mprotect address length protection => error
address -- A non-negative integer.
length -- A non-negative integer.
protection -- A non-negative fixnum.
error -- A fixnum.
This function changes the protection of those memory page(s) of the calling process that contain any part of the address range in the interval [address, address+length-1]. The argument address must be aligned to a page boundary.
If the calling process tries to access memory in a manner that violates the protection, then the kernel generates a SIGSEGV signal for the process.
The argument protection is either +prot-none+ or the bitwise OR of the other values in the following list:
| +prot-read+ | The memory can be read. |
| +prot-write+ | The memory can be modified. |
| +prot-exec+ | The memory can be executed. |
| +eaccess+ | The memory cannot be given the specified access. This can happen, for example, if you mmap a file to which you have read-only access, then ask mprotect to mark it +prot-write+. |
| +einval+ | addrress is not a valid address, or not a multiple of the system page size. |
| +enomem+ | Internal kernel structures could not be allocated. |
| +enomem+ | Addresses in the range [address, address+length-1] are invalid for the address space of the process, or specify one or more pages that are not mapped. (Before kernel 2.4.19, the error +efault+ was incorrectly produced for these cases.) |