diff --git a/lib/std/os/linux.zig b/lib/std/os/linux.zig index 11add50a05..df46a18cf7 100644 --- a/lib/std/os/linux.zig +++ b/lib/std/os/linux.zig @@ -1,10 +1,8 @@ //! This file provides the system interface functions for Linux matching those //! that are provided by libc, whether or not libc is linked. The following //! abstractions are made: -//! * Work around kernel bugs and limitations. For example, see sendmmsg. //! * Implement all the syscalls in the same way that libc functions will //! provide `rename` when only the `renameat` syscall exists. -//! * Does not support POSIX thread cancellation. const std = @import("../std.zig"); const builtin = @import("builtin"); const assert = std.debug.assert; @@ -1836,7 +1834,7 @@ pub fn seteuid(euid: uid_t) usize { // id will not be changed. Since uid_t is unsigned, this wraps around to the // max value in C. comptime assert(@typeInfo(uid_t) == .int and @typeInfo(uid_t).int.signedness == .unsigned); - return setresuid(std.math.maxInt(uid_t), euid, std.math.maxInt(uid_t)); + return setresuid(maxInt(uid_t), euid, maxInt(uid_t)); } pub fn setegid(egid: gid_t) usize { @@ -1847,7 +1845,7 @@ pub fn setegid(egid: gid_t) usize { // id will not be changed. Since gid_t is unsigned, this wraps around to the // max value in C. comptime assert(@typeInfo(uid_t) == .int and @typeInfo(uid_t).int.signedness == .unsigned); - return setresgid(std.math.maxInt(gid_t), egid, std.math.maxInt(gid_t)); + return setresgid(maxInt(gid_t), egid, maxInt(gid_t)); } pub fn getresuid(ruid: *uid_t, euid: *uid_t, suid: *uid_t) usize { @@ -2081,44 +2079,13 @@ pub fn sendmsg(fd: i32, msg: *const msghdr_const, flags: u32) usize { } } +/// Warning: libc is defined to have incompatible integer types with the +/// corresponding kernel data structures for this syscall. +/// +/// Warning: on 64-bit systems, if any message length would exceed `maxInt(i32)`, +/// number of bytes sent cannot be determined, because the kernel uses `ssize_t` +/// for `sendmsg` return value but `int` for the corresponding values here. pub fn sendmmsg(fd: i32, msgvec: [*]mmsghdr_const, vlen: u32, flags: u32) usize { - if (@typeInfo(usize).int.bits > @typeInfo(@typeInfo(mmsghdr).@"struct".fields[1].type).int.bits) { - // workaround kernel brokenness: - // if adding up all iov_len overflows a i32 then split into multiple calls - // see https://www.openwall.com/lists/musl/2014/06/07/5 - const kvlen = if (vlen > IOV_MAX) IOV_MAX else vlen; // matches kernel - var next_unsent: usize = 0; - for (msgvec[0..kvlen], 0..) |*msg, i| { - var size: i32 = 0; - const msg_iovlen = @as(usize, @intCast(msg.hdr.iovlen)); // kernel side this is treated as unsigned - for (msg.hdr.iov[0..msg_iovlen]) |iov| { - if (iov.len > std.math.maxInt(i32) or @addWithOverflow(size, @as(i32, @intCast(iov.len)))[1] != 0) { - // batch-send all messages up to the current message - if (next_unsent < i) { - const batch_size = i - next_unsent; - const r = syscall4(.sendmmsg, @as(usize, @bitCast(@as(isize, fd))), @intFromPtr(&msgvec[next_unsent]), batch_size, flags); - if (E.init(r) != .SUCCESS) return next_unsent; - if (r < batch_size) return next_unsent + r; - } - // send current message as own packet - const r = sendmsg(fd, &msg.hdr, flags); - if (E.init(r) != .SUCCESS) return r; - // Linux limits the total bytes sent by sendmsg to INT_MAX, so this cast is safe. - msg.len = @as(u32, @intCast(r)); - next_unsent = i + 1; - break; - } - size += @intCast(iov.len); - } - } - if (next_unsent < kvlen or next_unsent == 0) { // want to make sure at least one syscall occurs (e.g. to trigger MSG.EOR) - const batch_size = kvlen - next_unsent; - const r = syscall4(.sendmmsg, @as(usize, @bitCast(@as(isize, fd))), @intFromPtr(&msgvec[next_unsent]), batch_size, flags); - if (E.init(r) != .SUCCESS) return r; - return next_unsent + r; - } - return kvlen; - } return syscall4(.sendmmsg, @as(usize, @bitCast(@as(isize, fd))), @intFromPtr(msgvec), vlen, flags); } @@ -8700,7 +8667,7 @@ pub const PR = enum(i32) { pub const SET_MM_MAP = 14; pub const SET_MM_MAP_SIZE = 15; - pub const SET_PTRACER_ANY = std.math.maxInt(c_ulong); + pub const SET_PTRACER_ANY = maxInt(c_ulong); pub const FP_MODE_FR = 1 << 0; pub const FP_MODE_FRE = 1 << 1;