Function mprotect [src]

Prototype

pub fn mprotect(memory: []align(page_size_min) u8, protection: u32) MProtectError!void

Parameters

memory: []align(page_size_min) u8protection: u32

Possible Errors

AccessDenied

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.

OutOfMemory

Changing the protection of a memory region would result in the total number of map‐ pings with distinct attributes (e.g., read versus read/write protection) exceeding the allowed maximum. (For example, making the protection of a range PROT_READ in the mid‐ dle of a region currently protected as PROT_READ|PROT_WRITE would result in three map‐ pings: two read/write mappings at each end and a read-only mapping in the middle.)

Unexpected UnexpectedError

The Operating System returned an undocumented error code.

This error is in theory not possible, but it would be better to handle this error than to invoke undefined behavior.

When this error code is observed, it usually means the Zig Standard Library needs a small patch to add the error code to the error set for the respective function.

Source

  pub fn mprotect(memory: []align(page_size_min) u8, protection: u32) MProtectError!void {
    if (native_os == .windows) {
        const win_prot: windows.DWORD = switch (@as(u3, @truncate(protection))) {
            0b000 => windows.PAGE_NOACCESS,
            0b001 => windows.PAGE_READONLY,
            0b010 => unreachable, // +w -r not allowed
            0b011 => windows.PAGE_READWRITE,
            0b100 => windows.PAGE_EXECUTE,
            0b101 => windows.PAGE_EXECUTE_READ,
            0b110 => unreachable, // +w -r not allowed
            0b111 => windows.PAGE_EXECUTE_READWRITE,
        };
        var old: windows.DWORD = undefined;
        windows.VirtualProtect(memory.ptr, memory.len, win_prot, &old) catch |err| switch (err) {
            error.InvalidAddress => return error.AccessDenied,
            error.Unexpected => return error.Unexpected,
        };
    } else {
        switch (errno(system.mprotect(memory.ptr, memory.len, protection))) {
            .SUCCESS => return,
            .INVAL => unreachable,
            .ACCES => return error.AccessDenied,
            .NOMEM => return error.OutOfMemory,
            else => |err| return unexpectedErrno(err),
        }
    }
}  