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std.posix: remove unchecked std.os.linux usage
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Using std.os.linux directly in e.g. std.posix.timerfd_create() causes
the function to compile but silently fail at runtime when targeting any
OS other than Linux.

To catch errors like this at compile time, std.os.linux must only be
directly accessed within std.posix where there has been a comptime check
that the target os is in fact Linux.
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@ifreund
ifreund committed Jun 18, 2024
1 parent 7dc52a3 commit 5f2bdaf
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Showing 2 changed files with 47 additions and 32 deletions.
12 changes: 12 additions & 0 deletions lib/std/c/linux.zig
View file
Original file line number Diff line number Diff line change
Expand Up @@ -51,6 +51,7 @@ pub const Sigaction = linux.Sigaction;
pub const T = linux.T;
pub const TCP = linux.TCP;
pub const TCSA = linux.TCSA;
pub const TFD = linux.TFD;
pub const VDSO = linux.VDSO;
pub const W = linux.W;
pub const W_OK = linux.W_OK;
Expand All @@ -68,13 +69,15 @@ pub const fd_t = linux.fd_t;
pub const gid_t = linux.gid_t;
pub const ifreq = linux.ifreq;
pub const ino_t = linux.ino_t;
pub const itimerspec = linux.itimerspec;
pub const mcontext_t = linux.mcontext_t;
pub const mode_t = linux.mode_t;
pub const msghdr = linux.msghdr;
pub const msghdr_const = linux.msghdr_const;
pub const nfds_t = linux.nfds_t;
pub const nlink_t = linux.nlink_t;
pub const off_t = linux.off_t;
pub const perf_event_attr = linux.perf_event_attr;
pub const pid_t = linux.pid_t;
pub const pollfd = linux.pollfd;
pub const rlim_t = linux.rlim_t;
Expand Down Expand Up @@ -344,3 +347,12 @@ pub const dirent64 = extern struct {
type: u8,
name: [256]u8,
};

pub extern "c" fn timerfd_create(clockid: c_int, flags: c_int) c_int;
pub extern "c" fn timerfd_settime(
fd: c_int,
flags: c_int,
new_value: *const itimerspec,
old_value: ?*itimerspec,
) c_int;
pub extern "c" fn timerfd_gettime(fd: c_int, curr_value: *itimerspec) c_int;
67 changes: 35 additions & 32 deletions lib/std/posix.zig
View file
Original file line number Diff line number Diff line change
Expand Up @@ -3968,7 +3968,7 @@ pub const EpollCtlError = error{
FileDescriptorIncompatibleWithEpoll,
} || UnexpectedError;

pub fn epoll_ctl(epfd: i32, op: u32, fd: i32, event: ?*linux.epoll_event) EpollCtlError!void {
pub fn epoll_ctl(epfd: i32, op: u32, fd: i32, event: ?*system.epoll_event) EpollCtlError!void {
const rc = system.epoll_ctl(epfd, op, fd, event);
switch (errno(rc)) {
.SUCCESS => return,
Expand All @@ -3988,7 +3988,7 @@ pub fn epoll_ctl(epfd: i32, op: u32, fd: i32, event: ?*linux.epoll_event) EpollC
/// Waits for an I/O event on an epoll file descriptor.
/// Returns the number of file descriptors ready for the requested I/O,
/// or zero if no file descriptor became ready during the requested timeout milliseconds.
pub fn epoll_wait(epfd: i32, events: []linux.epoll_event, timeout: i32) usize {
pub fn epoll_wait(epfd: i32, events: []system.epoll_event, timeout: i32) usize {
while (true) {
// TODO get rid of the @intCast
const rc = system.epoll_wait(epfd, events.ptr, @intCast(events.len), timeout);
Expand Down Expand Up @@ -7142,32 +7142,35 @@ pub const PerfEventOpenError = error{
} || UnexpectedError;

pub fn perf_event_open(
attr: *linux.perf_event_attr,
attr: *system.perf_event_attr,
pid: pid_t,
cpu: i32,
group_fd: fd_t,
flags: usize,
) PerfEventOpenError!fd_t {
const rc = linux.perf_event_open(attr, pid, cpu, group_fd, flags);
switch (errno(rc)) {
.SUCCESS => return @intCast(rc),
.@"2BIG" => return error.TooBig,
.ACCES => return error.PermissionDenied,
.BADF => unreachable, // group_fd file descriptor is not valid.
.BUSY => return error.DeviceBusy,
.FAULT => unreachable, // Segmentation fault.
.INVAL => unreachable, // Bad attr settings.
.INTR => unreachable, // Mixed perf and ftrace handling for a uprobe.
.MFILE => return error.ProcessResources,
.NODEV => return error.EventRequiresUnsupportedCpuFeature,
.NOENT => unreachable, // Invalid type setting.
.NOSPC => return error.TooManyBreakpoints,
.NOSYS => return error.SampleStackNotSupported,
.OPNOTSUPP => return error.EventNotSupported,
.OVERFLOW => return error.SampleMaxStackOverflow,
.PERM => return error.PermissionDenied,
.SRCH => return error.ProcessNotFound,
else => |err| return unexpectedErrno(err),
if (native_os == .linux) {
// There is no syscall wrapper for this function exposed by libcs
const rc = linux.perf_event_open(attr, pid, cpu, group_fd, flags);
switch (errno(rc)) {
.SUCCESS => return @intCast(rc),
.@"2BIG" => return error.TooBig,
.ACCES => return error.PermissionDenied,
.BADF => unreachable, // group_fd file descriptor is not valid.
.BUSY => return error.DeviceBusy,
.FAULT => unreachable, // Segmentation fault.
.INVAL => unreachable, // Bad attr settings.
.INTR => unreachable, // Mixed perf and ftrace handling for a uprobe.
.MFILE => return error.ProcessResources,
.NODEV => return error.EventRequiresUnsupportedCpuFeature,
.NOENT => unreachable, // Invalid type setting.
.NOSPC => return error.TooManyBreakpoints,
.NOSYS => return error.SampleStackNotSupported,
.OPNOTSUPP => return error.EventNotSupported,
.OVERFLOW => return error.SampleMaxStackOverflow,
.PERM => return error.PermissionDenied,
.SRCH => return error.ProcessNotFound,
else => |err| return unexpectedErrno(err),
}
}
}

Expand All @@ -7182,8 +7185,8 @@ pub const TimerFdCreateError = error{
pub const TimerFdGetError = error{InvalidHandle} || UnexpectedError;
pub const TimerFdSetError = TimerFdGetError || error{Canceled};

pub fn timerfd_create(clokid: i32, flags: linux.TFD) TimerFdCreateError!fd_t {
const rc = linux.timerfd_create(clokid, flags);
pub fn timerfd_create(clokid: i32, flags: system.TFD) TimerFdCreateError!fd_t {
const rc = system.timerfd_create(clokid, @bitCast(flags));
return switch (errno(rc)) {
.SUCCESS => @intCast(rc),
.INVAL => unreachable,
Expand All @@ -7198,11 +7201,11 @@ pub fn timerfd_create(clokid: i32, flags: linux.TFD) TimerFdCreateError!fd_t {

pub fn timerfd_settime(
fd: i32,
flags: linux.TFD.TIMER,
new_value: *const linux.itimerspec,
old_value: ?*linux.itimerspec,
flags: system.TFD.TIMER,
new_value: *const system.itimerspec,
old_value: ?*system.itimerspec,
) TimerFdSetError!void {
const rc = linux.timerfd_settime(fd, flags, new_value, old_value);
const rc = system.timerfd_settime(fd, @bitCast(flags), new_value, old_value);
return switch (errno(rc)) {
.SUCCESS => {},
.BADF => error.InvalidHandle,
Expand All @@ -7213,9 +7216,9 @@ pub fn timerfd_settime(
};
}

pub fn timerfd_gettime(fd: i32) TimerFdGetError!linux.itimerspec {
var curr_value: linux.itimerspec = undefined;
const rc = linux.timerfd_gettime(fd, &curr_value);
pub fn timerfd_gettime(fd: i32) TimerFdGetError!system.itimerspec {
var curr_value: system.itimerspec = undefined;
const rc = system.timerfd_gettime(fd, &curr_value);
return switch (errno(rc)) {
.SUCCESS => return curr_value,
.BADF => error.InvalidHandle,
Expand Down

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