windows: File.pwrite/pread alters the file pointer

[kubkon]

Zig Version

0.10.0-dev.3922+b98b3252b

Steps to Reproduce

On POSIX-based OS, this succeeds. On Windows, this fails.

const std = @import("std");
const assert = std.debug.assert;

pub fn main() !void {
    const file = try std.fs.cwd().createFile("dummy", .{});
    defer file.close();

    try file.seekBy(10);
    const curr_pos = try file.getPos();
    assert(curr_pos == 10);
    try file.pwriteAll("\xaa", 0);
    assert(curr_pos == try file.getPos());
}

Expected Behavior

My question is: should we strive for File.pwrite/pread (and related) to be platform-independent? My gut is telling me yes but I want to see what others think about this.

Actual Behavior

Currently, File.pwrite/pread (and related) are platform-dependent.

[gooncreeper]

I would think that a majority of use cases for pread and pwrite would not also mix in seek-based I/O, since it is essentially an optimization to avoid seeking in the first place, so it could be worth leaving the file position unspecified.