MPROTECT
NAME SYNOPSIS DESCRIPTION RETURN VALUE ERRORS EXAMPLE CONFORMING TO SEE ALSO
mprotect - control allowable accesses to a region of memory
#include addr, size_t len, int prot);
mprotect controls how a section of memory may be accessed. If an access is disallowed by the protection given it, the program receives a SIGSEGV.
prot is a bitwise-or of the following values:
PROT_NONE
The memory cannot be accessed at all.
PROT_READ
The memory can be read.
PROT_WRITE
The memory can be written to.
PROT_EXEC
The memory can contain executing code.
The new protection replaces any existing protection. For example, if the memory had previously been marked PROT_READ, and mprotect is then called with prot PROT_WRITE, it will no longer be readable.
On success, mprotect returns zero. On error, -1 is returned, and errno is set appropriately.
EINVAL
addr is not a valid pointer, or not a multiple of PAGESIZE.
EFAULT
The memory cannot be accessed.
EACCES
The memory cannot be given the specified access. This can happen, for example, if you mmap(2) a file to which you have read-only access, then ask mprotect to mark it PROT_WRITE.
ENOMEM
Internal kernel structures could not be allocated.
SVr4, POSIX.1b (formerly POSIX.4). SVr4 defines an additional error code EAGAIN. The SVr4 error conditions don't map neatly onto Linux's. POSIX.1b says that mprotect can be used only on regions of memory obtained from mmap(2).
3 pages link to mprotect(2):