of the
page size as returned by sysconf.
- EINVAL
- the len argument has a value less
than or equal to 0.
- ENOMEM
- addresses in the range [addr, addr + len) are
invalid for the address space of a process, or specify one or more pages
which are not mapped.
When mprotect() fails for reasons other than EINVAL,
the protections on some of the pages in the range [addr, addr + len) may
have been changed. If the error occurs on some page at addr2, then the protections
of all whole pages in the range [addr, addr2] will have been modified.
mmap(2)
, plock(3C)
, mlock(3C)
, mlockall(3C)
, sysconf(3C)
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