unexpected errno: 13 when writing to file

[ItsMeSamey]

Zig Version

0.14.0-dev.2615+a7a5f3506

Steps to Reproduce and Observed Behavior

run the following code on linux (as normal/unprivelaged user)

const std = @import("std");

pub fn makeOomUnkillable() !void {
  var file = try std.fs.cwd().openFileZ("/proc/self/oom_score_adj", .{ .mode = .write_only });
  defer file.close();
  try file.writeAll("-1000\n"); // Fails with errno = 13
}

pub fn main() !void {
  try makeOomUnkillable();
}

~/Projects/zig/auto_preempt ❯❯ zig run test.zig
unexpected errno: 13
/home/a/.local/lib/zig/std/debug.zig:198:31: 0x105338f in dumpCurrentStackTrace (test)
        writeCurrentStackTrace(stderr, debug_info, io.tty.detectConfig(io.getStdErr()), start_addr) catch |err| {
                              ^
/home/a/.local/lib/zig/std/posix.zig:7432:40: 0x105391e in unexpectedErrno (test)
        std.debug.dumpCurrentStackTrace(null);
                                       ^
/home/a/.local/lib/zig/std/posix.zig:1277:49: 0x105467e in write (test)
            else => |err| return unexpectedErrno(err),
                                                ^
/home/a/.local/lib/zig/std/fs/File.zig:1327:23: 0x103ae1a in write (test)
    return posix.write(self.handle, bytes);
                      ^
/home/a/.local/lib/zig/std/fs/File.zig:1333:32: 0x10387b9 in writeAll (test)
        index += try self.write(bytes[index..]);
                               ^
/home/a/Projects/zig/auto_preempt/test.zig:6:20: 0x103825e in makeOomUnkillable (test)
  try file.writeAll("-1000\n"); // Fails with Errno = 13
                   ^
/home/a/Projects/zig/auto_preempt/test.zig:10:24: 0x1038860 in main (test)
  try makeOomUnkillable();
                       ^
/home/a/.local/lib/zig/std/start.zig:656:37: 0x1038122 in posixCallMainAndExit (test)
            const result = root.main() catch |err| {
                                    ^
/home/a/.local/lib/zig/std/start.zig:271:5: 0x1037d0d in _start (test)
    asm volatile (switch (native_arch) {
    ^
???:?:?: 0x0 in ??? (???)
error: Unexpected
/home/a/.local/lib/zig/std/posix.zig:7434:5: 0x1053927 in unexpectedErrno (test)
    return error.Unexpected;
    ^
/home/a/.local/lib/zig/std/posix.zig:1277:27: 0x105468b in write (test)
            else => |err| return unexpectedErrno(err),
                          ^
/home/a/.local/lib/zig/std/fs/File.zig:1327:5: 0x103ae47 in write (test)
    return posix.write(self.handle, bytes);
    ^
/home/a/.local/lib/zig/std/fs/File.zig:1333:18: 0x10387e2 in writeAll (test)
        index += try self.write(bytes[index..]);
                 ^
/home/a/Projects/zig/auto_preempt/test.zig:6:3: 0x103827a in makeOomUnkillable (test)
  try file.writeAll("-1000\n"); // Fails with Errno = 13
  ^
/home/a/Projects/zig/auto_preempt/test.zig:10:3: 0x1038873 in main (test)
  try makeOomUnkillable();
  ^

Operating System: Arch Linux
Kernel: Linux 6.12.8-zen1-1-zen
Architecture: x86-64

Expected Behavior

program should exit with some sort of PermissionError or AccessDenied

[alexrp]

Looks like this just needs to be made into an expected error in std.posix.write().

[andrewrk]

Fixed in 744771d